Browsing by Author "He, Minyan"
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Item Climate warming increases biological control agent impact on a non-target species(Wiley, 2015) Lu, Xinmin; Siemann, Evan; He, Minyan; Wei, Hui; Shao, Xu; Ding, JianqingClimate change may shift interactions of invasive plants, herbivorous insects and native plants, potentially affecting biological control efficacy and non-target effects on native species. Here, we show how climate warming affects impacts of a multivoltine introduced biocontrol beetle on the non-target native plant Alternanthera sessilis in China. In field surveys across a latitudinal gradient covering their full distributions, we found beetle damage on A. sessilis increased with rising temperature and plant life history changed from perennial to annual. Experiments showed that elevated temperature changed plant life history and increased insect overwintering, damage and impacts on seedling recruitment. These results suggest that warming can shift phenologies, increase non-target effect magnitude and increase non-target effect occurrence by beetle range expansion to additional areas where A. sessilis occurs. This study highlights the importance of understanding how climate change affects species interactions for future biological control of invasive species and conservation of native species.Item Effects of nutrient pulses on exotic species shift from positive to neutral with decreasing water availability(Wiley, 2024) Otieno, Evans O.; Shen, Changchao; Zhang, Kaoping; Wan, Jinlong; He, Minyan; Tao, Zhibin; Huang, Wei; Siemann, EvanTemporal fluctuation in nutrient availability generally promotes the growth of exotic plant species and has been recognized as an important driver of exotic plant invasions. However, little is known about how the impact of fluctuating nutrients on exotic species is dependent on the availability of other resources, although most ecosystems are experiencing dramatic variations in a wide variety of resources due to global change and human disturbance. Here, we explored how water availability mediates the effect of nutrient pulses on the growth of six exotic and six native plant species. We subjected individual plants of exotic and native species to well watered or water stressed conditions. For each level of water availability, we added equivalent amounts of nutrients at a constant rate, as a single large pulse, or in multiple small pulses. Under well watered conditions, nutrient pulses promoted exotic plant growth relative to nutrients supplied constantly, while they had no significant effect on natives. In contrast, under water stressed conditions, water deficiency inhibited the growth of all exotic and native species. More importantly, nutrient pulses did not increase plant growth relative to nutrients supplied constantly and these phenomena were observed for both exotic and native species. Taken together, our study shows that the impact of fluctuating nutrient availability on the growth of exotic plant species strongly depends on the variation of other resources, and that the positive effect of nutrient pulses under well watered conditions disappears under water stressed conditions. Our findings suggest that the variation in multiple resources may have complex feedback on exotic plant invasions and, therefore, it is critical to encompass multiple resources for the evaluation of fluctuating resource availability effects on exotic plant species. This will allow us to project the invasive trajectory of exotic plant species more accurately under future global change and human disturbance.Item Latitudinal variation in soil biota: testing the biotic interaction hypothesis with an invasive plant and a native congener(Springer Nature, 2018) Lu, Xinmin; He, Minyan; Ding, Jianqing; Siemann, EvanSoil biota community structure can change with latitude, but the effects of changes on native plants, invasive plants, and their herbivores remain unclear. Here, we examined latitudinal variation in the soil biota community associated with the invasive plant Alternanthera philoxeroides and its native congener A. sessilis, and the effects of soil biota community variation on these plants and the beetle Agasicles hygrophila. We characterized the soil bacterial and fungal communities and root-knot nematodes of plant rhizospheres collected from 22 °N to 36.6 °N in China. Soil biota community structure changed with latitude as a function of climate and soil properties. Root-knot nematode abundance and potential soil fungal pathogen diversity (classified with FUNGuild) decreased with latitude, apparently due to higher soil pH and lower temperatures. A greenhouse experiment and lab bioassay showed native plant mass, seed production, and mass of beetles fed native foliage increased with soil collection latitude. However, there were no latitudinal patterns for the invasive plant. These results suggest that invasive and native plants and, consequently, their herbivores have different responses to latitudinal changes in soil-borne enemies, potentially creating spatial variation in enemy release or biotic resistance. This highlights the importance of linking above- and below-ground multitrophic interactions to explore the role of soil biota in non-native plant invasions with a biogeographic approach.Item Soil bacterial communities and co-occurrence changes associated with multi-nutrient cycling under rice-wheat rotation reclamation in coastal wetland(Elsevier, 2022) Zhang, Kaoping; Shi, Yu; Lu, Haiying; He, Minyan; Huang, Wei; Siemann, EvanCoastal reclamation is a global threat to coastal wetland ecosystems, but the impacts of coastal reclamation on belowground biodiversity and their consequences for ecosystem nutrient cycling remain poorly understood. In this study, we examined soil bacterial communities, bacterial co-occurrence pattern and soil multi-nutrient cycling index after natural vegetated coastal wetlands were converted for 6-year and 30-year rice-wheat rotation fields. The soil multi-nutrient cycling index was higher in 6-year and 30-year rice-wheat rotation fields than natural vegetated coastal wetlands. For bacterial community, rice-wheat rotation reclamation increased soil bacterial alpha diversity but decreased beta diversity and co-occurrence network complexity than those in the vegetated coastal wetland. Rice-wheat rotation reclamation also changed soil bacterial community assemblages by increasing the relative abundance of Actinobacteriota and Desulfobacterota while decreasing the relative abundance of Alphaproteobacteria and Gammproteobacteria. Changes in the relative importance of dispersal limitation and homogenizing dispersal mainly controlled the variations in soil bacterial community assemblages. Soil bacterial community variations induced by rice-wheat reclamation were strongly related to soil multi-nutrient cycling, especially bacterial connection complexity. Our results provide experimental support that belowground microbial interactions are crucial for maintaining ecosystem functioning.