景观复杂性和林分因素对两种土壤条件下杨树腐烂病发生的混合影响

Mixed effects of landscape complexity and stand factors on cytospora canker of poplar across two different field soil conditions

【目的】本文探究了不同土壤条件下景观复杂性和林分因素对杨树腐烂病的影响机制,为合理配置景观格局从而有效控制杨树腐烂病提供理论依据,促进杨树人工林的可持续发展。【方法】于2018年和2019年分别调查了新疆维吾尔自治区克拉玛依市和玛纳斯县两种不同的土壤理化性质下杨树腐烂病的发病情况。通过建立广义线性混合效应模型(GLMMs),以年份为随机效应,在景观尺度上分析景观复杂性和林分因素对杨树腐烂病的发生影响。【结果】黑杨和新疆杨腐烂病的发生与林分密度和害虫的香农多样性指数呈显著正相关关系,黑杨腐烂病与第一活枝高有显著正相关关系。两种杨树的腐烂病的发生与非杨树寄主的比例,以及海拔高度呈负相关关系;腐烂病与土壤理化性质具有显著相关性,同一景观结构中,克拉玛依的病害发病率高于玛纳斯,而且同一土壤条件下,简单景观中腐烂病的发病率高于复杂景观。【结论】本研究表明可以通过样地管理和在景观尺度上增强树木抗性来降低杨树腐烂病的发病率,从而为森林有害生物的管理提供理论依据。在造林规划中要考虑周边的景观结构特征对有害生物的潜在影响。同时利用土地覆被数据长期有效地监管景观特征对杨树腐烂病的影响,可以达到改善经济和环境效益的目的。

[Objective] This paper explores the influence mechanism of landscape complexity and stand factors on cytospora canker of poplar caused by Cytospora chrysosperma across two different field soil conditions, to provide theoretical basis for rational allocation of landscape patterns to control cytospora canker effectively, and to further develop sustainable poplar(Populus spp.) plantations. [Method] We spent2 years(2018-2019) collecting cytospora canker data across two different soil physical and chemical properties in Xinjiang Uygur Autonomous Region of wester China: one in Karamay City and another in Manasi County. Using general linear mixed effect models(GLMMs) with the random effect of year to analyze how the landscape complexity and stand factors influence cytospora canker at landscape scale.[Result] Results showed that the cytospora canker of Populus nigra and P. alba var. pyramidalis both had significantly positive relationships with tree density, as well as the Shannon diversity index of pests.Compared with P. alba var. pyramidalis, P. nigra had a significant relationship with the height of first live branch. The cytospora canker of the two tree species was both correlated negatively with the proportion of non-poplar hosts, as well as elevation. The cytospora canker had a significant correlation with physical and chemical properties of soil, in the same landscape structure, the disease incidence in Karamay City was higher than that in Manasi County. Under the same soil conditions, the incidence of cytospora canker in simple landscape was higher than that in complex landscape. [Conclusion] Overall, our study shows that the occurrence of cytospora canker on poplar can be reduced via management of habitats and enhanced tree resistance at landscape scale, and provides valuable contributions to landscape research and for managing outbreaks of insects and pathogens. In afforestation planning, the potential impact of the surrounding landscape structure on insects and pathogens should be considered. The effects of landscape features on cytospora canker of poplar can be monitored on a large scale and over long periods of time using land cover data to improve economic and environmental benefits.