长期放牧对短花针茅荒漠草原不同功能群植物重要值的影响

Effects of long-term grazing on the important valuesof different plant functional groups in Stipabreviflora desert steppe

摘要:

为探究长期放牧对短花针茅(Stipa breviflora)荒漠草原植物功能群结构特征的影响,以内蒙古四子王旗短花针茅荒漠草原为研究对象,于2018年5月至9月对围封14年(2004~2018年)、不同放牧处理样地的物种组成、植物高度、盖度、密度进行测定,并对植物群落重要值进行分析。结果表明:5月、6月和9月对照区和放牧区多年生丛生禾草重要值明显大于其他功能群植物;5月至9月放牧区优势功能群多年生丛生禾草重要值呈增加-降低-增加的变化趋势,而对照区则是呈先降低后升高的变化趋势;除多年生杂类草外,其他功能群植物重要值与载畜率存在显著的线性相关关系,其中多年生丛生禾草重要值随放牧强度的增加而增加,其他功能群植物重要值均随放牧强度的增加而降低。研究认为,短花针茅荒漠草原随着放牧强度的增加多年生丛生禾草的优势度逐渐增强,而其他功能群的植物优势度逐渐被削弱,尤其是多年生根茎禾草、灌木和半灌木功能群。灌木和半灌木功能群植物特征对于衡量草地生态系统稳定性具有重要指导意义,拟合方程得出短花针茅荒漠草原实现可持续利用的最佳载畜率为1.268 4羊单位/(hm2·a)。

Abstract:

The effect of long-term grazing on community structure of plant functional groups in Stipa breviflora desert steppe under different grazing treatments was studied in Siziwangqi,Inner Mongolia.The species composition,plant height,coverage and density of desert steppe which was enclosed for 14 years (2004-2018) were investigated,and the important value of plant community was analyzed from May to September 2018.The results showed that in May,June and September,the important values of perennial cespitose grasses in control and treatment were significantly higher than those of other functional groups;From May to September,the important value of the perennial cespitose grasses in grazing area showed an increase-decrease-increase trend,while that in control was a decreasing first and then increasing trend;Except for the perennial forbs,there was a significant linear correlation between the important values of other plant functional groups and the stocking rate,among which the important values of perennial cespitose grasses increased with the increase of grazing intensity,but it was opposite for other functional groups.In conclusion,with the increase of grazing intensity,the dominance of perennial cespitose grasses gradually increased,while that of other functional groups gradually reduced,especially the functional groups of perennial rhizome grasses,shrubs and semi-shrubs.The characteristics of shrubs and semi-shrubs were of great significance to evaluate the stability of grassland ecosystem.The best stocking rate for S.breviflora desert grassland was 1.268 4 sheep units/(ha·a).