Urat Desert-Grassland Research Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
BMC Plant Biol. 2022 Mar 1;22(1):90. doi: 10.1186/s12870-022-03486-z.
Inter- and intraspecific variation in plant traits play an important role in grassland community assembly under global change scenarios. However, explorations of how these variations contribute to the responses of community traits to nitrogen (N) addition and drought in different grassland types are lacking. We measured the plant height, leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf N content (LNC) and the ratio of leaf carbon (C) to leaf N (C:N) in a typical and a meadow steppe after three years of N addition, drought and their interaction. We determined the community-weighted means (CWMs) of the six traits to quantify the relative contribution of inter- and intraspecific variation to the responses of community traits to N addition and drought in the two steppes.
The communities in the two steppes responded to N addition and the interaction by increasing the CWM of LNC and decreasing C:N. The community in the meadow steppe responded to drought through increased CWM of LNC and reduced C:N. Significant differences were observed in SLA, LDMC, LNC and C:N between the two steppes under different treatments. The SLA and LNC of the community in the meadow steppe were greater than those of the typical steppe, and the LDMC and C:N exhibited the opposite results. Moreover, variation in community traits in the typical steppe in response to N addition and drought was caused by intraspecific variation. In contrast, the shifts in community traits in the meadow steppe in response to N addition and drought were influenced by both inter- and intraspecific variation.
The results demonstrate that intraspecific variation contributed more to community functional shifts in the typical steppe than in the meadow steppe. Intraspecific variation should be considered to understand better and predict the response of typical steppe communities to global changes. The minor effects of interspecific variation on meadow steppe communities in response to environmental changes also should not be neglected.
在全球变化情景下，植物种间和种内变异在草原群落组装中起着重要作用。然而，对于这些变异如何影响不同草原类型群落特征对氮（N）添加和干旱的响应，还缺乏探索。我们在 N 添加、干旱及其相互作用三年后，测量了典型草原和草甸草原的植物高度、叶面积（LA）、比叶面积（SLA）、叶干物质含量（LDMC）、叶氮含量（LNC）和叶碳与氮的比值（C:N）。我们确定了六个特征的群落加权平均值（CWMs），以量化种间和种内变异对两个草原群落特征对 N 添加和干旱响应的相对贡献。
两个草原群落对 N 添加和相互作用的响应是通过增加 CWM 的 LNC 和降低 C:N 来实现的。草甸草原群落通过增加 LNC 的 CWM 和降低 C:N 来响应干旱。在不同处理下，两个草原之间在 SLA、LDMC、LNC 和 C:N 方面存在显著差异。草甸草原群落的 SLA 和 LNC 大于典型草原群落，而 LDMC 和 C:N 则相反。此外，典型草原群落对 N 添加和干旱的响应，其群落特征的变异是由种内变异引起的。相比之下，草甸草原群落对 N 添加和干旱的响应，其群落特征的变化受到种间和种内变异的影响。
结果表明，在典型草原中，种内变异对群落功能变化的贡献大于草甸草原。为了更好地理解和预测典型草原群落对全球变化的响应，应考虑种内变异。对于种间变异对草甸草原群落在环境变化下的响应的较小影响，也不应忽视。
