黄土丘陵区不同退耕年限植被多样性变化及其与土壤养分和酶活性的关系

VARIATION OF VEGETATION DIVERSITY AND ITS RELATIONSHIP WITH SOIL NUTRIENT AND ENZYME ACTIVITY IN LANDS OF DIFFERENT ABANDONED YEARS IN THE LOESS HILLY-GULLY REGION

通过野外植被调查研究黄土丘陵区草原带退耕地植被在自然恢复过程中的演替规律及物种多样性特征,通过室内土壤样品分析土壤有机碳、全氮、碱解氮、速效磷含量及土壤脲酶、转化酶、磷酸酶、过氧化氢酶活性动态变化过程,并对植物多样性指数和土壤养分及酶活性进行相关分析。研究结果表明,黄土丘陵区草原带退耕地在长达75a的自然恢复过程中,植物群落演替以菊科(猪毛蒿)与黎科(虫实)等为主的一年生草本开始,逐步演替为多年生草本群落,最后形成以大针茅+长芒草为优势种的顶级草原群落,植物物种数总体上呈现增加趋势;物种多样性指数随退耕年限延长均呈波动性上升趋势;土壤养分及酶活性均随退耕年限的增长亦呈波动性上升趋势。自然恢复75a,Margalef指数、Shannon-Wienner指数及Pielous指数分别增加83.3%、31.8%、21.4%;土壤有机碳、全氮、碱解氮、速效磷含量分别增加了185.0%、164.8%、152.9%、109.8%;土壤脲酶、转化酶、碱性磷酸酶及过氧化氢酶活性分别增加了64.0%、7.8%、51.1%、11.8%。土壤养分及酶活性与Margalef指数、Shannon-Wienner指数之间存在显著正相关关系,与Pielous指数相关性不显著。

Characteristics of vegetation succession and diversity were studied through field surveys of lands during a process of natural restoration in a pasture zone in the loess hilly region,and soil samples were taken for analysis of dynamic changes in soil organic carbon,alkalytic-nitrogen,total nitrogen,available phosphorus,and activities of urease,invertase,alkaline phosphates and catalase,and correlations of plant diversity with soil nutrients and enzyme activity as well.Results show that during 75 years of natural restoration,community succession began with annual herbs such as the Asteraceae（Artemisia scoparia） and the Chenopodiaceous（Corispermum chinganicum）,which were gradually succeeded by perennial herbs,and finally by Stipa grandis and S.bungeana,which were the dominant species typical of the pasture zone.On the whole,a rising trend was observed of the number of species and a wavy but rising trend of the species diversity index and of soil nutrient and enzyme activities as well with increasing of natural restoration years,soil nutrient and enzyme activities increased with an increase of natural restoration years too.After 75 years of natural restoration,Margalef index,Shannon-Wienner index and Pielous index increased by 83.3%,31.8% and 21.4%,respectively;soil organic carbon,alkaline-nitrogen,total nitrogen and available phosphorus by 185.0%,164.6%,152.9% and 109.8%,respectively;and soil urease activity,invertase activity,alkaline phosphates activity,and catalase activity by 64.0%,7.8%,51.1% and 11.8%,respectively.Significant positive correlations were observed of soil nutrient and enzyme activities with Margalef and Shannon-Wienner index,but an insignificant one was with Pielous index.