宁夏东部沙地柠条花棒混交固沙恢复区水氮添加对草本植物群落的影响

Effect of water and nitrogen addition on herbaceous plant community in the sand-fixing restoration area of the mixed shrubland of Caragana korshinskii and Corethrodendron scopariumin sandy land of eastern Ningxia

为研究降水变化和大气氮沉降对沙地植物群落结构和生物量的影响,在宁夏灵武白芨滩国家级自然保护区进行水氮添加试验,采用随机区组试验设计,包含4个水处理:W_(0)为自然降水量、W_(1)为多年平均降水量的33%、W_(2)为多年平均降水量的66%、W_(3)为多年平均降水量的100%,4个氮处理0gN·m^(-2)·a^(-1)(N_(0))、5gN·m^(-2)·a^(-1)(N_(1))、10gN·m^(-2)·a^(-1)(N_(2))、20gN·m^(-2)·a^(-1)(N_(3))。设置4个试验小区,每个小区包含4个水处理和4个氮处理随机组合的16个处理。结果表明:1)水氮添加使植物群落的重要值和群落结构发生了显著变化。2)氮添加导致群落物种丰富度指数先减小后增大,在W_(2)N_(1)处理下有最大值;随着水分含量的增加,Shannon-Wiener多样性指数、Simpson优势度指数和Pielou均匀度指数在同一氮素添加水平下呈先增大后减小的趋势,在W_(2)N_(1)处理下有最大值。3)水氮添加促进了地上生物量的增加,适量的水氮添加有利于植物的生长发育。在W_(2)N_(1)处理下固沙恢复区草本植物群落的地上生物量和盖度最大,在W_(0)N_(1)处理最小。

In order to study the effect of water and nitrogen addition on plant community structure and biomass in sandy land,A water and nitrogen addition experiment was conducted in the Lingwu Baijitan National Nature Reserve in Ningxia,and a randomized block experiment design was adopted,including four water treatments(W_(1) is precipitation;W_(1) is 33% of annual average precipitation.W_(2) is 66% of the annual average precipitation.W_(3) is 100% of the annual average precipitation) and four nitrogen treatments:0gN·m^(-2)·a^(-1)(N_0),5gN·m^(-2)·a^(-1)(N_5),10gN·m^(-2)·a^(-1)(N_(10)),20gN·m^(-2)·a^(-1)(N_(20)).Set up 4 test plots,each plot contains 16 treatments with a random combination of 4 water treatments and 4 nitrogen treatments.The results show that:1) The important value and community structure of plant community have changed significantly with the addition of water and nitrogen.2) With the increase of water content,Shannon-Wiener diversity index,Simpson dominance index and Pielou evenness index all increased first and then decreased with the same nitrogen addition,and reached the maximum under W_2N_(1) treatment.3) The addition of water and nitrogen promoted the increase of aboveground biomass,and proper addition of water and nitrogen was beneficial to the growth and development of plants.The aboveground biomass has a maximum value under W_2N_(1) treatment and a minimum value under W_0N_(1) treatment.