Abstract:

In order to gain a deeper understanding of the relation between understory plant diversity and soil physicochemical properties in Pinus massoniana plantation, the “spatial-temporal” method was used to select sample plot of Pinus massoniana plantations of different ages (5-, 12-, 28-, 37-, and 56-years) in hilly region of central Hubei Province. The differences and correlations between species richness, Shannon-Wiener diversity, Simpson dominance, Pielou evenness, and soil (0‒10 cm) physicochemical properties in the understory shrub and herb layers were analyzed, and the effects of soil physicochemical properties on understory plant diversity were explored. The results showed significant differences in plant diversity between the shrub and herb layers of different ages. Plant diversity initially increased, then decreased, and finally increased in the shrub layer. The Shannon-Wiener diversity and Pielou evenness at 28-years were 92.02% and 86.67% higher than those at 5-years, respectively. Plant diversity first decreased and then increased with increasing age in the herb layer, and 5-years was significantly higher than at other ages. Species richness, Shannon-Wiener diversity, Simpson dominance, and Pielou evenness of the shrub layer were significantly higher than those of the herb layer (except 5-years). There were significant differences in physicochemical properties at different ages; and pH, moisture content, total nutrients, and available potassium decreased first and then increased with stand age, pH, total phosphorus, and total potassium at 5-years were significantly higher than at other ages. Organic carbon and alkaline nitrogen first increased and then decreased with stand age, and 37-years were significantly higher than those at 5, 12, and 28-years. The pH, total phosphorus, and total potassium were significantly related to plant diversity in the shrub and herb layers of P. massoniana plantations of different ages. Redundancy analysis of soil physicochemical properties explained 89.1% and 78.5% of plant diversity in the shrub and herb layers, respectively. Stepwise regression analysis showed that increasing the total phosphorus content can enhance plant diversity in the herb layer, whereas pH, total phosphorus, total potassium, and stand density can regulate plant diversity in the shrub layer. In summary, the understory plant diversity of Pinus massoniana plantations is influenced by soil physicochemical properties, and total phosphorus is a key factor in regulating the understory plant diversity in the region. Strengthening the management of phosphorus fertilizers can enhance the understory plant diversity.

Key words: Pinus massoniana plantation, stand age, plant diversity, soil physicochemical properties, hilly region of central Hubei province

摘要：

为深入了解马尾松人工林林下植物多样性与土壤理化性质的关系，采用“空间代时间”法在鄂中丘陵区选取不同林龄（5、12、28、37、56 a）马尾松（Pinus massoniana）人工林样地，通过分析林下灌草层物种丰富度、Shannon-Wiener多样性、Simpson优势度和Pielou均匀度及土壤（0－10 cm）理化性质的差异及彼此间的相关性，探索土壤理化性质对林下植物多样性的影响。 结果表明：不同林龄灌草层植物多样性差异显著，灌木层植物多样性随林龄的增加而先增加后减少再增加，28 a的Shannon-Wiener多样性和Pielou均匀度分别高于5 a的92.02%和86.67%；草本层各植物多样性随林龄的增加而先减后增，5 a显著高于其他林龄。灌木层物种丰富度、Shannon-wiener多样性、Simpson优势度和Pielou均匀度显著高于草本层（5 a除外）。不同林龄土壤理化性质差异显著，pH、含水量、全量养分和速效钾含量随林龄的增加而先减后增，pH、全磷和全钾含量在5 a显著高于其他林龄。有机碳与碱解氮随林龄的增加而先增后减，37 a的显著高于5、12和28 a的。不同林龄马尾松林下灌草层植物多样性与pH、全磷和全钾含量显著相关。冗余分析表明土壤理化性质分别解释灌木层和草本层植物多样性的89.1%和78.5%。逐步回归分析表明增加全磷含量可提高草本层植物多样性，pH、全磷、全钾和林分密度可调控灌木层植物多样性。综上，马尾松人工林林下植物多样性受土壤理化性质的影响，全磷是调控该地区林下植物多样性的关键因子，加强磷肥的管理可提升林下植物多样性。

关键词: 马尾松人工林, 林龄, 植物多样性, 土壤理化性质, 鄂中丘陵区