Abstract
Trees and forests often feature as solutions to environmental crises, thereby encouraging tree planting projects. This article considers how “trillion trees” projects operationalize trees and forests as productive entities for addressing planetary crises. The research asks: How do trees and forests operate through distinct technicities, or technical relations and processes, for mitigating environmental change? What values, benefits, and inequalities does the mobilization of forests-as-technologies generate? How might forests and technologies be transformed toward more equitable environmental relations and practices, especially in a time of proliferating climate technologies? To answer these questions, this text discursively analyzes Crowther Lab research, which proposed trillion tree metrics to inform restoration opportunities worldwide. While these speculative metrics, in turn, supported tree-planting and restoration projects, including the Plant-for-the-Planet Trillion Trees initiative, trees and forests materialized in these situated projects less as carbon removal machinery and more as ongoing practices of communities planting, monitoring, and maintaining environments. This discussion suggests that a more deliberate encounter with forests as technologies could transform social-ecological relations by examining how trees and forests activate and are activated within expressions of technicity. In this way, “forests as technologies” could offer a counterintuitive strategy for cultivating and crafting more equitable and just forest worlds.
Introduction
In their role as carbon absorbers, trees and forests frequently feature not just as vegetation but also as technologies. “This Machine Kills CO2,” the title of The Guardian's 4 July 2019 weekly edition, reinforces this image. 1 Reporting on Bastin et al.'s 2019 study on the potential for planetary forest restoration, the edition delivers “a rare spot of good news,” noting how planting one trillion trees could tackle the climate crisis (Dean 2019; Carrington 2019). The proposal to cultivate trillions of trees demonstrates how tree planting continues to be a favored response to planetary crises while bringing into focus research and initiatives that would develop technology at speed and scale to address climate change. Tree planting has been a long-standing environmental action to improve and restore environments (Maathai 2006). While often carried out as a local and grassroots activity (Bäckstrand and Lövbrand 2006), it has also been operationalized at an industrial scale by NGOs and governments in an attempt to stave off catastrophic climate change (Fleischman et al. 2020). There are initiatives to plant trees in the millions and billions, further scaling to “trillion tree” campaigns (Pearce 2021; St. George 2022). At the same time, many researchers have drawn attention to the uneven effects of tree-planting programs, suggesting that they often do not realize sustained forest development and can create damaging effects on communities and environments (Holl and Brancalion 2020; Martin et al. 2021).
The narration of trees and forests as “machines” points to the role of technological thinking in composing and addressing the problem of environmental change. In restoration projects, trees and forests do not just intersect with technology; they also operate as technologies. This article considers how “trillion trees” research and initiatives identify and operationalize trees and forests as productive entities for aiding restoration projects and addressing planetary crises. The research asks: How do trees and forests operate through distinct technicities, or social-ecological technical relations, for mitigating environmental change? What values, benefits, and inequalities does the mobilization of forests-as-technologies generate? How might forests and technologies be transformed toward more equitable environmental relations and practices, especially in a time of proliferating climate technologies? To answer these questions, this article is organized into four subsequent sections. The following section considers research in science and technology studies and the history and philosophy of science that investigates the concept and framing of organismal entities “as technologies.” From cells to life and potatoes to trees, there is no shortage of entities that have been subtended into technological operations. Through a theoretical engagement with the mutable designations and operations of technologies and forests, this section considers how the “as technology” analytic could be expanded by building on Simondon's concept of technicity ([1958] 2017). For Simondon, technicity is the ongoing and transformative process through which technology “informs” humans and environments in reciprocal exchange. While technicity designates the relatively autonomous development and concretization of technologies, this is not a one-way process, since technologies and social-ecological milieus are co-constituted and mutually altered within technical ensembles. By extending technicity to trees and forests, it is possible to see how they both activate and are activated within technical relations across machines, organisms, milieus, social worlds, and economies. Here, trees and forests are less metaphorical machines; instead, they take shape as technical actors and relations through distributions of energy, information, and capital. Rather than espouse a perceived binary across nature and technology, or work through the social construction of nature, I examine how technical relations compose trees and forests as distinct productive entities and milieus. In this sense, forests transform to operate as particular kinds of technologies for absorbing CO2 in the context of climate change.
In the second section of this article, I examine a specific scientific debate about tree planting and forest restoration that grew out of research by the Crowther Lab and collaborators at the ETH in Zurich, Switzerland. Taking the form of two highly cited and debated articles, the Crowther Lab research first sought to estimate the number of trees on Earth and, in a subsequent study, proposed expanding tree numbers to address deforestation and facilitate restoration efforts. By discursively examining these scientific articles, along with subsequent academic responses, social media, and press materials, I consider how this indexical and speculative research at turns activates trees and forests as particular kinds of technologized entities and milieus for restoring tree cover, primarily to store carbon. The two research articles used digital technology in the form of machine learning, photointerpretation, satellite image datasets, spatial analysis, and models to estimate and propose tree numbers (Crowther et al. 2015; Bastin et al. 2019), which created a calculative and expansionist approach to the maximization of tree cover. In this sense, the research also contributed to the intensification of tree-planting campaigns and projects focused on the numbers of trees planted or pledged, analyzed, and amplified through digital tools and platforms.
Because the Crowther Lab metrics have contributed to tree planting and restoration projects, including the Plant-for-the-Planet Trillion Trees initiative, the third section of this article then considers how billion and trillion tree campaigns attempt to build on the more speculative Crowther Lab research, including how they mobilize trees and forests as—and through—technologies. Through a scan of restoration and reforestation research, news reports, social media posts, policy proposals, and environmental NGO projects, I examine how such initiatives advocate for reforestation and afforestation and, in the process, constitute trees and forests as technologies that would provide a range of solutions and services, primarily in the form of carbon storage. However, within some situated tree-planting projects such as Plant-for-the-Planet, trees and forests begin to materialize less as carbon removal machinery and more as ongoing projects of communities planting, monitoring, and maintaining forest environments. Technical and technological aspects of environmental engagement are not missing from these endeavors but instead are differently configured. Across these research and restoration initiatives, trees and forests are operationalized as technologies through extensive digital infrastructures. Tree-planting initiatives and proposals rely on modeling, machine learning, AI, remote sensing, digital platforms and apps, automated planting devices, drones, and many other digital infrastructures and tools to research, identify, and implement planting schemes and augment carbon storage. Distinct technical formations of trees and forests as technologies materialize along with digital techniques to identify, model, augment, and implement these entities as nature-based solutions and ecosystem services. In other words, digital technologies enable and amplify distinct forms of eco-technicity.
Based on this discursive and inductive examination of tree planting and forest restoration research and projects, I return to the “forests as technology” concept in the final sections of this article to consider how forests and technologies are constituted and mobilized to mitigate climate change. By analyzing and expanding on forests-as-technologies developments, this article rethinks the designations of forests and technologies in a time of planetary crisis. Bringing science and technology studies into conversation with political ecology, my analysis questions how forests and technologies cohere as distinct tools, functions, methods, processes, and networks for addressing environmental change. While this research could offer a familiar critique of the technical fix, I instead consider how an analysis of the technicity of forest research and projects plots a course for reworking technical relations. Forests and technologies can be configured in a multiplicity of ways. They can replicate an extractive and accumulative approach to environments that persists through some restoration economies, where communities are dispossessed of lands that become carbon-offset empires, in what has been referred to as “carbon colonialism” or “green grabbing” (Lyons and Westoby 2014; Fairhead, Leach and Scoones 2012). Or they can articulate eco-technical relations that create and support more flourishing milieus. This article suggests that in the context of planetary environmental change and increasing “climate tech” developments, it is necessary to engage with the technicities of environmental projects as they attempt to generate social, economic, and ecological value. The co-constitution of environments and technologies generates distinct technical processes, social-ecological worlds, and political possibilities—from the actors and actions mobilized to the relations and modes of governance implemented. This discussion proposes that a more deliberate encounter with forests as technologies could transform the technologization of forests while providing tools for analyzing the technicities and milieus that materialize through attempts to address planetary crises. In this way, “forests as technologies” could offer a counterintuitive strategy for cultivating and crafting more equitable and just forest worlds (Longdon et al. 2024; Pritchard et al. 2022).
Forests as Technologies
If you take a preliminary scan through the literature that advances the conceptual framing of different entities “as technology,” you will find an extensive range of investigations. Cells, potatoes, ducks, biology, trees, plants, and more have entered into technological designations (e.g., Rabinow 2011; Berry 2018; Riskin 2016; Keller 2009; Gardner 2009). Broader social-cultural organizations and designations also unfold through an “as technology” heuristic, including ecosystem services, race, spirits, and life, among many others (e.g., Bubandt 2019; Coleman 2009; Ernstson and Sörlin 2013; Kay 2000). By comparing an entity to technology and noting how it acquires or performs technical functions, an inversion or conversion would seem to occur: This is not an entity or condition that would ordinarily or self-evidently be understood as a technology. Or it is an entity that has been naturalized, such that an “as technology” analytic can draw attention to the constitution and operation of how complex sociopolitical and cultural matters have been made into routine functions. It also can be a way to configure organisms as machinic (Riskin 2016). At first glance, an “as technology” comparison is seemingly aligned with machines and mechanization, where “natural” entities transform into mechanized ones and register within a logic of machinic regularity and functioning (Canguilhem 2008). In a different but related way, information technologies have become figurative devices for understanding cellular life as the search and storage of information (Kay 2000) or ecosystems as the flow and exchange of information across entities (Worster 1994). Life and ecosystems are not just described as technologies but, more specifically, as computational ones. In this sense, technical modalities and effects take hold at particular historical, social, and political moments.
However, it soon becomes clear that which counts as technological can be even more mutable, pluralistic, situated, and contested. When entities are parsed through an “as technology” analysis, they can take shape through expressions of function, productivity, efficiency, innovation, or profitability, among other conditions that might come to count as technological at any given time. Scholars have drawn attention to how technologies are expressive of social values, ranging from development as economic advancement (Mavhunga 2017) to techno-natural innovation (Biagioli and Buning 2019). In these analyses, an entity becomes a technology by expressing distinct attributes that count as technological. For instance, an entity can be modified to become patentable, embodying technological values and markers of innovation (Biagioli and Buning 2019). At the same time, well established within science and technology studies of literature is the assertion that technologies are not just gadgets or self-contained tools but also practices, institutions, networks, protocols, and distributed social-political relations (De Laet and Mol 2000; Haraway 1991; Latour 2013). Technologies can be “fluid,” taking hold or changing according to variable conditions of functionality and effectiveness while activating different formations of agency and use based on social practices (De Laet and Mol 2000, 227). As these works demonstrate, the objectives, commitments, values, functions, relations, and processes of technologies are frequently up for debate and under scrutiny.
An “as technology” analysis could assume the technologizing process is one of making entities conform to a limited technical agenda. However, from within this more fluid or distributed understanding, the “as technology” analytic directs attention to how entities, relations, actors, and dynamics contribute to making technological ensembles and milieus (Gabrys 2016; Mackenzie 2005; Simondon 2017). What Simondon refers to as “technicity” is at once these broader conditions informing the development and operation of technologies, as well as their interactions across persons, environments, and other entities. More than a description of the functionality of tools, technicity refers to the remaking of ways of life, including sensation, experience, and inhabitation, which show how technologies are in continual exchange with living environments. In one clear discussion of technicity and the technological reshaping of people and environments, Simondon (2015) described how agriculture and husbandry create cultivation practices that transform people, environments, and the entities cultivated, thereby creating ongoing relations of interdependence. While on the one hand, Simondon might seem to draw a line between a plow and a potato in these analyses of technicity, on the other hand, he demonstrates how some organisms could not survive without the technical relations through which they have concretized and on which they depend. Technology, in this sense, delineates not just productive operations or devices but also the modification of people, entities, environments, and their relations that have created distinct technical milieus.
A forest is often assumed to have a pre-technological state and become a technology within demarcations of territory and resource extraction, ecosystem services and biodiversity analyses, and climate change calculations of carbon storage. However, as many researchers have demonstrated, rather than existing in a natural or pre-technological state, forests are always already social, political, and technological projects (Peluso and Vandergeest 2020; Chazdon et al. 2016; Devine and Baca 2020). They have been developed as colonial technologies by capturing and cultivating land through land rights and land use, often for timber production to serve imperial centers (Braun 2002; Peluso and Vandergeest 2001; Prudham 2005). They are also sites of neocolonial technologies, including carbon storage and offsets, where vast swathes of land are purchased or organized by often privileged yet remote actors to mitigate carbon emissions (Asiyanbi, Ogar, and Akintoye 2019; Lyons and Westoby 2014). Carbon capture practices of these sorts are often called “negative emissions technologies” (Carton et al. 2020), where trees and forests become productive and mitigating entities in the service of fossil-fueled economies.
Whether carbon machines or restoration machines, the machinic designation of trees and forests poses a question about how vegetal organisms could perform technical projects. In addition to operating as climate technologies for diagnosing and fixing planetary crises, forests have been mobilized as technological spaces of conservation, production, and extraction. The uneven development of forests as plantations and state territories (Peluso and Vandergeest 2020; Li and Pujo 2021), resources and carbon markets (Andersson and Westholm 2019; Ehrenstein 2018, 2025), and sites for agroforestry and Indigenous livelihoods (Reo et al. 2017; Tsing 2015), shows how designations of forests are differently configured, valued, and operationalized as technologies. Digitalization has further contributed to optimizing trees and forests as productive and functional entities for addressing—and even profiting from—environmental change. Equipped with digital technologies, forests are increasingly monitored with and managed by satellites and sensors, lidar and robots, data dashboards, and civic apps (Gabrys 2020; Nitoslawski et al. 2021; Vurdubakis and Rajão 2020). Different expressions of forests and technologies materialize through these projects, since forests are not simply self-evident entities performing productive functions (Chazdon et al. 2016; Latour 1999), but rather are environments that take shape in relation to social, political, economic, ecological, and technical forces.
Trees and forests are monitored by technologies, and they also become technologies that absorb carbon, filter air, absorb stormwater, mitigate heat, and enhance biodiversity. Prior research has analyzed forests as technological commodities in the context of forestry and timber (Braun 2002; Demeritt 2001), where forests become “organic machines” through the capitalization of “biological time” to produce natural resources (Prudham 2005). By comparison, the mobilization of forests in the broader context of restoration economies and emerging climate technologies presents a configuration distinct from timber production. Forests become proxies and probes, carbon scrubbers, and climate mitigators. Trees act as atmospheric pumps, removing carbon and returning oxygen like an air purifier. Trees and forests materialize as climate technologies across research labs and field sites, policy documents and market incentives, international accords, and community planting plans. They are made into tools, green infrastructures, and systems to be optimized and planted in response to environmental change. The mobilization of trees and forests as carbon-capture and “negative emission” technologies is a common theme within environmental development projects (Carton et al. 2020), where the aspiration to create climate-fixing technologies constitutes trees and forests as technological operators and operations. Many reforestation and carbon-capture projects mobilize forests and trees as devices to manage planetary crises by absorbing carbon and slowing the rate of global temperature rise. This is the schema of nature-based solutions and related approaches, such as ecosystem services, which configure forested environments as productive entities and processes in response to planetary crises (Woroniecki et al. 2020).
In this way, trees and forests are operationalized through ecosystem services and nature-based solutions proposals and projects, which would organize vegetation as a useful and profitable remedy to environment-destroying practices elsewhere. Preventing deforestation through initiatives such as REDD + further delineates and incorporates trees and forests as function-full entities that can yield value through conservation practices and systems focused primarily on vegetation's carbon-saving capacities (Mathews 2014; Nel 2017). Extensive research has analyzed how neoliberal economies profit from environments in crisis, including through conservation projects to save nature (Büscher et al. 2012; Sullivan 2013). These studies helpfully point to the depoliticizing role that technology and technological innovation can have in nature-saving projects. However, within these analyses technology is often flattened into a tool serving capitalist innovation. This article reconsiders how technology can be diversely constituted and operationalized, where the very composition of forests unfolds through and as multiple projects of technicity.
With the increasing digitalization of environments, it is common for forests to be offered as a remedy and retreat from technology, where encounters with unmediated nature can occur, despite long-standing work that problematizes this approach (cf. Baldwin 2004). Nature-based solutions would seem to be continuous with this logic, where environments are meant to naturally solve the problem of climate change, however manufactured this framing may be (Osaka, Bellamy and Castree 2021; Woroniecki et al. 2020). In this sense, it is important to remember that forests have never been natural (Peluso and Vandergeest 2001; Devine and Baca 2020). Politics, power, capital—and technicities—play a central role in the designation and cultivation of forests. Many tree-planting projects take the form of plantations, even more than forests. Moreover, plantations in the form of oil palm often contribute to some of the highest levels of deforestation worldwide. This is a dynamic where, as Li and Pujo (2021, vii) note, a plantation is a “giant” and a “machine” of vegetal development. In other words: a plantation is a machine that assembles land, labor, and capital in huge quantities to produce monocrops for a world market. It is intrinsically colonial, based on the assumption that the people on the spot are incapable of efficient production. It takes life under control: space, time, flora, fauna, water, chemicals, people. It is owned by a corporation and run by managers along bureaucratic lines.
Similarly, when forests operate as technologies of mitigation and restoration within the broader politics of climate change, these environments concretize as distinct expressions of technicity. Technicity involves the ongoing transformation of technologies and environments in ways that also reflect and inform power dynamics and social (in)justice. Forests can be reduced to singular operations of carbon absorption and climate mitigation within power-laden processes that reinforce and exacerbate inequities. In other words, the “as technology” analytic involves attending not just to the machinic or functional constitution of entities but also to the ongoing wrangling over which techniques and technicities are most valued and prevalent in forming forest worlds. Such an approach is aligned with feminist and anti-colonial technoscience research, which examines and questions the power dynamics that take hold or are contested within technological formations (Philip, Irani, and Dourish 2012; Pollock and Subramaniam 2016; Subramaniam et al. 2017). The next sections put the concept of technicity to work to examine how tree planting and restoration efforts mobilize forests as distinct technologies, and what values, benefits, and inequalities this creates. The below sections further consider how the “as technology” analytic can offer a more pluralistic and equitable approach to these processes since technologies and technicity are increasingly oriented toward optimization, productivity, extraction, and efficiency at the expense of ongoing and diverse forest livelihoods.
Trees and forests are mobilized and cultivated as particular technical entities, relations, and milieus in the context of restoration projects and climate change. Rather than engaging with forests as a pre-technological entity to which technologies are added, the “as technology” concept underscores the importance of examining how forest worlds are continually made and remade through technical relations and processes. An analysis of forests as technologies draws attention to their formation as practices, procedures, methods, effects, entities, and relations whereby environmental change would be addressed. This approach points to the importance of identifying the designations of forests and technology, their co-constitution, and their effects since these processes and practices contribute to forming, cultivating, and continuing forest worlds—and power dynamics (Gabrys et al. 2022). Even more than putting technologies in a social context or showing how technology is socially constructed, a technicity-led approach to forests as technologies shows how distinct environments and worlds concretize, which further informs the possibilities for cultural, social, political, and economic benefits—and inequalities—since technical arrangements of forests have effects far beyond an individual machinic designation.
Counting All the Trees on Earth
Tree-planting projects have been pervasive in reforesting, regenerating, and reclaiming environments (Fleischman et al. 2020; Maathai 2007). Research has considered how tree planting as a “civic” initiative can animate and activate democratic engagement in environmental issues (Bäckstrand and Lövbrand 2006). However, the scale and extent of many tree-planting proposals can exceed civic projects to encompass more expansive endeavors that, in some cases, expand to industrial-scale monocrops and carbon plantations (Holl and Brancalion 2020; Martin et al. 2021). As is well known by now, the IPCC (2018; 2023) has consistently identified tree planting as a central component of carbon storage and mitigation. Alongside IPCC recommendations, multiple policy programs and environmental initiatives have pledged to plant trees in the billions to counteract the effects of deforestation and improve carbon storage. The Bonn Challenge has been one of the primary projects through which tree-planting pledges have been made, with up to 300 billion trees pledged to be planted on 350 million hectares of land by 2030 (Dave et al. 2017; IUCN 2011). As discussed below, Crowther et al. (2015) and Bastin et al. (2019) cite both IPCC (2018) recommendations and tree-planting initiatives such as Bonn as context and influence for their research into identifying how many trees the Earth could sustain and as a central climate mitigation strategy. Tree planting, reforestation, and restoration are thus mutually implicated and influential in advancing research, policies, and projects. Here, trees and forests are the tools, technological processes, and modes of operation for calculating and planting a planetary fix.
In the context of ongoing tree-planting campaigns, policies, and pledges that have promised to plant trees in the billions and trillions, ecologist Thomas Crowther has been credited with further catalyzing planting efforts with research to estimate the total number of trees worldwide. As the story is usually told, the spark for his initial investigation began when, in 2012, “a German high school student, Felix Finkbeiner, emailed Crowther's roommate with a question: How many trees are on Earth?” (Popkin 2019). Crowther was a postdoc at Yale University, and his roommate was a founding member of Plant-for-the-Planet, along with Finkbeiner. Crowther was sufficiently intrigued by the question to begin collecting extensive forest measurement data from governments and other researchers to estimate tree density and numbers worldwide.
Three years later, Crowther and co-authors published their investigation results in a 2015 Nature article. Articulating the significance of their research, they underscore how forests are useful and functional ecosystems that make various contributions, including biodiversity, water control, carbon sequestration, timber, and more. The number of trees on Earth was the headline finding, with the authors estimating there were approximately 3 trillion trees worldwide. Current numbers had declined from approximately 6 trillion total trees at the end of the Pleistocene Era, approximately 11,700 years ago when the end of the last ice age enabled more widespread agricultural land use (Crowther et al. 2015). The 3 trillion trees calculation was significantly higher than previous estimates of approximately 400.25 billion trees on Earth (Crowther et al. 2015; Nadkarni 2008).
To arrive at the estimated total number of trees in the world, the research group combined extensive and disparate datasets from multiple sources, especially forest inventory datasets. The authors write, “We use 429,775 ground-sourced measurements of tree density from every continent on Earth except Antarctica to generate a global map of forest trees” (Crowther et al. 2015, 201). The researchers applied predictive regression models to forested areas, bringing together tree density data with “spatially explicit remote sensing and geographic information systems (GIS) layers of climate, topography, vegetation characteristics, and anthropogenic land use” (Crowther et al. 2015, 201). To be counted as a tree, a plant had to have a woody stem larger than 10 cm in diameter at breast height (DBH), which is the standard designation of a tree in the majority of datasets (Crowther et al. 2015, 201). With the aid of digital tools and techniques for merging datasets and extrapolating to a planetary estimate, the authors identified a significantly larger number of trees worldwide, both in terms of those currently existing and the likely loss of forest cover.
The 3 trillion trees number was significant for its size and scope as a planetary metric. Tree numbers and density estimates took the form of a stock-taking exercise, where an itemized inventory doubled as a tool for assessing the robustness and contribution of forests. This is a valuation practice that not only takes account (McAfee 1999) but also operationalizes trees and forests for their ability to mitigate carbon emissions and curtail biodiversity loss. Enumeration becomes central to the expression and articulation of technicity, where taking into account is a way to isolate, emphasize, and/or activate enumerated entities within technical milieus (cf. Asdal 2008; Nafus 2014). Through digital calculation practices, trees and forests become newly productive units and resources for mitigating climate change. Numbers can be a “generative device,” as Verran (2012) suggests when discussing Constanza et al.'s (1997) earlier work on natural capital and ecosystem services, which established another iconic number for nature valuation. Taking this number-making exercise to task, Verran demonstrates the work that numbers do to express values, make worlds, and grapple with living and contingent environmental conditions (cf. Lippert and Verran 2018). Numbers enable distinct political possibilities while foreclosing others. In a related way, numbers such as the 3 trillion trees metric are not just expressions of value; they are also ways of ordering and making worlds as tree-planting projects for mitigating ongoing environmental destruction. The 3 trillion metric, in terms that resonate with Porter (2009, 399), makes social-ecological realities through standardizing and counting. However, while the 3 trillion trees calculation reveals a greater abundance of trees than previously suggested and provides a roadmap for augmenting existing tree numbers, it also potentially obscures broader ecological populations, their complexity and diversity, and human and more-than-human participants, which contribute to forest environments (cf. Veldman et al. 2019). While the 3 trillion trees number is a generative device for making and ordering worlds, it is also a technical device for operationalizing and concretizing technological practices and relations.
“A Meaningful Metric”
Estimating the number of trees on Earth, as Crowther and co-authors (2015, 201) asserted, can be a way to produce “a meaningful metric to guide forest management practices and inform decision-making in public and non-governmental sectors.” In other words, the metric helps to mobilize broader technical milieus and practices. Estimates of tree numbers can serve as seemingly neutral evidence and a straightforward goal to support environmental projects. This is the power of numbers: to be seemingly self-evident (Verran 2012; Porter 1994; 2009). As countable and calculable entities, trees gain significance as productive units. Their numbers inform planting and climate targets for governments, NGOs, and industry. Quantified trees are ready attractors for funding, both within academia and environmental organizations. Yet numbers, as many science and technology researchers have demonstrated, are never “simple facts” (Lippert 2016, 6). Measurement is as much an expression of social as numerical value (Turnhout, Neves, and Lijster 2014), and in this sense involves more than quantifying entities, since to calculate is to indicate what counts and how (Porter 2009). Environmental metrics are performative, shaping both environments and governance and, in the process, reinscribing power structures (Cusworth et al. 2023; Stanley 2024). They are also speculative, and as tools for managing uncertainty can give rise to unanticipated forms of action and agency (Jensen and Venot 2023). In this way, converting forests into a trillion-scale metric generates distinct and potentially unforeseen ecologies, economies, and technicities.
Tree numbers can validate—and propel—tree-planting initiatives, such as the “Billion Trees Campaign” and “Million Tree” projects that Crowther et al. refer to in their text, which I discuss in more detail below. In a 2018 interview with Crowther and Finkbeiner, the pair discuss how they began to collaborate through the 2015 planetary tree-counting investigation, with Finkbeiner identifying more ambitious targets for tree planting and Crowther realizing the potential to put science in action through implementing research findings for impact (Goymer 2018). To support his wider research, in 2017 Crowther received a generous two-part award of USD2.7 million and USD15 million from DOB Ecology to fund his lab at ETH (Popkin 2019), and Finkbeiner subsequently became a PhD student in Crowther's Lab at ETH (Goymer 2018). The 3 trillion trees metric formed a political economy as much as ecology, not just for quantifying forests but also for attracting funding through grand calculative exercises continuous with green growth.
Alongside these developments and following the 2015 investigation, Crowther's Lab began to question whether country-level reforestation pledges were credible based on land available for planting (Mooney et al. 2021). In line with IPCC recommendations, many countries have made ambitious tree-planting commitments. However, the researchers reasoned that it would be helpful to assess the viability of land area for planting more trees in relation to existing and potential future forested environments. This inquiry led to a now well-known and intensely scrutinized 2019 Science article that looked at “The global tree restoration potential” to spatially assess existing and possible tree cover (Bastin et al. 2019). Using machine learning, photointerpretation, and satellite image datasets, the analysis built on previous estimates of the total number of trees on Earth to assess land suitability for tree planting based on whether tree cover was present or absent. Here, tree cover assembles as a digital object that stands in for trees and forests. The configuration of tree cover relied on building predictive models that input “78,774 direct photo-interpretation measurements” primarily from protected areas and through “a random forest machine-learning approach” estimating what “Earth's tree carrying capacity” could be. The techniques and variables that compose tree cover rely on “the absence of human activity” and predictive extrapolation from protected areas to a planetary-scale estimation (Bastin et al. 2019, 76). Forests, in this estimation, were most likely to be categorized as such in the absence of humans, and not through any measure of co-existence.
Presented in map form, the 2019 study included calculations on tree numbers as well as “restoration potential” identifying land where trees could be planted, including 0.9 billion hectares worldwide that could be suitable for planting an additional 1 trillion trees (Bastin et al. 2019, 77). As the article outlined, greater carbon storage could be achieved through a higher number of trees. “Restoration potential” hinges on trees and tree cover as productive units with the “potential” to alleviate environmental damage, from which forests assemble in more or less indeterminate form. Indeed, the forest was not entirely visible through the trees since this analysis focused on the productive unit of the standardized tree, such as the carbon pump and sponge, the biogeochemical regulator, and the biodiversity enhancer. With this logic, trees become technologies of displacement as much as restoration, whereby planting enables further extraction and pollution in a cycle of green growth that restores some environments while destroying others (Bäckstrand and Lövbrand 2006; Büscher et al. 2012; Dalsgaard 2022; Dooley, Nicholls and Meinshausen 2022). At the same time, this logic assumes restoration is a successful project of planting trees that live long enough to store carbon rather than die, burn, or convert to a carbon source. An enumerative approach that accounts for less restorative eventualities would need to be more “indexical,” as Verran (2012) has suggested, grappling with the uncertainty of environments in flux.
Several scientists subsequently wrote at least five eLetters, one perspective, and four comments to Science to respond and, in some cases, object to the study, with critiques ranging from concern about the framing of the problem, the methods, the lack of reference to earlier similar work (Grainger et al. 2019), the underestimation of land area required (Skidmore et al. 2019), and the findings that could lead to the conversion or diminishment of other vital ecosystems such as grasslands and wetlands (Veldman et al. 2019). Veldman et al. (2019) objected that carbon sequestration was significantly overestimated and overlooked the carbon sequestration in soils. Multiple commentators drew attention to the remote sensing and machine learning techniques, implicitly or explicitly suggesting that the use of flashy digital technology could have compromised the research. Critiques were also issued at a rapid pace on social media and in response to feature articles on Crowther Lab (Popkin 2019). Criticisms issued through social media included global change scientist Simon Lewis's suggestion that the study overestimated forest carbon storage because the over 200 billion tonnes of carbon that 1 trillion additional trees could sequester led to a miscalculation in the overall atmospheric reduction of CO2 in relation to the broader carbon cycle including oceans and atmospheres. 2
As a component of technicity, enumeration is further enabled by specific devices. The estimate of 3 trillion trees is a distinctly digital numbering practice that involves itemizing, designating, estimating, observing, measuring, and valuing, especially for carbon storage. The 3 trillion trees metric forms part of a computational practice that involves assessing, extrapolating, synthesizing data layers and variables, and implementing tree-planting endeavors that amass more productive units, more than cultivating complex forest ecologies. Computers can amplify the urge for quantification, providing techniques for grappling with ever-larger datasets and generating new worlds through enumeration (Porter 2009, 404). But this drive to quantify requires asking what epistemological, ethical, social, and political transformations take root as part of these quantification practices. Indeed, such calculative processes can reinforce and replicate “hegemonic” commitments, where algorithmic thinking can diminish democratic politics (Machen and Nost 2021). When forests operate as technologies within the 3 trillion tree metric, they do so as calculative ones that must be enumerated to become productive, or to become calculable commodities within exchanges such as carbon offset markets (Lansing 2012). But this enumeration generates particular activations of trees and forest worlds, which as many respondents to the 3 trillion trees research noted, does not enable a plurality of forest inhabitations. At the same time, the endurance of trees and forests as carbon stores is far from certain when increasing climate change contributes to drought, aridification, wildfires, and the extensive decimation of forest ecologies. If trees and forests operate as carbon technologies, they would do so as imperfect ones, prone to failure and breakdown within the context of climate change.
In the Bastin et al. study, trees were converted into technology in the form of itemizable carbon machines disconnected from broader ecosystems or social-ecological worlds. Many commentators suggested that trees were less significant for carbon absorption than overall ecosystems. The land required to plant one trillion trees also points to potential disputes over land ownership and occupation and the likely plantation land practices required to achieve these numbers. In this sense, another perspective emphasized how tree restoration potential could not be realized without a commitment to a holistic restoration system that includes social and economic factors—as the title of the perspective suggests, “restoring forests [is] a means to many ends” (Chazdon and Brancalion 2019). Based on these exchanges, Bastin et al. issued an Erratum in Science (2019), together with responses on social media and through their press team to clarify how they were not suggesting that other ecosystems be converted to forests or that social factors be overlooked. At the same time, the article by Bastin et al. became the second-most featured climate paper in the media in 2019 (Greenfield 2021). Despite these debates, qualifications, and heated exchanges, the article's speculative metrics provided ballast for multiple trillion-tree campaigns and projects, as discussed in the next section.
Planting One Trillion Trees
At the time of the initial Crowther et al. (2015) study, most tree-planting initiatives were million- and billion-tree pledges. By the time of the subsequent study by Bastin et al. (2019), multiple trillion tree campaigns had literally taken root. Trillion tree campaigns underway at the time of this writing include not just the Plant-for-the-Planet initiative from Finkbeiner mentioned earlier. They also include the Trillion Trees project collaboration of BirdLife International, Wildlife Conservation Society, and WWF based in Cambridge, UK; 1t.org established through the World Economic Forum in Davos, Switzerland, and now extending to seven regional locations worldwide; Greenverz Solutions in Bangalore, India; and Trillion Trees Australia, which was set up as Men of the Trees in 1979 and subsequently rebranded. 3 This is not a definitive list, and some million- and billion-tree campaigns have set targets to plant trillions of trees without renaming their initiatives, such as the Million Tree Pledge in Norwich, UK, which also cites the research by Crowther et al. (2015) in its organization description. 4 Platforms and apps have similarly gathered speed to facilitate planting projects, whether through the above-named initiatives or through stand-alone projects that seek to facilitate tree planting, such as the Silvi reforestation app, which commits to “helping a billion people plant a trillion trees.” A more general scan of forest reforestation platforms can also be found in Urzedo, Westerlaken and Gabrys (2023), which examines the geopolitics of how and where reforestation platforms and projects develop.
What is clear from these initiatives is that the trillion-tree metric did become meaningful and mobilizing by variously boosting NGO initiatives, civic campaigns, digital apps and platforms, and environmental development projects. The metric further contributed to environmental policies across local, national, and international levels. In a sign of the potential new and expanding markets that tree planting at such scales could enable, the Davos forum launched 1t.org during the World Economic Forum meeting. In 2020, Donald Trump signed the One Trillion Trees Executive Order in response to the “Trillion Trees Challenge” at Davos. 5 Trump’s Executive Order established a US chapter of 1t.org and the One Trillion Trees Interagency Council, which described 1t.org as “a global platform for conserving, restoring, and growing 1 trillion trees by 2030” (cf. Friedman 2020; United States One Trillion Trees Interagency Council 2020). Republican Representative Bruce Westerman from Arkansas subsequently introduced a bipartisan bill to support tree planting dubbed the “Trillion Trees Act.” It specifically outlined reforestation goals to improve national forest carbon stock, to set up a “Trillion Trees Task Force,” to identify and create relevant funding vehicles, and to contribute to reforestation and restoration, while also coordinating with international forest initiatives primarily focused on carbon sequestration (Westerman 2021). The bill was referred to committees on environment, agriculture, conservation, and forestry, but did not progress after June 2021.
The trillion-trees metric effectively mobilized trees as targets and technologies across or despite political differences. At the same time, environmental scholars and journalists took aim at these initiatives to reiterate critiques of the Bastin et al. (2019) study while also expressing environmental and social justice concerns about the possible reduction in biodiversity, conversion of land use to monocrop plantations, and the rise of land grabbing and dispossession, which could lead to the continuation of extractive and unjust environmental practices (e.g., Chazdon and Brancalion 2019; St. George 2022). Aligned research has shown how tree-planting projects can reduce biodiversity, fail to engage communities, and neglect planted trees through lack of monitoring (Cernansky 2018). Moreover, at current tree-planting rates among environmental NGOs, planting one trillion trees would take 1,000 years, assuming no trees die (Martin et al. 2021) or are consumed by wildfires.
Lost in the trillion-trees metric were the complex ecosystems and social-ecological worlds to which forests connect. The speculative metric composes a certain kind of forest world—one that is meant to mitigate environmental change mechanistically, but that could take the form of plantations dispossessing forest dwellers and reinforcing colonial, capitalist, and racist land practices (cf. Li and Pujo 2021; Davis et al. 2019). In many parts of the world, such land grabs and displacement practices are already occurring to support conservation projects, carbon offset, and tree-planting projects (Fairhead, Leach and Scoones 2012; Lyons and Westoby 2014). Restoration is often imposed by external and powerful actors (Elias, Joshi and Meinzen-Dick 2021), and it can fail to improve ecologies or enhance community self-sufficiency (Coleman et al. 2021; Pritchard 2021). The scaling up of such established practices to trillion-tree projects could further exacerbate environmental inequalities. The technicity of trees and forests as proliferating carbon sponges is one that reinscribes inequitable and extractive land practices while enabling higher emissions from wealthier countries.
Planting for the Planet
Within this broader context, Plant-for-the-Planet continued to develop its trillion trees campaign apace. Originally launched in January 2007 when Finkbeiner was nine years old, the project initially called for “children to plant one million trees in every country.” 6 Finkbeiner was subsequently asked to speak at the UN in February 2011 during the International Year of Forests, where he proposed planting one trillion trees worldwide. A distinctive feature of Finkbeiner's appeal was his emphasis on saving existing forests and integrating climate and social justice concerns. In the latter sense, he referred to Maathai's (2006) landmark tree-planting project in Kenya, which could inform new initiatives. Planting one trillion trees would only require every person on Earth to plant 150 trees, as Finkbeiner outlined in his UN address. The metrics of planting a trillion trees created a technique for breaking down and solving the problem of climate change. He noted that all that was needed was to “stop talking and start planting.” 7
The Trillion Trees action sits within the overall Plant-for-the-Planet initiative. The Plant-for-the-Planet Trillion Trees webpage includes references to Crowther et al. (2015) and Bastin et al. (2019) research, which it distills into a further metric: Six. Three. One. In other words, it refers to the historical, current, and proposed number of additional trees on Earth. More than 225 projects are contributing to this Trillion Trees endeavor. Included within the initiative is an open platform for documenting project locations, as well as a TreeMapper App for documenting tree planting and making donations to projects. With projects in at least 50 countries, the website outlines metrics variously documenting the number of trees planted and climate justice ambassadors in each country. The webpages indicate that in 2021 there were chapters in Brazil, Czech Republic (9,289 trees in 2021), Germany (23,218 climate justice ambassadors), Ghana (678,612 trees), Italy (1,351 trees), Mexico (25,890,868 trees), Spain (341,031 trees in Andalucia, 4,543 climate justice ambassadors), Switzerland, UK (315,692 trees planted, 580 climate justice ambassadors), and US (2,407 climate justice ambassadors).
As is evident from the number of trees planted within regional chapters, Mexico is the most productive site, mainly due to a pilot project in the Yucatán peninsula at Campeche, Mexico. Plant-for-the-Planet purchased this degraded and deforested site in 2014 as an experimental restoration site. As Finkbeiner describes in a video outlining the reforestation practices underway as of 2021, the intention was to plant 2.5 million trees in two locations degraded due to cattle ranching and fire. 8 Drawing on NASA satellite imagery and weather data, and documenting site conditions and planting with drones and the TreeMapper App, the Plant-for-the-Planet team uses a range of digital kits to undertake the restoration. A later video further outlines the importance of Plant-for-the-Planet's in-house restoration platform, pp.eco. Described in another video as “the center, the heart, the brain of everything,” the platform is required for use in restoration partners. It joins together all TreeMapper App data daily and serves as part restoration tracker and part networking tool. 9
What becomes clear from the videos, website, and restoration platform is just how vital the social-ecological components of tree planting are when these projects hit the ground. The main components of the video focus on the local labor force of reforesters, nursery technicians, data collectors, and other often-seasonal workers who contribute to the extensive infrastructure of gathering, preparing, and planting a diverse tree seed mix; monitoring weather, soil, and other conditions to ensure optimal planting times; undertaking planting activities during specific seasons; monitoring and maintaining trees to ensure their survival; documenting and communicating planting activities, and coordinating with other local and reference sites; looking after the site facilities and workers; and pitching to funders for ongoing support, among many other activities. While the over-arching objectives of the Plant-for-the-Planet Trillion Trees initiative are to increase tree numbers to address climate change and increase biodiversity, in pursuing this objective, a social-ecological matrix materializes to support, enable, and maintain the trees—and forests. Here, forests as technologies transform into distributed socio-ecological practices and technical relations for making and sustaining forest worlds. However, the restoration project also leaves questions about who has access or ownership over the land, to what extent community engagement with the land is part of the ongoing and future restoration plans, and what livelihoods could be supported by the restoration project over longer durations. These are ways of cultivating and concretizing milieus, as part of the expression of forest technicities.
“Stop Planting Trees”
As mentioned above, Crowther credits Finkbeiner with sparking the question of how many trees are actually on the planet, in the context of billion tree campaigns already underway, and with creating a trajectory for testing how science could make an impact, which pushes it beyond the usual scope of what counts as science (Goymer 2018). Their dialogue and interaction have informed broader understandings of what is involved in undertaking tree-planting projects in practice and the difficulties to which they give rise. Fast-forward to COP28 in Dubai, in December 2023, where Crowther presented his latest research. In an update and revision to his original proposal to focus on tree planting, he instead emphasized the importance of preserving forests and supporting forest communities. Instead of presenting an epic number to galvanize tree-planting efforts, he spoke to the importance of paying forest communities to look after existing forests as carbon stores, biodiversity hotspots, and environmental livelihoods (Mo et al. 2023). Tree planting, as it was playing out in practice, was contributing to monocrop plantations; the dispossession of traditional, Indigenous, and local land dwellers; and oiling the machinery of dubious carbon offsets (Dooley, Nicholls and Meinshausen 2022; Martin et al. 2021; cf. Dalsgaard 2022). What had seemed to be an uncomplicated metric for organizing environmental practices and mobilizing trees as carbon-storing technologies that could be multiplied at scale had become a potentially disastrous undertaking on the ground. The press reported Crowther's pitch and latest research as a complete reversal on prior proposals, with one Wired article bluntly titled, “Stop planting trees, says the guy who inspired the world to plant a trillion trees” (Luhn 2023).
Based on putting science into practice, together with broader critiques and dialogues with fellow environmental researchers, Crowther updated his findings to present his most informed recommendations, which resonated with earlier critiques and social science research on tree planting. At the same time, he had noted in an earlier Guardian article that he “never said we should plant a trillion trees” (Greenfield 2021). Along the way, the media hype, the academic celebrity status, and the promise of an easy and monetizable solution to climate change led not just to numerous debates and critiques, but also to the closure of the Crowther lab at ETH due to allegations of misconduct (Else 2025).
The itemization of trees as a functional and expansive metric that amasses into a forest aligns with a seemingly more achievable approach to climate change mitigation. In this approach, trees and forests operate as fragmented and simple mechanisms working in isolation from what supports and sustains them. By contrast, projects to preserve existing forests and forest relations are often not as appealing as tree-planting pledges, since they could require grappling with more complex social-political conditions. Projects of cultivating and sustaining forests as social-ecological technologies are also as likely to challenge rather than reinforce existing extractive economies. The forest as technology analytic is thus reworked but not, I would suggest, abandoned. It instead demonstrates how difficult it can be to compose environments and technologies beyond extractive registers. Such social-ecological technicities pose the ongoing question of how to cultivate and sustain forests, including how or whether they shape environments, to what purpose, and for which actors and communities—whether in immediate settings or farther afield to address climate emissions and biodiversity loss.
Discussion: “Team Technology Versus Team Trees”
The title of this article and The Guardian weekly in which it featured—“this machine kills CO2”—signals how tree-counting and tree-planting research and initiatives mobilize forests as technologies. What difference does it make to attend to how trees and forests perform as technologies? It would be easy to revert to the familiar sense that forests are not technologies. And yet, as extensive research on forests within political ecology has shown, and as parallel research in science and technology studies and history and philosophy of science has demonstrated, the composition of organisms, environments, and technologies is a moving technical ensemble of power and practical effects. For this reason, this article asks what forests and technologies these are in an attempt to consider what other forests and technologies could be proposed and implemented. Analyzing forests as technologies is an opportunity to break with a naturalizing and depoliticizing logic of environments to consider which forest worlds are made and sustained, and how (cf. Head 2022).
Lest this seem like a niche concept and discussion, it is instructive to consider how Big Tech is making significant investments in climate technology as the next “frontier.” As Meta notes in a January 2024 blog post on carbon removal: Team Technology vs. Team Trees is an unhelpful distraction from the very real and exciting challenges that carbon removal presents. Both nature-based and technology-based carbon removal offer powerful tools to complement companies’ priority efforts in reducing their emissions to the maximum possible levels. They each represent vital pieces of the mitigation puzzle, offering pathways to impact at scale, with durability covering the crucial decades-to-century time frame and beyond. (Johns 2024)
By asking how trees and forests operate through distinct technicities for mitigating environmental change, it is possible to engage with how forests are composed and operationalized, whether as individual productive units, tree cover, carbon sinks, monocrop plantations, or social-ecological relations and livelihoods. Such an approach further involves attending to the diversity or scarcity of entities and humans involved in cultivating and sustaining forests. The calculative project of planting trees in the trillions is often not one of cultivating social-ecological worlds. However, as some of the examples discussed here show, forest projects that include tree planting can demonstrate the necessity of reworking the political ecologies and economies of restoration projects toward more engaged and inclusive practices within affected communities (Elias, Joshi and Meinzen-Dick 2021), as part of a project of reworking the values, benefits, and inequalities that the mobilization of forests-as-technologies can generate.
The processes whereby entities become technological or are activated as techniques within broader milieus are expressive of values that make and sustain worlds. For this reason, the technicities and technologies that are operationalized are as critical as the forests that are composed. Trees can be activated as more palatable technologies than mechanized carbon removal technologies, where planting can be a way to forestall and forego geoengineering-type approaches to climate change (Waller, Rayner, and Chilvers 2023). But such approaches to forests as technologies do not necessarily rework forest technicities. At the same time, digital technologies compose and amplify the counting, estimating, modeling, and planting of trees as calculable and productive units. Drones, platforms, apps, automated technologies, and emerging climate tech further contribute to mass reforestation efforts (Elliott, Gale, and Robertson 2020; Nitoslawski et al. 2021; Urzedo, Westerlaken, and Gabrys 2023). While digital techniques can contribute to further technocratic organization and control, these compositions of environments, technologies, and techniques can also be recast as practices for preserving and sustaining forest worlds for livelihoods and a multiplicity of organisms; for relations and cosmologies that are more attuned to reciprocal cultivation, rather than the reproduction of forests as resources for ongoing extraction.
Conclusion: Cultivating Forest Worlds
Tree planting promises a simple and achievable practice that anyone anywhere on Earth can undertake to solve planetary crises. The “forests as technology” analytic draws attention to practices for making and sustaining forest worlds to understand prevailing approaches and consider what other engagements could be foregrounded or proposed. Such an approach could reflect on the variable social-political ways that forests are configured and how they are organized as entities central to addressing environmental change. Indeed, it could be helpful to think of forests as technologies to study the practices and forms of effectiveness organized with and through them. This is a way to understand better how forests are composed and operationalized as productive environments and how these land practices are expressive of particular environmental relations that can benefit some actors and entities at the expense of others. Technology and the formation of environmental problems through “as technology” approaches can seemingly stand in for politics, where planting one trillion trees presents an efficient solution within a more complex and extensive range of social-political conditions. However, the one trillion trees approach rehearses the problems of the technological fix, which has been critiqued for its elision of social-ecological worlds (Nightingale et al. 2020).
This article keeps these critiques of the technical fix in view while proposing an alternative engagement with technology and technologization that asks how entities and environments are operationalized to address planetary crises. The technical fix shows up as a reductive, mechanistic, functionalist, asocial, and technocratic mobilization of trees, forests, and, by extension, forest dwellers, as though they are mere participants in a planetary-scale carbon plantation. However, by focusing on forests “as technology,” this article asks what and how forest technicities are composed to offer an opening into other social-ecological and technical relations.
The question of how such technicities form and what worlds they sustain further raises the question of how entities and technologies “would have been otherwise had other plans prevailed” Bijker and Law (1992, 9). These could be technologies that express a particular “weakness” in their low-tech characteristics but are also less rigid and more able to adapt to environments (Danowski and Viveiros De Castro 2016, 95). They could also be forest worlds that activate less inequitable and extractive planetary relations. There are multiple projects underway that query, transform, and differently operate within this environmental matrix, from community drone projects for monitoring deforestation (Paneque-Gálvez et al. 2017; Bersaglio et al. 2023) to agroforestry projects for enabling forest livelihoods (Li 2007; Tsing 2015), and community fire monitoring networks that find other ways to live with changing forest environments (Head 2020). These projects engage with forests and technology not just as sites of resistance, a recurring thread within critiques of technoscience (Subramaniam et al. 2017), but also as sites for remaking forest worlds. The “forests as technology” analytic then seeks to offer a practice and moving composition of environments, technologies, and social-political effects that can work toward more equitable and pluralistic forest worlds.
Footnotes
Funding
The author disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant agreement No. 866006).
