影响不同林型天然红松混交林林隙更新的土壤特征因子

采用野外调查、样品采集和统计分析等相结合的方法,对小兴安岭天然红松混交林3种不同林型(椴树红松混交林(TP)、枫桦红松混交林(BP)、云冷杉红松混交林(PAP))的林隙及其邻近郁闭林分的土壤特征因子和树木更新的相关性进行了研究,旨在阐明林隙土壤特征因子对树木更新的影响,从而为小兴安岭天然红松混交林植被更新、退化生态系统的恢复和可持续经营提供基础数据和实践参考。结果表明:郁闭林分土壤有机质、全氮质量分数显著高于3种不同林型的林隙。有效磷和速效钾含量在BP内与其他林型之间差异显著。3种林型林隙内p H值均略高于其郁闭林分,但与其差异均不显著。3种林型林隙内更新总密度、幼树更新密度与郁闭林分差异显著(P0.05),PAP林隙中更新总密度和幼树更新密度最高。BP林隙面积与更新密度相关不显著,乔木幼苗、幼树更新密度与有机质(r=-0.400,r=-0.475)、全氮均呈显著负相关(r=-0.519,r=-0.603)。TP林隙内全氮与乔木幼苗更新密度呈正相关(r=0.092),而与乔木幼树更新密度呈显著负相关(r=-0.585)。PAP林隙内全氮与乔木幼苗、幼树更新密度均呈负相关。郁闭林分幼苗更新密度分别与有机质、全氮、速效钾、p H值、脲酶和蛋白酶呈负相关。主成分分析表明,全氮是影响林隙和郁闭林分树木更新的关键因素。

Effects of soil characteristics on forest gap regeneration in different types of natural Pinus koraiensis mixed forest

The present study examined the correlation of soil characteristics and tree regeneration in canopy gaps and adjacent closed areas of three forest types, including Tilia amurensis-Pinus koraiensis mixed forest (TP), Betula costata-P. koraiensis mixed forest (BP), and Picea koraiensis-Abies fabri-P. koraiensis mixed forest (PAP), using a combination of field investigation, sample collection, and statistics and analysis. The study aimed to provide basic data that could be used as a practical reference for plant regeneration, restoration of degraded ecosystems, and sustainable management of P.koraiensis mixed forests in the Xiaoxing''an Mountains of Northeast China. The results indicated that levels of soil organic matter and total nitrogen were significantly lower under gaps than under the adjacent closed stands, and the levels of available P and K in the BP soil were significantly different from those in the other forest soils. In addition, the pH of the soil under the gaps was slightly higher than under the adjacent closed stands, but the difference was not statistically significant. However, the difference in the total and sapling regeneration densities of the gaps and closed stands was significant (P < 0.05), and the total and sapling regeneration densities were highest in the PAP. In the BP, there was no significant correlation between gap area and regeneration density, but the regeneration densities (seedling and sapling of tree) were significantly negatively correlated with soil organic matter(r=-0.400, r=-0.475). The regeneration densities of seedling and sapling of tree were significantly negatively correlated with total N(r=-0.519, r=-0.603). In the TP gap, total N was positively correlated with seedling regeneration density (r=0.092), but negatively correlated with sapling regeneration density (r=-0.585). Meanwhile, in the PAP gap, total N was negatively correlated with both seedling and sapling regeneration densities. In the closed stands, seedling regeneration density was negatively correlated with pH and levels of soil organic matter, total N, available K, urease, and protease, respectively. Principal component analysis indicated that total N was a critically influential factor in determining tree regeneration in both forest gaps and closed stand.