Mountains Ecoregion Research Articles

Long-Term Impacts of Invasive Insects and Pathogens on Composition, Biomass, and Diversity of Forests in Virginia’s Blue Ridge Mountains

Exotic forest insects and pathogens (EFIP) have become regular features of temperate forest ecosystems, yet we lack a long-term perspective on their net impacts on tree mortality, carbon sequestration, and tree species diversity. Here, we analyze 3 decades (1987–2019) of forest monitoring data from the Blue Ridge Mountains ecoregion in eastern North America, including 67 plots totaling 29.4 ha, along with a historical survey from 1939. Over the past century, EFIP substantially affected at least eight tree genera. Tree host taxa had anomalously high mortality rates (≥ 6% year−1 from 2008 to 2019 vs 1.4% year−1 for less-impacted taxa). Following the arrival of EFIP, affected taxa declined in abundance (− 25 to − 100%) and live aboveground biomass (AGB; − 13 to − 100%) within our monitoring plots. We estimate that EFIP were responsible for 21–29% of ecosystem AGB loss through mortality (− 87 g m−2 year−1) from 1991 to 2013 across 66 sites. Over a century, net AGB loss among affected species totaled roughly 6.6–10 kg m−2. The affected host taxa accounted for 23–29% of genera losses at the plot scale, with mixed net effects on α-diversity. Several taxa were lost from our monitoring plots but not completely extirpated from the region. Despite these losses, both total AGB and α-diversity were largely recovered through increases in sympatric genera. These results indicate that EFIP have been an important force shaping forest composition, carbon cycling, and diversity. At the same time, less-affected taxa in these relatively diverse temperate forests have conferred substantial resilience with regard to biomass and α-diversity.

Snowmelt velocity predicts vegetation green-wave velocity in mountainous ecological systems of North America

The timing of spring initiates an important period for resource availability for large trophic webs within ecosystems, including forage for grazing animals, flowers for pollinators, and the higher trophic levels that depend on these resources. Spring timing is highly variable across space, being influenced strongly by the departure of snow cover (i.e. snowmelt timing, in locations with a seasonal snowpack), climate, weather, elevation, and latitude. When spring timing occurs along a gradient (e.g. spring arriving later in higher elevations of mountainous terrain), the organisms that rely on spring resources often migrate to maintain an optimal position for spring resources – a phenomenon known as ‘surfing the green wave.’ While this behavior has been observed by tracking animals, there have been no studies to quantify the green wave as a movement across space and time. Furthermore, considering that snowmelt timing has moderate power to explain green-up timing for a given location, we ask the question: does snowmelt velocity predict green wave velocity? Here, we introduce the first continental maps of snowmelt and green wave velocity for North America from 2001 to 2016 as derived from the MODIS MCD12Q2 phenology dataset. We show that both snowmelt and green wave velocities are influenced strongly by topography, including slope and aspect. Furthermore, we quantify the relationships between snowmelt and green wave velocities according to three variables: direction, speed, and distance traveled. We conclude that mountainous ecoregions, such as the western North American cordillera, have the highest correspondence between snowmelt and green wave velocities, compared to flatter regions such as the Great Plains and tundra. This work will be of interest to wildlife ecologists, biologists, and land managers who seek to conserve migratory animals and the ecosystems that support them.

The NPP-Based Composite Indicator for Assessing the Variations of Water Provision Services at the National Scale

Water provision (WP) is an important service of the terrestrial ecosystem, which contributes to water availability for consumptive use and in situ water supply, sustains the production or flows of multiple ecosystem services (ES). Spatially explicit mapping of WP is critical for incorporating the ES concept into the decision-making processes of land-use and ecological conservation planning. Traditionally, regional complexes hydrological process models were simplified and used for mapping WP of the ecosystem at broad scales, but this approach is significantly limited by data accessibility and difficulty validating the results. To fill the gap, an NPP-based composite indicator model that simulates WP by multiplying NPP and its variations with the soil infiltration capacity factor, annual precipitation and the slope of the land surface is proposed in this paper. These parameters are chosen to map WP because they are closely related to hydrological processes. The model results were validated using observed runoff data of the eleven river basins in China. We then applied this approach to analyze the spatiotemporal changes of WP in China from 2000 to 2013. The results show that: (1) the average value of WP was lowest in the Northwest Arid Area ecoregions while the highest value of WP was in the South China ecoregion. (2) The linear trend of WP in the Loess Plateau and Hengduan Mountains ecoregions were increased while decreased in the other nine ecoregions. (3) The WP in the north of the Qinghai-Tibet Plateau presented a significant decrease trend mostly because the land cover change (e.g., grassland convert into dessert) and decreasing precipitation; the decreasing of the WP in Yunan-Guizhou Plateau are because the farmland convert into settlement land and the significant decrease of precipitation and significantly increase of temperature; the significant increase of the WP in Northeast China are because the increasing of forest and farmland, the grassland and wetland convert into farmland and forest, and the significant decrease of temperature and increase of precipitation; Although the increase of precipitation has played an important role in promoting WP, the significant increase of WP in the Loess Plateau was mainly due to the farmland convert into forest and grassland ecosystem types. The indicator explored by this research is benefiting for revealing the variations of WP under different land-use change and climate change, and informed the decision-making process of land-use policy or conservation planning at data-scarce regions or broaden spatial scales.

Forest Management Cost at Household Level in the Bale Mountains Eco-Region Redd+Project, Southern Ethiopia

Effective forest use and management/governance requires a deeper understanding of forest’s multiple socio-economic functions or benefits at various scales, in particular at local level. Hence, reliable and up to-date information on the state of forest resources are very important. Thus, the main objective of the study was to assess the cost of forest management at household level. Accordingly, Data were collected through household survey, group discussions and key informant interviews. Statistical methods such as descriptive statistics and Leaner regression was used to analyse data. The results of the study show that the performance of user groups and the attitudes and intention of households towards participating in collective management are associated with level of income and dependence on forest income. User groups that are more dependent on forest income and have higher heterogeneity in terms of dependence on the forest resource have shown lower performance. Forest dependent households have also shown a less positive attitude and intention towards engaging in planting activities. Forest prices were obtained by surveying local markets, and from information from interviews with local residents and from focus group discussions. The amount of forest management cost is calculated by the sum of thinning, cleaning, pruning, patrolling, fie line development, forest products collection costs transaction costs, costs of operational, plan preparation, attending a meeting, Capacity building, material costs and annual membership and fee that a member household has to pay were identified in study. The cost of forest management is estimated by the sum of Forest products collection costs, Transaction costs, Material costs, the annual membership fee that a member household has to pay. Accordingly, results revealed that in the study areas estimation of forest management cost is about 19,925 birr per ha up to the forest can give the actual function. It is recommended that a better outcome in terms of poverty alleviation can be achieved if pro-poor forest-based activities are specifically considered in planning conservation and development interventions. Keywords/ phrases: Bale Eco Region, Forest income, forest-management at household level, Oromia, Ethiopia, REDD+ DOI : 10.7176/JRDM/58-01 Publication date : August 31 st 2019

Economic Contribution of Forest Resource at Household Level in the Bale Mountains Eco-Region Redd+Project, Southern Ethiopia

Forest significantly contributes to household incomes and influences patterns of economic development by promoting sustainable or green development. Yet, effective forest use and management/governance requires a deeper understanding of forest’s multiple socio-economic functions or benefits at various scales, in particular at local level. Hence, reliable and up to-date information on the state of forest resources - not only on area and area change, but also on such variables as economic contribution for household environment and others variables are very important. This study was conducted in Southern Ethiopia in the Oromia region in the district of Dodola. The main objective of the study was to assess the economic contribution of forest resource at household level. Data were collected through household survey, group discussions and key informant interviews. Data was analysed by statistical methods include descriptive statistics, Leaner regression analysis. The results of the study show that forest products are important sources of income contributing to 30% and 51.3% of household per capita income and per capita cash income, respectively. Forest income is an important bumper against extreme poverty by filling seasonal gaps of income and by serving as safety net in times of income crisis. Forest income also provides the opportunity to diversify livelihoods, particularly for low income groups. Households’ decisions on livelihood strategies including dependence on forest income are associated with socioeconomic and geographical factors. It is recommended that a better outcome in terms of poverty alleviation can be achieved if pro-poor forest-based activities are specifically considered in planning conservation and development interventions. Keywords/Phrases: Bale Eco Region, Forest income, forest-management at household level, Oromia, Ethiopia, REDD+ DOI : 10.7176/JRDM/53-02 Publication date :March 31 st 2019

Climate and water balance change among public, private, and tribal lands within Greater Wild land Ecosystems across North Central USA

The remaining wildlands in the North Central US include varying proportions of public, private, and tribal lands across water balance ecotones. These wildlands may be highly vulnerable changing climate impacting their ability to sustain biodiversity and ecosystem functioning. We quantified projected changes in growing season climate (temperature) and water balance (MI: moisture index) in Greater Wildland Ecosystems (GWEs) and land allocation types (public, private, and tribal lands) across Central Plains, Western Plains, and Western Mountains ecoregions of North Central US by using high-resolution climate data from GCM output of 1980–2005 to 2071–2099. We also tested for the evidence of systematic climatic bias on tribal lands, which are often claimed to be distributed non-randomly. We found that the historic temperature was lower for Western Mountains compared to Western and Central Plains’ GWEs. The climate model projected drier and warmer GWEs with a narrow difference in increased temperature (4.6 to 5.5 °C). The MI was projected to have the greatest decrease in Central Plains (− 28%) and the least in Western Plains (− -17%) GWEs. Our findings revealed that the GWEs and land allocation types are increasingly vulnerable to changing climate. We conclude that the distribution of tribal and public lands is not climatically biased in the historic period and the projected rates of change in climate are similar among land allocation types within each GWE. All GWEs, however, are projected to warm and undergo increasing aridity, which may challenge management to sustain ecological health and human wellbeing across all land allocation types.

Evidence for scale‐dependent topographic controls on wildfire spread

AbstractWildfire ecosystems are thought to be self‐regulated through pattern–process interactions between ignition frequency and location, and patterns of burned and recovering vegetation. Yet, recent increases in the frequency of large wildfires call into question the application of self‐organization theory to landscape resilience. Topography represents a stable bottom‐up template upon which fire interacts as both a physical and an ecological process. However, it is unclear how topographic control changes geographically and across spatial scales. We analyzed fire perimeter and topography data from 16 Bailey ecoregions across the State of California to identify spatial correspondence between ecoregional fire event and topographic patch size distributions. We found both sets of distributions followed a power‐law form and were statistically similar across several orders of magnitude, for most ecoregions. As a direct test of topographic controls on fire event perimeters, we used a paired t‐test across ~11,000 fires to identify differences in topographic attributes at fire boundaries versus fire interiors. Statistical significance was determined using 500 iterations of a neutral landscape model. Level of topographic control varied significantly by ecoregion and across topographic features. For example, north–south aspect breaks, valley bottoms, and roads showed a consistently high degree of spatial control on wildfire perimeters. Topographic controls were most pronounced in mountainous ecoregions and were least influential in arid regions. Ridgetops provided a low‐level control across all ecoregions. Spatial control was strongest for small (100–102 ha) to medium (103–104 ha) fire sizes, suggesting that controls were scale‐dependent rather than scale‐invariant. Roads were the dominant control across all ecoregions; however, removing roads from the analyses had no significant effect on the overall role of topography on wildfire extinguishment in this analysis. This result suggested that certain topographic settings show strong spatial control on fire growth, despite the presence of roads. Our results support the observation that both bottom‐up and top‐down factors constrain fire sizes and that there are likely scaling regions within fire size distributions wherein the dominance of these spatial controls varies. Human influences on fire spread may either diminish or enhance the role of some bottom‐up and top‐down factors, adding further complexity.

Climate Controls on Runoff and Low Flows in Mountain Catchments of Western North America

AbstractIn the mountainous regions of western North America, snowmelt recharges groundwater and provides ecosystem‐sustaining base flow during low‐flow periods. Continued warming is expected to have large impacts on snowmelt hydrology and on low‐flow regimes, but the relative impact of temperature and precipitation on low flows is unclear. To address this knowledge gap, the dominant climate controls on summer and winter season low flows in 63 near‐natural catchments in mountainous ecoregions of western North America are identified with correlation analysis, and low‐flow sensitivity to temperature and precipitation is quantified with multiple linear regression analysis. Results show that precipitation is the dominant control on the interannual variability of annual runoff and on the duration and severity of summer and winter low flows. The temperature sensitivity of low flows, however, can be as much as twice that of annual runoff. Warm winters correspond to significantly lower runoff; significantly longer, more severe summer low flows; and significantly shorter winter low flows. This highlights the importance of winter climate conditions for runoff and low flows in these mountain catchments and provides another line of evidence regarding the impacts of climate change on snowmelt hydrology.

Estimating Soil Respiration in a Subalpine Landscape Using Point, Terrain, Climate, and Greenness Data

AbstractLandscape carbon (C) flux estimates help assess the ability of terrestrial ecosystems to buffer further increases in anthropogenic carbon dioxide (CO2) emissions. Advances in remote sensing have led to coarse‐scale estimates of gross primary productivity (GPP; e.g., MODIS 17), yet efforts to develop spatial respiration products are lacking. Here we demonstrate a method to predict growing season soil respiration at a regional scale in a mixed subalpine ecosystem. We related field measurements (n = 396) of growing season soil respiration mostly from subalpine forests in the Southern Rocky Mountains ecoregion to a suite of biophysical predictors using a Random Forest model (30‐m pixel size). We found that Landsat Enhanced Vegetation Index, growing season aridity index, temperature, precipitation, elevation, and slope aspect explained spatiotemporal variability in soil respiration. Our model had a psuedo‐r2 of 0.45 and root‐mean‐square error of roughly one quarter of the mean value of respiration. Predicted growing season soil respiration across the region was remarkably consistent across 2004, 2005, and 2006 (150‐day sums of 542.8, 544.3, and 536.5 g C/m2, respectively). Yet we observed substantial variability in spatial patterns of soil respiration predictions that varied among years, suggesting that our method is sensitive to changes in respiration drivers. Mean predicted growing season soil respiration was 73% of MODIS GPP, while predicted soil respiration was generally within 20% of nocturnal net ecosystem exchange from nearby eddy covariance towers. Thus, geospatial and remotely sensed data sets can be used to estimate soil respiration at landscape scales.

Water clarity measures as indicators of recreational benefits provided by U.S. lakes: Swimming and aesthetics

Lakes provide recreational benefits related to water quality. Using data from the 2007 and 2012 United States National Lake Assessments (N = 2067 lake visits), we developed indicators for three benefits: swimming, general recreational value, and aesthetic appeal. For two combined ecoregions (“Mountains” and “Plains”) we related objective measures of water clarity, including Secchi depth, turbidity, and water-column chlorophyll-a concentration to subjective visual assessments of recreational benefit quality. There were significant associations between water clarity measures and visual assessments from which we derived water-clarity based thresholds between benefit quality classes (exceptional, high, low, marginal) for each benefit type. More variation in Secchi depth and turbidity was explained by benefit quality than was variation in chlorophyll-a. Threshold values were different between combined ecoregions. Compared to lakes in the Mountains ecoregion, recreational users of Plains lakes have lower expectations for water clarity. Thresholds were generally in accord with water clarity thresholds and guidance derived from published regional studies. Including indicators of the quality of benefits humans receive from lakes in assessments of lake conditions can increase public participation in decision-making and reveal changes in benefit quality over time.

Habitat Associations of Three Crayfish Endemic to the Ouachita Mountain Ecoregion

Many crayfish are of conservation concern because of their use of unique habitats and often narrow ranges. In this study, we determined fine-scale habitat use by 3 crayfishes that are endemic to the Ouachita Mountains, in Oklahoma and Arkansas. We sampled Faxonius menae (Mena Crayfish), F. leptogonopodus (Little River Creek Crayfish), and Fallicambarus tenuis (Ouachita Mountain Crayfish) from wet and dry erosional channel units of 29 reaches within the Little River catchment. We compared channel-unit and microhabitat selection for each species. Crayfish of all species and life stages selected erosional channel units more often than depositional units, even though these sites were often dry. Accordingly, crayfish at all life stages typically selected the shallowest available microhabitats. Adult crayfish of all species and juvenile Little River Creek Crayfish selected patches of coarse substrate, and all crayfish tended to use the lowest amount of bedrock available. In general, we showed that these endemic crayfish used erosional channel units of streams, even when the channel units were dry. Conservation efforts that protect erosional channel units and mitigate actions that cause channel downcutting to bedrock would benefit these crayfish, particularly during harsh, summer drying periods.

Snowmelt‐Driven Trade‐Offs Between Early and Late Season Productivity Negatively Impact Forest Carbon Uptake During Drought

AbstractFuture projections of declining snowpack and increasing potential evaporation are predicted to advance the timing of snowmelt in mountain ecosystems globally with unknown implications for snowmelt‐driven forest productivity. Accordingly, this study combined satellite‐ and tower‐based observations to investigate the forest productivity response to snowpack and potential evaporation variability between 1989 and 2012 throughout the Southern Rocky Mountain ecoregion, United States. Our results show that early and late season productivity were significantly and inversely related and that future shifts toward earlier and/or reduced snowmelt could decrease snowmelt water use efficiency and thus restrict productivity despite a longer growing season. This was explained by increasing snow aridity, which incorporated evaporative demand and snow water supply, and was modified by summer precipitation to determine total annual productivity. The combination of low snow accumulation and record high potential evaporation in 2012 resulted in the 34 year minimum ecosystem productivity that could be indicative of future conditions.

Simulating vegetation response to climate change in the Blue Mountains with MC2 dynamic global vegetation model

Warming temperatures are projected to greatly alter many forests in the Pacific Northwest. MC2 is a dynamic global vegetation model, a climate-aware, process-based, and gridded vegetation model. We calibrated and ran MC2 simulations for the Blue Mountains Ecoregion, Oregon, USA, at 30 arc-second spatial resolution. We calibrated MC2 using the best available spatial datasets from land managers. We ran future simulations using climate projections from four global circulation models (GCM) under representative concentration pathway 8.5. Under this scenario, forest productivity is projected to increase as the growing season lengthens, and fire occurrence is projected to increase steeply throughout the century, with burned area peaking early- to mid-century. Subalpine forests are projected to disappear, and the coniferous forests to contract by 32.8%. Large portions of the dry and mesic forests are projected to convert to woodlands, unless precipitation were to increase. Low levels of change are projected for the Umatilla National Forest consistently across the four GCM’s. For the Wallowa-Whitman and the Malheur National Forest, forest conversions are projected to vary more across the four GCM-based simulations, reflecting high levels of uncertainty arising from climate. For simulations based on three of the four GCMs, sharply increased fire activity results in decreases in forest carbon stocks by the mid-century, and the fire activity catalyzes widespread biome shift across the study area. We document the full cycle of a structured approach to calibrating and running MC2 for transparency and to serve as a template for applications of MC2.

Influences of environmental factors on macroinvertebrate assemblages: differences between mountain and lowland ecoregions, Wei River, China.

Key environmental factors and the mechanisms of their influence on the physicochemical habitats and macroinvertebrate communities of streams may vary among ecoregions. We studied the differences in environmental (land use and physicochemical) factors and the mechanisms of their influence on macroinvertebrate assemblages between mountain and lowland ecoregions in central China. We applied generalized linear models to identify key environmental factors that influence macroinvertebrate metrics consisting of taxa richness, Ephemeroptera, Plecoptera, and Trichoptera (EPT) taxa, percentages of EPT and intolerant individuals, and the Shannon-Wiener diversity index. Environmental factors and macroinvertebrate metrics significantly differed between the ecoregions. Mountain streams had significantly lower nutrients and %silt, but had twice higher total taxa richness than lowland streams. Watershed land uses were key drivers that influenced the physical habitat in the mountain ecoregion and were the main drivers that influenced both physical and chemical conditions in the lowland ecoregion. Correspondingly, watershed scale land uses, as well as physical and chemical variables, explained more variance in macroinvertebrate metrics than local-scale land uses in both mountain and lowland ecoregions. The overall biological variation was explained better by watershed-scale than by reach-scale land uses, whereas the spatial scale over which land use and physicochemical variables influence streams varied across ecoregions. Our results suggest that better landscape planning should be adopted for watershed management to improve water quality and physical habitat, and thus the conservation and restoration of macroinvertebrate biodiversity.

Risk Indicators for Identifying Critical Source Areas in Five Arkansas Watersheds

Abstract. Change point analysis was used to explore the interactions between watershed characteristics and concentrations of nitrate-nitrogen, total nitrogen, soluble reactive phosphorus, and total phosphorus in streams within the Ozark Highlands, Arkansas Valley, and Ouachita Mountains ecoregions of Arkansas. Thresholds were identified for multiple watershed metrics used to predict water quality, including percent forest in the catchment, agricultural and forested land use in the riparian buffer, stream density, and poultry house density. Based on the observed relationships from the sampled watersheds, we propose four risk indicators to improve the identification of critical source areas for NPS pollution mitigation: subwatersheds that have less than 50% forested area within the drainage area, less than 50% forested area in the riparian buffer zone, more than 0.9 poultry houses km-2, and a stream density that exceeds 50 m ha-1. Keywords: Nonpoint-source pollution, Source water protection, Watershed management.

Long-Term Effects of Burn Season and Frequency on Ponderosa Pine Forest Fuels and Seedlings

Prescribed fire is widely applied in western US forests to limit future fire severity by reducing tree density, fuels, and excessive seedlings. Repeated prescribed burning attempts to simulate historical fire regimes in frequent-fire forests, yet there is limited long-term information regarding optimal burn season and frequency. In addition, burns are operationally feasible only in the spring and late fall, largely outside the historical wildfire season. This study quantifies the effect of seasonal reburns on woody surface fuels, forest floor fuels, and understory tree regeneration abundance in six previously thinned ponderosa pine (Pinus ponderosa Lawson & C. Lawson) stands in the southern Blue Mountain Ecoregion of Oregon, USA. Each stand consisted of an unburned control, and four season by reburn treatments: spring 5 yr, spring 15 yr, fall 5 yr, and fall 15 yr. We evaluated season and frequency of reburn for woody surface fuel (1 hr to 1000 hr), forest floor fuel (litter and duff, undifferentiated), and understory conifer seedling density (regeneration). Burning was initiated in the fall of 1997 and spring of 1998; we present results in this paper through 2014 for fuel, and 2015 for seedlings. All reburn treatments reduced the forest floor depth compared to those areas not burned (controls). Fall burning, regardless of frequency, generated 1000 hr fuel primarily from overstory mortality resulting from the initial entry burns and subsequent snag and branch fall. But, for the other woody fuel types, reburning had minimal impact, regardless of season or frequency. All reburn treatments reduced regeneration survival, but 5 yr fall reburning was most effective in reducing excessive conifer seedlings. Repeated spring or fall reburns following thinning will reduce forest floor depth but, to achieve low woody fuel loads and control excessive conifer regeneration, it may be necessary to conduct reburns using different timing, such as during drier periods when wildfire ignitions by lightning occurred historically.

Controls of reburn severity vary with fire interval in the Klamath Mountains, California, USA

AbstractOver the past few decades, the frequency and number of large fires has increased in the western United States following a paucity of fire activity in many forests during most of the 20th century. Areas of repeated burning are of particular interest for understanding where there may be qualitative shifts in fire severity and the ecological consequences related to ecosystem resilience and climate change. In the context of recent increases in fire activity, we evaluated the relative importance of potential factors contributing to reburn severity (fire severity in areas that have burned twice) from 1985 to 2012 in the Klamath Mountains ecoregion of California. A unique component of our study was the evaluation of different scales of analysis within the ecoregion. The variables prior burn severity (continuous relative difference‐normalized burn ratio values from 1 to 1300), time since fire, biophysical setting, and average monthly weather were evaluated using generalized additive models to identify the relative importance of factors related to reburn severity patterns for 28 individual repeat fires (>375 ha), shorter (<15 yr) and longer (≥19 yr) fire interval categories, and across all repeat fires combined (79,112 ha). We found that evaluation of all repeat fires combined had masked important trends occurring across individual reburn areas of study particularly when dominated by one or more large fires. Averaging the variance of reburn severity explained across individual reburn areas (equal representation) yielded more explanatory power of predictor variables compared to the composite of all reburn areas combined. Over the period of analysis, topographic controls were relatively consistent regardless of fire interval, but vegetation characteristics had a stronger relationship than weather on reburn severity at longer fire intervals compared to shorter intervals. Likewise, we found greater similarity between prior and reburn severity at longer fire intervals than at shorter fire intervals. Our results underscore the presence of a self‐reinforcing pattern of fire severity related to the biophysical setting in the Klamath Mountains ecoregion, but also highlight the importance of spatial and temporal scale of evaluation and the interactions of vegetation characteristics, time since fire, and fire weather on reburn fire severity.

Summer and winter drought drive the initiation and spread of spruce beetle outbreak.

This study used Landsat-based detection of spruce beetle (Dendroctonus rufipennis) outbreak over the years 2000-2014 across the Southern Rocky Mountain Ecoregion to examine the spatiotemporal patterns of outbreak and assess the influence of temperature, drought, forest characteristics, and previous spruce beetle activity on outbreak development. During the 1999-2013 period, time series of spruce beetle activity were highly spatially correlated (r>0.5) at distances <5km, but remained weakly correlated (r=0.08) at distances >400km. Furthermore, cluster analysis on time series of outbreak activity revealed the outbreak developed at multiple incipient locations and spread to unaffected forest, highlighting the importance of both local-scale dispersal and regional-scale drivers in synchronizing spruce beetle outbreak. Spatial overlay analysis and Random Forest modeling of outbreak development show that outbreaks initiate in areas characterized by summer, winter, and multi-year drought and that outbreak spread is strongly linked to the proximity and extent of nearby outbreak, but remains associated with drought. Notably, we find that spruce beetle outbreak is associated with low peak snow water equivalent, not just summer drought. As such, future alterations to both winter and summer precipitation regimes are likely to drive important changes in subalpine forests.

Analog‐based fire regime and vegetation shifts in mountainous regions of the western US

Climate change is expected to result in substantial ecological impacts across the globe. These impacts are uncertain but there is strong consensus that they will almost certainly affect fire regimes and vegetation. In this study, we evaluated how climate change may influence fire frequency, fire severity, and broad classes of vegetation in mountainous ecoregions of the contiguous western US for early, middle, and late 21st century (2025, 2055, and 2085, respectively). To do so, we employed the concept of a climate analog, whereby specific locations with the best climatic match between one time period and a different time period are identified. For each location (i.e. 1‐km2 pixel), we evaluated potential changes by comparing the reference period fire regime and vegetation to that of the fire regime and vegetation of the nearest pixels representative of its future climate. For the mountainous regions we investigated, we found no universal increase or decrease in fire frequency or severity. Instead, potential changes depend on the bioclimatic domain. Specifically, wet and cold regions (i.e. mesic and cold forest) generally exhibited increased fire frequency but decreased fire severity, whereas drier, moisture‐limited regions (i.e. shrubland/grassland) displayed the opposite trend. Results also indicate the potential for substantial changes in the amount and distribution of some vegetation types, highlighting important interactions and feedbacks among climate, fire, and vegetation. Our findings also shed light on a potential threshold or tipping point at intermediate moisture conditions that suggest shifts in vegetation from forest to shrubland/grassland are possible as the climate becomes warmer and drier. However, our study assumes that fire and vegetation are in a state of equilibrium with climate, and, consequently, natural and human‐induced disequilibrium dynamics should be considered when interpreting our findings.

Genetic Characteristics of Red Foxes In Northeastern Oregon

The Rocky Mountain Red Fox (Vulpes vulpes macroura), once common in the Blue Mountains ecoregion of northeastern Oregon, was considered rare in eastern Oregon by the 1930s and thought to be extirpated by the 1960s, when putatively new Red Fox populations began to appear. Although the new foxes were long presumed to be nonnative (originating from fur-farms or deliberate release), they were often phenotypically similar to native Red Foxes, suggesting the alternative possibility that they arose from range expansions, either by small numbers of remnant native foxes at higher elevations or by Rocky Mountain Red Foxes to the east. In this study, we used mitochondrial DNA to investigate the origins of extant Red Fox populations in northeastern Oregon. Our findings show that both native and nonnative sources contributed to the Red Fox populations currently occupying this region. In particular, Red Foxes in montane habitats of their former range in northeastern Oregon reflect predominantly native ancestry, whereas those in more lowland habitats outside the boundaries of their former range represent a mix of native and nonnative ancestry. Recognizing the existence of foxes with native ancestry in northeastern Oregon may shape management decisions regarding this species, especially in respect to control versus conservation.