These mapping efforts are constrained to variables that can be quantified at a large scale, and they typically define abandoned agricultural land as land that was previously used for agriculture but where intensive human management appears to have ceased . Some definitions specify a minimum of 2–5 years of observations of non-use, whereas others specify observations of successional processes resulting in the natural establishment of forests or other secondary vegetation. Certain agricultural uses, such as recent fallow or pasture lands, make these types of observations difficult to detect in large-scale land cover maps. Definitions of abandoned agricultural land based on remote observation of land cover changes over time often overlook the complexity of landholder decision-making and how landholder choices affect the cessation of agricultural use and potentially its later recurrence . These definitions result in overestimation of the available land area for reforestation for climate mitigation and other purposes, as well as of the permanence of newly established forest cover . We suspect that this is why Crawford et al. find such variation in abandoned land estimates. Moreover, these definitions and the semantics of the term “abandonment” imply a decline in land utility for agricultural livelihoods and a ceding of land rights to others. Using a definition that assumes away local residents’ landholding rights may inadvertently create social vulnerabilities in localities where there appear to be opportunities for reforestation. Without attention to landholding status and associated livelihoods,hydroponic nft system reforestation projects on abandoned agricultural land risk overstating their impact and sustainability. We propose a new conceptualization of abandoned agricultural land that incorporates changes in landholding status over time into determining whether land should be considered as abandoned.
While challenging to implement empirically, this conceptualization offers an improved approach to understanding the significant heterogeneity in land use changes—not simply land cover changes. Whereas land cover changes can be observed directly through remotely sensed imagery, land use changes cannot always be inferred from changes in land cover. For example, land that exists under “forest” cover could be used for selective logging, shade grown agroforestry, or biodiversity conservation, each of which confers different environmental and socio-economic outcomes. These changes in land use ultimately derive from landholding status because landholding status affects landholders’ planning horizons. For example, medium- and long-term availability of abandoned land needed to sequester carbon and achieve other desired reforestation benefits depends on secure landholding that can only be known through incorporating information about landholding status. We focus on land that was originally forested but then converted to an agricultural use that has currently ceased . We identify the decision points that determine whether this abandoned agricultural land follows pathways that lead to a persistent transition to forest, either natural forest cover or woody tree plantations sensu FAO . After a period of deforestation driven by agricultural expansion, economic development creates sufficient off-farm employment that the agricultural labor force shrinks, agricultural labor costs rise and profits fall, and some land shifts from agriculture to uses that are less labor-intensive, including secondary forest or tree plantations ; often the land has low agricultural productivity. Forest transitions may also result from a rise in the price of wood rather than just a change in the relative return on labor .
This land is then commonly considered to be “abandoned” in terms of agricultural use, and it is assumed that forests will grow back on it through either natural regeneration or tree planting. This process has been documented in Europe, the eastern United States, Japan, Mexico, China, India, Brazil, and other regions worldwide . In fact, abandoned agricultural land results from a series of land-use decisions that are influenced by complex biophysical, demographic, and socioeconomic processes . This means that land that is currently “abandoned” from agricultural use will not necessarily result in a persistent, net increase in forest cover . To begin, the current landholder might have ceased agricultural use only temporarily, leaving the land fallow for multiple years to allow soil nutrients to accumulate, pathogens to subside, or market conditions to become more favorable . Even if the current landholder’s intention is a permanent cessation of agriculture, the land might not be biophysically suitable for reforestation, either because it is highly degraded or is in a biome where grassland or another low tree cover ecosystem is the naturally occurring vegetation . Considerations of land tenure, namely the landholder’s and potentially others’ formal or informal rights to own or use the land and how these rights are enforced, add complexity when the current landholder “abandons” agricultural use of land that is suitable for forest regeneration. By ceasing agricultural use, the current landholder may or may not abandon their rights to the land. In some locations, ending agricultural use necessitates relinquishing land rights because land that is not cultivated or grazed is considered “idle” or unassigned, but this linkage of use abandonment and rights abandonment is not universal . If no new landholder acquires rights to the land, then natural succession will likely result in forest regeneration .
However, if a new landholder acquires the rights to the land through voluntary sale or reassignment by a governmental or communal authority, then they, in turn, will decide whether to increase forest cover on it or revert to using it for agriculture or another non-forest purpose, such as urbanization . Forest regeneration is similarly not assured if the current landholder retains their rights to the land, as they too could decide to convert the land to a non-forest use . In cases where the original or new landholder decides to increase forest cover on the site, then they also must decide whether to regenerate the forest using natural or artificial means, which entails considering a mix of ecological, silvicultural, and socioeconomic factors . A fourth possibility is that the current landholder’s rights are not enforced, in which case an involuntary land transfer occurs against the current landholder’s wishes: a “land grab.” For example, Ugandan villagers report that Norwegian investments in forest carbon plantations caused “forced relocations of agriculture, grazing, and other livelihood activities” . A non-forest land use, typically some form of commercial agriculture, could also follow a land grab . Even if the landholder initially decides to establish forest cover on the land, the forest cover might not persist for a host of reasons. Changes in agricultural prices and technologies, off-farm employment opportunities, wood scarcity, political instability, and government policies and subsidies can prompt landholders to reverse a decision to retain forest cover . For example, some of the extensive area of agricultural land abandoned in eastern Europe following the fall of the Soviet Union has been re-cultivated in the past decade,nft channel mostly due to increases in agricultural subsidies and commodity prices . Whereas it is commonly assumed that forest cover will increase as opportunities for non-agricultural employment increase and people migrate to cities, there are examples of reverse migration to rural areas when economic opportunities or personal situations change . Climate change also decreases the likelihood of sustained forest cover increases in some locations due to changes in disturbance regimes and migration of both forest species and humans to more suitable climatic conditions. Finally, forest cover changes must be evaluated at sufficient scale to determine whether there is a net increase over a region or the globe, given documented cases in which ceasing agriculture in one location has led to displacement of agriculture to other locations , with any increase in forest cover in the first location being partially or completely offset by deforestation elsewhere . This displacement of deforestation can be challenging to quantify, as it may happen far from the study region given the ever-increasing globalization of the trade of forestry and agricultural products .
In sum, landholding status and land rights are complicated core factors affecting the net increase in persistent forest cover that ultimately results from abandoned agricultural land . Although agricultural and forestry policies, also mediate the use of abandoned agricultural land, we argue that landholding status and land rights are fundamental factors that cannot be ignored when implementing reforestation programs. Despite the challenge of mapping complex land-use decisions, there are important policy reasons to estimate how much land is potentially available for reforestation in the future. To that end we suggest the following. First, those undertaking these efforts should clearly state how they are defining “abandoned” land and other related terms , including the temporal and spatial scale of those definitions. We recommend using more specific terms such as fallow , agroforestry or silvopastoral systems , timber plantation , or secondary forest. We also advocate evaluating the persistence of these different land uses. These definitions are best defined regionally, given differences in production systems by locality and ecosystem. Likewise, it is important to more transparently acknowledge the complex suite of factors that affect forest transitions and reversals that are likely to bias estimates of land available for reforestation . Second, more attention should be paid to who owns and has rights to use the land when mapping global land uses and looking for investment opportunities for carbon or land purchase. In some regions of the world, land ownership maps exist that could be included as part of mapping efforts. In other regions, this can be challenging given issues of unclear land tenure . In general, local stakeholders want tenure mapped and formally recognized, but tenure and land claims are often unclear or contested . Mapping tenure and resolving contested claims can hinder or complicate landbased projects and programs , but is critical to their success. Further, absence of legally recognized tenure due to incomplete or partial mapping processes may invite land grabbing and induce conflict, particularly in common property systems . Participatory mapping is a technique that can help illuminate and resolve potential conflicts but using this approach at broad geographic scales remains a challenge . Ultimately, it may not be possible to accurately map “abandoned” land in regions where land tenure is particularly contentious. Third, a promising approach to developing more realistic and inclusive maps of abandoned agricultural land and potential forest cover is to combine remotely sensed data with household/stakeholder surveys to understand landowner motivations for not cropping lands. For example, Zhang et al. combined remotely sensed data of forest cover change with household surveys and focus groups to elucidate factors affecting increases in forest cover in northwest Yunnan Province, China. They found that forest cover increases were not greater on lands receiving payments from the Grain-for Green program, in contrast to the reported net positive effect of the program on forest cover at the national level . Instead, the surveys and focus groups revealed that forest cover changes in the study area were influenced by a suite of factors that cannot be remotely sensed, including off- farm labor opportunities, changing energy sources, and tree crop planting for income . We realize this combined approach is time consuming and necessarily will need to be done at a regional or local scale, but this is the scale at which most policy decisions are made, and the estimates of land area available for reforestation will be more realistic. Furthermore, attention to these details prior to major investments in reforestation will reduce the likelihood of significantly diminished, net zero, or net negative returns. With varying degrees of enthusiasm, the governments of the central and eastern European Countries all aspire to join the European Union . These aspirations were given strong encouragement at the EU’s 1993 Copenhagen Summit, at which time associated CEECs were told they would eventually gain membership. Along the path to accession, however, lie difficult policy choices and delicate negotiations concerning the pace and terms of economic integration. Of these, among the most challenging are those affecting the fate of agriculture in the emerging market economies. Accession to the EU has historically implied the integration of the new member into the community’s Common Agricultural Policy , a complicated system of interventions whose most prominent and expensive features are designed to support prices of program commoditiesl through intervention purchases, and to shield markets from external competition through tariff barriers.