黄河故道刺槐人工林结构多样性特征

Structural diversity characteristics of the Robinia pseudoacacia forest in the Yellow River Original Course

【目的】刺槐人工林是黄河故道防风固沙的主要屏障,量化描述其林分结构多样性是深入挖掘森林结构异质性信息和精准提升森林质量的前提和关键。【方法】对黄河故道沙地100 m×100 m刺槐人工林固定样地进行每木定位和调查,采用α多样性指数(Shannon-Weaver多样性指数、Pielou均匀度指数、Simpson指数等)和林分结构参数(角尺度、混交度、大小比数等)定量描述林分非空间和空间结构多样性。【结果】黄河故道沙地刺槐人工林群落出现21科37属39种植物,以刺槐为建群种和优势种且草本层物种多样性最为丰富;林分中60.6%的林木与同种伴生,树种空间多样性较低(TSS=2.79),林分整体混交较差(M=0.07);胸径大小分化的Gini系数和Shannon-weaver多样性指数分别为0.40和2.870,明显高于树高,且二者在不同大小比数等级均占20.0%左右,使林木大小分化整体处于劣势(U_(DBH)=0.69、U_(H)=0.79);林分中58.7%的林木呈随机分布,但林分整体呈聚集分布(W=0.539);42.2%的林木之间很少存在树冠重叠,使得林分较为稀疏(C=0.480、K=1.39);林分整体结构异质性较差(FSSI=0.290、FSSD=1.327),处于弱度竞争状态(SCI=0.290)。【结论】黄河故道刺槐人工林整体结构多样性较差,迫需林分结构调整和优化,这将为黄河故道刺槐人工林森林质量的精准提升和森林经营方案的科学制定奠定基础,从而有效推进黄河流域生态保护和高质量发展。

【Objective】The Robinia pseudoacacia plantation is the main barrier for windbreak and sand-fixation of the Yellow River Original Course.A quantitative description of its structural diversity is the premise and key to comprehensively understanding the forest’s structural heterogeneity and accurately improving forest quality.【Method】A 100 m×100 m permanent plot of the R.pseudoacacia plantation in the Yellow River Original Course was located and investigated.Theαdiversity indices(Shannon-Weaver diversity index,Pielou evenness index,Simpson index,etc.)and stand structure parameters(uniform angle index,mingling,dominance,etc.)were used to quantitatively describe the diversity of nonspatial and spatial forest structure.【Result】There were 39 species belonging to 37 genera and 21 families in the R.pseudoacacia plantation in the Yellow River Original Course.R.pseudoacacia was the constructive and dominant species,and the herbal layer diversity showed the highest species diversity.60.6%of the trees were associated with the same species,and the spatial diversity of tree species and the mingling degree of the whole stand were both low(TSS=2.79,M=0.07).The Gini coefficient and Shannon-Weaver diversity index of DBH differentiation degree were 0.40 and 2.870,respectively,which were significantly higher than those of tree height,and both accounted for 20.0%in different dominance degrees,making the overall stand size differentiation inferior(U_(DBH)=0.69,U_(H)=0.79).58.7%of the individual trees were randomly distributed,but the spatial distribution pattern of the overall stand was clustered(W=0.539).42.2%of the trees were rarely overlapped,making the overall stand sparse(C=0.480,K=1.39).The structural heterogeneity of the overall stand was poor(FSSI=0.290,FSSD=1.327),and the stand was in a weak competition state(SCI=0.290).【Conclusion】The structural diversity of the R.pseudoacacia plantation is poor,and it requires the adjustment and optimization of the stand structure,which would be helpful to accurately improve the forest quality of R.pseudoacacia plantation and scientifically formulate its forest management plan,so as to effectively promote the ecological protection and high-quality development of the Yellow River Basin.