半灌木扩张驱动的草地植物多样性与地上生产力特征及其关系研究  

Characteristics of plant diversity and aboveground productivity and their relationship driven by subshrub expansion

作　　者：李美慧 李玉华 晏昕辉 拓行行 杨梦茹 王子临 李伟 LI Mei-hui;LI Yu-hua;YAN Xin-hui;TUO Hang-hang;YANG Meng-ru;WANG Zi-lin;LI Wei(College of Grassland Agriculture,Northwest Agriculture and Forestry University,Xianyang 712000,China;Administration Bureau of Yunwu Mountain National Nature Reserve,Guyuan 756000,China;Institute of Soil and Water Conservation,Northwest Agriculture and Forestry University,Xianyang 712000,China)

机构地区：[1]西北农林科技大学草业与草原学院,陕西咸阳712000 [2]宁夏云雾山国家级自然保护区管理局,宁夏固原756000 [3]西北农林科技大学水土保持研究所,陕西咸阳712000

出　　处：《草业学报》2023年第5期27-39,共13页Acta Prataculturae Sinica

基　　金：国家自然科学基金项目(42277464);国家重点研发计划项目(2022YFF1302805)资助。

摘　　要：灌木/半灌木扩张能够显著改变原有植被景观及其生态学过程,但目前仍缺乏对半灌木扩张驱动下草地植物多样性、地上生产力变化特征及其二者关系的系统研究。本研究以黄土高原宁夏云雾山典型草原为研究对象,通过选择3个半灌木扩张强度草地(轻度、中度和重度),并以未扩张的天然草地作为对照,分析物种多样性、群落水平植物功能性状、功能多样性和地上生产力的变化特征及其内在关系。结果表明:1)半灌木扩张驱动下草地群落组成、结构发生了明显改变,半灌木物种白莲蒿已取代了原有的草本植物成为新的草地优势种,且导致物种多样性显著降低;2)与对照相比,半灌木扩张显著降低了群落水平叶干物质含量,但增加了群落水平比叶面积、叶碳、叶氮和叶磷含量;功能丰富度无显著性差异,而功能离散度和功能均匀度在不同扩张强度下差异显著;3)半灌木扩张显著增加了群落地上生产力和凋落物生物量,具体表现为杂草生物量显著增加,豆科生物量显著降低,而禾类草生物量在重度扩张下显著增加;4)半灌木扩张驱动下草地群落地上生产力与物种多样性、群落水平叶干物质含量及功能离散度呈负相关关系,而与群落水平叶碳、叶氮和叶磷含量呈正相关关系。随机森林模型和方差分析结果进一步显示,群落水平功能性状对地上生产力变异解释度为68.28%,其中群落水平叶氮含量和叶干物质含量为最主要的解释因子,物种多样性指数解释度为64.38%,功能多样性指数解释度为11.16%。研究表明半灌木扩张驱动下,物种向快速生长、资源获取型策略转变,且物种生态位分化程度更高;植物功能性状和物种多样性比功能多样性更能解释群落地上生产力的变异。本研究结果可为黄土高原天然草地的稳态转变理论研究和新时期灌丛化草地的适应性和可持续管理提供数据支撑�Shrub/subshrub expansion can significantly change the original vegetation landscape and its ecological processes.However,there is still a lack of systematic research on the characteristics of grassland plant diversity,aboveground productivity,and their relationship driven by subshrub expansion.In this study,the typical grassland of Yunwu Mountain in Ningxia on the Loess Plateau was selected as the study site.Grasslands with subshrub expansion at three levels of intensity(light,moderate,and heavy)were selected,and natural grassland without subshrub expansion served as the control.We analyzed species diversity,community level plant functional traits,functional diversity,and aboveground productivity and their intrinsic relationships.The results showed that:1)The composition and structure of the grassland community changed significantly under the driver of subshrub expansion.The subshrub species Artemisia sacrorum replaced the original herb as the new dominant grassland species,which resulted in a significant decrease in species diversity.2)Compared with the control,sites with subshrub expansion showed significantly decreased community-level leaf dry matter content,but increased community-level specific leaf area,and leaf carbon,nitrogen,and phosphorus contents.There was no significant difference in functional richness,while functional dispersion and functional evenness had significant differences under different expansion intensities.3)Subshrub expansion significantly increased the aboveground biomass and litter biomass of the community,which was manifested as a significant increase in the biomass of weeds and a significant decrease in the biomass of legumes.However,grass biomass increased significantly under severe subshrub expansion.4)The aboveground productivity of the grassland community was negatively correlated with species diversity,community-level leaf dry matter content,and functional dispersion,while positively correlated with leaf carbon,leaf nitrogen and leaf phosphorus contents at community level.The re

关 键 词：半灌木扩张 地上生产力 物种多样性 功能多样性 植物功能性状 

分 类 号：S812[农业科学—草业科学]