53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in n...53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).展开更多
The juniper species Juniperus polycarpos C. Koch, J. indica Bertol. and J. communis L. var. saxatilis (Pallas) are important elements of the forest vegetation in Lahaul valley in the north-western Himalaya. Their ab...The juniper species Juniperus polycarpos C. Koch, J. indica Bertol. and J. communis L. var. saxatilis (Pallas) are important elements of the forest vegetation in Lahaul valley in the north-western Himalaya. Their ability to grow under the barren and xeric conditions of cold deserts makes them particularly suited for afforestation programmes under these eeologieal conditions. In the Lahaul valley, juniper species are used as subsistence resources and for religious purposes. Excessive removal of juniper wood and leaves by the local population, overgrazing, habitat fragmentation and low regeneration potential are the main obstacles to eonservation of juniper forests in this region. The present study was carried out to assess density, basal area and importance value index (WI) of the local vegetation as well as uses and amounts of juniper wood and leaves removed from the local forests. Pressure on relict juniper forests due to grazing animals and intensive removal of wood and leaves by the loeal population was found to be greater at an altitude above 3,00o m. The results of the study demonstrated that the different juniper speeies were adapted to specific altitude ranges. A higher species density was recorded at lower altitude except for J. indica which was only present at high altitude (〉3,200 m) on south-facing slopes. Density, basal area and IVI of J. polycarpos were higher at Hinsa (2,7oo m) than at Jahlma (3,000 m). The rapid loss of vegetation due to overuse and habitat degradation has made the eonservation of juniper forests an important priority in the Lahaul valley. J. polycarpos at loweraltitude and J. indica at higher altitude are ecologically the more suitable species for the successful implementation of conservation programmes. The support of rehabilitation programmes by regional authorities is essential for the reestablishment of the local juniper forests.展开更多
Throughfall, stemflow, evapotranspiration and infiltration are likely to vary with forest types, and consequently affect soil moisture regimes in different soil layers. In this study, the spatial and temporal characte...Throughfall, stemflow, evapotranspiration and infiltration are likely to vary with forest types, and consequently affect soil moisture regimes in different soil layers. In this study, the spatial and temporal characteristics of soil moisture were investigated to understand variations in soil moisture in three typical forests, including Phyllostachys pubescens forest (abbreviated as PPF), Schima superba forest (abbreviated as SSF) and Cunninghamia lanceolata forest (abbreviated as CLF) in the upper reaches of Lijiang River basin in southern China. The results showed that,(1) Litterfall and soil physical properties differed significantly in the three typical forests. Infiltration capacity in SSF was more favorable to soil moisture than in PPF and CLF.(2) Large variations were found in soil moisture at different forest stands and depths. Due to complicated vertical structures, there were obvious differences in soil moisture from the 0-20 cm soil layer to the 50-80 cm soil layer.(3) Average soil moisture in each layer was higher in SSF than in PPF and CLF.(4) Soil moisture in different layers correlated closely with precipitation (P<0.01) and the three typical forests had the same change trends with rainfall during the studying period.(5) In topsoil, soil moisture was influe need by soil properties which were mostly determined by litterfall, while in deep soil, soil moisture was affected by variations of soil characteristics, which were mostly determined by root distribution. This study provides a scie ntific basis for better un dersta nding the relati on ships betwee n forest vegetati on and its hydrological effects, helping to facilitate water resources conservation and achieving wise forest management in the upper reaches of Lijiang River basin.展开更多
基金Preliminary Special Foundation for National Key Basic Research of China, No.2003CCA01800Key National Natural Science Foundation of China, No.40730103+3 种基金National Natural Science Foundation of China, No.40672107 No.40571166Natural Science Foundation of Hebei Province, No.D2008000186 No.D2009000300
文摘53 pollen traps and surface samples were collected in order to detect the characteristics of pollen assemblages and their relationships with vegetation and climate in 16 forest communities located in 10 mountains in northern China. The results show that 72% of the pollen taxa (80 taxa) are the same between the traps and the surface samples. The dominant taxa in the plant communities are consistent with the main pollen taxa in the pollen assemblages at the same sites. In Pinus plant communities, both Pinus pollen influx and concentration are higher, indicating the high pollen productivity and good pollen preservation ability of Pinus. In Picea and Abies plant communities, Picea and Abies have lower pollen influxes but higher concentrations, suggesting their low pollen productivities but better pollen preservation abilities. In Betula and Quercus plant communities, Betula and Quercus have higher pollen influxes but lower concentrations, revealing their high pollen productivities but poor pollen preservation abilities. The study of relationships between pollen and vegetation with discriminant analysis shows that pollen assemblages from both trap and surface samples can reflect the characteristics of different communities and distinguish different ecological areas, but surface samples can reflect the dominant components of communities much better than the traps. The study on correlations between pollen assemblages and climate with DCCA reveals that significant correlations exist between pollen assemblages and mean temperature of the coldest month (r = 0.84 for trap samples, r = 0.72 for surface samples), and then annual mean precipitation (r = 0.73 for trap samples, r = 0.71 for surface samples).
基金the financial support by the Ministry of Environment and Forests, India
文摘The juniper species Juniperus polycarpos C. Koch, J. indica Bertol. and J. communis L. var. saxatilis (Pallas) are important elements of the forest vegetation in Lahaul valley in the north-western Himalaya. Their ability to grow under the barren and xeric conditions of cold deserts makes them particularly suited for afforestation programmes under these eeologieal conditions. In the Lahaul valley, juniper species are used as subsistence resources and for religious purposes. Excessive removal of juniper wood and leaves by the local population, overgrazing, habitat fragmentation and low regeneration potential are the main obstacles to eonservation of juniper forests in this region. The present study was carried out to assess density, basal area and importance value index (WI) of the local vegetation as well as uses and amounts of juniper wood and leaves removed from the local forests. Pressure on relict juniper forests due to grazing animals and intensive removal of wood and leaves by the loeal population was found to be greater at an altitude above 3,00o m. The results of the study demonstrated that the different juniper speeies were adapted to specific altitude ranges. A higher species density was recorded at lower altitude except for J. indica which was only present at high altitude (〉3,200 m) on south-facing slopes. Density, basal area and IVI of J. polycarpos were higher at Hinsa (2,7oo m) than at Jahlma (3,000 m). The rapid loss of vegetation due to overuse and habitat degradation has made the eonservation of juniper forests an important priority in the Lahaul valley. J. polycarpos at loweraltitude and J. indica at higher altitude are ecologically the more suitable species for the successful implementation of conservation programmes. The support of rehabilitation programmes by regional authorities is essential for the reestablishment of the local juniper forests.
基金National Natural Science Foundation of China(41261006)
文摘Throughfall, stemflow, evapotranspiration and infiltration are likely to vary with forest types, and consequently affect soil moisture regimes in different soil layers. In this study, the spatial and temporal characteristics of soil moisture were investigated to understand variations in soil moisture in three typical forests, including Phyllostachys pubescens forest (abbreviated as PPF), Schima superba forest (abbreviated as SSF) and Cunninghamia lanceolata forest (abbreviated as CLF) in the upper reaches of Lijiang River basin in southern China. The results showed that,(1) Litterfall and soil physical properties differed significantly in the three typical forests. Infiltration capacity in SSF was more favorable to soil moisture than in PPF and CLF.(2) Large variations were found in soil moisture at different forest stands and depths. Due to complicated vertical structures, there were obvious differences in soil moisture from the 0-20 cm soil layer to the 50-80 cm soil layer.(3) Average soil moisture in each layer was higher in SSF than in PPF and CLF.(4) Soil moisture in different layers correlated closely with precipitation (P<0.01) and the three typical forests had the same change trends with rainfall during the studying period.(5) In topsoil, soil moisture was influe need by soil properties which were mostly determined by litterfall, while in deep soil, soil moisture was affected by variations of soil characteristics, which were mostly determined by root distribution. This study provides a scie ntific basis for better un dersta nding the relati on ships betwee n forest vegetati on and its hydrological effects, helping to facilitate water resources conservation and achieving wise forest management in the upper reaches of Lijiang River basin.