For preventing ecosystem degradation, protecting natural habitats and conserving biodiversity within the habitats, 2588 nature reserves have been established in China at the end of 2010. The total area is up to 149.44...For preventing ecosystem degradation, protecting natural habitats and conserving biodiversity within the habitats, 2588 nature reserves have been established in China at the end of 2010. The total area is up to 149.44 million ha and covers over 15% of Chinese terrestrial surface. Land-cover change, as the primary driver of biodiversity change, directly impacts ecosystem structures and functions. In this paper, 180 National Nature Reserves （NNRs） are selected and their total area is 44.71 million ha, accounting for 29.9% of all NNRs in China. In terms of the ecosystem characteristics and their major protected object, all selected NNRs are classified into 7 types. A Positive and Negative Change Index of Land-cover （PNCIL） was developed to analyze the land-cover change of each NNRs type from the late 1980s to 2005. The results show that the land-cover of all selected NNRs types have degradated to a certain degree except the forest ecosystem reserves with a decreasing rate, but the rate of degrada tion alleviated gradually. The mean positive and negative change rates of land-cover in all core zones decreased by 0.69% and 0.16% respectively. The landscape pattern of land-cover in the core zones was more stable than that in the buffer zones and the experimental zones. Furthermore, the ecological diversity and patch connectivity of land-cover in selected NNRs increased generally. In short, the land-cover of 180 selected NNRs in China had a beneficial chan qe trend after NNRs established, especially between 1995 and 2005.展开更多
A study was conducted in a hilly area of Sichuan Province,Southwestern China, to compare the streamflow and soil moisture in two upland watersheds with different land use patterns. One was an agroforestry watershed, w...A study was conducted in a hilly area of Sichuan Province,Southwestern China, to compare the streamflow and soil moisture in two upland watersheds with different land use patterns. One was an agroforestry watershed, which consisted mainly of trees with alder (Alnus cremastogyne Burkill) and cypress (Cupressus funebris Endl.) planted in belts or strips with a coverage of about 46%, and the other was a grassland primarily composed of lalang grass (Imperata cylindrica var. major (Nees) C. E. Hubb.), filamentary clematis (Clematis filamentosa Dunn) and common eulaliopsis (Eulaliopsis binata (Retz.) C. E. Hubb) with a coverage of about 44%. Streamflow measurement with a hydrograph established at the watershed outlet showed that the average annual streamflow per 100 mm rainfall from 1983 to 1992 was 0.36 and 1.08 L s-1 km-2 for the agroforestry watershed and the grass watershed, respectively. This showed that the streamflow of the agroforestry watershed was reduced by 67% when compared to that of the grass watershed. The peak average monthly streamflow in the agroforestry watershed was over 5 times lower than that of the grass watershed and lagged by one month. In addition, the peak streamflow during a typical rainfall event of 38.3 mm in August 1986 was 37% lower in the agroforestry watershed than in the grass watershed. Results of the moisture contents of the soil samples from 3 slope locations (upper, middle and lower slopes) indicated that the agroforestry watershed maintained generally higher soil moisture contents than the grass watershed within 0-20 and 20-80 cm soil depths for the upper slope, especially for the period from May through July. For the other (middle and lower) slopes, soil moisture contents within 20-80 cm depth in the agroforestry watershed was generally lower than those in the grass watershed, particularly in September, revealing that water consumption by trees took place mainly below the plow layer. Therefore, agroforestry land use types might offer a complimentary model for tree-annual crop water utilization.展开更多
基金National Natural Science Foundation of China, No.41271406 No.40801150+3 种基金 China National Science Fund for Distinguished Young Scholars, No.40825003 National Basic Research Program of China, No.2009CB421105 No.2010CB95090403 Youth Science Funds of State Key Laboratory of Resources and Environment Information System, CAS
文摘For preventing ecosystem degradation, protecting natural habitats and conserving biodiversity within the habitats, 2588 nature reserves have been established in China at the end of 2010. The total area is up to 149.44 million ha and covers over 15% of Chinese terrestrial surface. Land-cover change, as the primary driver of biodiversity change, directly impacts ecosystem structures and functions. In this paper, 180 National Nature Reserves （NNRs） are selected and their total area is 44.71 million ha, accounting for 29.9% of all NNRs in China. In terms of the ecosystem characteristics and their major protected object, all selected NNRs are classified into 7 types. A Positive and Negative Change Index of Land-cover （PNCIL） was developed to analyze the land-cover change of each NNRs type from the late 1980s to 2005. The results show that the land-cover of all selected NNRs types have degradated to a certain degree except the forest ecosystem reserves with a decreasing rate, but the rate of degrada tion alleviated gradually. The mean positive and negative change rates of land-cover in all core zones decreased by 0.69% and 0.16% respectively. The landscape pattern of land-cover in the core zones was more stable than that in the buffer zones and the experimental zones. Furthermore, the ecological diversity and patch connectivity of land-cover in selected NNRs increased generally. In short, the land-cover of 180 selected NNRs in China had a beneficial chan qe trend after NNRs established, especially between 1995 and 2005.
基金Project supported by the Innovation Project of the Chinese Academy of Sciences (Nos. KZCX3-SW-330 and KZCX2-413) and the National Natural Science Youth Foundation of China (No. 40201029).
文摘A study was conducted in a hilly area of Sichuan Province,Southwestern China, to compare the streamflow and soil moisture in two upland watersheds with different land use patterns. One was an agroforestry watershed, which consisted mainly of trees with alder (Alnus cremastogyne Burkill) and cypress (Cupressus funebris Endl.) planted in belts or strips with a coverage of about 46%, and the other was a grassland primarily composed of lalang grass (Imperata cylindrica var. major (Nees) C. E. Hubb.), filamentary clematis (Clematis filamentosa Dunn) and common eulaliopsis (Eulaliopsis binata (Retz.) C. E. Hubb) with a coverage of about 44%. Streamflow measurement with a hydrograph established at the watershed outlet showed that the average annual streamflow per 100 mm rainfall from 1983 to 1992 was 0.36 and 1.08 L s-1 km-2 for the agroforestry watershed and the grass watershed, respectively. This showed that the streamflow of the agroforestry watershed was reduced by 67% when compared to that of the grass watershed. The peak average monthly streamflow in the agroforestry watershed was over 5 times lower than that of the grass watershed and lagged by one month. In addition, the peak streamflow during a typical rainfall event of 38.3 mm in August 1986 was 37% lower in the agroforestry watershed than in the grass watershed. Results of the moisture contents of the soil samples from 3 slope locations (upper, middle and lower slopes) indicated that the agroforestry watershed maintained generally higher soil moisture contents than the grass watershed within 0-20 and 20-80 cm soil depths for the upper slope, especially for the period from May through July. For the other (middle and lower) slopes, soil moisture contents within 20-80 cm depth in the agroforestry watershed was generally lower than those in the grass watershed, particularly in September, revealing that water consumption by trees took place mainly below the plow layer. Therefore, agroforestry land use types might offer a complimentary model for tree-annual crop water utilization.
