State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China.
Ecol Appl. 2023 Jul;33(5):e2863. doi: 10.1002/eap.2863. Epub 2023 May 25.
Mowing is common grassland management to feed livestock during winter by harvesting hay in many high-latitude regions in autumn. The trait-based approach has been used to explain the responses of the plant community to disturbance resulting from environmental changes and human activities. However, few studies have focused on the mechanisms underlying the responses of grassland ecosystems to mowing from the perspective of plant traits. Here, we investigated the effects of mowing on the plant community of a temperate steppe in Inner Mongolia of northern China by field experiments to dissect the trade-off between morphological and physiological traits in response to short-term (4 years) and long-term (16 years) mowing. Specifically, we evaluated the two strategies associated with the nutrient acquisition of two dominant species in response to mowing by measuring leaf and root morphological traits and physiological traits of root carboxylate exudation, arbuscular mycorrhizal fungi (AMF) colonization and soil microbial community. We found that long-term mowing, but not short-term mowing, led to an increase in species richness. In addition, mowing decreased the overall plant biomass of the grassland community, but enhanced and suppressed the growth of forbs and grasses, respectively. However, the ratio of forbs to grasses in the community was dependent on mowing duration, such that forbs became more dominant than the grasses under long-term mowing. Our results revealed that short-term mowing reduced soil microbial biodiversity and root colonization of AMF in the grass Stipa krylovii, while the root AMF colonization and carboxylate exudation in the forb Artemisia frigida were enhanced by short-term mowing. In long-term mowing, the functional traits associated with leaf resource conservation (i.e., leaf tissue density) and root resource acquisition were reduced in the grass, while the functional traits related to leaf resource acquisition and root resource conservation were increased in the forb, highlighting the species specificity and divergence in leaf and root traits in the grass and forb of temperate steppe in response to mowing. These novel findings demonstrate that physiological and morphological strategies are the main drivers for dominant species in response to mowing in temperate grasslands.
割草是一种常见的草地管理方式，即在许多高纬度地区的秋季收获干草，以在冬季为牲畜提供饲料。基于特征的方法已被用于解释植物群落对环境变化和人类活动引起的干扰的响应。然而，很少有研究从植物特征的角度关注草地生态系统对割草的响应机制。在这里，我们通过野外实验研究了割草对中国内蒙古温带草原植物群落的影响，以剖析短期（4 年）和长期（16 年）割草对草原生态系统的影响。具体来说，我们通过测量叶和根形态特征以及根羧酸盐分泌、丛枝菌根真菌（AMF）定殖和土壤微生物群落的生理特征，评估了与两种优势物种养分获取相关的两种策略对割草的响应。我们发现，长期割草而不是短期割草会导致物种丰富度增加。此外，割草会降低草地群落的总生物量，但分别增强和抑制杂类草和禾本科植物的生长。然而，群落中杂类草与禾本科植物的比例取决于割草时间，即长期割草会使杂类草比禾本科植物更占优势。我们的研究结果表明，短期割草会降低草地中 Stipa krylovii 的土壤微生物生物多样性和根 AMF 定殖，而 Artemisia frigida 的根 AMF 定殖和羧酸盐分泌则会因短期割草而增强。在长期割草中，与叶片资源保存相关的功能特征（即叶片组织密度）和根资源获取相关的功能特征在禾本科植物中降低，而与叶片资源获取和根资源保存相关的功能特征在杂类草中增加，突出了温带草原禾本科和杂类草对割草的叶和根特征的物种特异性和分化。这些新发现表明，生理和形态策略是温带草地中主要物种对割草响应的主要驱动因素。
