不同类型杉木人工林林下草本植物多样性特征

林下草本多样性是衡量森林群落结构和功能的重要指标。以湖北九华山林场不同类型的杉木(Cunninghamia lanceolata)人工林(杉木纯林(Ⅰ)、杉木-檫木混交林(Ⅱ)、杉木-檫木-亮叶桦混交林(Ⅲ))为研究对象,通过分析林下草本层物种组成及其多样性特征,探讨林地类型与林下草本多样性的相互关系。结果表明:研究区林下草本层共有植物72种,分属于37科65属,其中以蔷薇科(Rosaceae)、金星蕨科(Thelypteridaceae)、禾本科(Gramineae)、菊科(Compositae)植物居多;林下草本植物以多年生草本为主,合计有67种,占全部草本植物的93.06%;物种丰富度指数、Shannon-Wiener指数、Simpson指数以及Pielou均匀度指数均表现为混交林样地(Ⅱ和Ⅲ)高于纯林样地(Ⅰ),但差异性不显著;各样地林下草本层优势物种与林地树种组成密切相关,其中,Ⅰ型样地以高粱泡(Rubus lambertianu)、金星蕨(Parathelypteris glanduligera)和鱼腥草(Houttuynia cordata)为优势种,其重要值分别为13.65%、8.79%和5.27%;Ⅱ型和Ⅲ型样地均以金星蕨、荩草(Arthraxon hispidus)和山马兰(Kalimeris lautureana)为优势种,重要值分别为10.75%、8.37%、7.47%和11.84%、6.16%、5.82%。此外,草本层的优势物种显著影响土壤理化性质:金星蕨与土壤含水量之间呈显著正相关(P<0.05),高粱泡与土壤磷含量显著正相关(P<0.05),而麦冬(Opiopogon japonicus)则与土壤磷含量呈负相关(P<0.05);并且,草本层各优势物种间存在一定的协同、竞争关系(P<0.05)。

Characteristics of herbaceous plant biodiversity in Cunninghamia lanceolate plantations with different community structures

Understory herb diversity is an important indicator to measure the structure and function of forest communities. In this study, pure forest of Cunninghamia lanceolata plantations(Ⅰ), mixed forest with C. lanceolate and Sassafras tzumu plantations(Ⅱ), and mixed forest with C. lanceolate, S. tzumu and Betula luminifera plantations(Ⅲ)), these three different types of Cunninghamia lanceolata plantations in Jiuhua Mountain Forest Farm, which located in the west of Hubei Province, were selected as the research object. By analyzing the understory herbs layer species composition and its diversity characteristics, we explored the relationship between forest types and understory herb diversity. Results showed that totally 72 species of plants in the herb layer were found in this study area, belonging to 65 genera of 37 families, of which the Rosaceae, Thelypteridaceae, Gramineae, and Compositae were the majority. Research indicated that the understory herbaceous species were dominated by perennials, with 67 species in total, accounting for 93.06% of all species. The species richness index, Shannon index, and Pielou uniformity index were higher in the mixed forests(Ⅱ and Ⅲ) than those in pure forests(Ⅰ). However, the difference was not significant. Meanwhile, we found that the elite species of herb layer were closely related to the tree species composition of the woodland. Among them, the type Ⅰ forest was dominated by Rubus lambertianu, Parathelypteris glanduligera, and Houttuynia cordata, and their important values were 13.65%, 8.79%, and 5.27%, respectively. Type Ⅱ and type Ⅲ plots were dominated by P. glanduligera, Arthraxon hispidus, and Kalimeris lautureana, with important values of 10.75%, 8.37%, 7.47% and 11.84%, 6.16%, 5.82%, respectively. In addition, the dominant species of the herb layer can significantly affect soil properties. For example, P. glanduligera was significantly positive with soil moisture content(P<0.05) and R. lambertianu had a significant positive correlation with soil phosphorus content(P<0.05), while Opiopogon japonicus was negatively correlated with soil phosphorus content(P<0.05). Moreover, a certain synergy and competitive relationship was found among the elite species in the herb layer.