Protected area, easement, and rental contract data reveal five communities of land protection in the United States.

Land protection efforts represent large societal investments and are critical to biodiversity conservation. Land protection involves a complex mosaic of areas managed by multiple organizations, using a variety of mechanisms to achieve different levels of protection. We develop an approach to synthesize, describe, and map this land protection diversity over large spatial scales. We use cluster analysis to find distinct "communities" of land protection based on the organizations involved, the strictness of land protection, and the protection mechanisms used. We also associate identified land protection communities with socioenvironmental variables. Applying these methods to describe land protection communities in counties across the coterminous United States, we recognize five different land protection communities. Two land protection communities occur in areas with low human population size at higher elevations and include a large amount of protected land primarily under federal management. These two community types are differentiated from one another by the particular federal agencies involved, the relative contributions of smaller actors, and the amount of protection by designations vs. conservation easements or covenants. Three remaining land protection communities have less overall protection. Land in one community is primarily protected by federally managed rental contracts and government managed easements; another is managed by a diversity of non-federal actors through fee-ownership and easements; and the third stands out for having the lowest amount of formally recorded protection overall. High elevation and poor quality soils are over-represented in U.S. protected lands. Rental contracts help fill in gaps in counties with high productivity soil while the U.S. Fish and Wildlife Service fills in gaps in low-elevation counties. Counties with large numbers of threatened species have more and stricter protection, particularly by regional entities like water management districts. The ability to synthesize and map land protection communities can help conservation planners tailor interventions to local contexts, position local agencies to approach collaborations more strategically, and suggest new hypotheses for researchers regarding interactions among different protection mechanisms.

Allocating resources for land protection using continuous optimization: biodiversity conservation in the United States.

Spatial optimization approaches that were originally developed to help conservation organizations determine protection decisions over small spatial scales are now used to inform global or continental scale priority setting. However, the different decision contexts involved in large-scale resource allocation need to be considered. We present a continuous optimization approach in which a decision-maker allocates funding to regional offices. Local decision-makers then use these funds to implement habitat protection efforts with varying effectiveness when evaluated in terms of the funder's goals. We illustrate this continuous formulation by examining the relative priority that should be given to different counties in the coterminous United States when acquiring land to establish new protected areas. If weighting all species equally, counties in the southwest United States, where large areas can be bought cheaply, are priorities for protection. If focusing only on species of conservation concern, priorities shift to locations rich in such species, particularly near expanding exurban areas facing high rates of future habitat conversion (e.g., south-central Texas). Priorities for protection are sensitive to what is assumed about local ecological and decision-making processes. For example, decision-makers who doubt the efficacy of local land protection efforts should focus on a few key areas, while optimistic decision-makers should disperse funding more widely. Efforts to inform large-scale conservation priorities should reflect better the types of choice that decision-makers actually face when working over these scales. They also need to report the sensitivity of recommended priorities to what are often unstated assumptions about local processes affecting conservation outcomes.

Mechanisms driving the density-area relationship in a saproxylic beetle.

Mechanisms underlying density-area relationships (correlations between population density and patch size) have rarely been tested experimentally. It is often assumed that higher density on large patches is evidence that large patches are high quality (i.e. have greater survival and reproduction), but the same pattern could result from disproportionate movement from small to large patches. Movement-based and within-patch processes must be experimentally separated to show that large patches are indeed of higher quality, but few studies have done so. We experimentally tested movement-based and within-patch hypotheses to explain the positive density-area relationship observed for a saproxylic (decayed wood-dependent) beetle, Odontotaenius disjunctus Illiger (Coleoptera: Passalidae). In separate experiments we quantified (1) immigration into and (2) finite growth rate within logs (=patches) that varied in size and density of conspecific beetles. A log was 11.7-fold [95 % confidence interval (CI) 3.4-40.8) and 10.5-fold (95 % CI 2.7-40.9) more likely to contain a new immigrant if it was large or contained a conspecific pair of beetles, respectively. Neither log size nor conspecific density was associated with changes in finite growth rate that would lead to higher density: decreased log size and increased conspecific density reduced finite growth rate in direct proportion to the loss in available resources per mating pair. We conclude that movement behavior rather than habitat quality is responsible for the positive density-area relationship for O. disjunctus. An important implication of our results is that population density is an imperfect indicator of habitat quality.

Factoring economic costs into conservation planning may not improve agreement over priorities for protection.

Conservation organizations must redouble efforts to protect habitat given continuing biodiversity declines. Prioritization of future areas for protection is hampered by disagreements over what the ecological targets of conservation should be. Here we test the claim that such disagreements will become less important as conservation moves away from prioritizing areas for protection based only on ecological considerations and accounts for varying costs of protection using return-on-investment (ROI) methods. We combine a simulation approach with a case study of forests in the eastern United States, paying particular attention to how covariation between ecological benefits and economic costs influences agreement levels. For many conservation goals, agreement over spatial priorities improves with ROI methods. However, we also show that a reliance on ROI-based prioritization can sometimes exacerbate disagreements over priorities. As such, accounting for costs in conservation planning does not enable society to sidestep careful consideration of the ecological goals of conservation.

Landscape context outweighs local habitat quality in its effects on herbivore dispersal and distribution.

Past studies with spatially structured herbivore populations have emphasized the primacy of intrinsic factors (e.g., patch quality), patch geometry (e.g., patch size and isolation), and more recently landscape context (e.g., matrix composition) in affecting local population abundance and dispersal rate. However, few studies have examined the relative importance of each factor, or how they might interact to affect herbivore abundance or dispersal. Here, we performed a factorial field experiment to examine the independent and interactive effects of patch quality (plant biomass, leaf protein, leaf phenolics) and matrix composition [mudflat or non-host grass (Bromus inermis)] on planthopper (Prokelisia crocea) emigration from host-plant patches (prairie cordgrass, Spartina pectinata). In addition, a field survey was conducted to examine the relative importance of patch quality, geography, and matrix composition on planthopper occupancy and density. In the experiment, we found that rates of emigration from low and intermediate quality patches were, on average, 21% percent higher for patches embedded in brome than mudflat. In contrast, the emigration rate was unaffected by matrix composition in nutrient-rich patches. Within matrix types, plant quality had little effect on emigration. In the survey, planthopper density and the patch occupancy rate of planthoppers increased nonadditively with increasing patch size and the percentage of the surrounding matrix composed of mudflat. This study suggests that landscape-level factors, such as the matrix, may be more important than factors intrinsic to the patches.