草原生长期地表辐射和能量通量月平均日变化特征

利用2008年5—9月锡林浩特国家气候观象台辐射和通量观测资料,分析了锡林浩特典型草原生长期各辐射分能量和同期能量通量的月平均日变化以及地表能量闭合度.结果表明:草原生长期总辐射月平均日最大值出现在7月,平均日最大辐射强度达到753.14W·m-2,最小值出现在5月,为697.27W·m-2.受地表反照率和太阳总辐射的影响,生长期反射辐射最大值出现在5月份,平均日积分值为4.92MJ·m-2;9月份最小,平均日积分值为3.76MJ·m-2.生长期获得的辐射能量为1385.67MJ·m-2,平均净辐射(Rn)强度为104.52W·m-2;感热通量(H)共支出640.39MJ·m-2,日平均强度为53.40W·m-2;潜热通量(LH)共支出772.96M·m-2,日平均强度为55.10W·m-2.Rn和H+HL+G线性回归的结果显示,草原生长期日平均能量闭合率为90%,能量不闭合程度为10%.     

草原浅覆盖区浅钻取样技术的研究与应用

为实现草原浅覆盖区快速揭露,并最大限度减少对环境的破坏,采用浅层钻探取样技术揭穿第四系,采取残坡积层及基岩层样品,用于浅钻金属矿产地球化学勘查、浅覆盖区地球化学立体填图及代替槽探的工作中。研究了干旱半干旱草原浅覆盖区浅钻取样技术方法组合。该方法在花敖包特铅锌矿及东乌旗地区的应用表明,通过灵活合理地调整钻探装备及钻进工艺方法,可以顺利地采取目的层样品。     

藏北高寒草原土壤粒径分布分形维数特征

基于样带采样方法,应用土壤颗粒的体积分布计算了藏北高寒草原44个土壤样品的粒径分布分形。结果显示,研究区的土壤质地主要是砂土、壤质砂土和砂质壤土,其所占比例分别为29.55%、38.64%和27.27%。分形维数介于1.979~2.743,均值为2.492。随着土壤质地向壤土、粉壤土、砂质壤土、壤质砂土、砂土的变化,分形维数逐渐增小;研究区土壤中砂粒、粉粒和粘粒的平均含量为77.65%,18.2%和4.15%,粉粒和粘粒变异程度高。土壤粒径分形维数与土壤颗粒含量之间的关系显著,其与砂粒含量呈负相关,而与粉粒和粘粒含量呈正相关。研究结果表明:土壤粒径分布分形维数可以作为判断藏北高寒草原土壤质地差异的重要指标。     

西藏不同退化高寒草地土壤酶的活性

对退化高寒草原土壤酶活性研究的结果表明:1)相对于正常草地,轻度退化草地土壤纤维素酶、脲酶、碱性磷酸酶活性均呈不同程度的提高;中度退化草地土壤纤维素酶、碱性磷酸酶活性亦呈同一趋势,仅土壤脲酶活性显著降低;严重退化草地中3种土壤酶活性则均呈显著降低。2)不同土壤酶活性对土壤环境变化的敏感性总体呈碱性磷酸酶活性>脲酶活性>纤维素酶活性;土壤酶活性大小则均呈脲酶活性>碱性磷酸酶活性>纤维素酶活性。3)不同土壤酶活性与土壤有机碳均呈极显著正相关(r值为0.728 8~0.980 8,p≤0.01),与土壤全氮、有效氮、有效钾亦呈不同程度的正相关,与土壤有效磷含量则均呈显著或极显著负相关;土壤pH对土壤脲酶活性具有显著影响,对纤维素酶、碱性磷酸酶活性的影响则不甚明显。4)西藏高原高寒、干旱条件下,中度,特别是轻度退化草地一定程度的沙化所导致的土壤通透性能的显著改善对提高土壤酶活性,进而促进土壤有机残体的分解和有机质的形成具有重要作用。5)土壤酶活性不仅可以反映不同程度退化高寒草原土壤肥力水平的差异,同时亦可作为评价草地土壤肥力的一个基本指标。     

Detecting the storage and change on topsoil organic carbon in grasslands of Inner Mongolia from 1980s to 2010s

Soil carbon sequestration and potential has been a focal issue in global carbon research. Under the background of global change, the estimation of the size as well as its change of soil organic carbon（SOC） storage is of great importance. Based on soil data from the second national soil survey and field survey during 2011–2012, by using the regression method between sampling soil data and remote sensing data, this paper aimed to investigate spatial distribution and changes of topsoil（0–20 cm） organic carbon storage in grasslands of Inner Mongolia between the 1980 s and 2010 s. The results showed that：（1） the SOC storage in grasslands of Inner Mongolia between the 1980 s and 2010 s was estimated to be 2.05 and 2.17 Pg C, with an average density of 3.48 and 3.69 kg C·m–2, respectively. The SOC storage was mainly distributed in the typical steppe and meadow steppe, which accounted for over 98% of the total SOC storage. The spatial distribution showed a decreased trend from the meadow steppe, typical steppe to the desert steppe, corresponding to the temperature and precipitation gradient.（2） SOC changes during 1982–2012 were estimated to be 0.12 Pg C, at 7.00 g C·m–2·yr–1, which didn＇t show a significant change, indicating that SOC storage in grasslands of Inner Mongolia remained relatively stable over this period. However, topsoil organic carbon showed different trends of carbon source/sink during the past three decades. Meadow steppe and typical steppe had sequestered 0.15 and 0.03 Pg C, respectively, served as a carbon sink; while desert steppe lost 0.06 Pg C, served as a carbon source. It appears that SOC storage in grassland ecosystem may respond differently to climate change, related to vegetation type, regional climate type and grazing intensity. These results might give advice to decision makers on adopting suitable countermeasures for sustainable grassland utilization and protection.