中国北方不同地带沙地封育草场土壤性质和植被特征比较

Comparison of Soil Properties and Vegetation Characteristics between Two Sandy Grassland under Exclosure in Northern China

为了探明不同水热地带沙地封育草场土壤性质和植被特征的差异性,以科尔沁沙地和毛乌素沙地封育草地为研究对象,通过调查2个沙地的土壤理化性质和草本植被特征,比较不同地带沙地土壤性质与植被特征,并分析影响不同地带沙地土壤性质和植被分布的原因,以期为区域退化沙质草地生态系统恢复、保护与管理以及应对气候变化提供依据。结果表明:降雨量较高的科尔沁沙地(397 mm)封育草场土壤含水量(t=7.318,P=0.000)、有机碳含量(t=6.395,P=0.000)、全氮含量(t=4.532,P=0.003)以及土壤C/N(t=2.491,P=0.041)均显著高于偏干旱的毛乌素沙地(292 mm),前者分别是后者的2.5、2.5、2.2、1.2倍,而土壤p H(t=-39.576,P=0.000)、电导率(t=-10.031,P=0.000)和土壤温度(t=-11.559,P=0.000)均表现为科尔沁沙地(年均温6.3℃)显著低于毛乌素沙地(年均温7.7℃),后者分别是前者的1.2、1.8、1.1倍。科尔沁沙地植物个体数(t=-7.774,P=0.000)、优势度指数(t=-4.066,P=0.004)显著低于毛乌素沙地,后者分别是前者的10、2倍,而植物高度(t=7.003,P=0.000)和均匀度指数(t=2.829,P=0.025)表现为科尔沁沙地显著高于毛乌素沙地(P<0.001),前者分别是后者的1.7、1.4倍。植物群落Shannon指数和物种丰富度在2个沙地间未呈现出显著差异性(P>0.05)。研究表明,沙地水热等气候条件的改变不仅对沙质草地土壤理化性质产生深刻影响,还影响到植物群落组成与结构特征,但对植物多样性的影响有限,可能存在一个水热阈值条件。

The aim of this project was to elucidate the differences of soil properties and vegetation characteristics between Horqin sandy grassland and Mu Us sandy grassland, in order to provide the basis for the recovery of degraded sandy ecosystems, for the management and utilization, and for the strategies to climate changes in northern China. An investigation on soil physical-chemical properties and vegetation diversity indices were carried out in the two sandy grasslands. The results were shown that the soil water content (t=7.318, P=0.000), organic carbon (t=6.395, P=0.000) and total nitrogen (t=4.532, P=0.003) and soil C/N (t=2.491, P=0.041) were markedly higher in Horqin sandy grassland with much rainfall (397 mm) compared with the relatively arid Mu Us sandy grassland (292 mm), with the 2.5, 2.5, 2.2, 1.2 times more for the former than the latter, respectively. Soil pH (t=-39.576, P=0.000), electrical conductivity (t=-10.031, P=0.000) and temperature (t=-11.559, P=0.000) was markedly lower in Horqin sandy grassland with low air temperature (Multi-annual average value, 6.3 ℃) compared with the hot Mu Us sandy grassland (7.7 ℃), with the 1.2, 1.8, 1.1 times more for the latter than the former, respectively. Plant density(t=-7.774, P=0.000), and Simpson index (t=-4.066, P=0.004) was markedly lower in Horqin sandy grassland compared with Mu Us sandy grassland, with the 10, 2 times more for the latter than the former, respectively. Whereas, plant height (t=7.003, P=0.000) and evenness index (t=2.829, P=0.025) was markedly higher in Horqin sandy grassland compared with Mu Us sandy grassland, with the 1.7, 1.4 times more for the former than the latter, respectively. However, no significant (P>0.05) differences in plant richness and Shannon index were found between these two sandy grassland. In conclusion, the changes of rainfall amount and temperature was found to indicate marked impact on both the soil physical-chemical properties and plant community structure, whereas the effect on plant diversity was limited and depended much on a threshold of water and temperature levels.