补植对防护林生长和物种多样性的影响

Effects of replanted on stand growth and species diversity

开展高寒荒漠区防护林林内补植对林分结构和物种多样性的短期效益分析,为当地防护林稳定和持续发育提供理论依据。以青海共和盆地东缘贵南县黄沙头2019年补植青海云杉的青杨林群落为对象,未补植为对照,对沙化土地丘间地造林后5、10、15、20和25 a防护林林分结构、群落组成、物种多样性、林内环境因子进行对比分析。结果表明:补植后林内生物量显著高于未补植林地,且以25年生青杨-青海云杉混交林为最大;灌木层多样性指数以20年生青杨-青海云杉混交林最大(0.56),Simpson优势度指数以15年生青杨-青海云杉混交林最大(0.73);草本层多样性、Simpson优势度指数以25年生青杨-青海云杉混交林最大(0.93、0.53);补植后林内月平均相对湿度、10和30 cm土壤含水量高于未补植林分(P>0.05);物种丰富度指数、Shannon-Wiener多样性指数、Pielou均匀度指数、Simpson优势度指数与平均树高、平均胸径、郁闭度、土壤表层(10 cm)、深层(150、200 cm)含水量具有显著正相关性(P<0.05)。未来该地区以青杨为先锋树种的防护林经营中,可对25年林分开展以青海云杉为主的次林层补植,乡土树种较强的有性生殖能力可为群落正向演替提供稳定的生殖策略,有利于防护林持续健康发育。

The community of Picea crassifolia planted in the Populus cathayana forest in Huangshatou,Guinan County at the eastern edge of the Gonghe Basin in Qinghai Province in 2019 was taken as the research object,and the non-replanted vegetation community was compared.The structure,community composition,species diversity,and environmental factors in the forest were compared and analyzed.This was undertaken 5,10,15,20,and 25 years after afforestation in the dune land of the sandy land to analyze the short-term benefit for forest structure and species diversity from replanted in shelter forest in an alpine desert area.This study has also provided a theoretical basis for stability and sustainable development of the local shelter forest.The results have shown that the replanted forest biomass was significantly higher than the non-replanted forest,and that the 25-year-old Populus cathayana-Picea crassifolia mixed forest was the largest biomass.The Shannon-Wiener index for the shrub layer was the highest in the 20-year-old Populus cathayana-Picea crassifolia mixed forest(0.56),and the Simpson index was the highest in 15-year-old Populus cathayana-Picea crassifolia mixed forest(0.73).The Shannon-Wiener and Simpson index for the herb layer were the highest in the 25-year-old Populus cathayana-Picea crassifolia mixed forest(0.93,0.53).After replanted,the humidity and soil moisture(10,30 cm)in the forest were higher than those of the non-replanted forest(P>0.05).There were positive correlations between indices for species richness,Shannon-Wiener index,evenness index,Simpson index and average tree height,average diameter at breast height,canopy density,surface(10 cm),and deep(150,200 cm)soil moisture content(P<0.05).In the future,Qinghai spruce can be replanted in the 25-year-old Populus cathayana forest during management of the protective forest with Populus cathayana as a pioneer tree.The sexual reproduction ability of native tree species can provide a stable reproductive strategy for positive succession of the vegetation community,which is conducive to sustainable and healthy development of the shelter forest.