摘要
【目的】评估中国草地地上生产力氮限制强度的时空变化,为全球环境变化背景下草地适应性管理和氮循环模拟评估提供参考。【方法】以中国草地为研究对象,系统收集了1980—2020年已发表的423组氮添加试验数据,整合分析地上生产力响应比(ln RR)和氮素敏感系数(ln RR/N,即ln RR与氮添加量的比值)及其影响因素。利用直线、双直线和逐步回归等方法,评估了ln RR/N的时空动态及其驱动因子。【结果】ln RR随氮添加量的增加总体呈先增加后持平的趋势。当氮添加量超过(21.1±5.5)g N·m^(2)·a^(-1)(平均值±95%置信区间)时,ln RR达到最大值(0.60±0.08)。整合分析结果显示,ln RR/N总体平均为0.043±0.004,即单位氮添加量(1 g N·m^(2)·a^(-1))可提高地上生产力(4.36±0.38)%,且因草地类型、氮添加量、试验持续年限和年代而异。时间尺度上,过去40年来ln RR/N呈显著降低趋势,且在相对湿润(年降水量MAP>450 mm)和温暖区(年均温MAT>4.5℃)的下降速率是相对干旱(MAP≤450 mm)和寒冷区(MAT≤4.5℃)的1.5—1.7倍。空间尺度上,降水量和土壤养分是ln RR/N变化的主要影响因子。其中,ln RR/N随着MAP的增加而增加,随着土壤氮含量的增加而降低。在相对湿润区,ln RR/N的变化由土壤氮含量和MAP共同占主导,而在相对干旱和温暖区则分别由MAP和MAT占主导。【结论】中国草地地上生产力仍受氮限制,但在全球环境变化背景下生产力氮限制强度或氮素敏感性持续减弱,尤其以相对湿润区和温暖区最为明显。要准确评估草地生态系统对全球环境变化的响应,需更多关注生产力关键限制因子及其限制强度的时空变化。
【Objective】This study was to investigate the temporal and spatial patterns of nitrogen (N) limitation (indicated by N response efficiency) on aboveground productivity of China’s grasslands, which was important for the adoptive management and accurately simulating of ecosystem N cycling under global environmental change. 【Method】A meta-analysis was performed to investigate N response ratio (ln RR) and N response efficiency (ln RR/N, the ratio of ln RR to N addition rate) of aboveground productivity across China’s grasslands. All data (423 groups) were collected from in-situ N addition experiments published over1980-2020. Linear, double-linear and multi-step regressions were explored to estimate the spatial and temporal dynamics of lnRR/N and its driving factors. 【Result】In general, ln RR increased with N addition rates and saturated at (21.1±5.5) g N·m^(2)·a^(-1)(mean±95%CI) with the maximum of 0.60±0.08. ln RR/N was, on average, 0.043±0.004, i.e., aboveground productivity could increase by (4.36±0.38) % per unit N addition (1 g N·m^(2)·a^(-1)). ln RR/N also differed significantly among grassland types, N addition rates, experimental durations, and years. Over the past four decades, ln RR/N significantly decreased, with a much (1.5-1.7 times)faster rate in the warmer (MAT>4.5℃) and wetter (MAP>450 mm) climatic regions than that in the cooler (MAT≤4.5℃) and drier (MAP≤450 mm) climatic regions. Regression analyses revealed that the spatial variation of ln RR/N was mainly driving by annual precipitation and soil fertility (i.e., soil N content). In general, ln RR/N increased along with MAP and decreased with soil N content. However, the driving factors varied by climatic regions, with both MAP and soil N content in the wetter regions, MAP in the drier regions and MAT in the warmer regions. 【Conclusion】 The aboveground productivity in China’s grasslands was still limited by N, but the extent of N limitation or N response efficiency decreased over time, especially in those wetter
作者
侯将将
王金洲
孙平
朱文琰
徐靖
卢昌艾
HOU JiangJiang;WANG JinZhou;SUN Ping;ZHU WenYan;XU Jing;LU ChangAi(College of Animal Science and Technology,Henan University of Science and Technology,Luoyang 471000,Henan;Institute of Ecology,Chinese Research Academy of Environmental Sciences,Beijing 100012;College of Horticultuer and Plant Protection,Henan University of Science and Technology,Luoyang 471000,Henan;Institute of Agricultural Resources and Regional Planning,Chinese Academy of Agricultural Sciences,Beijing 100081)
出处
《中国农业科学》
CAS
CSCD
北大核心
2022年第9期1811-1821,共11页
Scientia Agricultura Sinica
基金
国家自然科学基金(31700362)
青海省重点研发与转化计划(219-NK-173)。
关键词
草地
地上生产力
氮添加
氮素敏感性
全球环境变化
grassland
aboveground productivity
nitrogen addition
nitrogen response efficiency
global environmental change
