In mixed-jurisdiction landscapes of the Intermountain West, unprotected wildlands in private and State Trust ownership buffer protected areas, support ecosystem and watershed processes, and maintain landscape connectivity, while their subdivision and development, results in losses of habitat and biodiversity, fragmentation, and isolation of neighboring protected areas. In recent decades, conservation easements (CEs) have emerged as the primary tool for protecting private lands, but as private agreements, there is no explicit expectation that land protected provides these conservation values. With this dependence on CEs, identifying their conservation outcomes is critical to understanding their role in landscape-scale conservation efforts. Focusing on the Madrean Archipelago in Arizona and New Mexico, I conducted a mixed methods study assessing the spatial pattern of existing CEs relative to grasslands, riparian areas, and distance from protected areas, and completed stakeholder interviews to identify any process underlying these spatial patterns. Results show that more than 10% of private wildlands in the region are in CEs. They exhibited a strong affinity towards grasslands (almost 20% of private grassland area is in CEs) and protected areas (more than 80% of CEs lie within 1 km of a protected area) but tend to avoid riparian areas. Interviews revealed a moderate level of consistency between the spatial patterns identified and stakeholder objectives. These results suggest that CEs in the Madrean Archipelago do support landscape-scale conservation outcomes, in part because stakeholders engaged in establishing them are prioritizing resources and values with landscape-scale significance. They also affirm the need for more access to spatial data on CEs to better integrate them into regional conservation planning efforts.

Estimates from radiocarbon-dated packrat middens indicate that the high elevation woodland communities of the Madrean Sky Islands were continuous as recently as 8,000 to 12,000 years ago. A number of population studies on a diverse collection of taxa have investigated the extent to which the Madrean Sky Island system has limited gene flow among mountain ranges. The results of several of these studies indicate that population divergences may be more ancient than the Holocene. Yarrow’s spiny lizards, Sceloporus jarrovii, were sampled from eight sites representing seven mountain ranges. The populations of S. jarrovii are host to the malarial parasite, Plasmodium chiricahuae. DNA sequences from the lizards and their malarial parasites were used to reconstruct the evolutionary relationships and estimate the ages of the populations for both host and parasite. The findings of these analyses indicate that the sky island populations of S. jarrovii have been isolated for hundreds of thousands of years and did not experience gene flow during the last woodland expansion. In contrast, the results indicate that the malarial infection occurred more recently, possibly during the Holocene woodland expansion. In addition, the prevalence of the malarial infection was compared to multiple attributes of the lizards. This analysis revealed a negative relationship between the genetic diversity of the lizard populations and the prevalence of infection. Furthermore, lizard populations with lower prevalence of infection have a lower frequency of multiclonal infections.

Climate change is increasing the frequency and extent of high-severity disturbance, with potential to alter vegetation community composition and structure in environments sensitive to tipping points between alternative states. Shrub species display a range of characteristics that promote resistance and resilience to disturbance, and which yield differential post-disturbance outcomes. We investigated differences in shrub patch size and stem density in response to variations in fire severity, vegetation community, and post-disturbance reproductive strategies in Sky Island forested ecosystems in the southwestern United States. Patterns in shrub structure reflect the effects of fire severity as well as differences among species with alternate post-fire reproductive strategies. Increased fire severity correlates with larger patch sizes and greater stem densities; these patterns are observed across multiple fire events, indicating that disturbance legacies can persist for decades. High severity fire produces the largest shrub patches, and variance in shrub patch size increases with severity. High severity fire is likely to promote expansion of shrub species on the landscape, with implications for future community structure. Resprouting species have the greatest variability in patch structure, while seeding species show a strong response to disturbance: resprouting species dominateatlowdisturbanceseverities,andobligateseedersdominatehighseverityareas. Differential post-fire reproductive strategies are likely to generate distinct patterns of vegetation distribution following disturbance, with implications for community composition at various scales. Shrub species demonstrate flexible responses to wildfire disturbance severity that are reflected in shrub patch dynamics at small and intermediate scales.