J Plant Ecol ›› 2022, Vol. 15 ›› Issue (2): 286-293 .DOI: 10.1093/jpe/rtab092

• Research Articles • Previous Articles     Next Articles

Neutral responses of plant community Ca concentration to nitrogen enrichment in a semiarid grassland

Shuang-Li Hou1, Xiao-Tao Lü1,*, and Jun-Jie Yang1,2   

  1. 1 Erguna Forest-Steppe Ecotone Research Station, CAS Key Laboratory of Forest Ecology and Management, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China, 2 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China

    *Corresponding author. E-mail: lvxiaotao@iae.ac.cn
  • Received:2021-03-12 Revised:2021-04-17 Accepted:2021-07-31 Online:2021-08-25 Published:2022-04-01

Abstract:

Calcium (Ca) is an essential nutrient for plant growth and Ca concentrations in forage have important implications for ruminant diet and health. It remains an open question whether forage Ca concentration would be decreased by increasing nitrogen (N) deposition. We manipulated the increasing rates of N addition (2008–2015) in a semiarid grassland, northern China. Plant Ca concentrations for all species were examined in each plot under N treatment. The Ca concentrations at functional group and community levels were calculated based on the concentration of each species presented and their relative biomass in each plot. We found that community-level Ca concentration remained stable across a gradient of wide-ranged N addition rates, although Ca concentration at both species and functional group levels showed negative responses to N enrichment. Given that forbs had higher Ca concentration than grasses, the increasing relative biomass of forbs canceled out the negative responses of species-level and functional group-level Ca concentration. Our results further showed that community Ca pool showed a positive but saturating response to N addition, with a threshold at the rate of 10 g N m−2 yr−1. Our findings highlight the role of changes in plant relative biomass in controlling the responses of forage Ca concentration and stock to N enrichment.

Key words: calcium stock, community composition, ecological processes, global changes, nitrogen deposition, temperate steppe

摘要:
氮沉降对半干旱草原植物群落钙浓度的影响

钙(Ca)是植物生长所必需的营养物质,牧草中钙的含量对反刍动物的饲粮和健康具有重要意义。目前,关于氮沉降增加是否改变牧草的Ca浓度仍不是十分清楚。我们于2008–2015年在中国北方半干旱草原开展了氮沉降速率增加实验,测定了不同氮处理下每个样方内所有植物的Ca浓度,并且 根据各样方内每个物种的Ca浓度及其相对生物量,计算出功能群水平和群落水平的植物Ca浓度。研究结果表明,尽管物种水平和功能群水平的Ca浓度对氮沉降表现为负响应,但群落水平Ca浓度在整个氮添 加速率梯度上保持稳定。由于杂类草Ca浓度显著高于禾草,杂类草相对生物量的增加抵消了物种水平和功能群水平Ca浓度对氮沉降的负响应。另外,群落Ca库对氮添加速率表现为正饱和响应,且阈值为10 g N m−2 yr−1。本研究表明了氮沉降背景下植物相对生物量的变化对调控牧草Ca浓度和储量具有重要作用。

关键词: 钙储量, 群落组成, 生态过程, 全球变化, 氮沉降, 温带草原