通过对1961 年以来青南高原气候变化的分析,发现该地区年平均降水量及秋季降水量无明显的变化趋势,且其年际间的波动趋于缓和;冬季(12～2 月)和春季(3～5 月)降水量的变化趋势呈现出逐年增多的趋势,气候倾向率分别为2.6 m m /10 a 和3.6...通过对1961 年以来青南高原气候变化的分析,发现该地区年平均降水量及秋季降水量无明显的变化趋势,且其年际间的波动趋于缓和;冬季(12～2 月)和春季(3～5 月)降水量的变化趋势呈现出逐年增多的趋势,气候倾向率分别为2.6 m m /10 a 和3.6 m m /10 a;夏季(6～8 月)降水量变化却表现出显著的减少趋势,其倾向率为- 6.5 m m /10 a。青南牧区牧草返青期气温回升速度在逐年减缓,而牧草枯黄期气温降低速度在逐年增大。该区的气候变化使青南高原主要优势牧草——嵩草的生长高度由80 年代末期的6～8 cm 下降到现在的3～5cm ,牧草开花期和籽粒成熟期的发育百分率普遍下降25% ～50% ,发育程度一般达不到50% ,天然草地产鲜草量和干草产量减少约为70% ～80% 。展开更多
Over-exploitation and rural growth have severely damaged native vegetations of Aravalli hills in Rajasthan, India. This study was conducted to evaluate the effects of different restoration practices （i.e., rainwater ...Over-exploitation and rural growth have severely damaged native vegetations of Aravalli hills in Rajasthan, India. This study was conducted to evaluate the effects of different restoration practices （i.e., rainwater harvesting （RWH） and planting of tree seedlings） on improve- ment in soil water and nutrients and growth and biomass of herbaceous vegetation. Contour trench （CT）, Gradonie （G）, Box trench （BT）, V-ditch （VD） and a control were imposed on 75 plots （each of 700 m 2 ） in natural slope gradient defined as 10%, 10% 20% and 20% slopes in 2005. Each plot had three micro-sites of 1-m 2 at up （USP）, middle （MSP） and lower （LSP） part of the plot for observation in 2008. The existed gradient （due to soil texture and topographic features） of soil pH, EC, SOC, NH 4 - N, NO 3 -N and PO 4 -P in June 2005 between 20% to 10% slopes were decreased in 2008 after applying RWH techniques. Such improvement in soil status promoted vegetation growth and biomass in higher slope gra- dients. Soil water, species diversity and herbage biomass increased from USP to LSP, and RWH techniques had positive role in improving SOC, nutrients, vegetation population, evenness and growth at MSP. Despite of lowest SWC, regular rain and greater soil water usage enhanced green and dry herbage biomasses in 10% 20% and 20% slopes, compared with 10% slope. The highest diversity in CT treatment was related to herbage biomass, which was enhanced further by highest concentrations of SOC and PO 4 -P. Further, CT treatment was found to be the best treat- ment in minimizing biomass variance in different slopes. Conclusively, soil texture and topographic features controlled soil water and nutrients availability. Rainwater harvesting techniques increased soil water storage and nutrient retention and also enhanced vegetation status and biomass by minimizing the effects of hillslopes. Thus depending upon the site conditions, suitable RWH technique could be adopted to increase herb- age biomass while rehabilitatin展开更多
文摘通过对1961 年以来青南高原气候变化的分析,发现该地区年平均降水量及秋季降水量无明显的变化趋势,且其年际间的波动趋于缓和;冬季(12～2 月)和春季(3～5 月)降水量的变化趋势呈现出逐年增多的趋势,气候倾向率分别为2.6 m m /10 a 和3.6 m m /10 a;夏季(6～8 月)降水量变化却表现出显著的减少趋势,其倾向率为- 6.5 m m /10 a。青南牧区牧草返青期气温回升速度在逐年减缓,而牧草枯黄期气温降低速度在逐年增大。该区的气候变化使青南高原主要优势牧草——嵩草的生长高度由80 年代末期的6～8 cm 下降到现在的3～5cm ,牧草开花期和籽粒成熟期的发育百分率普遍下降25% ～50% ,发育程度一般达不到50% ,天然草地产鲜草量和干草产量减少约为70% ～80% 。
文摘Over-exploitation and rural growth have severely damaged native vegetations of Aravalli hills in Rajasthan, India. This study was conducted to evaluate the effects of different restoration practices （i.e., rainwater harvesting （RWH） and planting of tree seedlings） on improve- ment in soil water and nutrients and growth and biomass of herbaceous vegetation. Contour trench （CT）, Gradonie （G）, Box trench （BT）, V-ditch （VD） and a control were imposed on 75 plots （each of 700 m 2 ） in natural slope gradient defined as 10%, 10% 20% and 20% slopes in 2005. Each plot had three micro-sites of 1-m 2 at up （USP）, middle （MSP） and lower （LSP） part of the plot for observation in 2008. The existed gradient （due to soil texture and topographic features） of soil pH, EC, SOC, NH 4 - N, NO 3 -N and PO 4 -P in June 2005 between 20% to 10% slopes were decreased in 2008 after applying RWH techniques. Such improvement in soil status promoted vegetation growth and biomass in higher slope gra- dients. Soil water, species diversity and herbage biomass increased from USP to LSP, and RWH techniques had positive role in improving SOC, nutrients, vegetation population, evenness and growth at MSP. Despite of lowest SWC, regular rain and greater soil water usage enhanced green and dry herbage biomasses in 10% 20% and 20% slopes, compared with 10% slope. The highest diversity in CT treatment was related to herbage biomass, which was enhanced further by highest concentrations of SOC and PO 4 -P. Further, CT treatment was found to be the best treat- ment in minimizing biomass variance in different slopes. Conclusively, soil texture and topographic features controlled soil water and nutrients availability. Rainwater harvesting techniques increased soil water storage and nutrient retention and also enhanced vegetation status and biomass by minimizing the effects of hillslopes. Thus depending upon the site conditions, suitable RWH technique could be adopted to increase herb- age biomass while rehabilitatin
