Canopy Cover Type Research Articles

Spatial Distribution of Soil Organic Carbon in the Forests of Nepal

Soil organic carbon (SOC) is the major constituent of the soil organic matter. SOC stocks are determined by several factors such as altitude, slope, aspect, canopy cover, and vegetation type. Using the Third National Forest Inventory (2010–2014) data of Nepal, we assessed SOC status in forests at a national scale for the better understanding of the SOC distribution within Nepal. In this study, we estimated SOC against different factors and tested the spatial distribution of SOC using analysis of variance (ANOVA). The results showed that the forests located at a higher altitude have higher SOC accumulation. In particular, broadleaved forests exhibit a higher amount of carbon stock compared to other forest types. Moreover, forests with a larger canopy cover, located on a higher slope, and with a cooler aspect are associated with a higher accumulation of SOC. The SOC stock in the forest varies according to altitude, slope, aspect, canopy cover, and forest type, which might be attributed to the change in the microclimate of the area. The significant increase in SOC amount with the increase in slope, altitude, and crown cover helps to understand the extent of SOC distribution in forests. Broadleaved forests with a larger canopy cover in the higher altitude region have a higher SOC retention potential, which is likely to contribute to mitigating the impacts of climate change by sinking more carbon into the soil.

Struktur Komunitas Keong Di Empat Zona yang Berbeda di Mangrove Munjang Kurau Barat, Bangka Tengah

Snails in the mangrove ecosystem have an important role in the ecology of nutrient dynamics, especially in the West Munjang Kurau mangrove forest, Central Bangka. On the other hand, 60-70% of the forest has experienced significant damage and potential decline. Therefore, limited research has been carried out to provide information about the species composition of mangrove snails in four mangrove ecosystem zones with different conditions. Gastropod samples were taken based on purposive sampling method. The environmental data observed were air temperature (°C), air pH, DO (mg/l), salinity (%), canopy cover (%), maximum INP, tree density (trees/Ha), and substrate type. The study found 17 types of gastropods with the highest number of individuals being Sphaerassiminea miniata and the lowest being Littoraria pallescens, Lisachatina fulica, and Vittoida variegata. The results of the CCA analysis showed three groups of snails in association with environmental variables, namely groups that were not strongly associated with any variables. The second group is slightly associated with tree density and the group is related to INP max and substrate.

Evaluating the restoration potential of soil seed banks in degraded semi-arid oak forests: Influence of canopy cover types and fire-related cues on seed germination

Soil seed bank is an important driver of vegetation dynamics, particularly in fire-prone Mediterranean ecosystems. In this study, we disentangle the effects of fire-related cues on the dynamics of the soil seed bank in semiarid oak forests of western Iran. Soil samples were collected in two types of forests: below closed canopy or below the open canopy of more intensively used forests. In a greenhouse experiment, the effects of five treatments were tested application of: ash (Ash), smoke (Smoke), 50 °C temperature (Heat50), 100 °C temperature (Heat100) and control. Soil samples were regularly monitored and the number of germinated seeds (seedlings) by species were recorded in each treatment. Diversity indices were also computed. Knowing the effects of fire and its cues on fied 18 species from 16 genera and 9 families. 56 % of the seedlings emerged from the closed canopy forest soils and 44 % from the open canopy forests. Seedling density and diversity values were the lowest in the Heat100 treatment. No annual grasses and tree species were recorded in this treatment. In contrast, the influence of the other fire-related cues was mediated by the forest type cover: the number of emerged seedlings was the highest in Smoke and Heat50 in the open canopy and closed canopy, respectively. This mediation effect was also reflected in the composition of the control as tree species were only present in the closed canopy and annual forbs were less abundant there compared to the open canopy type. Considering all fire treatments together, the seedling density was significantly higher in the closed canopy type than in the open canopy (309.6 ± 28.03 vs 240.8 ± 20.78 seeds/m2). Our results showed that intense fires leading to high soil temperatures are largely detrimental to soil seed bank germination and species diversity, whereas less intense fires can be favourable depending on species life form and the type of forest. Our findings highlight that post-fire regeneration from the soil seed bank is more promising in closed forests than in forests with an open canopy in the studied ecosystem.

Open habitats in a tropical biodiversity hotspot support pollinator diversity in both protected and unprotected areas

AbstractProtected areas (PAs) are vital in the global effort to preserve biodiversity, particularly for disturbance‐intolerant pollinator species in the tropics. As there is little information on the potential of PAs for pollinator conservation in sensitive tropical ecosystems, we assessed here insect pollinator diversity in protected vs. unprotected areas in two vegetation zones in Nigeria, within the West African Guinea Biodiversity Hotspot. We selected two land‐use types based on predominant canopy cover type (open and tree‐shaded habitats) and these were sampled in both protected and unprotected areas of tropical rain forest and savanna vegetation zones. Pollinator composition varied significantly between protected vs. unprotected areas in each vegetation zone, signifying both areas support unique assemblages of insect pollinators. However, pollinator diversity varied according to land‐use type (open vs. shaded habitats) rather than protected area per se, such that pollinators were more abundant and species‐rich in open habitat than shaded habitat. These findings emphasize that beyond the protection of ecosystems, fine scale habitat management promoting the availability of adequate floral resources in natural areas is critical for ensuring conservation of these pollinators in tropical ecosystems.

Abiotic Factors Influence Thermal Conditions Determining Site Occupancy of Plestiodon fasciatus at High-Latitude Range Limits

Climate change has historically resulted in the expansion, contraction, and shift of species ranges. High-latitude range limits in areas where no physical barrier prevents dispersal are of particular interest in light of species range contraction or expansion because they represent limits that may inhibit occupancy. MacArthur proposed that abiotic factors have a greater influence on species distribution approaching high-latitude range limits. We examined aspects of environmental structure that influence distribution of Common Five-lined Skinks (Plestiodon fasciatus) and are expressed in that species' population dynamics. Eight sites in the southern Shield region of Ontario, Canada were surveyed during the active season for P. fasciatus. We collected data on the canopy cover, slope angle, slope aspect, substrate, cover type, and temperature at sites where P. fasciatus was observed (microsites) and compared these data to the general site conditions (macrosite). We assessed population size using capture–mark–recapture methods and compared population age structure at eight sites to detect if there was a correlation between the characteristics of the macrosites, population size, and age structure. Abiotic factors were the primary limiting factors affecting distribution at high-latitude range limits of the species. Spatial ecology at the individual scale was influenced by sites with suitable thermal conditions. Our results confirm the importance of microsites with suitable thermal profiles as key habitat for ectothermic vertebrates at high latitudes. The influence of temperature as a limiting abiotic factor is expressed in population density of P. fasciatus. Conservation and restoration of high-latitude populations of ectothermic vertebrates should focus on ensuring thermal requirements of the species are met before other factors are addressed, as temperature is likely the single most significant limiting factor at high-latitude range limits.

Environmental and biotic factors affecting freshwater snail intermediate hosts in the Ethiopian Rift Valley region

BackgroundKnowledge of the distribution and habitat preference of freshwater snail intermediate hosts can provide information to initiate and set-up effective snail control programmes. However, there is limited research conducted on the factors driving the occurrence and abundance of freshwater snail intermediate hosts in the Ethiopian Rift Valley. Hence, in this study, we investigated how environmental and biotic factors influence the occurrence and abundance of the snail intermediate hosts in Ethiopian Rift Valley region.MethodsData on freshwater snails, physico-chemical water quality parameters, physical characteristics of habitat, predators and competitors, and anthropogenic activity variables were collected from 174 sampling sites during the wet season of 2017 and 2018. Generalized linear models were used to identify the main environmental and biotic factors affecting the occurrence and abundance of the snail species.ResultsIt was found that Bulinus globosus (31.7%) was the most abundant snail species followed by Lymnaea natalensis (21.6%), Lymnaea truncatula (15.1%) and Biomphalaria pfeifferi (14.6%). Generalized linear models indicated that physico-chemical parameters (water temperature, turbidity, chlorophyll-a, dissolved oxygen, chemical oxygen demand, alkalinity, calcium, magnesium, nitrate and ammonia), physical habitat characteristics (water depth, canopy cover, macrophyte cover and substrate type) and biotic factors (abundance of predators and competitors) were found to be the main variables determining the occurrence and abundance of snail species in the Ethiopian Rift Valley region. In terms of anthropogenic activities, human settlement, farming, bathing and swimming, clothes washing, grazing, drainage of land, car washing, boating, fishing and silviculture were also important variables determining the occurrence and abundance of snail species in the region.ConclusionsThe findings reported herein suggest that integrated snail control strategies should be considered to control snails via protection of water bodies from disturbance by anthropogenic activities. In this way, it is possible to reduce the concentration of organic matter and dissolved ions in aquatic ecosystems which are conducive for the presence of snails.

An integration framework for linking avifauna niche and forest landscape models.

Avian cavity nesters (ACN) are viable indicators of forest structure, composition, and diversity. Utilizing these species responses in multi-disciplinary climate-avian-forest modeling can improve climate adaptive management. We propose a framework for integrating and evaluating climate-avian-forest models by linking two ACN niche models with a forest landscape model (FLM), LANDIS-II. The framework facilitates the selection of available ACN models for integration, evaluation of model transferability, and evaluation of successful integration of ACN models with a FLM. We found selecting a model for integration depended on its transferability to the study area (Northern Rockies Ecoregion of Idaho in the United States), which limited the species and model types available for transfer. However, transfer evaluation of the tested ACN models indicated a good fit for the study area. Several niche model variables (canopy cover, snag density, and forest cover type) were not directly informed by the LANDIS-II model, which required secondary modeling (Random Forest) to derive values from the FLM outputs. In instances where the Random Forest models performed with a moderate classification accuracy, the overall effect on niche predictions was negligible. Predictions based on LANDIS-II simulations performed similarly to predictions based on the niche model’s original training input types. This supported the conclusion that the proposed framework is viable for informing avian niche models with FLM simulations. Even models that poorly approximate habitat suitability, due to the inherent constraints of predicting spatial niche use of irruptive species produced informative results by identifying areas of management focus. This is primarily because LANDIS-II estimates spatially explicit variables that were unavailable over large spatial extents from alternative datasets. Thus, without integration, one of the ACN niche models was not applicable to the study area. The framework will be useful for integrating avifauna niche and forest ecosystem models, which can inform management of contemporary and future landscapes under differing management and climate scenarios.

Mapping the multi-decadal mangrove dynamics of the Australian coastline

Mangroves globally provide a diverse array of ecosystem services but these are impacted upon by both natural and anthropogenic drivers of change. In Australia, mangroves are protected by law and hence the natural drivers predominate. To determine annual national level changes in mangroves between 1987 and 2016, their extent (by canopy cover type) and dynamics were quantified using dense time-series (nominally every 16 days cloud permitting) of 25 m spatial resolution Landsat sensor data available within Digital Earth Australia (DEA). The potential area that mangroves occupied over this period was established as the union of mangrove maps generated for 1996, 2007–2010 and 2015/16 through the Global Mangrove Watch (GMW). Within this area, the green vegetation fractional cover (GVpc) was retrieved from each available cloud-masked Landsat scene through linear spectral unmixing. The 10th percentile (GVpc10) was then determined for each calendar year by comparing these data in a time-series. The percentage Planimetric Canopy Cover (PCC%) for each Landsat pixel was then estimated using a relationship between GVpc10 and LiDAR-derived PCC% (<1 m resolution and based on acquisitions from all states supporting mangroves, excluding Victoria). The resulting annual maps of mangrove extent and cover for Australia are the first to be generated at a continental scale and on an annual basis. These indicated that the total area of mangrove forest (canopy cover >20%; resolvable at the Landsat resolution) varied from a minima of 10,715 ± 36 km2 (95% confidence interval) in 1992 to a maxima of 11,388 km2 ± 38 km2 (95% CI) in 2010, declining to 11,142 ± 57 km2 (95% CI) in 2017. In 2010 (maximum extent), the forests were classified as closed canopy (38.8%), open canopy (49.0%) and woodland mangrove (12.2%). The majority of change occurred along the northern Australian coastline and was concentrated in the major gulfs and sounds. The 30 national maps of annual mangrove extent represent a reference dataset, which is publicly available through the Terrestrial Environment Research Network (TERN) landscapes portal. Future efforts are focusing on the routine production of annual mangrove maps beyond 2019 as part of Australia's efforts to monitor the coastal environment.

Tracking the fate of deposited nitrogen and its redistribution in a subtropical watershed in China

AbstractVegetation cover and soil infiltration can result in nitrogen (N) redistribution and associative isotopic fractionation. This study investigated N and its isotopic characteristics from deposition to baseflow under different vegetation canopy cover types in a subtropical watershed in China. Results showed that canopy interception via vegetation cover types exhibited notable dilution effects on reactive nitrogen (Nr) deposition during the rainy season, with the highest maximum value of 287.4%. The range of δ15N changed from 3.0‰ to 11.9‰ in throughfall, which may have resulted from an increase in N taken up by vegetation and particles washed away from plant leaves during rainfall events. Throughfall, soil water, precipitation, and rainfall run‐off were the sources of D and 18O‐H2O in baseflow river water, wherein the rainwater and rainfall run‐off contributed 73% ± 8% and 15% ± 12%, respectively. Soil water was the main source of 15N‐NO3 in baseflow river water, which contributes 78% ± 4% of overall source, but precipitation only contributes 10%. The average annual Nr deposition flux was 24.4 ± 4.2 kg·ha−1·yr−1, whereas the annual total nitrogen exportation flux was 1062 ± 269.8 kg·yr−1. The 46% of HDO or D2O for river water came from rainfall run‐off, which would transport a maximum nitrate flux of 354 kg·yr−1. Moreover, vegetation cover and soil infiltration resulted in δ15N enrichment and a decrease in Nr in river flow.

Zonal classification of microclimates and their relationship with landscape design parameters in an urban park

Microclimates in urban areas arise through the interaction between prevailing weather conditions and landscape design parameters. A well-arranged landscape creates a pleasant outdoor environment. Additionally, the classification of microclimates helps to illustrate variations therein and analyze influencing factors. This study classified microclimate zones (MZs) based on a statistical method and identified influential landscape design parameters with the aim of enhancing human comfort. We conducted our study at Yeouido Park in Seoul, Korea, which has various landscape design parameters, including tree canopy cover and ground surface type. A novel MZ classification method was developed in this study, then stepwise regression was used to analyze the relationship between microclimate and landscape design parameters. It was found that the MZ classification effectively demonstrated spatial microclimatic differences and characteristics on a park scale. The efficiency with which trees improved the microclimate depended on the ground surface type. However, the significant effects of landscape design parameters on the microclimate and human comfort differed by season and time of day. This study provides a statistical method for analyzing an urban microclimate and serves as a reference regarding how to effectively modify the meteorological environment on a microscale via landscape design, in both summer and winter urban outdoor spaces.

Convergent evolution of coloration in experimental introductions of the guppy (Poecilia reticulata).

Despite the multitude of examples of evolution in action, relatively fewer studies have taken a replicated approach to understand the repeatability of evolution. Here, we examine the convergent evolution of adaptive coloration in experimental introductions of guppies from a high‐predation (HP) environment into four low‐predation (LP) environments. LP introductions were replicated across 2 years and in two different forest canopy cover types. We take a complementary approach by examining both phenotypes and genetics. For phenotypes, we categorize the whole color pattern on the tail fin of male guppies and analyze evolution using a correspondence analysis. We find that coloration in the introduction sites diverged from the founding Guanapo HP site. Sites group together based on canopy cover, indicating convergence in response to light environment. However, the axis that explains the most variation indicates a lack of convergence. Therefore, evolution may proceed along similar phenotypic trajectories, but still maintain unique variation within sites. For the genetics underlying the divergent phenotypes, we examine expression levels of color genes. We find no evidence for differential expression, indicating that the genetic basis for the color changes remains undetermined.

Effect of activity states on habitat selection by black‐tailed deer

ABSTRACTHabitat selection is a complex hierarchical process and in ungulates typically varies at broad spatial and temporal scales and among individuals. Recent advancements in the ability of global positioning system (GPS)‐collars to collect activity data provide opportunities to understand underlying mechanisms or trade‐offs responsible for fine‐scale variation in habitat selection. Based on data from 64 female black‐tailed deer (Odocoileus hemionus columbianus) fitted with GPS‐collars in northern California, USA, between 2004 and 2013, we first investigated habitat selection at the home range scale. We then used data from a subset of 27 individuals to determine if habitat selection within home ranges was influenced by activity states (active or inactive). Habitat selection by black‐tailed deer varied between summer and winter and was mostly explained by differences in elevation, terrain, and vegetation. Within their home ranges, black‐tailed deer showed fine‐scale selection for habitats that varied with activity states. In summer, selection for edge density and forest types varied across activity states highlighting important fine‐scale selection patterns. Activity state also affected our conclusions about the selection of habitats including slope, canopy cover, and forest types by black‐tailed deer in winter. During both seasons, deer selected for apparently secure habitat when inactive, likely to minimize risk of predation. These results highlight the importance of considering activity states when evaluating habitat selection from animal location data. This is particularly important in multi‐use landscapes such as national forests where habitat needs of ungulates are important considerations in management decisions, including timber harvest. © 2018 The Wildlife Society.

Using synthetic data to evaluate the benefits of large field plots for forest biomass estimation with LiDAR

With the maturation of methods for estimating aboveground forest biomass by remote sensing, researchers increasingly need test data, particularly ground reference data, that are large enough to fine-tune existing approaches and test their robustness under diverse conditions. In this context, realistic synthetic datasets present an interesting alternative to costly and limited field data. Here, we present a new approach to simulate realistic canopy height and cover type data by combining an individual-tree forest simulator with real LiDAR point clouds of individual trees.We demonstrate the utility of our approach by re-examining the influence of field plot size on the predictive power of remote-sensing models for biomass estimation. Our approach with a complete (wall-to-wall) field reference dataset and matching synthetic remote sensing data allowed us to not only perform internal cross-validations with field plots that were used to fit the model (as in studies with real data), but to also consider the quality of model predictions to a standardized spatial grid or to the entire region.Our results confirm earlier reports of smaller predictive errors with increased field plot sizes under internal model validation (RMSE of 125 t/ha at 10 m field plot size and RMSE of 40 t/ha for 50 m field plots). However, we show that this is mainly an artifact of comparing the models with the same data they were fit, thus with validation data of different scales. When validating on a grid with standardized scale, smaller field plots performed almost equally well as larger field plots (small RMSE decrease between 4 t/ha and 7 t/ha when going from 10 m to 50 m plots), and even outperformed them if we assumed that increasing the plot size means that fewer field plots can be obtained (small RMSE increase between 9 t/ha and 12 t/ha when going from 10 m to 50 m plots).We conclude that synthetic remote sensing datasets are a useful tool for method testing. The suggested approach may be used to reexamine our current methodological understanding, which is often based on tests with real data of very limited sizes, as well as to optimize workflows, model choices and data collection. A wider use of synthetic data could be instrumental in improving remote sensing methodology.

Novel location data reveal spatiotemporal strategies used by a central-place forager

Central-place foragers in risky landscapes experience conflicting behavioral demands that they must balance by appropriately adjusting how they move throughout their home ranges. We used novel mini-GPS technology and time local convex hull analyses to determine how golden-mantled ground squirrels (Callospermophilus lateralis) use a spatiotemporal strategy to optimize foraging early in the year when individuals are in an energy deficit. By using serial correlation from GPS data, we could better understand how individuals use a time management strategy influenced by distance traveled from the burrow, location of food patches, location of refuge patches, and vegetative cover type. Individuals maximized time spent in food patches rather than in travel corridors or at the burrow, suggesting the need to forage was prioritized. Individuals spent more time at patches farther from the burrow relative to nearer patches, potentially as a function of intermittent antipredator vigilance activity and energy optimization. Individuals also had high rates of revisitation, but low visit duration, in risky canopy cover types, suggesting that individuals used areas of low vegetative understory cover to travel efficiently between high-value food patches. Increased predation risk incurred while traveling in these open areas was possibly offset by use of refuges. Understanding these spatiotemporal movement patterns and how they relate to dynamic intrinsic and extrinsic demands has the potential to redefine optimal foraging behavior and better inform management and conservation practices.

Canopy cover type, and not fine-scale resource availability, explains native and exotic species richness in a landscape affected by anthropogenic fires and posterior land-use change

Anthropogenic fires and land-use change, including the conversion from native to exotic species canopies, are two major types of disturbances that strongly affect the functioning of forest ecosystems around the world. These disturbances alter the resource availability for plants, which may lead to changes in species richness. Here we examined the relative effects of canopy cover type, light availability and soil nutrient (N and P) availability on species richness, including invasive species, at different post-fire plant systems. Additionally, we tested the resource heterogeneity hypothesis (RHH) for plant diversity, which proposes that diversity is higher in habitats with spatially heterogeneous resources. We evaluated four different canopy cover types, including mature and second-growth Nothofagus pumilio forests, treeless prairie, Pinus sylvestris afforestations, all of which were converted from mature N. pumilio forests. Using generalized mixed-effects model correlations, we determined (1) the relative influence of canopy cover type, light and soil nutrient availability on understory species richness and (2) the relationship between species richness and resource heterogeneity. We found that canopy cover type was the factor that best explained species richness, much more than fine-scale light and soil nutrient availability. Additionally, we found that the more homogeneous the light environment the higher the number of exotic species (mainly found in the prairie where the highest light intensity occurred), which is contrary to what the RHH states. In conclusion, canopy cover type, a stand-scale driver, and not fine-scale resource (light, N and P) availability, was most important for explaining native and exotic (including invasive) species understory richness in a landscape affected by anthropogenic fires and posterior land-use change.

Factors driving structure of natural and anthropogenic forest edges from temperate to boreal ecosystems

AbstractQuestionsWhat factors control broad‐scale variation in edge length and three‐dimensional boundary structure for a large region extending across two biomes? What is the difference in structure between natural and anthropogenic edges?LocationTemperate and boreal forests across all of Sweden, spanning latitudes 55–69° N.MethodsWe sampled more than 2000 forest edges using line intersect sampling in a monitoring programme (National Inventory of Landscapes in Sweden). We compared edge length, ecosystem attributes (width of adjacent ecosystem, canopy cover, canopy height, patch contrast in canopy height, forest type) and boundary attributes (profile, abruptness, shape) of natural edges (lakeshore, wetland) with anthropogenic edges (clear‐cut, agricultural, linear disturbance) in five regions.ResultsAnthropogenic edges were nearly twice as abundant as natural edges. Length of anthropogenic edges was largest in southern regions, while the abundance of natural edges increased towards the north. Edge types displayed unique spectrums of boundary structures, but abrupt edges dominated, constituting 72% of edge length. Anthropogenic edges were more abrupt than natural edges; wetland edges had the most gradual and sinuous boundaries. Canopy cover, canopy height, patch contrast and forest type depended on region, whereas overall boundary abruptness and shape showed no regional pattern. Patch contrast was related to temperature sum (degree days ≥ 5 °C), suggesting that regional variability can be predicted from climate‐controlled forest productivity. Boundary abruptness was coupled with the underlying environmental gradient, land use and forest type, with higher variability in deciduous than in conifer forest.ConclusionsEdge origin, land use, climate and tree species are main drivers of broad‐scale variability in forest edge structure. Our findings have important implications for developing ecological theory that can explain and predict how different factors affect forest edge structure, and help to understand how land use and climate change affect biodiversity at forest edges.

Experimental manipulation of leaf litter colonization by aquatic invertebrates in a third order tropical stream.

Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition.

Identifying plant traits associated with topographic contrasts in a rugged and diverse region (Klamath‐Siskiyou Mts, OR, USA)

Rugged topography affects species distributions and community composition by creating contrasting mesic (cool, moist) and xeric (warm, dry) microclimates on adjacent slopes. This microclimatic heterogeneity is thought to have contributed to species survival during past climate fluctuations. Within a rugged and botanically rich region, we asked what functional, distributional, and/or biogeographic traits distinguished the species significantly associated with xeric or mesic microclimates. For each of 236 species in 4773 plots in the Klamath‐Siskiyou Mountains, we tested for significant associations with mesic or xeric topographic microclimates inferred from high‐resolution topographic variables. For the subset of species showing significant associations, we then compared their functional traits, biogeographic origins, and macroclimatic attributes to those of other species. We also tested the dependence of topographic associations on elevation, canopy cover, and soil type. Many species in the region (40%) showed significant tendencies to be found only in either mesic or xeric topography. ‘Mesic’ species tended to be of northern biogeographic origin and to have geographic ranges with higher mean precipitation; ‘xeric’ species had the opposite attributes. Species occurred more often in mesic microclimates when they occurred on low‐nutrient serpentine soils, and were more often found in xeric microclimates at high elevations. Functional traits such as specific leaf area were not significant predictors of species association with topographic microclimate. Biogeographic origins and the mean precipitation (rather than temperature) of species geographic ranges are the best indicators of species that are found in cool/moist northerly or hot/dry southerly microclimates.

Fuel treatments and landform modify landscape patterns of burn severity in an extreme fire event.

Under a rapidly warming climate, a critical management issue in semiarid forests of western North America is how to increase forest resilience to wildfire. We evaluated relationships between fuel reduction treatments and burn severity in the 2006 Tripod Complex fires, which burned over 70,000 ha of mixed-conifer forests in the North Cascades range of Washington State and involved 387 past harvest and fuel treatment units. A secondary objective was to investigate other drivers of burn severity including landform, weather, vegetation characteristics, and a recent mountain pine beetle outbreak. We used sequential autoregression (SAR) to evaluate drivers of burn severity, represented by the relative differenced Normalized Burn Ratio index, in two study areas that are centered on early progressions of the wildfire complex. Significant predictor variables include treatment type, landform (elevation), fire weather (minimum relative humidity and maximum temperature), and vegetation characteristics, including canopy closure, cover type, and mountain pine beetle attack. Recent mountain pine beetle damage was a statistically significant predictor variable with red and mixed classes of beetle attack associated with higher burn severity. Treatment age and size were only weakly correlated with burn severity and may be partly explained by the lack of treatments older than 30 years and the low rates of fuel succession in these semiarid forests. Even during extreme weather, fuel conditions and landform strongly influenced patterns of burn severity. Fuel treatments that included recent prescribed burning of surface fuels were particularly effective at mitigating burn severity. Although surface and canopy fuel treatments are unlikely to substantially reduce the area burned in regional fire years, recent research, including this study, suggests that they can be an effective management strategy for increasing forest landscape resilience to wildfires.

Nesting Characteristics and Habitat Use of the Endangered Hawaiian Petrel (Pterodroma sandwichensis) on the Island of Lāna'i

Abstract. The endangered Hawaiian Petrel (Pterodroma sandwichensis) is endemic to the main Hawaiian Islands where it nests in underground burrows surrounded by vegetation that varies greatly from island to island. Information regarding island-specific nest site selection and habitat characteristics is important when considering the management needs of the species, including control of invasive plants and protection from introduced predators. Extensive search efforts, using nocturnal vocalization and visual surveys, resulted in locating 71 nesting burrows on the Island of Lāna'i. Logistic regression was used to examine the influence of elevation, planar curvature, percent slope, canopy cover, and vegetation type on nest site locations. The top model in predicting Hawaiian Petrel nest site selection was influenced by increasing slopes, an understory dominated by native vegetation, and open canopy. The top model was supported by a model weight (wi) of 0.53, with the second model holding most of the remaining...