安西自然保护区放归普氏野马的采食斑块选择研究

Grazing Patch Selection by Reintroduced Prezewalski’s Horse in Anxi Extra-Arid Desert National Nature Reserve,Anxi,Gansu,China

客观地划分普氏野马放归区的植被群落,以此研究放归普氏野马在群落水平对采食斑块的选择策略,对评估放归区的食物资源状况和保护普氏野马具有重要意义。本文采用样线法结合双向指示种分类法( TWINSPAN )对安西自然保护区普氏野马放归区植被进行数量分类。之后以TWINSPAN分类的74个样方为对照,采用直接观察采样测定了80个普氏野马采食样方的9种生态因子,通过生态因子对比分析、Bailey s判别分析对普氏野马采食斑块选择进行了分析。结果表明,TWINSPAN分类将研究区74个样方归并为12个群丛类型。普氏野马采食斑块的植被盖度、草本盖度、针茅盖度、芨芨草盖度、群丛类型、生境类型都与对照地中的相应成分具有显著差异。普氏野马偏好的采食斑块特征是针茅、柽柳+芨芨草、驼绒藜为主要建群种的群丛,草本盖度(>15%),针茅盖度( 10%<C Stipa ≤15%),芨芨草盖度( 20%<C Achnatherum ≤40%),生境类型为流水滩地半灌木草原或湿地灌丛草甸。主成分分析表明斑块的生境类型( 0.955 )和群丛类型( 0.941 )对普氏野马的采食选择具有重要影响。

We classified vegetation communities in a Prezewalski s horse ( Equus przewalskii ) reint-roduction area and studied the foraging strategies of reintroduced Prezewalski s horse to evaluate and manage the food resources for Prezewalski s horse and to enhance its protection.We sampled transects and used two-way indicator species analysis ( TWINSPAN ) to classify plant communities in the reintroduction area.We directly measured 9 significant feed-influencing factors in 80 plots used by Przewalski s horse.To provide comparison plots for the analysis of habitat selection,74 plots were analyzed using TWINSPAN as control plots.We used contrasting analyses of ecological factors and Bailey s method to analyze the selectivity of Przewalski s horse use of food patches.The results showed that 74 plots were classified into 12 vegetation patches by TWINSPAN.The vegetation coverage,herbage coverage,coverage of Stipa capillata ,coverage of Achnatherum splendens and habitat types of food patches differed significantly from that of control plots.Prezewalski s horse preferentially used food patches with the following attributes:plant community type specialized on dominant constructive species such as Stipa capillata,Tamarix chinensis and Achnatherum splendens ,and Ceratoides latens ,herbage coverage>15%, Stipa glareosa coverage of 10-15%, Achnatherum splendens coverage at 20-40%,and habitat types of desert steppe and wetland shrub meadow.According to the results of principal component analysis,the main factors affecting the grazing patch selection of Przewalski s horses were vegetation type ( 0.955 ) and habitat type ( 0.941 ).