The forest transition: Towards a more comprehensive theoretical framework

Building on the contributions of Mather and others, this paper offers an approach for developing a more comprehensive theory of the forest transition. We argue that long-run changes in forest cover in a country or region cannot be separated from the overall pattern of land use changes. Moreover, this pattern is determined by relative land values; forest cover changes over time as the value of one land use relative to the value of its competing use changes over time. However, the actual values that are used to allocate land may be far from optimal; that is, the presence of market, policy and institutional failures can distort economic and political incentives that can lead to bias in favour of one type of land use over the other, and may ultimately explain why a forest transition may be delayed unnecessarily in some countries and regions.     

Land use transitions: Socio-ecological feedback versus socio-economic change

The concept of land use transition highlights that land use change is non-linear and is associated with other societal and biophysical system changes. A transition in land use is not a fixed pattern, nor is it deterministic. Land use transitions can be caused by negative socio-ecological feedbacks that arise from a depletion of key resources or from socio-economic change and innovation that take place rather independently from the ecological system. Here, we explore whether the sources of land use transitions are mostly endogenous socio-ecological forces or exogenous socio-economic factors. We first review a few generic pathways of forest transition as identified in national case studies, and evaluate the varying ecological quality of expanding forests associated with these pathways. We then discuss possible explanatory frameworks of land use transitions. We use the case of the recent forest transition in Vietnam as an illustration. Socio-ecological feedbacks seem to better explain a slowing down of deforestation and stabilization of forest cover, while exogenous socio-economic factors better account for reforestation. We conclude by discussing the prospects of accelerating land use transitions in tropical forest countries.     

Dynamic land use and land cover changes and their effect on forest resources in a coastal village of Matemwe,Zanzibar, Tanzania

Recent land cover change estimates show overall decline of tropical forests at the regional and global scales caused by multiple social, cultural and economic factors. There is an overall concern on the prevailing land use practices, such as shifting cultivation and extraction of forest materials as agents of forests losses, but also new, emerging land uses are threatening tropical forests. Understanding of the long-term development and driving forces of forest changes are needed, especially at local levels where many decisions on forest policies and land uses are made. This paper addresses the importance of such information for improved estimates of forest dynamics by studying local level land cover and land use changes during the last 50–70 years in the Eastern African tropical island of Zanzibar, Tanzania. The paper discusses the role of traditional and new land uses mainly subsistence farming, tourism and government interference through tree planting, in the long-term development of the forests at the village level. The material for the study is gathered from the interpretation of archival maps and aerial photographs combined with contemporary digital aerial photographs. The analyses are based on the mapping, spatial sampling and spatio-temporal change trajectory analysis (LCTA) of forest land cover, forest land uses and settlement patterns with GIS and statistics. Six distinct forest land cover change trajectories were identified and these illustrate dynamic and heterogeneous nature of the forests. Closed forest cover has dominated throughout due to cyclical land use patterns, but over 70% of the land area has been continuously transforming between closed, semi-open and open land cover conditions. Land use turnover rates indicate that hardly any forest areas are left untouched from the forces, which remove and re-establish forest vegetation in the long run. Land cover and land use change trajectories are spatially fragmented in the studied landscape. Majority of forest loss-gain dynamics is caused by shifting cultivation, while forest losses are most dramatic along the coast, where traditional and new land uses meet and land uses pressures are highest. The study suggests that landscape change trajectory analyses, where contemporary and historical information on land uses and land cover changes are spatially linked, can provide valuable aspects into local level forest land use planning and management strategies. For the case study, the findings suggest the following key forest management strategies for consideration: (1) establishment of a protected forest/scrubland in participation with the local stakeholders, especially the farmers, (2) promotion of areas for permanent agricultural practices, while simultaneously introducing management controls in the traditional slash-and-burn farming areas, and (3) promoting new livelihood opportunities for the farmers, who have traditionally been dependent on forest resources, meanwhile introducing alternatives for fuel wood for cooking.     

The institutional drivers of sustainable landscapes: a case study of the ‘Mayan Zone’ in Quintana Roo, Mexico

Research on the dynamics of tropical forest land use and cover change (LUCC) has focused on the three scenarios: (1) deforestation/degradation; (2) settled, degraded areas in recovery, and (3) sparsely settled, expansive, intact forest. Through examination of a central Quintana Roo, Mexico case study we propose a fourth scenario of a ‘sustainable landscape’: an inhabited, productively used, forested landscape that nonetheless shows little change or net gains in forest cover over the last 25 years. We use Landsat images to demonstrate a low incidence of net deforestation, 0.01% for the 1984–2000 period, the lowest recorded deforestation rate for southeastern Mexico. Institutional innovations such as an agrarian reform process that established large common property forests for non-timber forest product extraction, and later innovations such as sustainable forest management institutions have driven the outcome of low net deforestation, added to multiple organizational processes that promote sustainable land use.     

Is Portugal’s forest transition going up in smoke?

The turnarounds from decrease to expansion in forest areas that took place during the last century have been examined through the lens of forest transition theory (FTT). Among temperate and Mediterranean European countries that have seen an expansion of forest cover, Portugal stands out as the only case in which this trend has recently been reverted. In this study, we explicitly map and document the forest transition (FT) in the country over the period 1907–2006, and investigate when and where forest transition happened de facto, and which were the land use transition pathways that resulted from the shrublands, agriculture, and forest interplay dynamics. After thematic and geometric harmonization of land cover maps from 1907, 1955, 1970, 1990, and 2006, a cluster analysis established four typologies, and a transition matrix was constructed to assess land cover dynamics. We found that up to 1955, FT occurred simultaneously with agricultural expansion, as shrubland areas diminished. Afterwards, with the retraction of agricultural area and the consequential decoupling of forest management from local actors, FT gained momentum and expanded up to the 1990s. While during the first half of the 20th century, forest expansion followed the “Scarcity” and “State Policy” pathways fostered by local socio-ecological feedback loops, throughout the second half of the century forest transition was driven by exogenous socio-economic forces, following “Economic Development” and “Globalization” pathways. We show how, despite these forces, FT can be derailed by endogenous factors such as wildfires, which limited and in some areas even reverted the afforestation process, initiating a deforestation phase. Since the necessary conditions for FT (technology shift, urbanization, agriculture retraction and public afforestation programs) were available in mainland Portugal, we advance the hypothesis that critical wildfire risk governance deficits may have been responsible for arresting FT. Considering the critical role of forests and other wooded areas in supporting climate change mitigation and sustainable development, our work provides useful evidence and insights for public decision makers on previously unaddressed dimensions of FTT.     

Knowing but not knowing: Systematic conservation planning and community conservation in the Sierra Norte of Oaxaca,Mexico

Systematic conservation planning (SCP) seeks to propose new reserves through a scientifically rigorous process using databases and research selection algorithims. However, SCP exercises have been criticized for “knowing but not doing”, i.e. not implementing the proposed reserve. But there is an additional problem that can be called “knowing but not knowing”, knowing things from databases, but not knowing crucial contextual information about community-based social processes that have supported the high forest cover and biodiversity detected. Examined here is how a common property region of the Sierra Norte of Oaxaca, Mexico has maintained high forest cover in the absence of public protected areas, while multiple SCP exercises have advocated for the creation of public protected areas in communal tropical montane cloud forests and pine forests as strategies for biodiversity conservation and resilience to climate change. Methods included archival research, review of community documents, focus group interviews, semi-structured interviews, participant observation, land use transects, and GIS analysis and remote sensing. Conservation in the region originally occurred because of low population densities, steep slopes and a lack of agricultural subsidies, supported by locally adapted agricultural practices. In the 1990s, a transition from passive to active conservation took place with land use zoning plans, community conservation rules, community forestry enterprises and payments for environmental service programs that consolidated a trend towards high, unthreatened forest cover. Today, the study communities have an average of 88.3% forest cover, with 61% of that in informal conservation based on community land use zoning and rules and another 14% governed by forest management plans approved by the Mexican government. We argue that truly systematic conservation plans would seek to understand how communities in the region are already managing forests for conservation. It is pointless and uninformed to advocate for top-down conservation interventions of forests that are already robustly conserved and resilient to climate change due to community action.     

Is there a forest transition outside forests? Trajectories of farm trees and effects on ecosystem services in an agricultural landscape in Eastern Germany

Most industrial countries have experienced a transformation of land use: from decreasing to expanding forest areas, the so-called forest transition. Outside closed forests, European rural landscapes exhibit a diversity of tree-based agricultural systems, but the question of whether this forest transition has also affected ‘trees outside forests’ has rarely been studied. The aim of this study is to analyze the spatial-temporal dynamics of farm trees and woodlands in an agricultural landscape in Eastern Germany from 1964 to 2008, based on aerial photographs and digital orthophotos. Taking a landscape ecological perspective, we quantify farm tree dynamics, disentangle processes of gain and loss in the socialist and post-socialist periods of Eastern Germany, and assess differences in ecosystem services provided by farm trees. A substantial increase of overall tree cover by 24.8% was observed for the selected time period, but trajectories have been disparate across different farm tree classes. The increase in tree cover was stronger in steep valleys than on hills and plateaus, indicating a significant interdependence between topography and trajectories of change. Patch numbers of farm trees did not increase, which suggests that the expansion of tree cover is mostly due to a spatial expansion of previously existing tree patches. Overall net gains in tree cover were rather similar during the socialist and post-socialist eras. The general increase in tree cover was accompanied by increase in agriculture-related ecosystem service provision, but the increase in pollination and pest control services was much lower than that in water purification services. These findings present the first empirical evidence from an industrialized country that there is also an ongoing ‘forest transition’ outside closed forests. Potential, partially counteracting drivers of change during the socialist and post-socialist periods have mainly been related to farm policies and the environmental consciousness of land users and society as a whole.     

Identifying deforestation attractors and patterns of fragmentation for seasonally dry tropical forest in central Veracruz,Mexico

Seasonally dry tropical forests (SDTF) are exposed to numerous threats stemming from human activity and are considered a high conservation priority globally. Nevertheless, planning the conservation, management, and restoration of forests requires a detailed regional understanding of current forest distribution, and patterns and attractors of deforestation. We explored SDTF cover in the state of Veracruz, Mexico, where little is known about this type of forest since it was erroneously considered to have been eliminated and thus has not be included in recent conservation planning in Mexico. A time-series of land use and land cover (LULC) maps, based on Landsat imagery from 1973 (MSS), 1990 (TM), and 2000 (ETM+), was used to analyze historical patterns of deforestation and fragmentation of SDTF in a priority watershed in central Veracruz. Stepwise logistic regression was used to identify the main attractors of forest loss. Maps based on higher resolution SPOT imagery (2007–2008) were used to determine the current extent of SDTF. Results from our LULC analysis revealed landscapes that were consistently dominated (>50%) by some combination of intensified land use including cattle pastures, rain-fed and irrigated agricultural lands, with closed SDTF cover fluctuating from 11.3 to 9.26% during the study period (1973–2007). Annualized rates of forest loss between Landsat images (1973 vs. 2000; −2.02%) and between Landsat and SPOT images (1973 vs. 2007; −0.59), were moderate to low, with historical records suggesting that most deforestation occurred more than a century ago before the Mexican revolution. Nevertheless, rates of forest loss varied considerable between different time periods, with slight reforestation initially (1.55%; 1973–1990), followed by a marked decline (−8.08%; 1990–2000), and finally a noticeable increases in forest cover (4.92%; 2000–2007) that corresponds with changes in public policy and trends in population migration. The number of forest patches tripled between 1973 and 2000 and the mean forest patch area decreased almost 80% over the same time period. Logistic regression analysis (1973–2000) indicated that the main attractors of closed forest transformation were proximity to gentle slopes, cattle pastures, and the hydraulic infrastructure needed for crop irrigation. Although SDTF is highly fragmented and perturbed, important remnants of this diverse native forest still persists in the region. Our findings are discussed in the context of future conservation and restoration efforts.     

The role of land use conversion in shaping the land cover of the Central American Dry Corridor

The Central American Dry Corridor (CADC) is a trans-border region characterized by climatic and ecological continuities. It is expected to experience rising aridity and severe hydro-climatic events due to climate change. Subsistence agriculture and other rural livelihoods to which land cover is central are widely practiced in this impoverished territory of approximately eleven million people.The CADC’s land cover was profiled to determine: a) how it differs from Non-CADC areas, and b) the role of land use in shaping these differences. Spatial autocorrelation analysis using satellite data showed that forest cover is a third less prevalent in the CADC than in the Non-CADC while the share of mosaic vegetation and mosaic cropland is nearly double. A naturally prevalent cover type in the CADC, tropical dry forest (TDF), has been largely eliminated.The significantly lesser proportion of forest and greater percentage of coverage consistent with agriculture and ranching implicate land use conversion, specifically deforestation for agricultural expansion and cattle ranching, in shaping CADC land coverage. The process began in the mid-1800s when small-scale agriculturalists migrated to the region followed by large-scale export crop and beef production, primarily for international markets. Deforestation peaked after WWII, concluding by the 1990s with the conversion of most woodlands. Similar patterns now threaten forests along the Caribbean coast.Traditional land use practices cannot sustain local communities or preserve the resource base, thereby contributing to rural outmigration. Adopting sustainable practices and promoting livelihoods strategies leading to forest regeneration will be fundamental for CC adaptation in the CADC.     

Forest and agricultural land change in the Carpathian region—A meta-analysis of long-term patterns and drivers of change

Humans have altered land cover for centuries, and land-cover change is a main component of global change. Land use transition trajectories, such as the forest transition theory (i.e. switch from deforestation to stable or increasing forest cover), relate long term changes in land use to gradual changes in underlying drivers, such as economic development, demographic change, and urbanization. However, because only few studies examined land change over centuries, it is not clear how land cover changes during very long time-periods which are punctuated by shifts in socio-economics and policies, such as wars. Our goal here was to examine broad land change patterns and processes, and their main driving forces in Central and Eastern Europe during distinct periods of the past 250 years. We conducted a meta-analysis of 66 publications describing 102 case study locations and quantified the main forest and agricultural changes in the Carpathian region since the 18th century. These studies captured gradual changes since the peak of the Austro-Hungarian Empire up to the accession to the European Union of most of the formerly socialist countries in the study region. Agricultural land-use increased during the Austro-Hungarian Empire in 70% of the case studies, but dropped sharply during and especially after the collapse of the Socialism (over 70% of the cases). The highest rates of abandonment occurred between 1990 and 2000. The Carpathian region experienced forest transition during the Interwar period (93% of the cases), and the forest expansion trend persisted after the collapse of Socialism (70% of the cases). In terms of the drivers, institutional and economic factors were most influential in shaping deforestation and agricultural expansion, while socio-demographics and institutional shifts were the key drivers of land abandonment. Our study highlights the drastic effects that socio-economic and institutional changes can have on land-use and land-cover change, and the value of longitudinal studies of land change to uncover these effects.     

Forests to fields. Restoring tropical lands to agriculture

In discussing land use in tropical forest regions, there is an emphasis on the following topics: the need for the expansion of cropping areas, the precedent for use of the tropical forest for cropping based on past use patterns, the pressure from conservationists against cropping, debunking the mythology that forests are "natural" and refuting the claims that forest clearance is not reversible, the archeological evidence of past forest use for agricultural purposes, abandonment of tropical land to forest, and rotation of forest and field. The assumption is that the way to stop food importation is to increase crop production in the tropics. Crop production can be increased through 1) land intensification or clearing new land, 2) output per unit of land increases, or 3) reallocation to agriculture land previously cleared and overgrown with tropical forest. "Temporary" reuse of land, which reverted back to tropical forest, is recommended. This reuse would ease population pressure, and benefit bioconservation, while populations stabilize and further progress is made in international plant breeding. The land would eventually be returned to a forest state. Conservation of tropical forest areas should be accomplished, after an assessment has been made of its former uses. Primary forests need to identified and conversion to farming ceased. Research needs to be directed to understanding the process of past forest regeneration, and to devising cropping systems with longterm viability. The green revolution is unsuitable for traditional cropping systems, is contrary to demands of international funding agencies for sustainability, and is not affordable by most poor farmers. Only .48 million sq. km of closed forest loss was in tropical rainforests; 6.53 million sq. km was lost from temperate forests cleared for intensive small-scale peasant farming. The use of tropical forest land for farming has some benefits; crops in the wetter tropics are perennial, which would "reduce seasonal soil tillage, increase nutrient cycling, and remove a lower proportion of biomass." Water availability would not be a problem. Low soil nutrient levels could be increased with cutting and burning or fertilizer. The key is proper and careful management, particularly under intensive cropping systems such as rice production or extensive long fallow shifting cultivation.     

From the Holocene to the Anthropocene: A historical framework for land cover change in southwestern South America in the past 15,000 years

The main forest transitions that took place in south-central Chile from the end of the last glaciation to the present are reviewed here with the aim of identifying the main climatic and socio-economic drivers of land cover change. The first great transition, driven primarily by global warming, is the postglacial expansion of forests, with human populations from about 15,000 cal. yr. BP, restricted to coastlines and river basins and localized impact of forest fire. Charcoal evidence of fire increased in south-central Chile and in global records from about 12,000 to 6000 cal. yr. BP, which could be attributed at least partly to people. The subsequent expansion of agriculture led to much clearing of forests and the spread of weeds and other indicators of open habitats. The Spanish colonial period in America may have been followed by a transient expansion of forest cover into abandoned land, as indigenous population declined rapidly due to disease and slaughter. The 18th and 19th centuries brought about extensive loss of forests due to the massive impact of lumber extraction for mining operations both in central Chile and in western North America. Two centuries of intensive deforestation, coupled to grazing by cattle and extremely variable rainfall had long-lasting effects on forest cover in south-central Chile, which persist until today. The transition from a preindustrial to an industrial society brought about the “golden age” of timber harvest, assisted by mobile sawmills and railway transportation since the late 1800s. These advances led to the exhaustion of native commercial timber by the late 20th century in south-central Chile. In North America, harvestable stands were exhausted in New England and the Midwest around 1920. Settlement of the independent territories in the late 1800s and early 1900s implied vast burning and clearing of land and mounting soil erosion. Industrial forestry, based on government-subsidized massive plantations of short-rotation exotic trees, developed in the late 20th century, in connection with postindustrial displacement of exploitative activities from developed to third-world nations. In the last two decades, economic globalization and free trade promoted the expansion of new crops and further decline of woodlands, despite modest increases in forest cover. These patterns are repeated in many Latin American countries. To prevent further depletion of native forest resources and to provide an insurance against climate change, in the 21st century developing nations should aim at: (1) relocating subsidies from fiber farms to restoring diverse forest cover, (2) promoting ecosystem management of diverse forest and crops within landscapes, and (3) fostering diverse cultural relationships between people and their land.     

Characterizing land disturbance in Atewa Range Forest Reserve and Buffer Zone

Changes in land cover of protected areas and their buffers have serious implications on the conservation of biodiversity within such biomes because land use has been recognized as one of the major drivers of biodiversity change. Atewa Range Forest Reserve is one of Ghana's Upper Guinea Forests declared as a Globally Significant Biodiversity Area (GSBA). But the reserve is under threat from several human disturbances which could impact on the land cover of the reserve.This study examined the spatial and temporal changes in land cover of Atewa Range Forest Reserve and it's buffer between 1986 and 2013 using remote sensing. Land use and land cover (LULC) classification and change detections were undertaken using one Landsat Multispectral Scanner (MSS) image of 1986 and Landsat ETM+ images of 2003 and 2013.The study also investigated the driving forces of LULC and the effectiveness of the Forest and Wildlife Policy of 1994 in the management of the reserve.Results of image classification showed that much of the peripheral closed and open vegetative covers have been converted to farms and bushes with little disturbance within the interior of the reserve. The study revealed that, the conservation management policies were yielding very little results due to a number of policy deficiencies including low staff strength, lack of logistics and low remuneration. Enforcement of legal instruments against illegal logging, small scale mining and farming activities within the reserve, improvement in the staff strength and their condition of service, intensification of public education on the value of forest and the need to protect it are some of the major recommendations that could curb encroachment on the reserve.     

Private property and Mennonites are major drivers of forest cover loss in central Yucatan Peninsula,Mexico

The role of land tenure and Mennonites as drivers of deforestation in the Central Yucatan Peninsula has not been empirically assessed. We evaluate different drivers and their relationship to forest cover change between 1986 and 2015 and assess how land tenure and Mennonite communities impact forest cover loss in the Municipality of Hopelchen, Campeche, Mexico. This study shows that forest cover loss has increased in the last decade (2005–2015), and that land tenure regime type is associated with this loss. Throughout the study period, statistical comparisons show rates of forest cover loss were significantly higher in private and federal property compared to forests in ejidos (communal property). Forest cover loss in Mennonite private property was also significantly higher than in non-Mennonite owned private property. The role of land tenure and the expansion of the agroindustrial production model as major drivers of forest cover loss in the region provide important insight into developing municipal land use plans and conservation strategies to reduce deforestation. Programs, incentives and policy directed towards forest conservation in the region that typically target ejido communities, will need to consider the growing trend of private property expansion within federal lands and work more closely with private property owners including Mennonite communities if deforestation reduction programs are to be successful.     

Forest transitions: An introduction

When people speak about ‘forest transitions’, they generalize about the ways in which the extent of forested land changes as societies undergo industrialization and urbanization. Alexander Mather coined the term ‘forest transition’, outlined a theory to explain it, and carried out a series of careful historical studies to illustrate the idea. The papers assembled in this special issue both extend and deepen Mather's pathbreaking work. They suggest that the idea of the forest transition, like the much critiqued idea of a demographic transition in population studies, has become a useful theoretical tool for understanding contemporary land use changes.     

Modeling of ecosystem services informs spatial planning in lands adjacent to the Sarvelat and Javaherdasht protected area in northern Iran

Dynamic models of ecosystem services supply and scenario analysis of changes in multiple services are being increasingly used to support land use planning and decision making. This approach reduces potential and real conflicts among various stakeholders potentially creating win–win solutions for all. It is particularly applicable in areas where insufficient land for agriculture and settlements is resulting in high rates of conversion of natural forest and grasslands. We quantified and mapped multiple ecosystem services, including habitat provision as a proxy for biodiversity, carbon storage and sequestration, and water balance and supply in the Sarvelat and Javaherdasht region of the globally-significant Hyrcanian (Caspian) forests in northern Iran using the Integrated Valuation of Ecosystem Services and Tradeoffs tool. This region is experiencing a rapidly increasing rate of forest conversion and as a result, the protected area located within the study landscape is threatened by human encroachment. Plausible future landscapes were modeled under three scenarios: (i) business as usual; (ii) protection-based zoning which reflects an expansion of the protected area boundary to prevent land use changes; and (iii) collaborative zoning through redefining the protection boundary simultaneously with an adjustment to meet local stakeholders’ objective of expansion of anthropogenic cover. The results showed that the collaborative zoning scenario would best contribute to effective policy because it presents a more rational spatial configuration of the landscape maintaining the provision of ecosystem services. This scenario may lead to reduced environmental impacts while achieving less conflict between the government and local communities. These results will help to inform and shape natural resource management policies in Iran and is applicable elsewhere in the world.     

The demise of swidden-fallow agriculture in an Atlantic Rainforest region: Implications for farmers’ livelihood and conservation

The Brazilian Atlantic Forest is widely recognized for its high levels of biodiversity and endemism. Its vast region concentrates also a large number of small farmers, who historically have been practicing swidden-fallow cultivation. Globally, there is contradictory evidence of the current fate of this traditional, integrated agricultural system, and the new land uses may have a strong impact on farmers’ livelihoods and ecosystem conservation. In this study, we assessed the land cover and land use change in a watershed where slash-and-burn cultivation was prevalent, aiming at understanding the drivers of change and discussing past and possible future impacts, including the perception of farmers on the drivers of land use change. We combined information gathered from interviews with 15 key informant farmers and from the analysis of remote sensing images for the years 1957, 1978 and 2011. Swidden-fallow cultivation has declined steadily since the 1950s. Part of the land was abandoned and forest succession was allowed to occur, increasing the total forest area; an apparently positive outcome. However, conversion to pastures and Eucalyptus plantations not only used much of the open land but also converted successional forests through deforestation, based on remote sensing. The willingness of farmers to grow more Eucalyptus and raise more cattle further increases concerns about the prospect for conservation. Our approach, combining remote sensing-based land change quantification and interviews, revealed to be complementary, allowing a better understanding of the past and possible future scenarios for the land use dynamics.     

Towards productive landscapes: Trade-offs in tree-cover and income across a matrix of smallholder agricultural land-use systems

One of the main causes of tropical forest loss is conversion to agriculture, which is constantly increasing as a dominant land cover in the tropics. The loss of forests greatly affects biodiversity and ecosystem services. This paper assesses the economic return from increasing tree cover in agricultural landscapes in two tropical locations, West Java, Indonesia and eastern Bangladesh. Agroforestry systems are compared with subsistence seasonal food-crop-based agricultural systems. Data were collected through rapid rural appraisal, field observation, focus groups and semi-structured interviews of farm households. The inclusion of agroforestry tree crops in seasonal agriculture improved the systems’ overall economic performance (net present value), even when it reduced understorey crop production. However, seasonal agriculture has higher income per unit of land area used for crop cultivation compared with the tree establishment and development phase of agroforestry farms. Thus, there is a trade-off between short-term loss of agricultural income and longer-term economic gain from planting trees in farmland. For resource-poor farmers to implement this change, institutional support is needed to improve their knowledge and skills with this unfamiliar form of land management, sufficient capital for the initial investment, and an increase in the security of land tenure.     

Designating tree crops as forest: Land competition and livelihood effects mediate tree crops impact on natural forest cover in south China

The Chinese government applies the term ‘tree crops’ (jingjilin) to a bundle of tree species with uses other than timber production, defining this category as a component of national forest statistics. Tree crops may displace either farmland or forestland, and can be a promising livelihood option for smallholders. The overall impact of this particular policy on natural forest growth remained unanswered. In the general expansion trend of tree cover in southern China, tree crops could compete for land with natural forests, their cultivation may pose environmental trade-offs with natural forest cover. However, in a context of large labor flows from countryside to cities, tree crops could provide promising opportunities for dealing with on-farm labor shortages and generating income for disadvantaged populations remaining in rural communities, then promoting remaining natural forest quality through alternative livelihoods process. There is a knowledge gap to thoroughly investigate tree crops’ impact on natural forest change both conceptually and empirically, especially a mechanism verification of the alternative livelihood hypothesis. Thus, we construct a framework assessing land use competition and alternative livelihood effects together to assess overall impacts of tree crop cultivation on natural forests. Our dataset combines forest resource inventory data and provincial social-economic factors for a panel analysis of contributions to change in natural forest cover, density, and stock in China’s biodiversity-rich southern provinces. Results show tree crop cover is negatively associated with natural forest extent, but positive associated with change in natural forest density, while the relationship with change in natural forest stock is insignificant. Further tests of mechanisms support the hypothesis that tree crops benefit disadvantaged rural populations, providing an alternative livelihood. Defining tree crops as forest in China obscures important patterns, particularly a trade-off between tree crops and natural forest cover and a possible synergy with natural forest density mediated by alternative livelihood processes. Policy makers should enact specific policies to incentivize natural forest recovery in the southern collective forest zone and reconsider the appropriateness of defining tree crops as forest. Concentration and intensification of tree crop production on suitable lands may have the potential to benefit both forests and impoverished populations.     

Carbon Sequestration and Conservation of Tropical Forests Under Uncertainty

Concern for global warming has focused attention on the role of tropical forests in the reduction of ambient CO₂ levels and mitigation of climate change. Deforestation is a major land use change in the tropics, with forest resources undergoing degradation through the influence of logging and conversion to other uses. Land use change is a product of varied local and regional resource use policies. Management of forest resources is one such major temporal factor, influencing resource stability and the carbon pool. Under a given management policy, both the long period of forest growth, and the slow turnover and decay of the carbon pool, enhance the relevance of stand level management policies as cost-effective mechanisms mitigating climate change. Apart from regional level uncertainties like the nature of land use and the estimation of carbon storage in vegetation and soil, the carbon flux of tropical forests is greatly influenced by uncertainty in regenerative capacity of forests and in harvest and management policies. A case study from India is used to develop a transition matrix model of natural forest management, and to explore the economic implications of maintaining and expanding existing carbon sinks. The study further explores the significance of investments in additional carbon sinks in plantation forests, given continued uncertainty in natural forest management.