Assessing forest fragmentation in north-western Himalaya:a case study from Ranikhet forest range,Uttarakhand,India

The northwestern Himalaya harbors high levels of biodiversity due to its unique topography, climatic conditions and heterogeneity. Forest fragmentation is one of the major threats causing a decline in biodiversity in the Himalayan region. We assesses forest fragmentation and changes in land use land cover（LULC） patterns using multi-temporal satellite data over a time span of four decades（1976–2013）. Fragmentation analysis using the Landscape Fragmentation Tool（LFT） reveals a decrease in core and edge areas by 14 and 2.3 %, respectively; while an increase in non-forest, patch area and perforation area by 2.1, 0.4, and 14 %, respectively. The LULC dynamics show that the areas under dense forest and scrub forest have decreased by 2.8 % and 1.9 %, respectively; and there is an increase in open forest, crop land and fallow land area by 2.6, 1.7 and 2.1 %, respectively. The quantification of landscape heterogeneity is undertaken with the help of landscape metrics computed using FRAGSTATS at class and landscape level, showing signs of increased fragmentation. Our study provides baseline database that can support the future biodiversity conservation and sustainable forest management initiatives.

Tornado effects on damage,resprouting and spatial heterogeneity in the Cross Timbers ecotone of Oklahoma,USA

Aims In order to better understand how tornados structure the ecotone between eastern deciduous forest and tallgrass prairie,we sampled trees in a recent tornado blowdown area and in the adjacent undisturbed forest.Both are part of the Cross Timbers ecotone of Osage County,Northeastern Oklahoma,USA.Methods We set up a 1-ha square plot in each area and sampled all tree stems at least 50 cm tall where stems were identified to species and measured for size and spatial location in both plots.For the stems in the blowdown plot,we also scored damage and resprouting.We then used the spatial location data to compute the spatial heterogeneity and degree of clumping in both areas.Important Findings Significant clumping was observed in the control forest at the small spatial scale of 1–8 m and at the medium spatial scale of 30–36 m.The blowdown area:showed domination by post oak(Quercus stellata)with small stems,branch damage and stem resprouting above 1 m most common;had no trees that either lost their leaves without branch or stem damage or lived without some sort of resprouting,had a significant negative correlation between damage and resprouting and clumped only at small spatial scales for stems of medium size,for stems with branch damage and for stems that resprouted at or below 1 m height.We conclude that in addition to largely eliminating a forest’s spatial heterogeneity,tornados may also structure this ecotone by increasing tree persistence through resprouting。