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Temporal and spatial variation of pollen yield in natural populations of Pinus roxburghii

Forestry Studies in China 2012年第1期14卷 20-29页

作者： Vinod Prasad KHANDURI Department of Forestry Mizoram UniversityTanhrilAizawl 796001India

Male components of the reproduction process in Pinus roxburghii were investigated for their variation in time and space as well as pollination, viz. flowering phenology, pollen production variability and pollen dispersal, for five successive years at two different locations （at the lower and higher elevations）. The study reveals that elevation and the hour of the day are the main determi- nants of anthesis and microsporangium dehiscence, because both are related to temperature and humidity. The receptivity of ovulate cone strobili or female strobili occurred earlier at the lower elevation than at the higher elevation, with a longer receptivity period in the latter case. The phenology of male and female cones varied significantly between years and elevations. The determinations of pol- len yield considered various sources of variability, i.e., the number of pollen strobili per branch, strobili per tree, microsporangia per tree and pollen grains per tree. Each of these parameters revealed significant year-to-year and elevation effects. Year-to-year varia- tion in the production of pollen cone and pollen grains with mass production after a three-year period revealed a three-year cycle of masting in pollen production in P. roxburghii. The pollen dispersal decreased quickly with distance from the pollen source. As a con- sequence, a distance of 600 m was proposed as a minimum to prevent contamination by pollen in the management of seed orchards. The results ultimately suggest that the ample production of pollen grains per tree along with flowering synchrony and long dispersal of pollen grains results in homogeneity in large populations.

关键词： chir pine pollen cone gene flow elevation Himalayas

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Status and distribution pattern of coarse woody debris along an altitudinal gradient in Askot Wildlife Sanctuary, Uttarakhand, West Himalaya

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Journal of Forestry Research 2009年第A3期20卷 205-212页

作者： Bhupendra Singh Adhikari Department of Habitat Ecology Wildlife Institute of India Chandrabani Dehradun 248 001 Uttarakhand India

A rapid assessment on the status and distribution patterns of coarse woody debris （CWD） was conducted by laying five curvilinear transects （transects A, B, C, D and E; major trails）, along an altitudinal gradient starting from 900 to 2 600 m, in three major watersheds （Charigad, Dogarhigad and upper Gosigad） of Goriganga catchment in Askot Wildlife Sanctuary, India. At every 100 m rise in altitude a hectare plot （100 m x 100 m） was selected. Results showed that the percentage contribution by different succession phases was in the decreasing order： phase I 〉 phase II 〉 phase IV 〉 phase III for snags, and phase III〉 phase II 〉 phase IV 〉 phase I for logs. Snag density in chir pine forest was high in transect A （11 snags＇ha^-1） at 1 500 m, and the value in rianj oak forest was high in transect B （10 ***-l） at 2 300 m. The total available mass of snags and logs in chit pine forest was 13.9 t, of which snags mass accounted for 41% of the total mass and logs mass for 59%. While the total value was 5.6 t in rianj oak forest, of which snags and logs accounted for 60% and 40% of the total mass, respectively. Moreover, the presence of CWD in the study area if not harvested, would provide a great opportunity to the orchids in future to flourish by providing protection. The high densities of snags and logs in chir pine forest at mid-altitudinal zone led to less species richness and lower density of ground flora as the zone receives more light, accompanying with lower soil moisture, and thus only the dominant species occupy the habitat.

关键词： Askot Wildlife Sanctuary chir pine coarse woody debris rianj oak Pinus roxburghii Quercus lanata

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