水平空间配置对南林-95杨人工林主要细根性状的影响

Effects of horizontal spatial allocation on main fine root characters of Populus × euramericana cv. ‘Nanlin-95’ plantations

【目的】本文主要研究杨树主要细根性状的空间分布规律与株行距配置间的关系。【方法】本文选取4种不同水平空间配置(株距×行距分别为3 m×8 m、5 m×5 m、6 m×6 m、4.5 m×8 m)的南林-95杨人工林为研究对象,采用根钻法对细根生物量、比根长和根长密度的空间分布特征进行研究。【结果】表明:水平空间配置对杨树人工林细根空间分布特征有显著影响。在垂直方向上,低密度(6 m×6 m)林分表层细根生物量、比根长及根长密度比高密度(3 m×8 m、5 m×5 m)林分显著较高;在水平方向上,长方形配置(3 m×8 m和4.5 m×8 m)的林分细根生物量随距树干距离的增加而减少,正方形配置(5 m×5 m和6 m×6 m)林分的细根生物量以及4种林分的细根根长密度、比根长与取样距离关系不明显。6 m×6 m林分在水平各距离处均高于其他林分。长方形配置林分,株距方向上的细根生物量、根长密度和比根长总是显著低于行距方向。【结论】株行距过小,细根生物量会显著减小,生长受限,株行距过大,在距树干较远处细根生物量会显著降低,造成空间浪费,低密度正方形配置(6 m×6 m)杨树人工林主要细根生长特征在4种株行距配置林分中最优,更适合杨树人工林初值株行距。

[Objective] This paper aims to study the relationship between spatial distribution of main fine root traits and row spacing allocation of poplar. [Method] Four different horizontal spatial allocations of Populus × euramericana cv. ‘Nanlin-95’ plantations(plant spacing × row spacing 3 m × 8 m, 5 m × 5 m,6 m × 6 m and 4.5 m × 8 m, respectively) were selected as the research objects, root drilling method was used to study fine root biomass and specific root length. The spatial distribution characteristics of root length and density were studied. [Result] The results showed that horizontal spatial allocation had a significant effect on the spatial distribution characteristics of fine roots in poplar plantations. In vertical direction, fine root biomass, specific root length and root length density of low density(6 m × 6 m) stand were significantly higher than those of high density(3 m × 8 m, 5 m × 5 m). In horizontal direction, fine root biomass of rectangular(3 m × 8 m and 4.5 m × 8 m) stand was decreased as the distance from the trunk increased, while fine root biomass of square(5 m × 5 m and 6 m × 6 m) stand was negatively correlated with sampling distance. There was no significant correlation between the fine root length density, specific root length and sampling distance. 6 m × 6 m stand was higher than other stands at all horizontal distances.The fine root biomass, root length density and specific root length in the direction of plant spacing were always significantly lower than those in the direction of row spacing. [Conclusion] The fine root biomass of poplar plantations with small row spacing, limited growth and large row spacing will decrease significantly at a distance from the trunk, resulting in space waste. The main fine root growth characteristics of low-density square(6 m × 6 m) poplar plantations are the best among the four row spacing allocation stands, which is more suitable for the initial row spacing of poplar plantations.