Assessing transhumance corridors on high mountain environments by least cost path analysis: the case of yak herds in Gilgit-Baltistan, Pakistan.

Mountain environments in the world host highly specialized flora and fauna which are vulnerable because of land use and climate change. Transhumance and other land use traditional practices are present in most of the mountains of the world, and management tools able to cope with new socioeconomic settings and environmental changes are urgently needed. During past centuries, yak (Bos grunniens) herding in Northern Pakistan involved the migration of herds to high mountain international rangelands, but the recent establishment of international borders breaks the traditional transhumance paths, promoting several ecological problems. In this paper, we propose the use of least cost path (LCP) algorithm to identify the most efficient corridors of transhumance for yak herds on northern high altitudes of Pakistan. Specifically, LCP was implemented to identify the critical grazing areas and the connecting zones to be accounted in a new management plan for the yaks in the region. The LCP analysis showed that some grazing areas are connected with several paths, whereas other areas are connected to a lesser extent. The analyses identified a set of best minimum cost paths able to guarantee local connectivity. We also delineated several medium and low efficient paths that could play a crucial role for maintaining regional connectivity which is essential for reducing the isolation of herds and the consequent inbreeding problems. The analytical framework implemented in this study allowed to (1) provide valuable information concerning the movement of yak herds in Gilgit-Baltistan, (2) identify potential corridors that are able to promote herd movement between villages and high mountain rangelands, and (3) identify critical areas for the connectivity of yaks by ranking of the potential corridors according to their length and permeability. The analysis would be extended to other transhumant herds and high mountain areas that are facing sociopolitical transformations and environmental changes.

Changes in composition, ecology and structure of high-mountain vegetation: a re-visitation study over 42 years.

High-mountain ecosystems are increasingly threatened by climate change, causing biodiversity loss, habitat degradation and landscape modifications. However, very few detailed studies have focussed on plant biodiversity in the high mountains of the Mediterranean. In this study, we investigated the long-term changes that have occurred in the composition, structure and ecology of high-mountain vegetation in the central Apennines (Majella) over the last 42 years. We performed a re-visitation study, using historical and newly collected vegetation data to explore which ecological and structural features have been the most successful in coping with climatic changes. Vegetation changes were analysed by comparing geo-referenced phytosociological relevés collected in high-mountain habitats (dolines, gentle slopes and ridges) on the Majella massif in 1972 and in 2014. Composition analysis was performed by detrended correspondence analysis, followed by an analysis of similarities for statistical significance assessment and by similarity percentage procedure (SIMPER) for identifying which species indicate temporal changes. Changes in ecological and structural indicators were analysed by a permutational multivariate analysis of variance, followed by a post hoc comparison. Over the last 42 years, clear floristic changes and significant ecological and structural variations occurred. We observed a significant increase in the thermophilic and mesonitrophilic plant species and an increment in the frequencies of hemicryptophytes. This re-visitation study in the Apennines agrees with observations in other alpine ecosystems, providing new insights for a better understanding of the effects of global change on Mediterranean high-mountain biodiversity. The observed changes in floristic composition, the thermophilization process and the shift towards a more nutrient-demanding vegetation are likely attributable to the combined effect of higher temperatures and the increase in soil nutrients triggered by global change. The re-visitation approach adopted herein represents a powerful tool for studying climate-related changes in sensitive high-mountain habitats.

Temporal Changes in Forest Contexts at Multiple Extents: Three Decades of Fragmentation in the Gran Chaco (1979-2010), Central Argentina.

The context in which a forest exists strongly influences its function and sustainability. Unveiling the multi-scale nature of forest fragmentation context is crucial to understand how human activities affect the spatial patterns of forests across a range of scales. However, this issue remains almost unexplored in subtropical ecosystems. In this study, we analyzed temporal changes (1979-2010) in forest contexts in the Argentinean dry Chaco at multiple extents. We classified forests over the last three decades based on forest context amount (Pf) and structural connectivity (Pff), which were measured using a moving window approach fixed at eight different extents (from local, ~ 6 ha, to regional, ~ 8300 ha). Specific multi-scale forest context profiles (for the years 1979 and 2010) were defined by projecting Pf vs. Pff mean values and were compared across spatial extents. The distributions of Pf across scales were described by scalograms and their shapes over time were compared. The amount of agricultural land and rangelands across the scales were also analyzed. The dry Chaco has undergone an intensive process of fragmentation, resulting in a shift from landscapes dominated by forests with gaps of rangelands to landscapes where small forest patches are embedded in agricultural lands. Multi-scale fragmentation analysis depicted landscapes in which local exploitation, which perforates forest cover, occurs alongside extensive forest clearings, reducing forests to small and isolated patches surrounded by agricultural lands. In addition, the temporal diminution of Pf's variability along with the increment of the mean slope of the Pf 's scalograms, indicate a simplification of the spatial pattern of forest over time. The observed changes have most likely been the result of the interplay between human activities and environmental constraints, which have shaped the spatial patterns of forests across scales. Based on our results, strategies for the conservation and sustainable management of the dry Chaco should take into account both the context of each habitat location and the scales over which a forest pattern might be preserved, altered or restored.

Seasonal habitat preference by the flagship species Testudo hermanni: Implications for the conservation of coastal dunes.

In this study, we explored if, how, and when the European Union habitats (EU sensu Habitats Directive 92/43/CEE) are used by the flagship species Testudo hermanni in a well-preserved coastal dune system of the Italian peninsula. Radio telemetry data and fine-scale vegetation habitat mapping were used to address the following questions: (a) is each EU habitat used differentially by Hermann's tortoises? (b) is there any seasonal variation in this utilization pattern? (c) how does each habitat contribute to the ecological requirements of the tortoises? Nine tortoises were fitted with transmitters and monitored for the entire season of activity. The eight EU habitats present in the study area were surveyed and mapped using GIS. The seasonal preferential use or avoidance of each habitat was tested by comparing, through bootstrap tests, the proportion of habitat occupied (piTh) with the proportion of available habitat in the entire landscape (piL). The analysis of 340 spatial locations showed a marked preference for the Cisto-Lavanduletalia dune sclerophyllous scrubs (EU code 2260) and a seasonal selection of Juniperus macrocarpa bushes (EU code 2250(*)), wooded dunes with Pinus (EU code 2270) and mosaic of dune grasslands and sclerophyllous scrubs (EU codes 2230, 2240, 2260). Seasonal variation of habitat preference was interpreted in light of the different feeding, thermoregulation and reproductive needs of the tortoises. Our results stress the ecological value of EU coastal dune habitats and suggest prioritization of conservation efforts in these ecosystems.