Integrating Agricultural Landscapes with Biodiversity Conservation in the Mesoamerican Hotspot

The major challenge in tropical land management is to meet the ever-growing demand for agricultural products while conserving biodiversity, providing critical ecosystem services, and maintaining rural livelihoods. This challenge is particularly acute in the Mesoamerican biodiversity hotspot, a region of high conservation value for both wild and domesticated species that is undergoing rapid human population growth, ecological degradation, and loss of traditional farming systems (Myers et al. 2000; Harvey et al. 2005a). Approximately 80% of the region's vegetation has been converted to agriculture, threatening biodiversity. More than 300 of the region's endemic species of flora and fauna are threatened, including at least 107 that are critically endangered (CI 2007). With continuing habitat loss (deforestation is 1.2%/year in Central America and Mexico combined; FAO 2005) and fragmentation of remaining forests, pressure on the region's biodiversity will intensify. Habitat destruction and fragmentation are not the only drivers of biodiversity loss in the region, however. Globalization of market forces, agricultural industrialization, migration, public policy, and cultural changes are driving the transformation of diverse, traditional, smallholder agroecosystems into agroindustrial systems dependent on chemical inputs and mechanization (Conway & Rosset 1996; Perfecto et al. 1996; Angelsen & Kaimowitz 2001). Agroindustrial intensification is often accompanied by significant reductions in tree cover, fallow vegetation, habitat diversity, and forest connectivity. These transformations directly threaten species dependent on natural habitat and undermine indigenous management practices that coevolved with this biodiversity for over 10,000 years (Nigh & Levy Tacher 2008). Despite considerable efforts to protect biodiversity in reserves and parks in Mesoamerica, many of these refuges are small, fragmented, isolated, or poorly protected (Miller et al. 2001), and not all ecosystems or species are represented adequately (Powell et al. 2000; Rodrigues et al. 2004). Besides having inadequate dimensions, most protected areas are embedded within an agricultural landscape, and existing buffer zones are inadequate to alleviate effects of fragmentation, contamination by agrochemicals, hunting, and unsustainable or illegal logging (DeFries et al. 2005). The fate of biodiversity within protected areas is therefore inextricably linked to the broader landscape context, including how the surrounding agricultural matrix is designed and managed (Wallace et al. 2005; Vandermeer et al. 2007). Protecting biodiversity while sustaining agricultural productivity, indigenous cultures, and rural livelihoods, requires a new approach to conservation, particularly in regions such as Mesoamerica, where substantial habitat conversion has already occurred. In contrast to the prevailing trend of managing protected areas and productive lands separately, we propose integrated landscape management in which conservation and production units within the agricultural matrix are managed jointly for long-term sustainability. We do not advocate agricultural intensification to spare further forest conversion (e.g., Green et al. 2005) because this approach is unlikely to have the intended outcome, for reasons discussed elsewhere (Vandermeer & Perfecto 2005, 2007; Matson & Vitousek 2006). Instead conservation efforts should be based on the recognition that how agriculture is conducted and how different land uses are distributed spatially and temporally determine the region's biodiversity (Perfecto & Vandermeer 1997; McNeely & Scherr 2003). Lasting conservation will therefore require alliances among conservation biologists, farmers, and land managers to actively plan the future of Mesoamerican landscapes. Here we use an integrated landscape approach to highlight opportunities for achieving long-term conservation in Mesoamerica. We provide an overview of the potential for agricultural landscapes and traditional smallholder farming to conserve biodiversity, propose an urgent action agenda to guide conservation in agricultural landscapes and stem the loss of biodiversity and traditional farming systems, and outline key socioeconomic, legal, and political conditions needed for successful implementation of the action plan. Although our examples and recommendations focus on Mesoamerica, our approach is relevant to other regions where there are similar challenges to conserving biodiversity in human-modified landscapes. An increasing number of studies in Mesoamerica show that certain agricultural landscapes and traditional smallholder practices contribute to biodiversity conservation (e.g., Estrada & Coates-Estrada 2002; Daily et al. 2003; Mayfield & Daily 2005) and at the same time contribute to increased food production and rural income (Pretty et al. 2003). In particular, heterogeneous agricultural landscapes that retain abundant tree cover (as forest fragments, fallows, riparian areas, live fences, dispersed trees, or shade canopies) provide complementary habitats, resources, and landscape connectivity for a significant portion of the original biota (e.g., Harvey et al. 2006a; Sekercioglu et al. 2007). Landscape configurations that connect forest patches, maintain a diverse array of habitats, and retain high structural and floristic complexity generally conserve more species than landscapes lacking connectivity or habitat complexity (Benton et al. 2003; Bennett et al. 2006). In addition, agricultural landscapes with abundant tree cover serve as buffers for remaining natural areas (Wallace et al. 2005) and contribute regionally to the maintenance of important ecosystem services, such as natural pest management, carbon sequestration, and water and soil conservation (Daily 1997; Soto-Pinto et al. 2002). Within agricultural landscapes, forested and nonforested habitats contribute to biodiversity conservation. Forest fragments, riparian forests, tree plantations, and other types of remnant and introduced tree cover serve as habitats for many species, enhance landscape connectivity, and retain potential for forest regeneration and restoration (Chazdon 2003; Harvey et al. 2006a). Nevertheless, other types of land uses, such as diverse coffee agroforestry (e.g., Moguel & Toledo 1999; Komar 2006), cocoa agroforestry (Rice & Greenberg 2000; Harvey et al. 2006b), silvopastoral systems (Harvey et al. 2005b, 2006a), and traditional agroecological land uses (such as diverse polycultures, organic farming, and swidden agriculture; Finegan & Nasi 2004) also harbor high levels of both wild and agricultural biodiversity and offer much greater conservation value than the agroindustrial systems that typically replace them. In general, biodiversity-friendly land uses are those that mimic the structural and floristic diversity of native vegetation and rely the least on agrochemicals (Tscharntke et al. 2005). The diverse agroecology systems and landscapes described above are typically (but not always) managed by smallholders (campesinos) and indigenous farmers. Although most environmentally friendly farming practices are not scale-specific in principle, landscapes that are composed of many small farms often demonstrate a high potential for sustaining both biodiversity and rural livelihoods (Rosset 1999). Small farmers are more likely to know their land intimately, embrace complexity and multifunctionality, retain multiple traditional varieties, focus on inputs of knowledge and labor rather than purchased agrochemicals and mechanization, and grow food for nearby consumption instead of commodities for export (Netting 1993; Nazarea 2006). Thus, conservation of biodiversity will often be well served by policies that favor smallholders, promote diverse farming landscapes, and support dissemination of traditional practices and agroecological knowledge (Castillo & Toledo 2000). On the basis of existing evidence and experiences, we propose an action agenda to seize opportunities to reconcile farming and biodiversity conservation and to respond to the immediate threats of biodiversity loss and unsustainable farming. The goal of the action agenda is to achieve sustainable and resilient landscapes in which conservation and agricultural production objectives are accomplished in mutually reinforcing ways. The specific conservation goals are to conserve plant and animal biodiversity; maintain intact habitats, ecological communities, and ecosystem functions; buffer existing protected areas; maintain landscape connectivity; and retain landscape resilience to disturbance and climate change. The agricultural goals are to fulfill human livelihood needs, sustain yields, conserve indigenous and smallholder agroecosystems and associated knowledge and culture, diversify products, minimize reliance on external inputs, and reduce vulnerability to natural disasters and climate change. Our action agenda contains six strategies (Table 1). The first consists of working with stakeholders in a participatory approach to identify priority landscapes where action for conservation and agricultural sustainability will bring the greatest results. Numerous tools already identify areas with high conservation value and the greatest need for protection (e.g., key biodiversity areas [Eken et al. 2004] and priority ecoregions [Olson & Dinerstein 2002]), but these tools rarely include information on rural livelihoods and agricultural systems. We advocate combining the analysis of biodiversity hotspots (Myers et al. 2000) with the identification of rural hotspots, where traditional smallholder livelihoods are most vulnerable and where agroecological systems and knowledge are being rapidly lost. This approach would allow the identification of landscapes where conservation priorities and rural development priorities overlap and where integration is most likely to succeed. Landscapes that are likely to emerge as priorities include those located near protected areas or in key biological corridors, those that conserve high diversity of traditional and indigenous crops, and those with high forest and tree cover that are being rapidly encroached upon by intensive agriculture or urbanization. In contrast, agricultural landscapes that are already dominated by agroindustrial production (such as industrially grown sugarcane, pineapple, or banana) are less likely to warrant attention because the chances of reconciling farming and biodiversity conservation there are slim. The second strategy is to address major threats to biodiversity within priority landscapes. Common threats include illegal logging, irresponsible use of agrochemicals, forest degradation by cattle grazing, shortening of fallows, unsustainable collection of firewood and other products, and conversion of diversified agricultural systems to agroindustrial monocultures with low biodiversity value (Carrillo & Vaughan 1994; Harvey et al. 2005a). Measures should be taken to mitigate these threats. For example, planting multipurpose trees on farms offers an alternative to firewood extraction from native forests (Barrance & Hellin 2003); integrated fire management (including prescribed burns, establishment of fire breaks, and training in sensible fire use) reduces unintended burning of native forests (Myers 2006); and adopting organic practices and integrated pest management can reduce dependence on pesticides (Kogan 1998; Morales & Perfecto 2000). Nevertheless, these promising approaches need to be applied systematically over large areas, with active participation and leadership of local rural communities (Nelson 1994). The protection of remaining native habitat (whether intact forest, wetland, or grassland) constitutes the third key strategy for conserving biodiversity and maintaining rural livelihoods in agricultural landscapes. Native habitat protection should continue to form the cornerstone of conservation activities because they provide resources to native species, maintain intact ecological communities, serve as genetic sources for recolonization of the agricultural matrix, and buffer against extreme weather events and climate change (Bengtsson et al. 2003; Taberelli & Gascon 2005). Large, contiguous areas of native habitat and vegetation along riparian areas (that form natural corridors) are of particularly high conservation value and should be priorities. Nevertheless, even small (<5 ha) and degraded forest patches can be important for some species, providing additional resources and landscape connectivity (Sekercioglu et al. 2007). Protecting native habitats within the agricultural landscape also benefits rural communities by providing products and ecosystem services such as pollination, pest management, flood control, and nutrient cycling on which agricultural systems (and farmers) depend (Ricketts 2004; Naidoo & Ricketts 2006). A fourth key strategy is to protect, diversify, and sustainably manage the heterogeneous tree cover within the agricultural matrix. On-farm tree cover contributes to biodiversity conservation by providing additional habitats and resources for plant and animal species and enhancing landscape connectivity (Schroth et al. 2004; Harvey et al. 2005b). In addition, tree cover in pastures and fields confers benefits to farmers, providing products (fruit, wood, fodder for livestock), ameliorating microclimatic conditions, and increasing soil fertility (Nair 1989). Nevertheles, trees may also reduce agricultural productivity through competition for light, water, and nutrients and serve as hosts for pest species (Ong & Huxley 1996). A key challenge is therefore to integrate tree species in densities and spatial arrangements that minimize competition and shading of agricultural land, yet still provide biodiversity benefits. Low densities of trees scattered across the agricultural matrix and linear plantings of trees along farm and field boundaries are often compatible with existing production systems and therefore are easily adopted by farmers (Harvey et al. 2005b). A fifth strategy is to promote and conserve traditional and ecologically based agricultural practices and indigenous knowledge practices, such as agroforestry, swidden agriculture, home gardens, low-input agriculture, polycultures, and traditional milpas. These agroecological systems conserve high levels of both agrobiodiversity and wild biodiversity, ensure better soil management, and minimize agrochemical use. Throughout Mesoamerica, numerous academic, governmental, and nongovernmental organizations (e.g., CATIE, ECOSUR, EARTH, Campesino a Campesino, PROMECAFE, ACICAFOC, Sustainable Agriculture Network; Harvey et al. 2005a) already promote the use of ecological agriculture and traditional knowledge, but these efforts need to be scaled up to cover a greater proportion of the region's agricultural lands and communities. Last, agricultural land that is highly degraded, unproductive, or unsuitable (e.g., prone to erosion or colonized by exotic species) should be reforested or allowed to regenerate naturally (Montagnini 2001; Lamb et al. 2005). Restoration goals can range from restoring soil fertility for agricultural use to establishing tree plantations or forests for timber or biodiversity conservation. Reforestation efforts should include diverse mixtures of native tree species, including species that provide resources to wildlife and species that have high timber value and provide future income to local farmers. Information on many native species that could be used in large-scale restoration efforts is available (e.g., Hooper et al. 2002; Wishnie et al. 2007). Restoration can also be achieved through natural regeneration, especially where remaining tree cover provides a source of propagules. Natural regeneration can be facilitated by fencing off areas to prevent cattle entry (Guevara et al. 2004), permitting light grazing to reduce competition from grasses on tree seedlings (Posada et al. 2000), using cattle to disperse tree seeds (Miceli-Méndez et al. 2007), or retaining isolated trees or live fences that serve as nuclei for natural regeneration (Slocum 2001; Zahawi & Augspurger 2006). The use of enrichment planting in fallows can also facilitate soil restoration (Finegan & Nasi 2004). An efficient implementation of the six strategies outlined above requires that certain enabling conditions be in place at local, regional, and/or national levels. We focus here on 5 major types of programs that could facilitate our agenda: providing economic incentives, strengthening and enforcing legislation, encouraging farmer alliances, promoting sustainable agriculture certification programs, and ensuring political support (Table 2). A variety of economic instruments can be used to encourage farmers to conserve forests, retain tree cover, adopt biodiversity-friendly cropping systems, and to cover additional costs these activities may involve. Payments for environmental services (PES) hold particular promise. A Costa Rican PES scheme, in which farmers receive payments for protecting existing forest and for integrating trees into their farming systems, has worked well (Pagiola et al. 2005a; Zbinden & Lee 2005) and similar schemes are now being applied in Honduras, Guatemala, Mexico, and Nicaragua (Kosoy et al. 2007). Although PES schemes appear to be successful in conserving forest cover, they could have a greater positive impact on rural landscapes and livelihoods if they included payments for a greater diversity of sustainable land uses, removed inappropriate access restrictions (such as minimum land size), lowered transaction costs, and carefully targeted priority landscapes that have the greatest potential to conserve both biodiversity and rural livelihoods (Grieg-Gran et al. 2005; Pagiola et al. 2005b). Another economic tool with potential to reduce the conflict between conservation and farming is carbon financing for either enhancing carbon sequestration (e.g., reforestation, agroforestry, and improved agricultural land management) or reducing emissions from deforestation (Orlando et al. 2002; Moutinho & Schwartzman 2005). Reforestation activities are already eligible for funding under the Clean Development Mechanism (CDM) of the Kyoto Protocol, and the rapidly expanding voluntary markets for carbon offer new opportunities for forest restoration and conservation (Bayon et al. 2007). The complexity and high costs of CDM projects have generally small and farmer organizations from et al. 2007), but as the carbon market and demand for carbon will opportunities for farmers. such as the in Mexico, which provides smallholder farmers with access to carbon are already the et al. 1997; & 2000). In to economic incentives, our action agenda requires increasing and new that logging and agrochemical and land and conservation of forests, riparian vegetation, and tree cover et al. 2005; et al. 2005). The of Costa as a of can be achieved in the the carefully forest of and forest conversion to other land uses, logging within on on either of and the for the PES that for forest conservation and 1996). is only the first are logging for of production in and in Nicaragua et al. 2003). of and environmental by systematically forest cover, and managing is critical for forest conservation. In addition, that the establishment of conservation buffer and conservation will likely encourage natural habitat conservation on lands et al. 2000; et al. 2005). The strengthening of alliances among farmers, and conservation will also promote ecologically sustainable production systems and to approaches to biodiversity conservation and food et al. 2007; Vandermeer & Perfecto 2007). The active participation of the more than Mesoamerican farmers will be critical for long-term conservation alliances, and that promote already but these often resources to be cover only a small proportion of the region's or have than the integrated approach we are to support these types of organizations and Our action agenda could also be by efforts to small farmers with markets for agricultural and forest commodities that have been with impact on biodiversity. These biodiversity-friendly are by certification programs by of Agriculture Forest and 2003; et al. 2007). of the schemes require to with environmental such as planting trees along agrochemical and planting native vegetation along also protect farm and ensure they are working conditions, and Nevertheless, or of is often transaction costs and often and are to high levels of participation 2003; 2003). political support at all levels is needed to the strategies outlined there are positive that Mesoamerican are of the of biodiversity conservation and the need to conservation with sustainable rural Mesoamerican are of the on and have to biodiversity action that ensure protection and sustainable use of biodiversity 2005). In addition, there are many programs (e.g., and and even a for in 2005) that to some the need for reconciling biodiversity conservation and rural The have also to the Mesoamerican an to existing protected areas within and between to facilitate of plant and animal species (Miller et al. 2001). be this large-scale will require the management of the agricultural landscapes in which the protected areas are embedded and will depend on the strategies outlined in our the generally positive and promising political there is a of action on the In many the political will has not yet been into funding for implementation is and support for and is place greater attention on their for sustainable development in rural regions with resources and We for a new approach to biodiversity conservation within Mesoamerican that a focus on ecologically sustainable agriculture with existing efforts in protected areas to achieve conservation at local and levels. This new approach farmers as stakeholders in conserving biodiversity and actively farmers as to resilient landscapes that wildlife and rural livelihoods and local Our action agenda provides strategies for reconciling farming and conservation and key socioeconomic, legal, and political that could their our agenda could significant positive changes for both conservation and farming. is however. Landscapes may be degraded that conservation and restoration will be and traditional knowledge may be We therefore farmers, and other stakeholders to actively and manage landscapes to a future for both biodiversity and rural livelihoods in Mesoamerica. This by a of the on and of Landscapes of Mesoamerica by the for and by the the of and the of The working by and We are to the for the