The riparian (tugai) forest ecosystems of Central Asia are a biodiversity hotspot with unique many trees and shrubs. Intense human pressure and global warming have caused habitat destruction in Zerafshan State Nationa...The riparian (tugai) forest ecosystems of Central Asia are a biodiversity hotspot with unique many trees and shrubs. Intense human pressure and global warming have caused habitat destruction in Zerafshan State National park and it’s 23.5 ha. There grow more than 300 higher plants. We analysed the wild flora and the remains of the species diversity that previously existed on the site of the forestry enterprise, the modern biodiversity of trees and shrubs in the described territory are represented by 52 species from among representatives of 21 plant families. These monitoring and results indicated that some tree species might in the near future become extinct in the wild. We therefore recommend that the local people be encouraged to stop using these trees.展开更多
Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of the...Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of these fragile ecosystems are supplied with additional(‘eco-logical’)water for protection and conservation.We investigated interrelationships among groundwater distance,stand structure and above-ground wood production(at the tree and the stand level)in P.euphratica stands along a groundwater gradient(distances of 2.0-12.0 m)that also included a plot supplied with‘ecological water’.Methods We measured the height,diameter at breast height and basal area of poplar trees and determined the annual above-ground wood production for the three most recent years on the basis of tree-ring analyses and allometric regressions at three sites at the upper,mid-dle and lower reaches of the tarim River,Xinjiang,NW china.Important Findingsthe distribution of age classes differed significantly among the plots:in accordance with their life histories,stands growing at a larger distance to the groundwater harboured a larger fraction of old trees(>80 years)and,in most cases,a smaller fraction of young trees(≤20 years).the annual above-ground wood production per ha was highest on a plot with a short groundwater distance(2.0 m;maxi-mum of the 3-year investigation period:3.0 t ha−1 a−1)and lowest,at a plot with a large distance to the water table(6.6 m;minimum:0.23 t ha^(−1)a^(−1)).However,the plot located close to the groundwater(and to the river)at the middle reaches exhibited a relatively large interannual variation in above-ground wood production,which can be attributed to interannual variations in the river discharge.At the middle and the lower reaches,these interannual variations on plots with the most favourable water supply were even more obvious at the tree level.For the fraction of mature trees(60-99 years old),no significant differences in above-ground wood production were found between the plots with the most and the least favourable water supply.Overall,the productivity at the stand level was most closely correlated with the stand density(number of trees per ha,tree cover percentage).Productivity was negatively related to tree age,whereas groundwater distance alone was not a good predictor of above-ground wood production.In conclusion,vigorous growth of P.euphratica is possible at sites with groundwater distances of up to 12 m.Supply with‘ecological water’may be beneficial to trees growing at groundwater distances not larger than~6 m.However,allocation of water should focus on stands with a short distance to the groundwater because only under these conditions,natural gen-erative reproduction of the poplars is possible.展开更多
文摘The riparian (tugai) forest ecosystems of Central Asia are a biodiversity hotspot with unique many trees and shrubs. Intense human pressure and global warming have caused habitat destruction in Zerafshan State National park and it’s 23.5 ha. There grow more than 300 higher plants. We analysed the wild flora and the remains of the species diversity that previously existed on the site of the forestry enterprise, the modern biodiversity of trees and shrubs in the described territory are represented by 52 species from among representatives of 21 plant families. These monitoring and results indicated that some tree species might in the near future become extinct in the wild. We therefore recommend that the local people be encouraged to stop using these trees.
基金German Federal Ministry of Education and Research(BMBF),Funding Measure‘Sustainable Land Management’(project number:01LL0918K).
文摘Aims Along central-Asian rivers in arid regions,lowering of the ground-water level constitutes a major threat to the riparian forests,whose tree layers are dominated by Euphrates poplar(Populus euphratica).Some of these fragile ecosystems are supplied with additional(‘eco-logical’)water for protection and conservation.We investigated interrelationships among groundwater distance,stand structure and above-ground wood production(at the tree and the stand level)in P.euphratica stands along a groundwater gradient(distances of 2.0-12.0 m)that also included a plot supplied with‘ecological water’.Methods We measured the height,diameter at breast height and basal area of poplar trees and determined the annual above-ground wood production for the three most recent years on the basis of tree-ring analyses and allometric regressions at three sites at the upper,mid-dle and lower reaches of the tarim River,Xinjiang,NW china.Important Findingsthe distribution of age classes differed significantly among the plots:in accordance with their life histories,stands growing at a larger distance to the groundwater harboured a larger fraction of old trees(>80 years)and,in most cases,a smaller fraction of young trees(≤20 years).the annual above-ground wood production per ha was highest on a plot with a short groundwater distance(2.0 m;maxi-mum of the 3-year investigation period:3.0 t ha−1 a−1)and lowest,at a plot with a large distance to the water table(6.6 m;minimum:0.23 t ha^(−1)a^(−1)).However,the plot located close to the groundwater(and to the river)at the middle reaches exhibited a relatively large interannual variation in above-ground wood production,which can be attributed to interannual variations in the river discharge.At the middle and the lower reaches,these interannual variations on plots with the most favourable water supply were even more obvious at the tree level.For the fraction of mature trees(60-99 years old),no significant differences in above-ground wood production were found between the plots with the most and the least favourable water supply.Overall,the productivity at the stand level was most closely correlated with the stand density(number of trees per ha,tree cover percentage).Productivity was negatively related to tree age,whereas groundwater distance alone was not a good predictor of above-ground wood production.In conclusion,vigorous growth of P.euphratica is possible at sites with groundwater distances of up to 12 m.Supply with‘ecological water’may be beneficial to trees growing at groundwater distances not larger than~6 m.However,allocation of water should focus on stands with a short distance to the groundwater because only under these conditions,natural gen-erative reproduction of the poplars is possible.
