林窗尺度对马尾松人工林林下灌草层优势种生态位的早期影响北大核心CSCD

马尾松作为中国广泛栽植的乡土树种,其人工林群落结构简单和生物多样性低下是普遍存在的生态学问题。探究不同林窗尺度对马尾松人工林林下植被群落的影响,可为马尾松人工林近自然经营提供理论依据。该研究在45 a生马尾松人工林中分别设置A(50 m^(2))、B(100 m^(2))、C(200 m^(2))和D(667 m^(2))4种不同尺度的林窗,以不做任何处理的马尾松人工林作为对照(CK),探究采伐开窗后林窗内自然更新1 a后的灌草层植物组成、优势种生态位宽度和生态位重叠度分布特征。结果显示:(1)除100 m^(2)林窗下灌木层物种数与对照无显著差异外,其余林窗灌草层物种数均显著高于对照(P<0.05),且200 m^(2)林窗下灌草层物种数均最多,分别为35种和20种;4种林窗下灌草层物种丰富度指数较对照均显著增加(P<0.05),最大值均出现在200 m^(2)林窗下,其值分别为对照的1.5倍和2.6倍。(2)林窗增加了灌草层喜光植物种类,且在200 m^(2)林窗下种类最多,灌木层喜光植物有13种,草本层喜光植物有5种。(3)4种林窗下灌草层优势种中,喜光植物生态位宽度均较大,200 m^(2)林窗下灌草层生态位宽度平均值最小,其对资源利用程度低,重要值与生态位宽度之间无显著相关性(P>0.05)。(4)4种林窗下灌草层优势种间生态位重叠度指数均较小。667 m^(2)林窗下,灌草层优势种平均生态位重叠度指数最小,分别为0.029和0.024,200 m^(2)林窗下灌草层优势种高生态位重叠度占总数比例最大,分别为20%和23.8%。研究表明,采伐开窗促进了马尾松人工林林下植被发育,丰富了林下植物多样性,有利于马尾松林稳定持续发展,对精准提升马尾松人工林质量具有重要意义。

Early Effect of Forest Gap Size on Niche of Dominant Species in Shrub and Herb Layers under Pinus massoniana Plantation

Pinus massoniana is a widely planted native tree species in China. The simple community structure and low biodiversity of P. massoniana plantation are common ecological problems. Exploring the influence of different forest gap sizes on the understory vegetation community of P. massoniana plantation can provide a theoretical basis for the near natural management of P. massoniana plantation. To explore the distribution of shrub and herb layer plant composition, niche breadth and niche overlap of dominant species in the gap after natural regeneration for 1 year after cutting, we set four different sizes of gaps A (50 m²), B (100 m²), C (200 m²) and D (667 m²) in 45 year old P. massoniana plantation, with the untreated P. massoniana plantation as control in this study. The results showed: (1) except that there was no significant difference in the number of species in the shrub layer under the 100 m² gap, the number of species in the shrub and herb layer in the other gaps was significantly higher than that in the control (P < 0.05), and the number of species in the shrub and herb layer under the 200 m² gap was the most, with 35 and 20 species, respectively. The species richness index of the shrub and herb layer under the four forest gaps significantly increased compared with the control (P < 0.05), the maximum values all appeared under the 200 m² gap, and their values were respectively 1.5 times and 2.6 times that of the control. (2) The species of sun plants of the shrub and herb layer increased in the forest gap, and there were the most species under the 200 m² gap. There were 13 species of sun plants in the shrub layer and 5 species of sun plants in the herb layer. (3) Among the dominant species in the shrub and herb layer under the four forest gaps, the niche breadth of the sun plants was larger, the average niche width of the shrub and herb layer under the 200 m² gap was the smallest, the degree of resource utilization was low, and there was no significant correlation between the important value and the niche breadth (P > 0.05). (4) The niche overlap index of the dominant species in the shrub and herb layer under the forest gap was small. Under 667 m² gap, the average niche overlap indexes of dominant species in shrub and herb layer were the lowest, 0.029 and 0.024, respectively. The proportions of high niche overlap of dominant species in 200 m² gap were the highest, 20% and 23.8%, respectively. Studies have shown that cutting and opening windows promote the development of understory vegetation in the P. massoniana plantation, enriche the diversity of understory plants, which is conducive to the stable and sustainable development of the P. massoniana forest, and is of great significance to accurately improve the quality of the P. massoniana plantation.