Forest Vulnerability Research Articles

Modeling future range expansion and management strategies for an invasive squirrel species

Successful management of an invasive species requires in depth knowledge of the invader, the invaded ecosystem, and their interactions. The complexity of the species-system interactions can be reduced and represented in ecological models for better comprehension. In this study, a spatially explicit population model was created using the RAMAS software package to simulate the past and future invasion dynamics of the eastern grey squirrel (Sciurus carolinensis) in the fragmented habitat in case study areas in Ireland. This invasive squirrel species causes economic damage by bark stripping forest crops and is associated with the decline of its native congener (S. vulgaris). Three combinations of demographic and dispersal parameters, which best matched the distribution of the species shortly after introduction, were used to simulate invasion dynamics. Future population expansion was modeled under scenarios of no control and two different management strategies: fatal culls and immunocontraceptive vaccination programmes. In the absence of control, the grey squirrel range is predicted to expand to the south and southwest of Ireland endangering internationally important habitats, vulnerable forest crops, and the native red squirrel. The model revealed that region-wide intensive and coordinated culls would have the greatest impact on grey squirrel populations. Control strategies consisting solely of immunocontraceptive vaccines, often preferred by public interest groups, are predicted to be less effective. Complete eradication of the grey squirrel from Ireland is not economically feasible and strategic evidence-based management is required to limit further range expansion. Ecological models can be used to choose between informed management strategies based on predicted outcomes.

Impact of introduced herbivores on understory vegetation along a regional moisture gradient in Patagonian beech forests

Introduced ungulates can alter understory structure and composition posing a serious threat to forest biodiversity. Yet how large-herbivore impacts in forested regions vary along major environmental gradients remains little explored. If ungulate effects shift with habitat conditions, then management could be tailored to protect most vulnerable forests. We tested the hypothesis that the extent of livestock impact on understory vegetation increases with habitat moisture across Nothofagus dombeyi forests in Nahuel Huapi National Park, NW Patagonia, Argentina. Understory composition and species diversity were compared for paired sites (N=5), which were historically used by cattle or remained free of livestock for more than 50yr, and were located along a regional precipitation gradient (1500–2800mm/yr). Long-term cattle presence reduced the cover of sub-canopy trees, shrubs and bamboo by 57–83%, and increased the relative cover of ground-layer herbs, regardless of habitat moisture. Livestock effects on species composition increased towards the wettest forests, which contained more species exclusive to either browsed or unbrowsed sites. Livestock presence increased species richness (α diversity) and within-site heterogeneity (β diversity) in some locations, but mostly reduced species evenness (30%) throughout the moisture gradient. Species turnover at the gradient scale was lower across browsed sites than for livestock-free sites. Our results indicate that the historical presence of domestic cattle induced region-wide changes in understory communities, highlighting the vulnerable nature of the local flora to ungulate disturbance. The greater impact of livestock browsing on the species composition of wetter forests was consistent with the role of plant growth–defence trade-offs along resource gradients. We suggest that the erosion of understory vegetation attributed to domestic herbivores in Patagonian beech forests can be mitigated by adjusting current animal stocks, while moister forests should be given the highest conservation priority.

Semi-parametric Geographically Weighted Regression (S-GWR): a Case Study on Invasive Plant Species Distribution in Subtropical Nepal

GIScience 2016 Short Paper Proceedings Semi-parametric Geographically Weighted Regression (S- GWR): a Case Study on Invasive Plant Species Distribution in Subtropical Nepal Qunshan Zhao 1 , Elizabeth A. Wentz 1 , Stewart Fotheringham 1 , Scott T. Yabiku 2 , Sharon J. Hall 3 , Jennifer E. Glick 2 , Jie Dai 4 , Michele Clark 3 , Hannah Heavenrich 3 Center for Geographical Information Science, School of Geographical Sciences and Urban Planning, Arizona State University, Tempe, AZ 85287, USA Email: {qszhao; wentz; sfotheri}@asu.edu Department of Sociology and Criminology, Pennsylvania State University, University Park, PA 16802, USA Email: {sty105; jeg115}@psu.edu School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA Email: {sharonjhall; mdclar10; hheavenr}@asu.edu Department of Geography, San Diego State University, San Diego, CA 92182, USA Email: jdai@rohan.sdsu.edu Abstract Geographically weighted regression (GWR) is a spatial statistical methodology to explore the impact of non-stationarity on the interaction between spatially measured dependent and inde- pendent variables. In this paper we use a semi-parametric geographically weighted regression (S- GWR) and demonstrate the effectiveness of the method on a case study on socio-ecological fac- tors on forest vulnerability. The case study is based on community forests in and around the buffer zone of Chitwan National Park, Nepal, a biodiversity hotspot that is being rapidly degrad- ed by exotic invasive plant species. This research integrated heterogeneous data sources such as observational ecological surveys, household interviews, and remotely sensed imagery. These data were utilized to extract and represent invasive plant species coverage, human activity inten- sity, topographical parameters and vegetation greenness indices. Research findings both demon- strate the S-GWR method and offer possible interventions that could slow the catastrophic spread of invasive plant species in Chitwan, Nepal. 1. Introduction Geographically weighted regression (GWR) is a spatial analysis method that uses the spatial dis- tribution of dependent and independent variables to specify non-stationarity to quantify the driv- ers of spatially dependent processes. GWR has been widely applied in application domains such as species distribution modeling in ecology and crime analysis in sociology (Foody 2004; Zhang and Song 2013). This paper presents a semi-parametric geographically weighted regression (S- GWR) method to model the factors that influence the spatial distribution of invasive plants in Nepal. We chose to use a semi-parametric model to include both parametric and non-parametric variables in the model specification. The S-GWR is implemented in a case study on the relation- ship between socio-ecological factors and invasive plant species in Chitwan, Nepal. Invasive plant species are considered as a serious global environmental threat to ecosystem structure and function by creating disturbances in ecosystems, reducing native species diversity and abundance, limiting human usage of ecosystems and triggering environmental changes. It is an emergent research topic to prevent invasive plant species spread and alleviate their influences in forest ecosystems. The case study aims to quantify the relationships between invasive plant species coverage and socio-ecological factors in community forests (CFs) in Chitwan, Nepal. We

Наиболее уязвимые леса северо-запада таежной зоны России: ландшафтные особенности, современное состояние, сохранение

Наиболее уязвимые леса северо-запада таежной зоны России: ландшафтные особенности, современное состояние, сохранение

Assessing vulnerability of forests to climate change in South Korea

This study demonstrated a framework to assess vulnerability of forests to climate change. We focused on how alterations of temperature and precipitation might affect forest type distributions and carbon-related functions. In particular, our framework considered three sectors of forest type distribution, net primary production, and soil carbon storage. Future projections were derived from mechanistic models for South Korean forests under the A1B scenarios of the intergovernmental panel on climate change. Forest type distributions were simulated by the Hydrological and thermal analogy group model, while the MAPSS and CENTURY1 models estimated forest carbon flux/storage. We quantified normalized vulnerability indices for each sector. Our results indicate that the overall vulnerability of forest type distribution is greater in the west central regions and southeastern inlands. The vulnerabilities of carbon flux/storage show that net primary production of South Korean forests is relatively less susceptible to climate change, but a highly vulnerable area of soil carbon storage mainly spreads from the west central to the south east region. The spatio-temporal vulnerability map with a synoptic overview from this study might be useful for policy makers in preparing adaptive measures and identifying management priorities.

A forest vulnerability index based on drought and high temperatures

ABSTRACT Increasing forest stress and tree mortality has been directly linked to combinations of drought and high temperatures. The climatic changes expected during the next decades – large increases in mean temperature, increased heat waves, and significant long-term regional drying in the western USA – will likely increase chronic forest stress and mortality. The aim of this research is to develop and apply a new forest vulnerability index (FVI) associated with drought and high temperatures across the Pacific Northwest region (PNW; Oregon and Washington) of the USA during the MODIS Aqua era (since 2003). Our technique incorporates the alterations to canopy water and energy exchange processes caused by drought and high temperatures with spatially continuous MODIS land surface temperature (LST) and evapotranspiration (ET), and with Parameter-elevation Relationships on Independent Slopes Model (PRISM) precipitation (P) data. With P and ET, we calculate a monthly water balance variable for each individual pixel normalized by forest type group (FTG), and then difference the water balance with the corresponding normalized monthly mean LST to calculate a monthly forest stress index (FSI). We then extract the pixel-specific (800-m resolution) statistically significant temporal trends of the FSI from 2003 to 2012 by month (April to October). The FVI is the slope of the monthly FSI across years, such that there is a FVI for each month. Statistically significant positive slopes indicate interannual increases in stress leading to expected forest vulnerability (positive FVI) for a given month. Positive FVI values were concentrated in the months of August and September, with peak vulnerability occurring at different times for different FTGs. Overall, increased vulnerability rates were the highest in drier FTGs such as Ponderosa Pine, Juniper, and Lodgepole Pine. Western Larch and Fir/Spruce/Mountain Hemlock groups occupy moister sites but also had relatively high proportion of positive FVI values. The Douglas-fir group had the second largest total area of increased vulnerability due to its large areal extent in the study area. Based on an analysis using imagery viewed in Google Earth, we confirm that areas with increased vulnerability are associated with greater amounts of stress and mortality. The FVI is a new way to conceptualize and monitor forest vulnerability based on first-order principles and has the potential to be generalized to other geographical areas.

Vulnerabilidade da Mata Atlântica no Sul da Bahia frente à Expansão da Fronteira Econômica

Este artigo apresenta a vulnerabilidade da Mata Atlântica existente na região norte da cidade de Ilhéus (BA) a partir da proposta de criação de uma nova fronteira econômica: o empreendimento Porto Sul. São apresentados conceitos para o termo fronteira, suas principais tipologias e aspectos relacionados à vulnerabilidade da Mata Atlântica na região. A partir da revisão teórica sobre o tema "fronteira" foram identificadas as sobreposições existentes no caso da futura implantação do empreendimento denominado Porto Sul. Para tanto, utilizou-se como metodologia o estudo de caso qualitativo, descritivo, a partir da análise de documentos públicos e de entrevista não estruturada. O objetivo deste artigo, portanto, é identificar, em termos de conservação da biodiversidade, se a fronteira ecológica poderá coexistir em com esta nova fronteira econômica.Palavras chave: Impacto Ambiental; Conservação; Fronteira.

Vulnerability of tropical forest ecosystems and forest dependent communities to droughts

Energy captured by and flowing through a forest ecosystem can be indexed by its total Net Primary Productivity (NPP). This forest NPP can also be a reflection of its sensitivity to, and its ability to adapt to, any climate change while also being harvested by humans. However detecting and identifying the vulnerability of forest and human ecosystems to climate change requires information on whether these coupled social and ecological systems are able to maintain functionality while responding to environmental variability.To better understand what parameters might be representative of environmental variability, we compiled a metadata analysis of 96 tropical forest sites. We found that three soil textural classes (i.e., sand, sandy loam and clay) had significant but different relationships between NPP and precipitation levels. Therefore, assessing the vulnerability of forests and forest dependent communities to drought was carried out using data from those sites that had one of those three soil textural classes. For example, forests growing on soil textures of sand and clay had NPP levels decreasing as precipitation levels increased, in contrast to those forest sites that had sandy loam soils where NPP levels increased. Also, forests growing on sandy loam soil textures appeared better adapted to grow at lower precipitation levels compared to the sand and clay textured soils. In fact in our tropical database the lowest precipitation level found for the sandy loam soils was 821mmyr−1 compared to sand at 1739mmyr−1 and clay at 1771mmyr−1. Soil texture also determined the level of NPP reached by a forest, i.e., forest growing on sandy loam and clay reached low-medium NPP levels while higher NPP levels (i.e., medium, high) were found on sand-textured soils. Intermediate precipitation levels (>1800–3000mmyr−1) were needed to grow forests at the medium and high NPP levels. Low thresholds of NPP were identified at both low (∼750mm) and high precipitation (>3500mm) levels.By combining data on the ratios of precipitation to the amount of biomass produced in a year with how much less precipitation input occurs during a drought year, it is possible to estimate whether productivity levels are sufficient to support forest growth and forest dependent communities following a drought. In this study, the ratios of annual precipitation inputs required to produce 1Mgha−1yr−1 biomass by soil texture class varied across the three soil textural classes. By using a conservative estimate of 20% of productivity collected or harvested by people and 30% precipitation reduction level as triggering a drought, it was possible to estimate a potential loss of annual productivity due to a drought. In this study, the total NPP unavailable due to drought and harvest by forest dependent communities per year was 10.2Mgha−1yr−1 for the sandy textured soils (64% of NPP still available), 8.4Mgha−1yr−1 for the sandy loam textured soils (60% available) and 12.7Mgha−1yr−1 for the clay textured soils (29% available). Forests growing on clay textured soils would be most vulnerable to drought triggered reductions in productivity so NPP levels would be inadequate to maintain ecosystem functions and would potentially cause a forest-to-savanna shift. Further, these forests would not be able to provide sufficient NPP to satisfy the requirements of forest dependent communities. By predicting the productivity responses of different tropical forest ecosystems to changes in precipitation patterns coupled with edaphic data, it could be possible to spatially identify where tropical forests are most vulnerable to climate change impacts and where mitigation efforts should be concentrated.

Impact of climate change on vulnerability of forests and ecosystem service supply in Western Rhodopes Mountains

The vulnerability of forest ecosystem services to climate change is expected to depend on landscape characteristic and management history, but may also be influenced by the proximity to the southern range limit of constituent tree species. In the Western Rhodopes in South Bulgaria, Norway spruce is an important commercial species, but is approaching its current southern limit. Using climate sensitive forest models, we projected the impact of climate change on timber production, carbon storage, biodiversity and soil retention in two representative landscapes in the Western Rhodopes; a lower elevation landscape (1000–1450 m a.s.l) dominated by mixed species forests, and a higher elevation landscape (1550–2100 m a.s.l.) currently dominated by spruce. In both landscapes climate change is projected to induce a shift in forest composition, with drought-sensitive species, such as Norway spruce, being replaced by more drought-tolerant species such as Scots pine and black pine at lower elevations. In the higher elevation landscape a reduction in spruce growth is projected, particularly under the more severe climate change scenarios. Under most climate scenarios a reduction in growing stock is projected to occur, but under some scenarios a moderate increase in higher elevation stands (>1500 m a.s.l.) is expected. Climate change is projected to negatively influence carbon storage potential across landscapes with the magnitude depending on the severity of the climate change scenario. The impact of climate change on forest diversity and habitat availability is projected to differ considerably between the two landscapes, with diversity and habitat quality generally increasing at higher elevations, and being reduced at lower elevations. Our results suggest that if currently management practices are maintained the sensitivity of forests and forest ecosystem services in the Western Rhodopes to climate change will differ between low and higher elevation sites and will depend strongly on current forest composition.

The vulnerability of Indo-Pacific mangrove forests to sea-level rise.

Sea-level rise can threaten the long-term sustainability of coastal communities and valuable ecosystems such as coral reefs, salt marshes and mangroves. Mangrove forests have the capacity to keep pace with sea-level rise and to avoid inundation through vertical accretion of sediments, which allows them to maintain wetland soil elevations suitable for plant growth. The Indo-Pacific region holds most of the world's mangrove forests, but sediment delivery in this region is declining, owing to anthropogenic activities such as damming of rivers. This decline is of particular concern because the Indo-Pacific region is expected to have variable, but high, rates of future sea-level rise. Here we analyse recent trends in mangrove surface elevation changes across the Indo-Pacific region using data from a network of surface elevation table instruments. We find that sediment availability can enable mangrove forests to maintain rates of soil-surface elevation gain that match or exceed that of sea-level rise, but for 69 per cent of our study sites the current rate of sea-level rise exceeded the soil surface elevation gain. We also present a model based on our field data, which suggests that mangrove forests at sites with low tidal range and low sediment supply could be submerged as early as 2070.

Adopting public values and climate change adaptation strategies in urban forest management: A review and analysis of the relevant literature

Urban trees are a dominant natural element in cities; they provide important ecosystem services to urban citizens and help urban areas adapt to climate change. Many rationales have been proposed to provide a purpose for urban forest management, some of which have been ineffective in addressing important ecological and social management themes. Among these rationales we find a values-based perspective, which sees management as a process where the desires of urban dwellers are met. Another perspective is climate change adaptation, which sees management as a process where urban forest vulnerability to climate change is reduced and resilience enhanced. Both these rationales have the advantage of complementing, enhancing, and broadening urban forest management objectives. A critical analysis of the literature on public values related to urban forests and climate change adaptation in the context of urban forests is undertaken to discuss what it means to adopt these two issues in urban forest management. The analysis suggests that by seeing urban forest management as a process by which public values are satisfied and urban-forest vulnerabilities to climate change are reduced, we can place issues such as naturalization, adaptive management, and engaging people in management at the centre of urban forest management. Focusing urban forest management on these issues may help ensure the success of programs focused on planting more trees and increasing citizen participation in urban forest management.

Disentangling the effects of competition and climate on individual tree growth: A retrospective and dynamic approach in Scots pine

Understanding the relative contributions of competition and climate on individual tree growth is critical to project realistic forest dynamics under projected climate scenarios. Furthermore, present competition levels may reflect legacies of past use. Here, we analyze the effects of climate, site conditions and competition on radial growth in three Scots pine stands located along an altitudinal gradient in central Spain. Current stand structure and retrospective analyses of radial growth (basal area increment, BAI) were used to model changes in tree growth as a function of a spatially-explicit competition index (CI) and climate. Linear mixed-effects models were employed to model BAI and to quantify the growth responses to climate of trees under low and high competition levels. Competition effects on growth were steady over time regardless of tree age. High competition levels negatively affected growth since negative exponential functions characterized the CI–BAI relationships. Tree growth sensitivity to climate increased with decreasing competition intensity. Growth at high elevations was mainly limited by low winter temperatures, whereas warm spring enhanced growth at middle elevations and warm late summer temperatures constrained growth at low elevation. Growth responsiveness to climate is enhanced under low competition levels. Overall, current competition is a more relevant driver of recent growth than climate. Proactive forest management should be adopted to reduce the vulnerability of Scots pine forests currently subjected to higher competition levels and warmer and drier conditions.

Papel de los factores bióticos y las sequías en el decaimiento del bosque: aportaciones desde la dendroecología

Sanguesa-Barreda, G., Camarero, J.J., Linares, J.C., Hernandez, R., Oliva, J., Gazol, A., et al. 2015. Role of biotic factors and droughts in the forest decline: contributions from dendroecology. Ecosistemas 24(2): 15-23. Doi.: 10.7818/ECOS.2015.24-2.03. Increasing mortality and decline of forests are affecting several tree species and biomes. These events of forest decline have been related to the interaction of several global change elements, like the increase in drought stress or a higher incidence of biotic stress factors. However, the roles played by biotic stressors have been scarcely explored as related to drought stress. In this paper we retrospectively characterize the effects of these organisms on radial growth of trees already stressed by drought using dendrochronology. The combined effect of mistletoe and droughts reduce tree growth in Scots pine and increase defoliation, being these effects more noticeable in the apex. The pine processionary moth induces growth losses in the affected stands of black pine, but they usually recover two years after the outbreak. We did not find a determinate role of root pathogens on silver fir dieback. Finally, dead Aleppo pine trees infested by bark beetles showed similar growth patterns than living pine trees. This study allows characterizing some of the complex and multiple effects of different biotic stressors on growth and vulnerability of forests subjected to the negative effects exerted by droughts.

Mapping Social and Economic Vulnerability in Forest and Peatland Fire Disaster in Bengkalis Regency, Riau Province

The aims of this research are (1) analyzing social and economic vulnerability of forest and peat land fire disaster in Bengkalis Regency; (2) Mapping social and economic vulnerability of forest and peat land fire disaster in Bengkalis Regency. Research Variable is social and economic vulnerability. The data that used is primary and secondary data with survey method. Analysis method is scoring and weightings. After that classified based on the value of the score to determine the level of vulnerability. The analysis based on the head of National Agency for Disaster Management (Perka BNPB) Number 02.2012 and literatures study. The results of research show that social vulnerability of forest and peat land fire in Bengkalis Regency is medium vulnerability because it has value of social vulnerability is 0.46663. While economic vulnerability in Bengkalis Regency is low vulnerability because economic vulnerability is 0.3333. In addition, required mitigation that is quick and appropriate by governments of Bengkalis Regency and the local community in management of forest and peat land fire disaster.

On underestimation of global vulnerability to tree mortality and forest die‐off from hotter drought in the Anthropocene

Patterns, mechanisms, projections, and consequences of tree mortality and associated broad‐scale forest die‐off due to drought accompanied by warmer temperatures—“hotter drought”, an emerging characteristic of the Anthropocene—are the focus of rapidly expanding literature. Despite recent observational, experimental, and modeling studies suggesting increased vulnerability of trees to hotter drought and associated pests and pathogens, substantial debate remains among research, management and policy‐making communities regarding future tree mortality risks. We summarize key mortality‐relevant findings, differentiating between those implying lesser versus greater levels of vulnerability. Evidence suggesting lesser vulnerability includes forest benefits of elevated [CO2] and increased water‐use efficiency; observed and modeled increases in forest growth and canopy greening; widespread increases in woody‐plant biomass, density, and extent; compensatory physiological, morphological, and genetic mechanisms; dampening ecological feedbacks; and potential mitigation by forest management. In contrast, recent studies document more rapid mortality under hotter drought due to negative tree physiological responses and accelerated biotic attacks. Additional evidence suggesting greater vulnerability includes rising background mortality rates; projected increases in drought frequency, intensity, and duration; limitations of vegetation models such as inadequately represented mortality processes; warming feedbacks from die‐off; and wildfire synergies. Grouping these findings we identify ten contrasting perspectives that shape the vulnerability debate but have not been discussed collectively. We also present a set of global vulnerability drivers that are known with high confidence: (1) droughts eventually occur everywhere; (2) warming produces hotter droughts; (3) atmospheric moisture demand increases nonlinearly with temperature during drought; (4) mortality can occur faster in hotter drought, consistent with fundamental physiology; (5) shorter droughts occur more frequently than longer droughts and can become lethal under warming, increasing the frequency of lethal drought nonlinearly; and (6) mortality happens rapidly relative to growth intervals needed for forest recovery. These high‐confidence drivers, in concert with research supporting greater vulnerability perspectives, support an overall viewpoint of greater forest vulnerability globally. We surmise that mortality vulnerability is being discounted in part due to difficulties in predicting threshold responses to extreme climate events. Given the profound ecological and societal implications of underestimating global vulnerability to hotter drought, we highlight urgent challenges for research, management, and policy‐making communities.

Assessing the potential distribution of insect pests: case studies on large pine weevil (Hylobius abietis L) and horse‐chestnut leaf miner (Cameraria ohridella) under present and future climate conditions in European forests

Forest insect pests represent a serious threat to European forests and their negative effects could be exacerbated by climate change. This paper illustrates how species distribution modelling integrated with host tree species distribution data can be used to assess forest vulnerability to this threat. Two case studies are used: large pine weevil (Hylobius abietis L) and horse‐chestnut leaf miner (Cameraria ohridella Deschka & Dimič) both at pan‐European level. The proposed approach integrates information from different sources. Occurrence data of insect pests were collected from the Global Biodiversity Information Facility (GBIF), climatic variables for present climate and future scenarios were sourced, respectively, from WorldClim and from the Research Program on Climate Change, Agriculture and Food Security (CCAFS), and distributional data of host tree species were obtained from the European Forest Data Centre (EFDAC), within the Forest Information System for Europe (FISE). The potential habitat of the target pests was calculated using the machine learning algorithm of Maxent model. On the one hand, the results highlight the potential of species distribution modelling as a valuable tool for decision makers. On the other hand, they stress how this approach can be limited by poor pest data availability, emphasizing the need to establish a harmonised open European database of geo‐referenced insect pest distribution data.

Age, competition, disturbance and elevation effects on tree and stand growth response of primary Picea abies forest to climate

Stands and trees may exhibit different climate–growth responses compared to neighbouring forests and individuals. The study of these differences is crucial to understanding the effects of climate change on the growth and vulnerability of forests and trees. In this research we analyse the growth responsiveness of primary Norway spruce forests to climate as a function of different stand (elevation, aspect, slope, crowding, historic disturbance regime) and tree (age, tree-to-tree competition) features in the Romanian Carpathians. Climate–growth relationships were analysed using Pearson correlation coefficients between ring-width indices (RWIs) and climate variables. The influence of stand and tree characteristics on the RWI responses to climate were investigated using linear mixed-effects models. Elevation greatly modulated the climate–growth associations and it frequently interacted with competition intensity or tree age to differentially influence growth responsiveness to climate. Old trees were more sensitive to climate than young trees, but while old tree’s response to climate highly depended on elevation (e.g. positive influence of summer temperature on old trees’ RWIs at high elevations, but negative effect at low elevations), differences of the young trees’ response across the elevation gradient were less evident. The severity of the past disturbance also modified the climate–growth associations because of contrasting canopy structures. Our results suggest that although an increase in temperature might enhance growth at high elevations, it may also induce growth declines due to drought stress at lower elevations, particularly for old trees or trees growing under high levels of competition, which may increase their vulnerability to disturbances.

Assessment of Wildfire Risk in Lebanon Using Geographic Object-Based Image Analysis

AbstractDuring the past decade, Lebanon has experienced a large number of severe wildfires that have had significant social and ecological consequences. In this context, the assessment of wildfire risk is important to support planning of fire preventionmeasures and riskmitigation. The purpose of this study was to assess the spatial distribution of wildfire risk in Lebanon. The objectives were to identify andmap (a) wildfire hazard, (b)wildfire vulnerability, and (c) wildfire risk. We developed amodel using geospatial biophysical and climatic data and Geographic Object-Based Image Analysis (GEOBIA). Development of the wildfire hazardmap included classification of forest fuel type, combustibility, and fire spread whereas the vulnerabilitymap included classification of demographic vulnerability (i.e., boundary, occupation and scatter indicators) and forest vulnerability (i.e., environmental and replacement values). The resulting geospatialmap of wildfire risk provided important information for potential use in fire riskmanagement.

Soil-moisture conditions indicated by field-layer plants help identify vulnerable forests in the forest-steppe of semi-arid Southern Siberia

High variability in soil-moisture conditions is typical for semi-arid forest-steppe ecosystems where precipitation varies greatly over time. Plant species that inhabit these environments integrate responses to broadly fluctuating wetness conditions. Indirect assessment of contrasting habitat wetness based on plant indicator values, species frequency, and species coverage was carried out in two sites representing the larch (Larix sibirica) and pine (Pinus sylvestris) forest-steppe communities. For the larch forest-steppe, we found that plant community composition and spatial structure depended strongly on wetness. In addition, we found that the vegetation was clearly differentiated into forest stands and steppe communities, depending on the slope aspect. There was also a strong correlation between dissimilarities of species composition and differences in habitat wetness revealed in the larch forest-steppe. In contrast, soil properties, such as gravel and stone content were found to be a key factor in the spatial distribution of plant species composition in the pine-forest-steppe communities. Indirect assessment of moisture conditions in the forest-steppe habitats, based on the field-layer plant species, was found to be preferable for indicating soil water deficits in the forest. Furthermore, as long-term observational data is often lacking, indirect assessment of the forest-steppe vegetation provides an opportunity to identify vulnerable forests at the marginal distribution. Based on indirect assessments of soil-moisture conditions, and taking into account differences in potential drought resistance between larch and pine forests, we concluded that increasing aridity will cause the replacement of Siberian larch by Scots pine in the South Siberian forest-steppe landscape. Consequently, in the future it is likely that forest-steppe typological diversity will decrease, and the semi-arid landscape may become more monotonous.

Assessment of inherent vulnerability of forests at landscape level: a case study from Western Ghats in India

Assessment of vulnerability is an important step in building long-term resilience in the forestry sector. The objective of this paper is to present a methodological approach to assess inherent vulnerability of forests at landscape level. The approach involves use of vulnerability indicators, the pairwise comparison method, and geographic information system (GIS) tools. We apply this approach to assess the inherent vulnerability of forests of the Western Ghats Karnataka (WGK) landscape, which is a part of the Western Ghats biodiversity hotspot in India. Four vulnerability indicators, namely biological richness, disturbance index, canopy cover, and slope, are selected. We find that forests in 30, 36, 19, and 15 % grid points in this region show low, medium, high, and very high inherent vulnerability, respectively. The forest showing high and very high inherent vulnerability are mostly dry deciduous forests and plantations located largely on the eastern side of the landscape. We also find that canopy cover is one of the key indicators that determine the inherent vulnerability of forests, and natural forests are inherently less vulnerable than man-made plantations. Spatial assessment of inherent vulnerability of forests at landscape level is particularly useful for developing strategies to build resilience to current stressors and climate change in future.