Effects of landscape complexity and stand factors on arthropod communities in poplar forests

Abstract

The arthropod communities are influenced by both local conditions and features of the surrounding landscape. Landscape complexity and stand factors may both influence arthropod communities in poplar forests, but the multiscale effects of these factors on poplar defoliators and natural enemies are still poorly understood. We collected poplar arthropods at 30 sampling sites within five forest landscapes in Xinjiang, China, and assessed whether landscape complexity and stand factors influence species abundance and diversity of poplar arthropods. Landscape complexity was quantified by several independent metrics of landscape composition, configuration, and connectivity at three spatial scales. We also determined the most powerful explanatory variables and the scale effect of each arthropod. Results found that landscape complexity and stand factors had different effects on different poplar arthropod communities. Landscape complexity promoted natural enemies at different spatial scales, but it inhibited the population of poplar defoliators at the scale of 200 m. Specifically, the abundance and diversity of all defoliators decreased with increasing proportion of nonhost plants. Landscape diversity only had a negative effect on defoliator abundance. The shape complexity of habitat patches increased the abundance of carabid beetles but reduced the abundance of green leafhoppers and migratory locusts. The abundance and diversity of predators increased with increasing structural connectivity of forest landscape. Additionally, both the abundance and diversity of all defoliators were positively correlated with the average height of herbaceous plants. Diversity of all defoliators increased with increasing size of host trees. The distance from sampling site to the nearest village positively influenced the abundance and diversity of all predators. Arthropod abundance and diversity in poplar forests were driven by stand factors and landscape complexity. Therefore, maintaining complex shape and structural connectivity of habitat patches and keeping poplar stands away from the village are crucial for management of forest landscape to enhance natural enemies. And in order to reduce the abundance of defoliators in poplar forest, the diversity of surrounding habitat types should be promoted within 200 m radii.

Background Insect Herbivory in Riparian Poplar Forests: the Role of Local, Landscape, and Regional Factors

“…Although we observed that insect herbivores caused more background damage in poplar stands at the nearer distance from river, our ndings contrast with previous work in that we found no clear effect of distance from river on the abundance and richness of defoliating insect herbivores (Wang et al 2019). Stone and Bacon (1995) also found that consumption of foliage by insects on the trees subjected to ooding compared to the non-ooded trees was not signi cantly different, but these results are less consistent for background herbivory itself.…”

“…And we can rule out the direct effects of human actions, because a variety of methods and tools (e.g. chemical or biological insecticides) that are widely used for pest control in agriculture are not available or are not suitable for application in forestry (Wang et al 2019). However, forestry operations could affect defoliation intensity of phytophagous insects in a number of indirect ways (Wesołowski and Rowiński 2006).…”

“…Then proportions of different habitat areas in each forest landscape were quanti ed using ArcGIS version 10.5. By using the 300 m radius buffer, we avoided spatial overlapping between nearby buffers, which is needed to make accurate landscape-scale inferences (Wang et al 2019). Moreover, this landscape size was large enough to include a large variation in landscape-level forest isolation (ranging from 13.5-92.3%) and was previously found to be suitable to study tree-insect herbivores interactions in riparian poplar forests (Wang et al 2019(Wang et al , 2021.…”

“…By using the 300 m radius buffer, we avoided spatial overlapping between nearby buffers, which is needed to make accurate landscape-scale inferences (Wang et al 2019). Moreover, this landscape size was large enough to include a large variation in landscape-level forest isolation (ranging from 13.5-92.3%) and was previously found to be suitable to study tree-insect herbivores interactions in riparian poplar forests (Wang et al 2019(Wang et al , 2021. Finally, we calculated the percentage of open area in buffers of 300 m radius around selected stands as a proxy for forest isolation at the landscape scale using ArcGIS version 10.5 (Castagneyrol et al 2019).…”

Landscape-Level And Stand-Level Factors Play Diverse Roles During Different Periods of Dendroctonus Valens Invasion In North China

“…The variables related to the stand characteristics, topographical characteristics, and soil properties of sample plots were treated as stand-level variables (Mezei et al, 2014). In addition, through remote sensing imagery of Gaofen-2 (China Centre for Resources Satellite Data and Application, 2020) and eld investigation, the forest coverage of the buffer with a radius of 1000 m around the sample plots ranges from 10% to 75% to ensure a reasonable distribution of the landscape-level variables (Wang et al, 2019).…”