希拉穆仁草原退化特征及其受损恢复机理研究
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摘要
为了有效控制草地退化,保护生物资源,保持“生态-经济-社会”的良性循环和生物资源的可持续利用。本研究以希拉穆仁荒漠草原为研究对象,运用恢复生态学有关原理和方法,采用野外调查和室内定量分析相结合手段,通过对草原退化特征、土壤水分物理特性、地表覆盖保墒机理、封禁草场生态恢复等方面进行试验,系统研究了希拉穆仁草原退化特征及其恢复机理。主要研究结论如下:
(1)希拉穆仁草原已经出现不同程度的退化,未退化草地有植物38种,从轻度退化到极度退化物种数分别减少了7种、12种、20和25种;随着草地退化,植被盖度、地上生物量、平均高度、物种多样性等群落指标均呈现降低趋势。与未退化草地相比,轻度、中度、重度和极度退化草地土壤0-30cm层容重分别增加了2.66%、6.3%、8.96%和17.43%,土壤全氮、全磷、速氮、速磷、速钾和有机质等指标出现不同程度的下降。植被平均高度、盖度、地上生物量和生物多样性指数与土壤养分表现出一致的正相关关系。
(2)该区受侵蚀比较严重,沙土比比例坡顶最高为42.1%,坡中27.2%,坡底仅为17.6%,土壤容重与稳渗率呈指数关系(R2=0.9764)。降水是该区土壤水分的主要来源,土壤年平均贮水量与年降水量的相关系数为0.7808(0.05信度检验)。土壤水分垂直变化层次可以划分为活跃层、次活跃层和相对稳定层3个层次,水分年际、生长季变化趋势与降水变化趋势相吻合。
(3)沙砾和秸秆覆盖均能有效抑制土壤表面蒸发,粒径2-4mm沙砾覆盖土壤蒸发仅为对照处理的81%。不同盖度的秸秆覆盖中,100%盖度覆盖的抑制率最大,可达50%。田间覆盖保墒试验结果表明, 3cm厚度沙砾覆盖土壤保水效果较好;秸秆覆盖后0-30cm土壤水分含量明显增加,当秸秆用量5000 kg/hm2,土壤水分较对照高出4%。1日内不同处理的土壤表层和5cm处地温均可拟合为时间的正弦函数,沙砾、秸秆覆盖具有调温效应,体现为高温时具有“降温作用”,低温具有“保温效应”。
(4)在不同水分梯度上,Simpson指数、Shannon-Wiener指数、Pielou指数和Margalef指数均出现了1倍以上的增加。人为松土翻耕后,表层土壤水分则可长时间维持在15%水平。采取灌溉措施后,沙棘、驼绒藜、小叶锦鸡儿成活率分别高出相应对照65.7%、32.1%、53.7%,样区周围植物高度增加了10%,物种数增加2种,盖度增加5%,生物量干重增加135.4g/m2。
(5)苜蓿饲草料生长期对水分仍有一定要求,降水和灌溉主要影响苜蓿地土壤80cm以上土层的土壤水分,种植2年后的苜蓿地,80-200cm土层的含水量维持在8%左右。灌水量与苜蓿产量之间有明显的相关关系,其数学模型为:Y=0.9025Q1.4732 (R2=0.94),灌溉苜蓿饲草料地生产力尚有较大的开发空间,现实产量的获得极大地依赖于人为水肥措施。
In order to control grassland degradate and protect biolocical resources, keep a benign cycle of“Ecology-Society-Economy”.With recovery ecology’s principle and method as guide, field investigation and laboratory analysis were used to study grassland deteriorative characteristics, soil moisture physical characteristics, moisture conservation mechnasim, water restoration. Results are as following:
(1)Xilamu-grassland is generally in a degradation state, with degradation level increasing, community species reduced, the species number of CK, light degraded , middle-degraded, heavily-degraded, extreme degradation were 38,31,26,18,13. Vegetation coverage, species height , above-ground biomass all showed lower trent. Compared with CK, 0-30cm soil bulk density of light, middle , heavily and extreme degradation increased 2.66%、6.3%、8.96% and 17.43%, meanwhile, soil mutrient content decreased at different degree.Soil height, coverage, above-ground biomass and biodiversity index were in positive correlation with soil nutrient.
(2)The area was eroded seriously, sand-soil ratio of slope top, middle, and bottom were 42.1%,27.2%,17.6%. There existed exponential relationship between Soil bulk density and the steady infiltration rate(R2=0.9764), Rainfall is a major source of soil moisture in the area, correlation coefficient of soil water storage capacity and average annual rainfall was 0.7808, soil moisture vertical changes can be divided into active layer, sub-active water layer and stable layer, water annual and seasonal change were in line with the trend of precipitation changes.
(3)Gravel and straw mulch cover can effectively inhibit soil surface evaporation, soil evaporation of 2-4mm diameter gravel covered was 81% of CK. Of different straw coverage, the inhibition rate of 100% coverage can reach up to 50%. Field test results show that the effect of 3cm thickness gravel covered soil water better; 0-30cm soil moisture content increased with straw covered, the amount of straw 5000 kg/hm2, soil moisture was 4% higher than CK. Soil surface and 5cm temperature can be fitted as sine function, the temperature adjusting effects of gravel, straw covered were insulation when temperature was cery low, cooling effect when in high temperature.
(4) Simpson index, Shannon-Wiener index, Pielou index and Margalef index showed double increasing at different moisture gradient. man-made soil tillage measure can keep soil surface moisture at a heigh level of 15% for a long time.After irrigating, sea buckthorn, Ceratoides, Caragana survival rate were 65.7%,32.1%, 53.7% higher than CK, around the district,plant height increasde 10%, species number increasde 10%, coverage increased 5% , Biomass dry weight increase 135.4g/m~2.
(5) Water is certain request when Alfalfa forage grass is in growth stage , rainfall and irrigation mainly affect less than 80cm layer soil moisture, 80-200cm layer soil moisture content is 8%.There was obvious correlation between Alfalfa productivity and irrigation volume ,the math model was: Y = 0.9025Q1.4732 (R2 = 0.94), there are still large room for alfalfa irrigated productivity ,the reality productivity depended on the measures of water and fertilizer.
(1)希拉穆仁草原已经出现不同程度的退化,未退化草地有植物38种,从轻度退化到极度退化物种数分别减少了7种、12种、20和25种;随着草地退化,植被盖度、地上生物量、平均高度、物种多样性等群落指标均呈现降低趋势。与未退化草地相比,轻度、中度、重度和极度退化草地土壤0-30cm层容重分别增加了2.66%、6.3%、8.96%和17.43%,土壤全氮、全磷、速氮、速磷、速钾和有机质等指标出现不同程度的下降。植被平均高度、盖度、地上生物量和生物多样性指数与土壤养分表现出一致的正相关关系。
(2)该区受侵蚀比较严重,沙土比比例坡顶最高为42.1%,坡中27.2%,坡底仅为17.6%,土壤容重与稳渗率呈指数关系(R2=0.9764)。降水是该区土壤水分的主要来源,土壤年平均贮水量与年降水量的相关系数为0.7808(0.05信度检验)。土壤水分垂直变化层次可以划分为活跃层、次活跃层和相对稳定层3个层次,水分年际、生长季变化趋势与降水变化趋势相吻合。
(3)沙砾和秸秆覆盖均能有效抑制土壤表面蒸发,粒径2-4mm沙砾覆盖土壤蒸发仅为对照处理的81%。不同盖度的秸秆覆盖中,100%盖度覆盖的抑制率最大,可达50%。田间覆盖保墒试验结果表明, 3cm厚度沙砾覆盖土壤保水效果较好;秸秆覆盖后0-30cm土壤水分含量明显增加,当秸秆用量5000 kg/hm2,土壤水分较对照高出4%。1日内不同处理的土壤表层和5cm处地温均可拟合为时间的正弦函数,沙砾、秸秆覆盖具有调温效应,体现为高温时具有“降温作用”,低温具有“保温效应”。
(4)在不同水分梯度上,Simpson指数、Shannon-Wiener指数、Pielou指数和Margalef指数均出现了1倍以上的增加。人为松土翻耕后,表层土壤水分则可长时间维持在15%水平。采取灌溉措施后,沙棘、驼绒藜、小叶锦鸡儿成活率分别高出相应对照65.7%、32.1%、53.7%,样区周围植物高度增加了10%,物种数增加2种,盖度增加5%,生物量干重增加135.4g/m2。
(5)苜蓿饲草料生长期对水分仍有一定要求,降水和灌溉主要影响苜蓿地土壤80cm以上土层的土壤水分,种植2年后的苜蓿地,80-200cm土层的含水量维持在8%左右。灌水量与苜蓿产量之间有明显的相关关系,其数学模型为:Y=0.9025Q1.4732 (R2=0.94),灌溉苜蓿饲草料地生产力尚有较大的开发空间,现实产量的获得极大地依赖于人为水肥措施。
In order to control grassland degradate and protect biolocical resources, keep a benign cycle of“Ecology-Society-Economy”.With recovery ecology’s principle and method as guide, field investigation and laboratory analysis were used to study grassland deteriorative characteristics, soil moisture physical characteristics, moisture conservation mechnasim, water restoration. Results are as following:
(1)Xilamu-grassland is generally in a degradation state, with degradation level increasing, community species reduced, the species number of CK, light degraded , middle-degraded, heavily-degraded, extreme degradation were 38,31,26,18,13. Vegetation coverage, species height , above-ground biomass all showed lower trent. Compared with CK, 0-30cm soil bulk density of light, middle , heavily and extreme degradation increased 2.66%、6.3%、8.96% and 17.43%, meanwhile, soil mutrient content decreased at different degree.Soil height, coverage, above-ground biomass and biodiversity index were in positive correlation with soil nutrient.
(2)The area was eroded seriously, sand-soil ratio of slope top, middle, and bottom were 42.1%,27.2%,17.6%. There existed exponential relationship between Soil bulk density and the steady infiltration rate(R2=0.9764), Rainfall is a major source of soil moisture in the area, correlation coefficient of soil water storage capacity and average annual rainfall was 0.7808, soil moisture vertical changes can be divided into active layer, sub-active water layer and stable layer, water annual and seasonal change were in line with the trend of precipitation changes.
(3)Gravel and straw mulch cover can effectively inhibit soil surface evaporation, soil evaporation of 2-4mm diameter gravel covered was 81% of CK. Of different straw coverage, the inhibition rate of 100% coverage can reach up to 50%. Field test results show that the effect of 3cm thickness gravel covered soil water better; 0-30cm soil moisture content increased with straw covered, the amount of straw 5000 kg/hm2, soil moisture was 4% higher than CK. Soil surface and 5cm temperature can be fitted as sine function, the temperature adjusting effects of gravel, straw covered were insulation when temperature was cery low, cooling effect when in high temperature.
(4) Simpson index, Shannon-Wiener index, Pielou index and Margalef index showed double increasing at different moisture gradient. man-made soil tillage measure can keep soil surface moisture at a heigh level of 15% for a long time.After irrigating, sea buckthorn, Ceratoides, Caragana survival rate were 65.7%,32.1%, 53.7% higher than CK, around the district,plant height increasde 10%, species number increasde 10%, coverage increased 5% , Biomass dry weight increase 135.4g/m~2.
(5) Water is certain request when Alfalfa forage grass is in growth stage , rainfall and irrigation mainly affect less than 80cm layer soil moisture, 80-200cm layer soil moisture content is 8%.There was obvious correlation between Alfalfa productivity and irrigation volume ,the math model was: Y = 0.9025Q1.4732 (R2 = 0.94), there are still large room for alfalfa irrigated productivity ,the reality productivity depended on the measures of water and fertilizer.
引文
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