Treeline ecotone dynamics of Abies spectabilis （D. Don） Mirb. in the Barun valley, Makalu Barun National Park, eastern Nepal Himalaya were studied by establishing seven plots （20 m x variable length） from the fore...Treeline ecotone dynamics of Abies spectabilis （D. Don） Mirb. in the Barun valley, Makalu Barun National Park, eastern Nepal Himalaya were studied by establishing seven plots （20 m x variable length） from the foresfline to the tree species limit： three plots on the south- and north-facing slopes each （S1-S3, N1-N3）, and one plot on the east- facing slope （E） in the relatively undisturbed forests. A dendroecological method was used to study treeline advance rate and recruitment pattern. In all the plots, most trees established in the early 20th century, and establishment in the second half of the 20th century was confined to the foresfline area. Treeline position has not advanced substantially in the Barun valley, with 0nly 22 m average elevational shift in the last 13o years, and with average current shifting rate of 14 cm/yr. Moreover, no significant relationship was found between tree age and elevation on the south-, north-, and east-facing slopes. The number of seedlings and saplings in near the treeline area was negligible compared to that near the foresfline area. Therefore, A. spectabilis treeline response to the temperature change was slow, despite the increasing temperature trend in the region. Beside the temperature change, factors such as high inter-annual variability in temperature, dense shrub cover, and local topography also play an important role in treeline advance and controlling recruitment pattern above the treeline.展开更多
The article is based on collection of small terrestrial mammals(Soriculus nigrescens,Episoriculus caudatus, Neodon sikimensis,Alticola stoliczkanus, Niviventer eha and Ochotona roylei) collected in the Barun Valley, e...The article is based on collection of small terrestrial mammals(Soriculus nigrescens,Episoriculus caudatus, Neodon sikimensis,Alticola stoliczkanus, Niviventer eha and Ochotona roylei) collected in the Barun Valley, east Nepal in the pre-monsoon period of 1973.Zoogeographic and ecological characteristics and altitudinal stratification of these species are analysed, depending both on abiotic(geomorphological and climatic) and biotic(vegetation, and human presence and activities)factors. All the captured mammals were examined for ecto- and endoparasities. Infestations of Trombiculid mites and Ixodid ticks were tightly linked to the local habitat where these ectoparasites must survive during their nonparasitic phase. Analysis of their occurrence completes the reconstruction of migration routes during the expansion of small mammals into the Barun Valley and the exacerbating influence of human activities(summer pasturing,mountaineering expeditions and trekking parties).An indicator of anthropogenic influence was the occurrence of synantropic flies. The potential medical importance of these findings is discussed.It is assumed a possible occurrence of arboviruses transmitted by ticks and also rickettsioses(transmitted by ticks and chigger mites). As far bacteriological infections, plague cannot be excluded.展开更多
文摘Treeline ecotone dynamics of Abies spectabilis （D. Don） Mirb. in the Barun valley, Makalu Barun National Park, eastern Nepal Himalaya were studied by establishing seven plots （20 m x variable length） from the foresfline to the tree species limit： three plots on the south- and north-facing slopes each （S1-S3, N1-N3）, and one plot on the east- facing slope （E） in the relatively undisturbed forests. A dendroecological method was used to study treeline advance rate and recruitment pattern. In all the plots, most trees established in the early 20th century, and establishment in the second half of the 20th century was confined to the foresfline area. Treeline position has not advanced substantially in the Barun valley, with 0nly 22 m average elevational shift in the last 13o years, and with average current shifting rate of 14 cm/yr. Moreover, no significant relationship was found between tree age and elevation on the south-, north-, and east-facing slopes. The number of seedlings and saplings in near the treeline area was negligible compared to that near the foresfline area. Therefore, A. spectabilis treeline response to the temperature change was slow, despite the increasing temperature trend in the region. Beside the temperature change, factors such as high inter-annual variability in temperature, dense shrub cover, and local topography also play an important role in treeline advance and controlling recruitment pattern above the treeline.
文摘The article is based on collection of small terrestrial mammals(Soriculus nigrescens,Episoriculus caudatus, Neodon sikimensis,Alticola stoliczkanus, Niviventer eha and Ochotona roylei) collected in the Barun Valley, east Nepal in the pre-monsoon period of 1973.Zoogeographic and ecological characteristics and altitudinal stratification of these species are analysed, depending both on abiotic(geomorphological and climatic) and biotic(vegetation, and human presence and activities)factors. All the captured mammals were examined for ecto- and endoparasities. Infestations of Trombiculid mites and Ixodid ticks were tightly linked to the local habitat where these ectoparasites must survive during their nonparasitic phase. Analysis of their occurrence completes the reconstruction of migration routes during the expansion of small mammals into the Barun Valley and the exacerbating influence of human activities(summer pasturing,mountaineering expeditions and trekking parties).An indicator of anthropogenic influence was the occurrence of synantropic flies. The potential medical importance of these findings is discussed.It is assumed a possible occurrence of arboviruses transmitted by ticks and also rickettsioses(transmitted by ticks and chigger mites). As far bacteriological infections, plague cannot be excluded.
