Southwest-facing Slopes Research Articles

Residual Stand Structure and Topography Predict Initial Survival and Animal Browsing of Redwood and Douglas-Fir Seedlings Planted in Coastal Forests of Northern California

Successful regeneration of commercial species is central to the long-term sustainability of forests managed for wood production. We studied two species of tree seedlings planted after group selection and single-tree selection harvesting in a 20 ha replicated silviculture experiment in stands dominated by coast redwood (Sequoia sempervirens (D.Don) Endl.). Treatments consisted of complete harvest in 1 ha group selection opening (GS), low-density dispersed retention (LD), aggregated high-density retention (HA), and dispersed high-density retention (HD). One year after planting, seedlings planted on a southwest aspect had the lowest survival rate, while northeast aspects had nearly complete survival rates. As expected, redwood had a higher survival rate than coast Douglas-fir (Pseudotsuga menziesii var menziesii (Mirb.) Franco). Survival rates exhibited a rise-peak-fall pattern with stand density, most notably on southwest-facing slopes, ranking LD > HA ≈ HD > GS treatments. Deer browsing of planted seedlings was a pervasive problem where Douglas-fir were preferentially browsed over redwood. In treatments with higher retention densities, browsing was less likely, ranking GS > LD > HA > HD treatments. Further from watercourses at higher elevation, the probability of browsing diminished. Overall, dispersed treatments outperformed aggregated and GS treatments by simultaneously maximizing survival and minimizing browsing of planted seedlings. We did not perform site preparation or herbicide treatment of re-sprouting hardwoods following harvest, and therefore recommend testing the effectiveness of understory vegetation management to enhance seedling survival. Consideration could also be given to planting more seedlings in anticipation of lower survival rates, and/or implementing seedling protection measures when and where heavy browsing is expected.

Co-Seismic Landslides Triggered by the 2014 Mw 6.2 Ludian Earthquake, Yunnan, China: Spatial Distribution, Directional Effect, and Controlling Factors

The 2014 Mw 6.2 Ludian earthquake exhibited a structurally complex source rupture process and an unusual spatial distribution pattern of co-seismic landslides. In this study, we constructed a spatial database consisting of 1470 co-seismic landslides, each exceeding 500 m2. These landslides covered a total area of 8.43 km2 and were identified through a comprehensive interpretation of high-resolution satellite images taken before and after the earthquake. It is noteworthy that the co-seismic landslides do not exhibit a linear concentration along the seismogenic fault; instead, they predominantly extend along major river systems with an NE–SW trend. Moreover, the southwest-facing slopes have the highest landslide area ratio of 1.41. To evaluate the susceptibility of the Ludian earthquake-triggered landslides, we performed a random forest model that considered topographic factors (elevation, slope, aspect, distance to rivers), geological factors (lithology), and seismic factors (ground motion parameters, epicentral distance, distance to the seismogenic fault). Our analysis revealed that the distance to rivers and elevation were the primary factors influencing the spatial distribution of the Ludian earthquake-triggered landslides. When we considered the directional variation in ground motion parameters, the AUC of the model slightly decreased. However, incorporating this variation led to a significant reduction in the proportion of areas classified as “high” and “very high” landslide susceptibility. Moreover, SEDd emerged as the most effective ground motion parameter for interpreting the distribution of the co-seismic landslides when compared to PGAd, PGVd, and Iad.

Drivers of wildfire burn severity in the montane rainforests of northern Vietnam

Background Fire impacts and drivers of wildfire burn severity remain poorly understood for tropical forests. Aims To assess variation and environmental drivers of burn severity for nine forest fires in northern Vietnam. Methods Burn severity was estimated from satellite image analyses, and associations with a remotely sensed index of annual fuel production, topographic factors (elevation, slope, aspect) and weather variables (temperature, rainfall, relative humidity, wind speed) were evaluated. Key results High severity burn areas were found to be fairly uncommon and were associated with steeper, south-west facing slopes, higher elevations and lower fuel abundance. There was a weak tendency for higher burn severity on days with lower relative humidity. Conclusions Conditions that increase fire intensity and the dryness and flammability of fuels are important contributors to high severity fires in wet tropical systems. However, the pattern of higher burn severity at high elevation, where forests tend to be denser and more humid, is counter to this interpretation and may be due to species compositional changes and greater vulnerability of high-elevation forests to fire impacts. Implications Better understanding of fire risk and where in the montane forests of northern Vietnam fires are most likely to burn at high severity will assist forest fire management and recovery strategies.

Millennial-scale coseismic landslide history inferred from topographic and stratigraphic features of a post-caldera cone of Aso Volcano in southwestern Japan

The 2016 Mw 7.0 Kumamoto earthquake triggered numerous landslides of fallout tephra deposits around Aso Volcano in southwestern Japan. Although rainfall-induced landslides have been repeatedly observed on the tephra-mantled slopes of this region, the spatial patterns and frequency of coseismic landslides remain unclear because of the scarce landslide evidence associated with palaeoseismicity. To examine the distribution of landslides induced by the 2016 Kumamoto earthquake and possibly by prior large earthquakes, we conducted geomorphological analyses using airborne light detection and ranging (LiDAR) data, together with geological investigations of tephra deposits in the Takanoobane lava dome (TLD), a post-caldera cone of Aso Volcano. Repeated LiDAR surveys performed before and after the earthquake allowed us to quantify the volume and geometry of five coseismic landslides (K1–K5), as well as three component blocks of the K1 landslide (K1a–c). The surveys also allowed identification of 12 older landslides (O1–O12) fully covered by vegetation. Source areas of recent coseismic landslides ranged from 1050 to 14,920 m2; those of older landslides were estimated to be 1110–15,730 m2. The H/L ratios of the K1 landslide and its component blocks K1a–c ranged from 0.139 to 0.165, despite their volumes ranging from 104 to 105 m3. The K1 landslide occurred on the southwest-facing slope, where older landslides were not recognised before the earthquake. Its slip surface was formed at the base of the 30 ka pumice layer. The largest one of the older landslides (O1) is located on the south-facing slope, adjacent to the K1 landslide. Stratigraphic investigations revealed that most of the tephra sequence, including the 30 ka pumice layer, has already been eroded at the centre of the O1 landslide. Radiocarbon dating further constrained the landslide age to ca. 7.0 ka. Because its topographic and stratigraphic features are similar to the features of the K1 landslide, the O1 landslide may have been triggered by a palaeoearthquake approximately 7000 years ago, which was previously unknown around the Aso caldera region.

A hybrid data–model approach to map soil thickness in mountain hillslopes

Abstract. Soil thickness plays a central role in the interactions between vegetation, soils, and topography, where it controls the retention and release of water, carbon, nitrogen, and metals. However, mapping soil thickness, here defined as the mobile regolith layer, at high spatial resolution remains challenging. Here, we develop a hybrid model that combines a process-based model and empirical relationships to estimate the spatial heterogeneity of soil thickness with fine spatial resolution (0.5 m). We apply this model to two aspects of hillslopes (southwest- and northeast-facing, respectively) in the East River watershed in Colorado. Two independent measurement methods – auger and cone penetrometer – are used to sample soil thickness at 78 locations to calibrate the local value of unconstrained parameters within the hybrid model. Sensitivity analysis using the hybrid model reveals that the diffusion coefficient used in hillslope diffusion modeling has the largest sensitivity among all input parameters. In addition, our results from both sampling and modeling show that, in general, the northeast-facing hillslope has a deeper soil layer than the southwest-facing hillslope. By comparing the soil thickness estimated between a machine-learning approach and this hybrid model, the hybrid model provides higher accuracy and requires less sampling data. Modeling results further reveal that the southwest-facing hillslope has a slightly faster surface soil erosion rate and soil production rate than the northeast-facing hillslope, which suggests that the relatively less dense vegetation cover and drier surface soils on the southwest-facing slopes influence soil properties. With seven parameters in total for calibration, this hybrid model can provide a realistic soil thickness map with a relatively small amount of sampling dataset comparing to machine-learning approach. Integrating process-based modeling and statistical analysis not only provides a thorough understanding of the fundamental mechanisms for soil thickness prediction but also integrates the strengths of both statistical approaches and process-based modeling approaches.

Spatial patterns of nineteenth century fire severity persist after fire exclusion and a twenty-first century wildfire in a mixed conifer forest landscape, Southern Cascades, USA

Spatial patterns of fire severity are influenced by fire-vegetation patch dynamics and topography. Since the late nineteenth century, fire exclusion has increased fuels and recent fire severity patterns may diverge from historical patterns. We used data from a 2008 wildfire burning in a landscape with known nineteenth century fire severity patterns to answer the following questions: (1) Were the spatial patterns of fire severity and fire effects after the 2008 fire similar to those in the late nineteenth century? (2) What factors were most important in controlling spatial patterns of fire severity in 2008? Fire severity patterns in the late nineteenth century were identified by Beaty and Taylor (J Veg Sci 18:879, 2001) using dendroecology. Plots were remeasured after the 2008 fire and geospatial layers of vegetation type, topography, fire weather, daily fire extent and fire severity were used to identify controls on 2008 fire severity. Fire severity in 2008 varied in ways similar to the nineteenth century. Tree mortality and bark char in plots were lowest on lower slopes and southwest facing slopes, intermediate on middle slopes, and highest on upper slopes and northeast slopes. At the landscape scale, vegetation type, elevation, slope aspect, slope position and weather were the variables controlling fire severity. Spatial patterns of fire severity persisted, despite more than a century of fire exclusion. Our findings suggest that wildfires burning under moderate conditions even with a warming climate can help reduce the fire deficit and promote forest resilience in fire prone landscapes.

Relations of land cover, topography, and climate to fire occurrence in natural regions of Iran: Applying new data mining techniques for modeling and mapping fire danger

In recent years, land uses have been changing and aridity has been increasing in the forests and rangelands of central Koohdasht which is a region in the forests of the Zagros Mountains in western Iran. Consequently, the number of fires has also increased. This study employs data-mining techniques to model fire danger using information regarding land cover, climate, topography, and other fire-danger influencing factors. A land cover map was prepared using Sentinel-2A satellite images and a maximum likelihood (ML) algorithm. Digital data describing other factors that influence fire danger (slope angle, aspect, elevation, climate, topographic wetness index, and distances from rivers and roads) were compiled from several sources and imported into a GIS. The locations of past fires in the study area were also determined from MODIS satellite images and data acquired from the region’s fire service. The quantitative and qualitative spatial relationships between effective factors and patterns of fires were investigated to model fire danger. A new machine-learning algorithm (the Boruta algorithm) was used to assess the relative importance of the fire-danger factors. Fire danger maps were created using several new data-mining algorithms including support vector machine (SVM), generalized linear model (GLM), functional data analysis (FDA), and random forest (RF). All were run in R 3.3.3 software. Finally, the fire danger maps were validated with several indices to determine the model that best predicts the fire danger in Koohdasht County. The results reveal that fire locations were determined mostly by elevation (low), aspect (south and southwest facing slopes), and aridity (semi-arid regions). Most fires occurred in non-natural landscapes: residential areas (46.74% of fires), agricultural lands (25.77%), and gardens (5.42%). In total, 77.93% of fires occurred in non-natural landscapes and within 500 m of roads. Only 22.07% of fires occurred on rangelands and forests. Three factors (distance from roads, climate, and aspect) were the strongest predictors of fire locations in the study area. Furthermore, area-under-the-curve (AUC) values indicate that the FDA (0.777) and GLM (0.772) algorithms generated the most accurate fire danger maps. These results have practical implications for fire danger management in the Zagros forests and provide baseline information for forest managers about the most important factors affecting fire danger in the similar regions. This methodology can be used by forest managers to predict the areas with greatest fire danger to prevent future fires through land use management, planning, and strategic decision-making. The results enable forest managers to find the best methods to monitor, manage, and control fire occurrence based on fire danger maps in the forests of western Iran, or in forests of other regions with similar conditions.

The Cerro Guanaco mass movements: A geophysical and morphometric approach on a megalandslide in the Fuegian Andes (Southern Patagonia)

The Fuegian Andes, in the southernmost part of South America, are characterized by a relatively young deglacial landscape, where the glacial erosive relief is strongly influenced by regional-scale geological structures, resulting in deep longitudinal valleys with steeply dipping hillslopes. The rock-slope stability response to receding ice masses and the contribution of the gravitational processes in landscape evolution of the southernmost Andes, however, have not been assessed so far. The remoteness of the region, comprising a mountainous area hardly to access and piedmont and valley floors densely covered by forest, peatbogs or water bodies might partly explain the lack of such studies. Therefore, the objective of this contribution is to document for the first time the occurrence of massive slope failures in the Fuegian Andes using a multidisciplinary approach. This involves the use of indirect methods such as applied geophysics and landscape morphometrics. The southwest-facing slope of Cerro Guanaco, near Ushuaia, hosts several slope failures, but a massive failure stands out. The morphostructural approach allowed the geometrical description of the main dimensional characteristics of the first megalandslide recognized in the Fuegian Andes, which involved almost 1,2 km3 of material. On the other hand, the geophysical data has proved valuable in estimating the depth and characteristic of the buried detachment surface. The slope failure consisted of an initial translational movement followed by secondary slides and was developed shortly after the glacier recession. The gravitational processes represent an important element in the Fuegian deglacial landscape evolution.

Distribution and features of landslides in the Tianshui Basin, Northwest China

Landslides in Tianshui Basin, Gansu Province, Northwest China, severely affect the local population and the economy; therefore, understanding their evolution and kinematics is of great interest for landslide risk assessment and prevention. However, there is no unified classification standard for the types of loess landslides in Tianshui. In this study, we explored the landslide distribution and failure characteristics by means of field investigation, remote sensing interpretation, geological mapping, drilling exploration and shearwave velocity tests, and established a database of Tianshui landslides. Our analysis shows that shear zones in mudstone usually develop in weak intercalated layers. Landslides occur mainly along the West Qinling faults on slopes with gradients of 10° to 25° and on southeast- and southwest-facing slopes. These landslides were classified into five types: loess landslides, loess–mudstone interface landslides, loess flow-slides, loess–mudstone plane landslides and loess–mudstone cutting landslides. We discussed the evolution and failure process of each landslide type and analyzed the formation mechanism and motion characteristics of large-scale landslides. The analysis results show that the landslides in the study area are characterized by a gentle slope, long runout and high risk. The relationship between the runout L and the vertical drop H of the large-scale landslides in the study area is L > 4H. There are good correlations between the equivalent friction coefficient of largescale landslides and their maximum height, runout, area and volume. The sliding zone of large-scale landslides often develops in the bedrock contact zone or in a weak interlayer within mudstone. From microstructure analysis, undisturbed mudstone consists mainly of small aggregates with dispersed inter-aggregate pores, whereas sheared clay has a more homogeneous structure. Linear striations are well developed on shear surfaces, and the clay pores in those surfaces have a more uniform distribution than those in undisturbed clay.

Controlling factors of plant community composition with respect to the slope aspect gradient in the Qilian Mountains

AbstractSlope aspect can affect soil temperature and soil type distribution, which, in turn, is likely to influence plant community composition. Three Qilian mountains, located in the northeastern part of the Qinghai–Tibetan Plateau, China, with four distinct slope aspects including south‐facing (SF), southwest‐facing (SW), northwest‐facing (NW), and north‐facing (NF) slope aspects, were studied to investigate the impact of slope aspect on plant assemblages. The results indicated that the environmental conditions were favorable under the NF and NW slope aspects as the soil water, soil organic carbon (SOC), and soil total nitrogen (STN) contents were significantly higher, and soil temperature (ST) and soil bulk density (SBD) were significantly lower than under the SF and SW aspects. Under all slope aspects, however, SOC, STN, and soil total phosphate in the top 0.2 m of topsoil accounted for about 60% of its total quantity, to a soil depth of 0.6 m. The plant communities on the SF and SW slopes were found to be primarily composed of Poa pratensis, Potentilla anrisena, and Carex aridula. In contrast, the plant community on the NW slope was mainly composed of Kobresia humilis, Carex crebra, and Potentilla bifurca, while on the NF slope it was mainly composed of Picea crassifolia, Carex scabrirostris, and Polygonum macrophyllum. The order of the influence of environmental factors on species distributions was ST > SBD > sand > STN. Results suggest that the slope aspect has an important role in the regulation of the soil environment and plant assemblages and that ST and SBD were the main factors influencing plant community composition. Furthermore, evidence from this study suggests that these mountains will become increasingly vulnerable to global warming. Thus, the plant community composition on these mountains must be monitored continuously in order to allow for strategic adaptive management.

Structure and Dynamics of Tree Stands at the Upper Timberline in the Western Part of the Putorana Plateau

Analysis of the age structure of Dahurian larch (Larix gmelinii Rupr.) forests in the western part of the Putorana Plateau (Sukhie Gory Range) and comparison of diachronous topographic maps and satellite images have revealed changes in the altitudinal position of the upper boundary of tree vegetation. The most significant changes occurred on south- and southwest-facing slopes. Correlations of trunk diameters with the phytomass of trees and its fractions have been found. The course of changes in the structure and phytomass of tree stands in the upper timberline over the past centuries has been reconstructed. Forest expansion has been facilitated by the general change in climate conditions (warming) in the study area.

The future of walnut–fruit forests in Kyrgyzstan and the status of the iconic Endangered apple Malus niedzwetzkyana

AbstractForest ecosystems are rich in biodiversity and provide valuable ecosystem services, but are declining worldwide. Malus niedzwetzkyana, an Endangered wild relative of domesticated apples, is an important component of the walnut–fruit forests of Central Asia. Its iconic pink blossom and genetic properties give it special cultural and scientific significance, but livestock grazing and firewood collection threaten its survival. The conservation of the species and its native forest ecosystem is critical and urgent. This study provides information on the ecology and population of M. niedzwetzkyana and the threats affecting its habitat, improving our understanding of its distribution and proposing measures to reduce threats. We collected ecological data and assessed population structure and threats at four forest sites in southern Kyrgyzstan. We mapped 149 individuals, creating the largest known dataset for this species. We developed species distribution models for M. niedzwetzkyana to identify climatically suitable regions and potential areas for restoration. Sary-Chelek Biosphere Reserve contained the largest expanse of pristine forest and the most stable M. niedzwetzkyana population, followed by Kara-Alma Forestry Unit. Forests in the Gava Forestry Unit and Dashman Reserve were most extensively damaged by humans and livestock. The wild apple's favoured habitat was south-west facing slopes with a gradient < 30° and a relatively open canopy. Overall, the study population was vulnerable to extinction with limited regeneration potential. We recommend short-term population enhancement through planting projects and increased protection of individuals in pristine sites. Community-based conservation initiatives should be prioritized in extensively damaged sites, and larger-scale reforestation of these forests needs to be considered.

Geographic variations in fine-scale vegetation patterns: aspect preferences of montane pine stands over Southern Appalachian landscapes

ABSTRACTLandscape mosaics commonly reflect local terrain interactions with broad-scale processes. In the northern hemisphere, insolation interacts with terrain such that south-facing slopes are warmer, drier, and have sparser and more flammable vegetation than north-facing slopes. These vegetation differences are reinforced through positive feedbacks. In the southern Appalachian Mountains, USA, south-facing slopes harbor xerophytic, fire-dependent pine stands within a hardwood-forest matrix. On certain landscapes, however, pines prefer west- and northwest-facing slopes. We examine pine distribution in the southern Appalachian Mountains (Virginia through Georgia), finding that pines prefer south- and southwest-facing slopes in the southern section of this region but west-, southwest-, and northwest-facing slopes in the northern section, suggesting that broad-scale processes interact differently with terrain in the two sections. To investigate these differences, we analyze three topo-climatic factors (topographic wetness, insolation, and wind) that may influence pine distributions, and discuss other potential influences (bedrock dip, soils, and ice storms). Insolation receipt can straightforwardly explain pine distribution on southern landscapes. No single explanation accounts fully for the anomalous northern pattern, but several mechanisms (especially wind and disturbances) may contribute. We present a conceptual model of these processes and the longer-term coevolution of pine forests with microclimates, fire regimes, soils, and landforms.

Spatial modeling and inventories for prioritizing investment into oak-hickory restoration

Oak (Quercus spp.) and hickory (Carya spp.) forests in the eastern United States provide a host of ecosystem services as their mast are prized by wildlife, the timber is a valued commodity, and they are generally more tolerant of extreme weather events under a changing climate. They are, however, undergoing a severe decline in prominence throughout the region, yielding to more mesic and shade-tolerant species, largely red maple (Acer rubrum). Two decades of research in Ohio have shown that silviculture and/or natural disturbances that reduce understory shade during seedling establishment and early growth, followed by canopy opening and competition management through prescribed fire and partial cutting, can encourage oak and hickory regeneration, most successfully on drier ridges and south- and southwest-facing slopes. We employed an ecological classification and mapping approach to prioritize areas across a 17-county region (∼22,000 km2) that may be more receptive, and thus more cost effective, to successful oak regeneration following silvicultural treatment. The ecomapping effort was comprised of two parts; a GIS model of the terrain, and a stand inventory of current vegetation condition coupled with the SILVAH decision-support system to recommend needed silvicultural treatments. The GIS model is based primarily on topography as vegetation patterns in the project area are largely driven by landscape position and soil moisture regimes. It uses transformed aspect, slope angle, topographic position index, and slope position as inputs to define six classes of landtype phases: ridge, southwest upper slopes, southwest lower slopes, northeast upper slopes, northeast lower slopes, and bottomland. The first three and following two classes, respectively, were hierarchically nested to form Dry Oak Forest and Dry-mesic Mixed Oak Hardwood Forest classes at the landtype level. Dry Oak Forests require the least silvicultural intervention to sustain or restore oak, while the other two landtypes normally require serious intervention to sustain oak into the future. To determine whether sufficient stocking is present for adequate regeneration, we use forest inventory data to represent current vegetation conditions including both overstory and understory stocking. Overall, these tools allow managers to identify ‘zones of investment’, i.e., those stands with the bulk of the area in the Dry Oak Forest landtype and with some level of advance oak regeneration, which will have a greater likelihood of growing into oak-dominated stands with minimal investment of scarce funding resources.

Forest Disturbance History from ‘Legacy’ Pitch Pine (Pinus rigida) at the New River Gorge, West Virginia

ABSTRACT: The mesosphytic forests of eastern North America represent a forest region characterized by dramatic 20th century changes in disturbance regimes, notably the exclusion of fire. Tree-ring reconstructions of forest disturbance can inform restoration and management plans by placing these changes into a historical context. This study examined forest disturbance with regard to land use change and drought in the New River Gorge region of West Virginia. I developed a 182-year pitch pine (Pinus rigida) growth chronology (1833–2014) using samples collected from 33 trees along 2 km of southand southwest-facing slopes at Babcock State Park. Samples cut from fire-scarred pitch and Virginia pine (Pinus virginiana) were used to generate a fire chronology for the site. Temporal trends in pitch pine growth variability were assessed using regime shift and growth release detection methods. There was no change in pitch pine growth during the transition from the early settlement to industrial era (ca. 1885), while ...

Investigating optimal site conditions for flower bud production in Eucalyptus smithii orchards in South Africa

ABSTRACTEucalyptus smithii is an important commercial forestry species in South Africa. The species’ shy and erratic flowering tendencies hinder its genetic improvement and seed production. Breeders and seed producers are highly dependent on paclobutrazol (PBZ) applications for encouraging flower and seed production in E. smithii orchards. During the summer of 2003/04, an E. smithii flowering field trial series was established across a range of high elevation (1568–1828 m asl), cool temperate (13.8–15.5°C mean annual temperature (MAT)) commercial forestry sites in South Africa. The main objective was to investigate the interaction between PBZ and a range of climatic and landscape factors on E. smithii floral bud (umbel) production. The main aim was to define optimum environmental conditions for E. smithii umbel production and potential orchard establishment. In the fifth and sixth years after planting, 64% and 83% of the control (nil PBZ) grafted trees and 94% and 94% of PBZ-treated trees produced umbels. In the fifth year, PBZ application increased mean (across-site) umbel production per tree by 132%. Regardless of whether PBZ was applied or not, mean umbel production varied markedly across sites. In the absence of PBZ application, E. smithii test orchards located on south-west facing slopes in high elevation (>1550 m asl) areas at the lower end of the applied MAT range were generally the most productive on the basis of umbel crop. The study demonstrated that, through careful site selection, dependency on PBZ to achieve satisfactory umbel production in reproductively mature E. smithii trees may be substantially reduced. Within the elevation and MAT ranges applied in the trial series, E. smithii orchards situated in low positions in the landscape were at high risk of being severely damaged by frosts.

Partial altitudinal migration of the Near Threatened satyr tragopan Tragopan satyra in the Bhutan Himalayas: implications for conservation in mountainous environments

AbstractRelative to long-distance migrants, altitudinal migrants have been understudied, perhaps because of a perception that their migrations are less complex and therefore easier to protect. Nonetheless, altitudinal migrants may be at risk as they are subject to ongoing anthropogenic pressure from land use and climate change. We used global positioning system/accelerometer telemetry to track the partial altitudinal migration of the satyr tragopan Tragopan satyra in central Bhutan. The birds displayed a surprising diversity of migratory strategies: some individuals did not migrate, others crossed multiple mountains to their winter ranges, others descended particular mountains, and others ascended higher up into the mountains in winter. In all cases migration between summer breeding and winter non-breeding grounds was accomplished largely by walking, not by flying. Females migrated in a south-easterly direction whereas males migrated in random directions. During winter, migrants occupied south-east facing slopes whereas residents remained on south-west facing slopes. Migratory and resident tragopans utilized a range of forest types, with migratory individuals preferring cool broadleaved forests during winter. These complex patterns of migration suggest that conservation measures should extend across multiple mountains, protect the full range of forest types and encompass multiple landscape configurations to protect aspect diversity. Given the diversity of migratory strategies employed by this single species it seems clear that more research on altitudinal migrants is needed to understand what must be done to ensure their future in an era of widespread land-use and climate change.

Tree- and Stand-Level Thinning Effects on Growth of European Beech (Fagus sylvatica L.) on a Northeast- and a Southwest-Facing Slope in Southwest Germany

Anticipated changes in climate and research findings on the drought sensitivity of beech have triggered controversial discussions about the future of European beech. We investigated the growth response of beech on the tree- and stand-level in mature stands to three different thinning intensities (no thinning, strong thinning, very strong thinning) on a northeast- and southwest-facing slope in Southwest Germany. Linear mixed-effects models were formulated to describe effects on growth parameters on the tree- and stand-level (diameter, height, basal area, volume). At the stand-level, the stand basal area increment and stand volume increment were lower on the thinned plots. At the tree-level, the basal area increment significantly increased with increasing thinning intensity. The growth of individual trees was also influenced by initial tree size, the size-related rank of the tree within a stand, and by the aspect of the site. Our data indicate that growth of European beech is impaired on the southwest-facing slope with a warmer and drier climate and that a very strong thinning regime applied at advanced age can accelerate growth of European beech trees even on the warmer and drier site. Our findings, therefore, imply that in a warmer climate intensive thinning may also represent an important adaptive forest management measure in European beech stands.

Structure of the forest ecotone in the Babia Góra Massif, Western Carpathians

The structure of forest stands and tree architecture at the forest ecotone were analysed at the Alpine timberline zone of the Babia Góra massif of the Western Carpathians. Tree stand and tree characteristics displayedlarge differences in various locations. On the north slope of the massif, trees at the timberline grow relatively tall and slender, and have narrow crowns. Trees at the timberline on the south-west facing slopes of the massif,at higher elevations, are shorter, with lower slenderness indices and relatively broader crowns. These results suggest, that different environmental factors play major roles in shaping the structure of the timberline in variouselevations and various exposures.

Effects of topography and land use on woody plant species composition and beta diversity in an arid Trans-Himalayan landscape, Nepal

Distribution patterns of plant species are believed to be impacted by small-scale habitat heterogeneity. However, there have been few comparative studies examining how woody vegetation composition and diversity varies with aspects of different orientations in the Trans-Himalayan region at a local scale. Here, we examined the effects of incoming solar radiation on variation in woody species composition and compared the diversity between the northeast- and southwest-facing slopes in a Trans-Himalayan valley of Nepal. We also examined the implicit interactions between slope orientation and land use in determining the compositional variations between the slopes. We selected two pairs of northeast- and southwest-facing slopes where the first pair has a similar land use and differs in exposure only (Pisang site) while the other pair has clear differences in land use in addition to slope exposure (Braka site). In each site, we sampled 72 plots (36 on each slope) in which the presence and absence of woody species, environmental variables, and disturbance were recorded. Correspondence Analysis (CA) results suggested that the woody species composition significantly varied between northeast- and southwest-facing slopes at both sites, and was significantly correlated with measured environmental variables such as radiation index, altitude, and canopy openness. In the Braka site, mean alpha diversity was significantly higher on southwest-facing slopes. In contrast, beta diversity and gamma diversity were greater on northeast-facing slopes at both sites. Our results suggest that topographic variables (e.g., radiation index) affect species composition between the slopes, likely due to their influence on small scale abiotic environmental variables. However, the effects of land use, such as livestock browsing/grazing may interact with the effects of slope exposure, effectively reducing differences in species composition within slopes but enhancing the differences in beta diversity between contrasting slopes in the Braka. We conclude that slope orientation and land use are important factors in structuring the woody species composition and diversity in the arid Trans-Himalayan region. We suggest that both environmental and land use variables should be taken into consideration in future studies on plant community structure along the cultural landscapes.