高寒草地生物量及牧草养分含量年度动态研究

Yearly Dynamics of Biomass and Nutrient Contents in Alpine Grassland

测定了西藏那曲地区高寒草地1～12月份围栏内和围栏外的地上生物量（BM）及牧草粗蛋白质（CP）、粗脂肪（EE）、中性洗涤纤维（NDF）、酸性洗涤纤维（ADF）和灰分（Ash）含量。结果表明：围栏内年平均BM极显著高于围栏外（15．02 DM g／m^2对11．70 DMg／m^2，P〈0．01），而围栏内外牧草各种养分含量差异不显著（P〉0．05）。不同季节BM和牧草养分含量变异较大，BM呈“单峰”曲线变化趋势，8月份最高（33．02 DM g／m^2），3月份最低（6．39DMg／m^2）；牧草CP、EE含量亦呈“单峰”曲线变化趋势，CP含量在8月份达到最高（10．68％DM），在2月份降到最低（2．72％DM），EE含量变异不大，在9月份较高（3．77％DM），1月份较低（2．26％DM）；NDF变化规律与CP相反，呈“V”型曲线变化趋势，最低和最高含量分别在8月份（49．38％DM）和12月份（69．08％DM）；ADF含量全年变化不大，夏季较（35．03％DM）冬春季低（42．92％DM）；Ash在6月份含量最高（18．29％DM），2月份含量最低（7．14％DM）。以月份为自变量，进行适当变换后建立了牧草生物量和养分含量的全年动态变化回归模型。

The investigation was carried out in alpine grassland of Nakchu prefecture from January to December to examine the distribution of aboveground biomass（BM） and the contents of crude protein（CP）, ether extract （EE）, neutral detergent fiber （NDF）, acid detergent fiber （ADF） and crude ash（Ash）. The results showed that the above ground biomass of outside exclosure was higher than that of inside exclosure, significantly （15.02 DM g/m^2 vs. 11.70 DM g/m^2 , P〈0.01）, otherwise the grass nutrient contents （CP, EE, NDF, ADF, Ash） were not different between inside and outside exclosure（P〉0.05）. BM and nutrient ingredients of grass had great changes in different seasons. The dynamic changes of BM showed single kurtosis, maximum of BM appeared in August（33.02 DM g/m^2）, and minimum of BM appeared in March（6.39 DM g/m^2 ）. The dynamic changes of CP and EE showed single kurtosis, too, maximum of CP appeared in August（10.67%DM）, and minimum of CP appeared in February （2.72%DM） ; EE contents of grass had a little variance in whole-year, which in September （3.77%DM） were higher than that in January （2.26%DM）. The dynamic changes of NDF showed ‘V＇ curve, minimum and maximum of NDF appeared in August（49.38%DM） and December （69.08%DM）, respectively; ADF changed less from Janu ary to December, it was lower in summer（35.03%DM）, but higher in winter（42.92%DM）. Themaximum and minimum of Ash appeared in June（18.29% DM） and February （7.14 %DM）, respectively. The dynamic regression models were established which expressed BM, CP, EE, NDF and ADF as functions respectively, and applied months as independent variable.