马尾松人工林目标树经营初期对土壤理化性质与植物多样性的影响

Effects of early management of Pinus massoniana plantation target trees on soil physicochemical properties and plant diversity

以川东低山区33年马尾松人工林为研究对象,研究3种目标树密度（100、150、200株/hm^2）下目标树经营对林下土壤理化性质与植物多样性的影响.结果表明,与对照林分相比,目标树经营初期各处理均显著提高了土壤物理性质、pH、有机质与全磷含量（P〈0.05）,与有效磷,水解氮无显著性差异（P〉0.05）.马尾松人工林灌木层和草本层植物物种丰富度指数显著增加（P〈0.05）,且灌木层优势种发生明显更替.灌木层Simpson指数、Shannon-Wiener指数和Pielou指数与未改造纯林均无显著差异（P〉0.05）,但草本层Simpson指数、Shannon-Wiener指数和Pielou指数都显著减小（P〈0.05）.植物与土壤理化性质相关分析表明,土壤pH、全磷和水解氮含量与植物多样性密切相关.目标树经营初期各处理均显著改善了马尾松人工林土壤理化性质与植物多样性,并且随处理程度的增加而发生变化.综合来看,目标树密度为150株/hm2的处理对该地区土壤理化性质和植物多样性影响效果最好.

In order to provide a theoretical reference for the early management of target trees in the low mountain region of eastern Sichuan, and a theoretical basis for the sustainable management of masson pine（Pinus massoniana） plantations, we chose three different kinds of densities（100 target trees per hectare, 150 target trees per hectare, and 200 target trees per hectare） in a 33-year-old masson pine plantation in the low mountain region of eastern Sichuan. We investigated the change patterns of soil physicochemical properties and plant diversity during the early stage of the management of the target trees. The results showed that compared to the control（CK）, the early stage of management of P. massoniana plantation target trees dramatically improved the soil physical properties, the pH value, contents of organic matter, and total phosphorus（P〈0.05）; however, the available phosphorus and the available nitrogen varied slightly（P〉0.05）. Compared to the control（CK）, significant（P〈0.05） differences in the richness index were observed between shrubs and herbs（P〈0.05）, and in the shrub layer, the dominant position was replaced by others. Simpson, Shannon, and Pielou indexes of shrubs showed no significant difference in the study（P〉0.05）. On the contrary, Simpson, Shannon, and Pielou indexes of herbs were significantly lower than those for CK（P〈0.05）. There were significant correlations between plant species diversity and soil physicochemical properties such as soil pH, contents of total phosphorus, and the available nitrogen. The early stage of management of P. massoniana plantation target trees significantly improved the plant diversity and soil physicochemical properties. Among all the three different treatments, the density of 150 target trees per hectare had the best effect on the soil physicochemical properties and plant diversity.