西南山地不同林下经济模式对植物多样性的影响

以西南山地桉树林下养禽(T1)、桉树林下养食用菌(T2)、麻竹林下养禽(T3)、麻竹林下养食用菌(T4)、马尾松林下养畜(T5)、黄葛树林下种草(T6)6种典型林下经济模式为研究对象,采用相邻样地比较法对各模式下植物群落的物种重要值(P)、丰富度指数(S)、Shannon-Wiener多样性指数(H′)、Pielou均匀度指数(Jw)、Alatalo优势度指数(Ea)、相似性指数Jaccard(Cj)和Sorenson(Cs)以及多样性阈值(Dv)进行调查分析,探讨不同林下经济模式对植物多样性的影响。结果表明:T6模式下植物种类最丰富,为11种;而T3和T4模式下植物种类最少,仅有2种。各经济模式均无灌木层,草本层为群落优势层。空心莲子草是T1和T2模式的优势种,重要值分别为67.16%和71.00%;桑树是T3和T4的优势种,重要值高达74.91%和72.82%;T5和T6优势种分别是竹叶草(54.10%)和牛鞭草(59.51%)。在不同林下经济模式中,植物丰富度指数(S)依次为T6T1T5=T2T3=T4,多样性指数H′呈T6T1T5T2T4T3,均匀度Jw呈T5T6T2T1T4T3,优势度指数Ea呈T5T4T3T2T1T6。林下经济模式与相应的纯林对照物种组成相似性指数,以T3和T4最高,Cj和Cs均为1.0;其次是T6,Cj和Cs分别为0.44和0.62;T1最小,Cj和Cs分别为0.15和0.27。植物多样性阈值评价结果显示,T6模式植物多样性阈值最高,属于多样性较好类型;而T3和T4模式多样性阈值最低,属于一般类型。林下种养殖改变了植物群落的物种组成,且不同种养殖方式影响结果不同,其中以林草模式影响最小,为林地干扰下植物群落最丰富的模式。

Influence of different typical under-forest economy modes on the plant community diversity in China’s Southwest Mountains

Ecological problems arising from under-forest economy have gained a wide recognition in recent years. With the development of under-forest economy, understory farming has become more sophisticated, and ecological environments under forests have also become more stable in Rongchang region of Chongqing. The adjacent-sample comparison method was used to study the effects of six different typical under-forest economy modes on importance value (P), species richness index (S), Shannon-Wiener diversity (H′), Pielou’s evenness index (Jw), Alatalo dominance index (Ea), Jaccard similarity index (Cj), Sorenson similarity index (Cs) and plant species diversity threshold (Dv) in China’s Southwest Mountains from August to September in 2012. The investigated six under-forest economy modes were poultry feeding in Eucalyptus robusta forest (T1), fungi cultivation in E. robusta forest (T2), poultry feeding in Dendrocalamus latiflorus forest (T3), fungi cultivation in D. latiflorus forest (T4), livestock feeding in Pinus massoniana forest (T5) and grass cultivation in Ficus lacor forest (T6), and with the corresponding pure forests as the controls. The results showed that among six under-forest economy modes, the highest species richness index (11) was observed in T6 and the lowest species richness index (2) was occurred in both T3 and T4. Herb layer was the most dominant layer for all the six under-forest economy modes, and no shrub layer was found. The highest importance values were of Alternanthera philoxeroides in T1 (67.16%) and T2 (71.00%), Morus alba in T3 (74. 91%) and T4 (72.82%), and Oplismenus compositus in T5 (54.10%), and Hemarthria altissima in T6 (59.51%). For six under-forest economy modes, the species richness index was in the order of T6>T1>T5=T2>T3=T4, the Shannon-Wiener diversity was T6 > T1 > T5 > T2 > T4 > T3, the Pielou’s evenness index was T5 > T6 > T2 > T1 > T4 > T3, and Alatalo dominance index was T5>T4>T3>T2>T1>T6. Based on the analysis of similarity of species composition, T3 and T4 had the highest similarity indexes with their corresponding pure forests, 1.0 of both Cj and Cs, followed by T6 with 0.44 Cj and 0.62 Cs, respectively. The minimum Cj (0.15) and Cs (0.27) were those of T1 with its pure forest. Based the evaluation of plant diversity threshold under different under-forest economy modes, T6 had the highest threshold with a better diversity. Then the lowest threshold was for T3 and T4. Understory farming altered species composition of plant community, and different farming methods had different results. Grass cultivation under forest had the least effect and also was the most abundant species above all inquisitional modes.