To assess the genetic diversity and phylogeography of the blunt-nosed leopard lizard (Gambelia sila), we sequenced 1,285 base pairs (bp) of the mitochondrial cytochrome oxidase-b (cyt-b, 682 bp) and cytochrome oxidase III (CO3, 603 bp) genes from 33 individuals representing eight natural populations in central California. Phylogenetic analysis indicated that 17 observed haplotypes are partitioned into two major clades, which correspond geographically to where the lizards were collected. We also conducted a focused analysis of individuals collected from the canyons leading into the Cuyama Valley in Ventura and Santa Barbara counties, a geographic area with lizards possibly representing a remnant hybrid (with G. wislizenii) population. All lizards from the Cuyama Valley and adjacent canyons exhibited the mitochondrial haplotype of G. sila and were embedded within one clade. Our morphological analysis placed some leopard lizards collected from Cuyama Valley with true G. sila, whereas some individuals aggregated with G. wislizenii. This finding suggests that the quantitative morphological characteristics often used to distinguish between the two species are fairly labile and may be influenced by prevailing environmental conditions.
Background: Frequent outbreaks of insects and diseases have been recorded in the native forests of western North America during the last few decades, but the distribution of these outbreaks has been far from uniform. In some cases, recent climatic variations may explain some of this spatial variation along with the presence of expansive forests composed of dense, older trees. Forest managers and policy makers would benefit if areas especially prone to disturbance could be recognized so that mitigating actions could be taken.
Methods: We use two ponderosa pine-dominated sites in western Montana, U.S.A. to apply a modeling approach that couples information acquired via remote sensing, soil surveys, and local weather stations to assess where bark beetle outbreaks might first occur and why. Although there was a general downward trend in precipitation for both sites over the period between 1998 and 2010 (slope = −1.3, R2 = 0.08), interannual variability was high. Some years showed large increases followed by sharp decreases. Both sites had similar topography and fire histories, but bark beetle activity occurred earlier (circa 2000 to 2001) and more severely on one site than on the other. The initial canopy density of the two sites was also similar, with leaf area indices ranging between 1.7-2.0 m2·m−2. We wondered if the difference in bark beetle activity was related to soils that were higher in clay content at site I than at site II. To assess this possibility, we applied a process-based stand growth model (3-PG) to analyze the data and evaluate the hypotheses.
Context Many tree species will shift their distribution as the climate continues to change. To assess species’ range changes, modeling efforts often rely on climatic predictors, sometimes incorporating biotic interactions (e.g. competition or facilitation), but without integrating topographic complexity or the dynamics of disturbance and forest succession.
Objectives We investigated the role of ‘safe islands’ of establishment (‘‘microrefugia’’) in conjunction with disturbance and succession, on mediating range shifts.
Methods We simulated eight tree species and multiple disturbances across an artificial landscape designed to highlight variation in topographic complexity. Specifically,we simulated spatially explicit successional changes for a 100-year period of climate warming under different scenarios of disturbance and climate microrefugia.
Results Disturbance regimes play a major role in mediating species range changes. The effects of disturbance range from expediting range contractions for some species to facilitating colonization of new ranges for others. Microrefugia generally had a significant but smaller effect on range changes. The existence of microrefugia could enhance range persistence but implies increased environmental heterogeneity, thereby hampering migration under some disturbance regimes and for species with low dispersal capabilities. Species that gained suitable habitat due to climate change largely depended on the interaction between species life history traits, environmental heterogeneity and disturbance regimes to expand their ranges.
Conclusions Disturbance and microrefugia play a key role in determining forest range shifts during climate change. The study highlights the urgent need of including non-deterministic successional pathways into climate change projections of species distributions.
As species’ geographic ranges and ecosystem functions are altered in response to climate change, there is a need to integrate biodiversity conservation approaches that promote natural adaptation into land use planning. Successful conservation will need to embrace multiple climate adaptation approaches, but to date they have not been conveyed in an integrated way to help support immediate conservation planning and action in the face of inherent spatial uncertainty about future conditions. Instead, these multiple approaches are often conveyed as competing or contradictory alternatives, when in fact, they are complementary. We present a framework that synthesizes six promising spatially explicit adaptation approaches for conserving biodiversity. We provide guidance on implementing these adaptation approaches and include case studies that highlight how biodiversity conservation can be used in planning. We conclude with general guidance on choosing appropriate climate adaptation approaches to amend for conservation planning.
We developed a process that links the mechanistic power of dynamic global vegetation models with the detailed vegetation dynamics of state-and-transition models to project local vegetation shifts driven by projected climate change. We applied our approach to central Oregon (USA) ecosystems using three climate change scenarios to assess potential future changes in species composition and community structure. Our results suggest that: (1) legacy effects incorporated in state-and-transition models realistically dampen climate change effects on vegetation; (2) species-specific response to fire built into state-and-transition models can result in increased resistance to climate change, as was the case for ponderosa pine (Pinus ponderosa) forests, or increased sensitivity to climate change, as was the case for some shrublands and grasslands in the study area; and (3) vegetation could remain relatively stable in the short term, then shift rapidly as a consequence of increased disturbance such as wildfire and altered environmental conditions. Managers and other land stewards can use results from our linked models to better anticipate potential climate-induced shifts in local vegetation and resulting effects on wildlife habitat.
Collaborative and community-based approaches to conservation and natural resource management often utilize maps that designate particular areas as being high priorities for conservation. These maps are used in stakeholder workshops and/or public discourse, but have often been highly contentious and counterproductive. We propose that quantifying and visualizing some of the uncertainty involved in making such maps could decrease their potential for causing conflict, thereby facilitating discourse and eventually, conservation action. We propose that an extra bonus could be attained by mapping the effects of missing or sparse input data regarding landowner ‘‘willingness to conserve’’ (given fair market compensation). The primary contributions of this action research are in the development of the propositions and in their implementation using a stochastic approach (Monte Carlo simulation). Preliminary assessment of the propositions occurred, but further research is needed to more formally evaluate them. Some practical suggestions and additional research considerations are provided.
It is becoming increasingly difficult to manage and expand statutory conservation areas (i.e., parks and formally protected areas). Therefore, alternative opportunities for land conservation merit closer attention. This paper examines the extent to which privately owned conservation areas contribute to biodiversity representation. Gap analyses were performed for a large semi-arid region in South Africa with a comprehensive database of private conservation areas. The distribution of private conservation areas was compared to statutory conservation areas using several landscape characteristics: biome and vegetation variant, elevation class, ecological process area, total area, and threat status (endangerment). Conservation target achievement for the vegetation variants was also assessed, as was the degree to which private conservation areas complemented statutory conservation areas by representing different landscape characteristics. The number of targets achieved nearly tripled if private conservation areas were considered in addition to statutory conservation areas. Further, private conservation areas signi?cantly complemented statutory conservation areas in the types of biomes, elevation classes, and threat status classes conserved. Private conservation areas were especially important in conserving lower elevation habitat, and by association, endangered vegetation. This particular relationship is expected to be common worldwide. Our results indicate that private lands conservation deserves an increased allocation of resources for both research and implementation.
Aim: To investigate the velocity of species-specific exposure to climate change for mid- and late 21st century and develop metrics that quantify exposure to climate change over space and time.
Location: California Floristic Province, south-western USA.
Methods: Occurrences from presence/absence inventories of eight Californian endemic tree species (Pinus balfouriana [Grev.&Balf.], Pinus coulteri [D.Don], Pinus muricata [D.Don.], Pinus sabiniana [D.Don], Quercus douglasii [Hook.&Arn.], Quercus engelmannii [Greene], Quercus lobata [Nee] and Quercus wislizeni [A.DC.]) were used to develop eight species distribution models (SDMs) for each species with the BIOMOD platform, and this ensemble was used to construct current suitability maps and future projections based on two global circulation models in two time periods [mid-century: 2041–2070 and late century (LC): 2071–2100]. From the resulting current and future suitability maps, we calculated a bioclimatic velocity as the ratio of temporal gradient to spatial gradient. We developed and compared eight metrics of temporal exposure to climate change for mid- and LC for each species.
Results: The velocity of species exposure to climate change varies across species and time periods, even for similarly distributed species. Weak support among the species analyzed for higher velocities in exposure to climate change towards the end of the 21st century, coinciding with harsher conditions. The variation in the pace of exposure was greater among species than for climate projections considered.
Main conclusions: The pace of climate change exposure varies depending on period of analysis, species and the spatial extent of conservation decisions (potential ranges versus current distributions). Translating physical climatic space into a biotic climatic space helps informing conservation decisions in a given time frame. However, the influence of spatial and temporal resolution on modeled species distributions needs further consideration in order to better characterize the dynamics of exposure and species-specific velocities.
Large shifts in species ranges have been predicted under future climate scenarios based primarily on niche-based species distribution models. However, the mechanisms that would cause such shifts are uncertain. Natural and anthropogenic fires have shaped the distributions of many plant species, but their effects have seldom been included in future projections of species ranges. Here, we examine how the combination of climate and fire influence historical and future distributions of the ponderosa pine–prairie ecotone at the edge of the Black Hills in South Dakota, USA, as simulated by MC1, a dynamic global vegetation model that includes the effects of fire, climate, and atmospheric CO2 concentration on vegetation dynamics. For this purpose, we parameterized MC1 for ponderosa pine in the Black Hills, designating the revised model as MC1-WCNP. Results show that fire frequency, as affected by humidity and temperature, is central to the simulation of historical prairies in the warmer lowlands versus woodlands in the cooler, moister highlands. Based on three downscaled general circulation model climate projections for the 21st century, we simulate greater frequencies of natural fire throughout the area due to substantial warming and, for two of the climate projections, lower relative humidity. However, established ponderosa pine forests are relatively fire resistant, and areas that were initially wooded remained so over the 21st century for most of our future climate x fire management scenarios. This result contrasts with projections for ponderosa pine based on climatic niches, which suggest that its suitable habitat in the Black Hills will be greatly diminished by the middle of the 21st century. We hypothesize that the differences between the future predictions from these two approaches are due in part to the inclusion of fire effects in MC1, and we highlight the importance of accounting for fire as managed by humans in assessing both historical species distributions and future climate change effects.
Conservation managers and policy makers require models that can rank the impacts of multiple, interacting threats on biodiversity so that actions can be prioritized. An integrated modeling framework was used to predict the viability of plant populations for five species in southern California’s Mediterranean type ecosystem. The framework integrates forecasts of land-use change from an urban growth model with projections of future climatically-suitable habitat from climate and species distribution models, which are linked to a stochastic population model. The population model incorporates the effects of disturbance regimes and management actions on population viability. This framework: (1) ranks threats by their relative and cumulative impacts on population viability, such as land-use change, climate change, altered disturbance regimes or invasive species, and (2) ranks management responses in terms of their effectiveness for land protection, assisted dispersal, fire management and invasive species control. Toofrequent fire was often the top threat for the species studied, thus fire reduction was ranked the most important management option. Projected changes in suitable habitat as a result of climate change were generally large, but varied across species and climate scenarios; urban development could exacerbate loss of suitable habitat.