Abstract：
Global warming is one of the most pressing environmental issues today. Our study aimed to investigate how warming affected plant and soil nematode communities in alpine meadows on the Qinghai−Tibetan Plateau over the past seven years. An artificial warming experiment with different gradients was conducted from 2011 to 2018, including temperature increases of 0 °C (CK), 0.53 °C (A), 1.15 °C (B), 2.07 °C (C), and 2.17 °C (D), respectively. Cyperaceae plants were shown to be eliminated by increasing temperature, and plant community composition tended to cluster differently under different warming gradients. The number of nematodes decreased with the increase in soil depth, and the majority of them were observed in the topsoil layer. The individual densities of soil nematodes were 197 ind.·100 g−1 dry soil at 10−20 cm and 188 ind.·100 g−1 dry soil at 20−30 cm in the A treatment, which was significantly higher than the CK (53 and 67 ind.·100 g−1 dry soil) (p < 0.05). The lowest relative abundance of bacterivore nematodes (Ba) was 31.31% in treatment A and reached the highest of 47.14% under the warming gradient of D (p < 0.05). The abundance of plant parasitic nematodes (Pp) was significantly reduced to 26.03% by excessive warming (2.17 °C increase) in comparison to CK (41.65%). The soil nematode community had the highest diversity with a 0.53 °C increase in soil temperature; 1.15 °C warming gradients were lower, and nematode communities tended to be simplified (p < 0.05). All nematode channel ratio (NCR) values were above 0.5, indicating that warming did not change the decomposition pathway of soil organic matter dominated by the bacterial channels. The Wasilewska Index (WI) in the D treatment increased significantly compared to other treatments (p < 0.05), indicating that the mineralized pathway of the food web was primarily involved with Ba and fungivores nematodes (Fu), which is conducive to the growth of micro-biophagous nematodes. The plant parasite index (PPI) decreased significantly in the D treatment compared with other treatments (p < 0.05), indicating that a high warming gradient caused a reduction in the maturity of Pp nematodes. The maturity index (MI) increased in the D treatment compared with A, B, and C treatments, indicating that overheating affected the nematode community in the later stage of succession and caused the soil to be less disturbed. A partial least squares path model (PLSPM) showed that warming indirectly affects Fu and Pp diversity by directly impacting the plant community as well as indirectly affecting Ba by directly affecting soil properties. In conclusion, plant diversity and community composition profoundly affect the soil nematode communities, thus reflecting the dynamic processes and evolution of soil ecosystems.
摘要：
全球变暖是当今最紧迫的环境问题之一。我们的研究旨在调查过去七年来变暖如何影响青藏高原高寒草甸的植物和土壤线虫群落。2011年至2018年进行了不同梯度的人工增温实验，包括温度升高0°C（CK），0.53°C(A),1.15°C(B),2.07°C(C),和2.17°C（D），分别。莎草科植物被证明可以通过升高温度来消除，在不同的增温梯度下，植物群落组成呈不同的聚类趋势。线虫数量随着土壤深度的增加而减少，其中大部分是在表土层中观察到的。土壤线虫的个体密度为197ind。·100g-1干土在10-20厘米和188ind。·100g-1干土在20-30厘米在A处理，显著高于CK(53和67ind。·100g-1干土)(p<0.05)。处理A的细菌线虫（Ba）的相对丰度最低，为31.31％，在D的增温梯度下达到最高的47.14％（p<0.05）。与CK（41.65％）相比，过度变暖（增加2.17°C）使植物寄生线虫（Pp）的丰度显着降低至26.03％。土壤线虫群落的多样性最高，土壤温度增加0.53°C；1.15°C的增温梯度较低，线虫群落趋于简化(p<0.05)。所有线虫通道比（NCR）值均在0.5以上，表明增温并未改变细菌通道主导的土壤有机质分解途径。与其他治疗相比，D治疗的Wasilewska指数（WI）显着增加（p<0.05），表明食物网的矿化途径主要与Ba和真菌线虫（Fu）有关，有利于微生物食线虫的生长。与其他处理相比，D处理的植物寄生虫指数（PPI）显着降低（p<0.05），表明高增温梯度导致Pp线虫的成熟度降低。与A相比，D处理的成熟度指数（MI）增加，B,和C治疗，表明过热在演替后期影响了线虫群落，并使土壤受到的干扰较小。偏最小二乘路径模型（PLSPM）表明，变暖通过直接影响植物群落间接影响Fu和Pp多样性，并通过直接影响土壤特性间接影响Ba。总之,植物多样性和群落组成深刻地影响着土壤线虫群落,从而反映土壤生态系统的动态过程和演变。
