State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Ecology, Lanzhou University, Lanzhou, Gansu, China.
Key Laboratory of Cell Activities and Stress Adaptations, Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou, Gansu, China.
Glob Chang Biol. 2023 May;29(10):2746-2758. doi: 10.1111/gcb.16638. Epub 2023 Mar 1.
Land use and climate change alter biodiversity patterns and ecosystem functioning worldwide. Land abandonment with consequent shrub encroachment and changes in precipitation gradients are known factors in global change. Yet, the consequences of interactions between these factors on the functional diversity of belowground communities remain insufficiently explored. Here, we investigated the dominant shrub effects on the functional diversity of soil nematode communities along a precipitation gradient on the Qinghai-Tibet Plateau. We collected three functional traits (life-history C-P value, body mass, and diet) and calculated the functional alpha and beta diversity of nematode communities using kernel density n-dimensional hypervolumes. We found that shrubs did not significantly alter the functional richness and dispersion, but significantly decreased the functional beta diversity of nematode communities in a pattern of functional homogenization. Shrubs benefited nematodes with longer life-history, larger body mass, and higher trophic levels. Moreover, the shrub effects on the functional diversity of nematodes depended strongly on precipitation. Increasing precipitation reversed the effects shrubs have on the functional richness and dispersion from negative to positive but amplified the negative effects shrubs have on functional beta diversity of nematodes. Benefactor shrubs had stronger effects on the functional alpha and beta diversity of nematodes than allelopathic shrubs along a precipitation gradient. A piecewise structural equation model showed that shrubs and its interactions with precipitation indirectly increased the functional richness and dispersion through plant biomass and soil total nitrogen, whereas it directly decreased the functional beta diversity. Our study reveals the expected changes in soil nematode functional diversity following shrub encroachment and precipitation, advancing our understanding of global climate change on nematode communities on the Qinghai-Tibet Plateau.
土地利用和气候变化改变了全球生物多样性模式和生态系统功能。土地废弃导致灌木侵入和降水梯度变化是全球变化的已知因素。然而，这些因素相互作用对地下群落功能多样性的影响仍未得到充分探索。在这里，我们研究了主导灌木对青藏高原降水梯度上土壤线虫群落功能多样性的影响。我们收集了三个功能特征（生活史 C-P 值、体重和饮食），并使用核密度多维超体积计算了线虫群落的功能 alpha 和 beta 多样性。我们发现，灌木并没有显著改变线虫群落的功能丰富度和分散度，但以功能同质化的模式显著降低了线虫群落的功能 beta 多样性。灌木有利于具有较长生活史、较大体重和较高营养级的线虫。此外，灌木对线虫功能多样性的影响强烈依赖于降水。增加降水会使灌木对功能丰富度和分散度的影响从负变正，但会放大灌木对线虫功能 beta 多样性的负面影响。在降水梯度上，有益灌木对线虫功能 alpha 和 beta 多样性的影响大于化感灌木。分段结构方程模型表明，灌木及其与降水的相互作用通过植物生物量和土壤总氮间接增加了功能丰富度和分散度，而直接降低了功能 beta 多样性。我们的研究揭示了灌木侵入和降水后土壤线虫功能多样性的预期变化，加深了我们对青藏高原线虫群落全球气候变化的理解。
