苦豆子斑块面积及斑块隔离度与豆荚螟发生情况的关联分析

Correlation analysis of patch area and patch isolation with the seed pest damage rate of Sophora alopecuroides

破碎化生态格局中斑块面积和斑块隔离度对生物种群有一定的影响。苦豆子是宁夏荒漠半荒漠地区防风固沙的主要物种,其分布呈现典型的斑块化格局,豆荚螟是其种子的主要害虫。本文在宁夏灵武市宁东镇的余家湖(YJH,6个斑块)和羊场湾(YCW,7个斑块)两个样地共选择了13个苦豆子斑块,采用五点取样法采摘苦豆子豆荚,室内剥检统计害虫数量、豆荚及豆粒的危害率,用单因素方差分析进行差异性检验,用逐步回归法进行斑块面积、斑块隔离度与危害率的关联分析。结果显示:YJH样地斑块平均面积为2 629. 08 m^2,苦豆子平均盖度50. 33%,斑块间豆荚及豆粒危害率差异显著(P <0. 05); YCW样地斑块平均面积为1 010. 34 m^2,苦豆子平均盖度31. 14%,斑块间豆荚豆粒危害率差异不显著(P> 0. 05)。13个斑块豆荚及豆粒的危害率均差异显著(P <0. 05)。斑块面积对豆荚螟数量的回归分析显示影响并不显著(R2=0. 084)。两样地间豆粒的危害率并无显著差异(P> 0. 05); Pearson相关分析显示斑块连接度指数与豆荚危害率(r=-0. 2215)、豆粒危害率(r=-0. 4102)、豆荚螟数量(r=0. 0561)有一定的相关性。斑块面积对苦豆子种实害虫数量、豆荚及豆粒的危害率影响不显著,但斑块隔离度增加,能够减轻苦豆子种子害虫的危害。

The patch area and patch isolation in the fragmented ecological pattern have a certain influence on the biological population. Sophora alopecuroides a major species of checking wind and controlling sand in the desert semi-desert area of Ningxia,has a typical patch pattern. Etiella zinckenella is a seed pest of Sophora alopecuroides. A total of 13 patches were selected from Yujiahu (YJH, 6 patches) plot and Yangchangwan (YCW,7 patches) plot in Ningdong region,Lingwu City,Ningxia. The pods of S. alopecuroides was plucked by five-point sampling method. The individual of pest,damage rate of pods and beans were counted. The single factor equation analysis was used to test the difference of damage rate of pods and beans. Stepwise regression was used to analysis the correlation of patch area, patch isolation with damage rate. The result showed that the average patch area was 2629.08 m^2 in YJH plot. The average coverage of S. alopecuroides was 50.33%. There was no significant difference in damage rates of pods and beans (P<0.05) among 6 patches in YJH plot. The average patch area was 1 010.34 m^2 in YCW plot. The average coverage of S. alopecuroides was 31. 14%. There was no significant difference in damage rate of pods and beans (P>0.05 ) among 7 patches. There were significant differences in the damage rates of pods and beans in 13 patches (P<0.05). Regression analysis showed that patch area had no significant effect on the number of seed pest of S. alopecuroides (R^2 = 0.084). There was no significant difference in the damage rate of pods and beans between two plots (P>0.05). Pearson correlation analysis showed that there was a certain correlation between the patches connectivity index and pods damage rate (r =- 0.2215),beans damage rate (r =- 0.4102) and the individual of seed pest (r = 0.0561). The patch area had no significant effect on the individual of seed pest,damage rate of pods and beans,but the increase of patch isolation can reduce the damage of pods and beans.