Assessing effects of land use on landscape connectivity: loss and fragmentation of western U.S. forests

Effects of land-use change on the conservation of biodiversity have become a concern to conservation scientists and land managers, who have identified loss and fragmentation of natural areas as a high-priority issue. Despite urgent calls to inform national, regional, and state planning efforts, there remains a critical need to develop practical approaches to identify where important lands are for landscape connectivity (i.e., linkages), where land use constrains connectivity, and which linkages are most important to maintain network-wide connectivity extents. Our overall goal in this paper was to develop an approach that provides comprehensive, quantitative estimates of the effects of land-use change on landscape connectivity and illustrate its use on a broad, regional expanse of the western United States. We quantified loss of habitat and landscape connectivity for western forested systems due to land uses associated with residential development, roads, and highway traffic. We examined how these land-use changes likely increase the resistance to movement of forest species in non-forested land cover types and, therefore, reduce the connectivity among forested habitat patches. To do so, we applied a graph-theoretic approach that incorporates ecological aspects within a geographic representation of a network. We found that roughly one-quarter of the forested lands in the western United States were integral to a network of forested patches, though the lands outside of patches remain critical for habitat and overall connectivity. Using remotely sensed land cover data (ca. 2000), we found 1.7 million km2 of forested lands. We estimate that land uses associated with residential development, roads, and highway traffic have caused roughly a 4.5% loss in area (20 000 km2) of these forested patches, and continued expansion of residential land will likely reduce forested patches by another 1.2% by 2030. We also identify linkages among forest patches that are critical for landscape connectivity. Our approach can be readily modified to examine connectivity for other habitats/ecological systems and for other geographic areas, as well as to address more specific requirements for particular conservation planning applications.     

Incentive Structure of and Private Landowner Participation in an Endangered Species Conservation Program

Abstract: In the United States, voluntary incentive programs that aid conservation of plant and wildlife species on private lands provide a structural solution to the problem of protecting endangered species by reducing costs and enhancing benefits to landowners. We explored the potential for incentives to encourage landowners to manage land cover for the benefit of endangered songbirds in central Texas (U.S.A.) by asking landowners to indicate their preferences for financial incentives, technical assistance, and regulatory assurances. We identified owners of potential songbird habitat and collected data in face‐to‐face interviews and self‐administered questionnaires. We used a latent‐class stated‐choice model to identify 3 classes of landowners whose choices varied on the basis of their attitudes and perceived social norms: (1) strong positive attitude, perceived social pressure to participate, and willing to participate with relatively few incentives, (2) weak positive attitude, perceived no social pressure to participate, and required strongest incentives, and (3) negative attitude, perceived social pressure not to enroll, and unwilling to participate regardless of incentive structure. Given this heterogeneity in preferences, conservation incentives may increase management of land cover to benefit endangered species on private lands to some degree; however, exclusive reliance on incentives may be insufficient. Promoting conservation on private lands may be enhanced by integrating incentives into an approach that incorporates other strategies for conservation, including social networks and collaborative processes that reinforce social norms.     

Incorporating private lands in conservation planning: protected areas in Britain.

Evaluations of the effectiveness of protected areas often report their inadequate representation of regional variation in environmental conditions, land cover, and biological diversity. One frequent contributory explanation is the heavy reliance placed upon the designation of public as opposed to private lands for statutory protection. Given that protected area designation in Britain has no such constraint, and indeed that more than half of such areas are on private lands, we tested the a priori assumption that within this region the representation of environmental conditions and land cover within statutory protected areas would be more equitable. Despite the reduction in land ownership constraints on where protected areas can be established, a marked bias in protected area coverage remains. Protected areas in Britain tend toward regions of higher elevation, soils of lower economic potential, and coastal/estuarine habitat and fail adequately to represent areas of lower elevation and woodland habitats. Improving the current situation requires not only a more systematic approach to site selection, but a more equitable and diverse portfolio of incentives for private landowners to facilitate the decision to manage sites for conservation.     

Influence of environment, disturbance, and ownership on forest vegetation of coastal Oregon.

Information about how vegetation composition and structure vary quantitatively and spatially with physical environment, disturbance history, and land ownership is fundamental to regional conservation planning. However, current knowledge about patterns of vegetation variability across large regions that is spatially explicit (i.e., mapped) tends to be general and qualitative. We used spatial predictions from gradient models to examine the influence of environment, disturbance, and ownership on patterns of forest vegetation biodiversity across a large forested region, the 3-million-ha Oregon Coast Range (USA). Gradients in tree species composition were strongly associated with environment, especially climate, and insensitive to disturbance, probably because many dominant tree species are long-lived and persist throughout forest succession. In contrast, forest structure was strongly correlated with disturbance and only weakly with environmental gradients. Although forest structure differed among ownerships, differences were blurred by the presence of legacy trees that originated prior to current forest management regimes. Our multi-ownership perspective revealed biodiversity concerns and benefits not readily visible in single-ownership analyses, and all ownerships contributed to regional biodiversity values. Federal lands provided most of the late-successional and old-growth forest. State lands contained a range of forest ages and structures, including diverse young forest, abundant legacy dead wood, and much of the high-elevation true fir forest. Nonindustrial private lands provided diverse young forest and the greatest abundance of hardwood trees, including almost all of the foothill oak woodlands. Forest industry lands encompassed much early-successional forest, most of the mixed hardwood-conifer forest, and large amounts of legacy down wood. The detailed tree- and species-level data in the maps revealed regional trends that would be masked in traditional coarse-filter assessment. Although abundant, most early-successional forests originated after timber harvest and lacked legacy live and dead trees important as habitat and for other ecological functions. Many large-conifer forests that might be classified as old growth using a generalized forest cover map lacked structural features of old growth such as multilayered canopies or dead wood. Our findings suggest that regional conservation planning include all ownerships and land allocations, as well as fine-scale elements of vegetation composition and structure.     

The importance of agricultural lands for Himalayan birds in winter

The impacts of land‐use change on biodiversity in the Himalayas are poorly known, notwithstanding widespread deforestation and agricultural intensification in this highly biodiverse region. Although intact primary forests harbor many Himalayan birds during breeding, a large number of bird species use agricultural lands during winter. We assessed how Himalayan bird species richness, abundance, and composition during winter are affected by forest loss stemming from agriculture and grazing. Bird surveys along 12 elevational transects within primary forest, low‐intensity agriculture, mixed subsistence agriculture, and intensively grazed pastures in winter revealed that bird species richness and abundance were greatest in low‐intensity and mixed agriculture, intermediate in grazed pastures, and lowest in primary forest at both local and landscape scales; over twice as many species and individuals were recorded in low‐intensity agriculture than in primary forest. Bird communities in primary forests were distinct from those in all other land‐use classes, but only 4 species were unique to primary forests. Low‐, medium‐, and high‐intensity agriculture harbored 32 unique species. Of the species observed in primary forest, 80% had equal or greater abundance in low‐intensity agricultural lands, underscoring the value of these lands in retaining diverse community assemblages at high densities in winter. Among disturbed landscapes, bird species richness and abundance declined as land‐use intensity increased, especially in high‐intensity pastures. Our results suggest that agricultural landscapes are important for most Himalayan bird species in winter. But agricultural intensification—especially increased grazing—will likely result in biodiversity losses. Given that forest reserves alone may inadequately conserve Himalayan birds in winter, comprehensive conservation strategies in the region must go beyond protecting intact primary forests and ensure that low‐intensity agricultural lands are not extensively converted to high‐intensity pastures.     

Planning for Long, Wide Conservation Corridors on Private Lands in the Oak Ridges Moraine, Ontario, Canada

Abstract:  We explored the role of conservation biology in the planning of a natural-heritage system that includes long, wide conservation corridors situated primarily on private lands, and established to connect natural core areas in the Oak Ridges Moraine of Ontario, Canada. We based our review on government documents, semi-structured interviews with participants involved in this land-use planning process, and our involvement with the issue from 1990 through 2002. Conservation biology had a major influence on the outcome of the land-use planning process for this moraine. The landform was identified as an area of value by the environmental movement within the context of a number of ongoing government studies that began in the late 1980s and early 1990s. Conservation biologists and planners in government, the environmental movement, and the private sector carried out work related to conservation biology, including inventories and the development and application of criteria for the delineation of core areas and conservation corridors. Once the political timing was favorable (2001–2002), decision makers linked the science of conservation biology to planning policies and law in Ontario. The Oak Ridges Moraine land-use planning process was precedent setting in Canada, and possibly internationally. To our knowledge this is the first time long, wide conservation corridors on private lands were regulated through land-use-planning legislation and led to restrictions on urban development and aggregate resource extraction.     

Songbird Use of Gallery Woodlands in Recently Cleared and Older Settled Landscapes of the Selva Lacandona, Chiapas, Mexico

Many regions of Central America have undergone wide-scale habitat change as land has been converted for cultivation or grazing. Clearing for agriculture often leaves a variety of regenerating and remnant patches of wooded vegetation. Of particular importance is arroyo vegetation, or strips of trees or tall shrubs growing along streams. Although it is widely acknowledged that tropical arroyo vegetation supports high densities of birds, as avian habitat it remains poorly studied. We used point counts to study populations of migrant and resident songbirds in the arroyo vegetation of settled areas of the Selva Lacandona adjacent to the Montes Azules Biosphere Reserve of southeastern México. Two study areas were established on lands that had been cleared and settled 20–35 and 10 years previously. Our objectives were to assess the value of arroyo vegetation to the conservation of avian species diversity and abundance in agricultural landscapes and to compare the composition and abundance of songbirds in cleared areas settled at different times over a 35-year period. Arroyo vegetation had a wide diversity of songbird species that, in overall terms, differed little between those landscapes cleared recently and those cleared up to 35 years previously. In both areas we found a high abundance of habitat generalists and a smaller number of forest-dependent species, particularly migrants. Loss of forest specialists occurs rapidly, with little further loss as the arroyos become increasingly isolated. Our data also suggest that birds do not crowd into limited habitat as the surrounding vegetation is eliminated, implying that the overall carrying capacity of the agricultural landscape is greatly enhanced as larger areas of arroyo vegetation are protected. Protection of arroyo vegetation will increase the diversity of birds living in agricultural areas and can be achieved simply by expanding upon land-use practices currently in use.     

Devising Appropriate Policies and Instruments in Support of Private Conservation Areas: Lessons Learned from the Klein Karoo,South Africa

Abstract: The amount of privately conserved land is increasing worldwide. The potential of these areas to contribute to the global conservation of biodiversity is significant, given that statutory protected areas alone will not suffice. Nevertheless, there is still inadequate support for private conservation areas, and further research on appropriate, flexible, and generally applicable incentive measures is necessary. We conducted 25 semistructured interviews with the owners of private conservation areas in the Little Karoo, South Africa, to examine landowner opinions of existing conservation policies and their relationships with the local conservation authority. We also assessed landowner preferences regarding conservation incentive measures. Landowners doubted the conservation authority's capacity to implement its stewardship program and were also discouraged by the bureaucracy of the program. The conservation authority was often viewed negatively, except where landowners had experienced personal contact from conservation staff or where strong social capital had formed among landowners. Landowners did not desire financial rewards for their conservation efforts, but sought recognition of their stewardship role and greater involvement from the conservation authority through personal contact. We conclude that conservation policies for private lands could benefit from the provision of extension services to landowners, promotion of formation of groups of landowners and other stakeholders, and public acknowledgment of the contributions private conservation areas make.     

Conservation Alliances with Indigenous Peoples of the Amazon

Abstract:  Ongoing alliances between indigenous peoples and conservation organizations in the Brazilian Amazon have helped achieve the official recognition of ∼1 million km² of indigenous lands. The future of Amazonian indigenous reserves is of strategic importance for the fate of biodiversity in the region. We examined the legislation governing resource use on indigenous lands and summarize the history of the Kayapo people's consolidation of their >100,000 km² territory. Like many Amazonian indigenous peoples, the Kayapo have halted the expansion of the agricultural frontier on their lands but allow selective logging and gold mining. Prospects for long-term conservation and sustainability in these lands depend on indigenous peoples' understandings of their resource base and on available economic alternatives. Although forest conservation is not guaranteed by either tenure security or indigenous knowledge, indigenous societies' relatively egalitarian common-property resource management regimes—along with adequate incentives and long-term partnerships with conservation organizations—can achieve this result. Successful initiatives include Conservation International's long-term project with the A'ukre Kayapo village and incipient large-scale territorial monitoring and control in the Kayapo territory, and the Instituto SocioAmbiental (ISA) 15-year partnership with the peoples of the Xingu Indigenous Park, with projects centered on territorial monitoring and control, education, community organization, and economic alternatives. The recent agreement on ecological restoration of the Xingu River headwaters between ranchers and private companies, indigenous peoples, and environmentalists, brokered by ISA, marks the emergence of an indigenous and conservation alliance of sufficient cohesiveness and legitimacy to negotiate effectively at a regional scale.     

Financial Mechanisms for Conservation in Brazil

Abstract:  I reviewed some of the financial mechanisms for biodiversity conservation activities in Brazil. There is a heavy dependence on the public sector, but macroeconomic policies aimed at reducing government spending have resulted in reduced budgets dedicated to public conservation measures. The financial constraints for environmental protection have also increased because of a reduction in foreign aid. Positive signs for the immediate future, however, come from new initiatives that create economic instruments to finance conservation. The most important initiatives include conservation criteria for tax redistribution; environmental compensation; water charges; royalties for electricity, petroleum, and natural gas; tradable obligations for forest reserves; and voluntary measures on the part of the business sector. Resources created from these initiatives have different origins and are managed by different public agencies according to varying laws and policies, so their efficient implementation will require that the institutions involved in biodiversity conservation in Brazil establish a minimum set of common priorities and objectives.     

Potential effects of forest policies on terrestrial biodiversity in a multi-ownership province.

We used spatial simulation models to evaluate how current and two alternative policies might affect potential biodiversity over 100 years in the Coast Ranges Physiographic Province of Oregon. This 2.3-million-ha province is characterized by a diversity of public and private forest owners, and a wide range of forest policy and management objectives. We evaluated habitat availability for seven focal species representing different life histories. We also examined how policies affected old-growth stand structure, age distributions relative to the historical range of variability, and landscape patterns of forest types. Under the current policy scenario, the area of habitat for old-growth forest structure and associated species increased over time, the habitat for some early-successional associates remained stable, and the area of hardwood vegetation and diverse early-successional stages declined. The province is projected to move toward but not reach the historical range of variation of forest age classes that may have occurred under the wildfire regimes of the pre-Euroamerican settlement period. Ownership explained much of the pattern of biodiversity in the province, and under the current policy scenario, its effect increased over time as the landscape diverged into highly contrasting forest structures and ages. Patch type diversity declined slightly overall but declined strongly within ownerships. Most of the modeled change in biodiversity over time resulted from policies on public forest lands that were intended to increase the area of late-successional forests and species. One of the alternative policies, increased retention of wildlife trees on private lands, reduced the contrast between ownerships and increased habitat availability over time for both early- and late-successional species. Analysis of another alternative, stopping thinning of plantations on federal lands, indicated that current thinning regimes improve habitat for the Olive-sided Flycatcher, but the no-thinning alternative had no effect on the habitat scores for the late-successional species in the 100-year simulation. A comparison of indicators of biological diversity suggests that using focal species and forest structural measures can provide complementary information on biodiversity. The multi-ownership perspective provided a more complete synthesis of province-wide biodiversity patterns than assessments based on single ownerships.     

Modeling the forest transition: forest scarcity and ecosystem service hypotheses.

An historical generalization about forest cover change in which rapid deforestation gives way over time to forest restoration is called "the forest transition." Prior research on the forest transition leaves three important questions unanswered: (1) How does forest loss influence an individual landowner's incentives to reforest? (2) How does the forest recovery rate affect the likelihood of forest transition? (3) What happens after the forest transition occurs? The purpose of this paper is to develop a minimum model of the forest transition to answer these questions. We assume that deforestation caused by landowners' decisions and forest regeneration initiated by agricultural abandonment have aggregated effects that characterize entire landscapes. These effects include feedback mechanisms called the "forest scarcity" and "ecosystem service" hypotheses. In the forest scarcity hypothesis, forest losses make forest products scarcer, which increases the economic value of forests. In the ecosystem service hypothesis, the environmental degradation that accompanies the loss of forests causes the value of ecosystem services provided by forests to decline. We examined the impact of each mechanism on the likelihood of forest transition through an investigation of the equilibrium and stability of landscape dynamics. We found that the forest transition occurs only when landowners employ a low rate of future discounting. After the forest transition, regenerated forests are protected in a sustainable way if forests regenerate slowly. When forests regenerate rapidly, the forest scarcity hypothesis expects instability in which cycles of large-scale deforestation followed by forest regeneration repeatedly characterize the landscape. In contrast, the ecosystem service hypothesis predicts a catastrophic shift from a forested to an abandoned landscape when the amount of deforestation exceeds the critical level, which can lead to a resource degrading poverty trap. These findings imply that incentives for forest conservation seem stronger in settings where forests regenerate slowly as well as when decision makers value the future.     

Governing intensification: the influence of state institutions on smallholder farming strategies in Calakmul,Mexico

ABSTRACT

In forest frontiers, smallholder agrarian livelihoods remain uneasily juxtaposed with conservation interests. Agricultural intensification is often considered a viable means of reconciling competing environmental and livelihood objectives given its potential to concentrate production on less land. However, intensification may have unintended consequences, including loss of resilient agricultural systems. The risks of smallholder agricultural intensification warrant a better understanding of its drivers. This study uses the case of Calakmul, Mexico, to examine the critical role of the state in intensification processes. Drawing on household surveys and key-informant interviews, it traces the linkages between state institutions and local farming practices. Statistical and qualitative analyses reveal how intensification is both incentivized and imposed by prevailing policies, the former via subsidies and the latter via regulations against field rotations. The outcome – increased external inputs and longer cultivation periods between fallows – may undermine the sustainability of smallholders’ agroecosystems, an undesirable consequence amid limited livelihood alternatives.     

Modeling Opportunity Costs of Conservation in Transitional Landscapes

Abstract:  Conservation scientists recognize the urgency of incorporating opportunity costs into conservation planning. Despite this, applications to date have been limited, perhaps partly because of the difficulty in determining costs in regions with limited data on land prices and ownership. We present methods for estimating opportunity costs of land preservation in landscapes or ecoregions that are a changing mix of agriculture and natural habitat. Our approach derives from the literature on estimating land values as opportunity costs of alternate land uses and takes advantage of general availability of necessary data, even in relatively data-poor regions. The methods integrate probabilities of habitat conversion with region-wide estimates of economic benefits from agricultural land uses and estimate land values with a discount rate to convert annual values into net present values. We applied our method in a landscape undergoing agricultural conversion in Paraguay. Our model of opportunity costs predicted an independent data set of land values and was consistent with implicit discount rates of 15–25%. Model-generated land values were strongly correlated with actual land values even after correcting for the effect of property size and proportion of property that was forested. We used the model to produce a map of opportunity costs and to estimate the costs of conserving forest within two proposed corridors in the landscape. This method can be applied to conservation planning in situations where natural habitat is currently being converted to market-oriented land uses. Incorporating not only biological attributes but also socioeconomic data can help in the design of efficient networks of protected areas that represent biodiversity at minimum costs.     

Integrating fast feedback and GIS to plan for important agricultural land designations in Kauai County,Hawaii

With increased affluence worldwide, planning for and preserving land for agriculture and conservation have become important goals in many communities. In Hawaii, the identification and designation of Important Agricultural Land (IAL) was first proposed at the 1978 Hawaii Constitutional Convention and approved by voters the same year. The state is required to conserve and protect agricultural lands, promote diversified agriculture, increase agricultural self-sufficiency, and assure the availability of agriculturally suitable lands. Act 183 in 2005 extended these efforts by defining IAL. The law established eight criteria to evaluate IAL and created county-led and landowner-initiated processes for designating IAL. It also specified policies for promoting agricultural production and identified landowner incentives for the designation of IAL. A central challenge facing policymakers is how to operationalize and implement these land use policies. This paper describes methods used to operationalize Act 183. We use fast feedback (i-Clicker technology) devices for capturing stakeholder preferences and geographic information systems and community mapping to visualize policy impacts and integrate community feedback. The methods developed in this paper have broad applications to jurisdictions around the world looking for data-driven approaches to planning and designating land uses according to legislative mandates or administrative requirements.     

Strategic Habitats for Biodiversity Conservation in Florida

Abstract: Privately owned lands support a large portion of the biodiversity in some areas, but procedures for identifying those private lands critical to the maintenance of biodiversity vary tremendously. We used habitat-based distribution maps in combination with population conservation goals to help identify strategic habitats on private lands in Florida. We used a vegetation map, occurrence data, and published life-history information to create habitat-based distribution maps for 179 rare taxa. We estimated the security of 130 of the taxa by overlaying public land boundaries on habitat maps and then estimating whether conservation lands satisfied a population goal of supporting at least 10 populations of approximately 200 breeding adults. The remaining taxa were evaluated in terms of number of occurrence records on conservation lands. Of the 179 taxa evaluated, existing conservation lands did not adequately protect 56. We then identified habitats on private lands that could best satisfy the minimum conservation goal or else significantly enhance the survival potential of inadequately protected taxa. Strategic habitats included a mix of large and small sites, incorporated some corridor or stepping-stone connections among habitat patches, and protected multiple species. Additional strategic habitats were identified for shorebirds, four natural plant communities, and 105 globally rare plants. The strategic habitats identified in Florida cover 1.65 million ha (12% of the land area) and would cost $8.2 billion (about 15% of Florida's annual state budget) to purchase and $122 million per year to manage. Existing conservation lands account for 3.07 million ha (22% of the land area).     

Improving inferences about private land conservation by accounting for incomplete reporting

Private lands provide key habitat for imperiled species and are core components of function protectected area networks; yet, their incorporation into national and regional conservation planning has been challenging. Identifying locations where private landowners are likely to participate in conservation initiatives can help avoid conflict and clarify trade-offs between ecological benefits and sociopolitical costs. Empirical, spatially explicit assessment of the factors associated with conservation on private land is an emerging tool for identifying future conservation opportunities. However, most data on private land conservation are voluntarily reported and incomplete, which complicates these assessments. We used a novel application of occupancy models to analyze the occurrence of conservation easements on private land. We compared multiple formulations of occupancy models with a logistic regression model to predict the locations of conservation easements based on a spatially explicit social–ecological systems framework. We combined a simulation experiment with a case study of easement data in Idaho and Montana (United States) to illustrate the utility of the occupancy framework for modeling conservation on private land. Occupancy models that explicitly accounted for variation in reporting produced estimates of predictors that were substantially less biased than estimates produced by logistic regression under all simulated conditions. Occupancy models produced estimates for the 6 predictors we evaluated in our case study that were larger in magnitude, but less certain than those produced by logistic regression. These results suggest that occupancy models result in qualitatively different inferences regarding the effects of predictors on conservation easement occurrence than logistic regression and highlight the importance of integrating variable and incomplete reporting of participation in empirical analysis of conservation initiatives. Failure to do so can lead to emphasizing the wrong social, institutional, and environmental factors that enable conservation and underestimating conservation opportunities in landscapes where social norms or institutional constraints inhibit reporting.     

Tradeoffs between forestry resource and conservation values under alternate policy regimes: A spatial analysis of the western Canadian boreal plains

An important element of resource management and conservation is an understanding of the tradeoffs between marketed products, such as timber, and measures of environmental quality, such as biodiversity. In this paper, we develop an integrated economic-ecological spatial optimization model that we then apply to evaluate alternate forest policies on a 560,000 km² study region of managed boreal forest in Alberta and British Columbia, Canada. The integrated model incorporates dynamic forest sector harvesting, current levels of oil and gas sector development, coarse-filter or habitat-based old forest indicators, a set of empirical forest bird abundance models, and statistical models of the natural and current fire regimes. Using our integrated model, economic tradeoff curves, or production possibility frontiers, are developed to illustrate the cost of achieving coarse-filter targets by a set time (50 years) within a 100-year time horizon. We found levels of ecological indicators and economic returns from the timber industry could both be increased if spatial constraints imposed by the current policy environment were relaxed; other factors being equal, this implies current policy should be revised. We explore the production possibility frontier's relationship to the range of natural variation of old forest habitat, and show how this range can be used to guide choices of preferred locations along the frontier. We also show that coarse-filter constraints on the abundance of certain habitat elements are sufficient to satisfy some fine-filter objectives, expressed as the predicted abundances of various species of songbirds.     

Ants as a Measure of Effectiveness of Habitat Conservation Planning in Southern California

Abstract: In the United States multispecies habitat conservation plans were meant to be the solution to conflicts between economic development and protection of biological diversity. Although now widely applied, questions exist concerning the scientific credibility of the conservation planning process and effectiveness of the plans. We used ants to assess performance of one of the first regional conservation plans developed in the United States, the Orange County Central‐Coastal Natural Community Conservation Plan (NCCP), in meeting its broader conservation objectives of biodiversity and ecosystem‐level protection. We collected pitfall data on ants for over 3 years on 172 sites established across a network of conservation lands in coastal southern California. Although recovered native ant diversity for the study area was high, site‐occupancy models indicated the invasive and ecologically disruptive Argentine ant (Linepithema humile) was present at 29% of sites, and sites located within 200 m of urban and agricultural areas were more likely to have been invaded. Within invaded sites, native ants were largely displaced, and their median species richness declined by more than 60% compared with uninvaded sites. At the time of planning, 24% of the 15,133‐ha reserve system established by Orange County NCCP fell within 200 m of an urban or agricultural edge. With complete build out of lands surrounding the reserve, the proportion of the reserve system vulnerable to invasion will grow to 44%. Our data indicate that simply protecting designated areas from development is not enough. If habitat conservation plans are to fulfill their conservation promise of ecosystem‐level protection, a more‐integrated and systematic approach to the process of habitat conservation planning is needed.     

Impact of cocoa agricultural intensification on bird diversity and community composition

To meet the growing demand for chocolate, cocoa (Theobroma cacao) agriculture is expanding and intensifying. Although this threatens tropical forests, cocoa sustainability initiatives largely overlook biodiversity conservation. To inform these initiatives, we analyzed how cocoa agriculture affects bird diversity at farm and landscape scales with a meta-analysis of 23 studies. We extracted 214 Hedges' g* comparisons of bird diversity and 14 comparisons of community similarity between a forest baseline and 4 farming systems that cover an intensification gradient in landscapes with high and low forest cover, and we summarized 119 correlations between cocoa farm features and bird diversity. Bird diversity declined sharply in low shade cocoa. Cocoa with >30% canopy cover from diverse trees retained bird diversity similar to nearby primary or mature secondary forest but held a different community of birds. Diversity of endemic species, frugivores, and insectivores (agriculture avoiders) declined, whereas diversity of habitat generalists, migrants, nectarivores, and granivores (agriculture associates) increased. As forest decreased on the landscape, the difference in bird community composition between forest and cocoa also decreased, indicating agriculture associates replaced agriculture avoiders in forest patches. Our results emphasize the need to conserve forested landscapes (land sparing) and invest in mixed-shade agroforestry (land sharing) because each strategy benefits a diverse and distinct biological community.