Li Bingbing, Wang Xiaoping, Li Zhi
College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China.
College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China.
Sci Total Environ. 2024 Mar 1;914:169689. doi: 10.1016/j.scitotenv.2023.169689. Epub 2023 Dec 29.
Exploring plant root characteristics is important to understand the aboveground plant growth and ecosystem, but has rarely been conducted because of the difficulties in obtaining root information. This study aims to clarify the root distribution and rooting strategy under the combined control of vegetation types and rainfall gradients. We compiled 64 plant root and 81 soil water profiles up to 10 m deep with plant ages of up to 40 years old in China's Loess Plateau, and then fitted the shape and extinction coefficients (β) and proposed the relation of D95/D50 (ratio of depth corresponding to 95 % of total biomass to that corresponding to 50 % of total biomass) to β to characterize the rooting strategy. The cumulative root biomass increase from shallow- to deep-rooted plants, and from >550 mm to <450 mm precipitation gradients. The root system parameters have large spatial variability, dominated by vegetation type but supplemented by climate. The negative correlation between D95/D50 and β indicated a tradeoff between rooting depths and root biomass. The plants would change rooting strategy from increasing root biomass to increasing rooting depths when the plant stand age and soil water depletion degree are >25.7 ± 3.6 years and 35.7 % ± 15.1 %, respectively. These results reveal a clear plant rooting strategy that extends root deeper rather than increases root biomass triggered by critical age and soil water depletion.
探究植物根系特征对于理解地上植物生长和生态系统很重要，但由于获取根系信息存在困难，相关研究很少。本研究旨在阐明在植被类型和降雨梯度共同控制下的根系分布和生根策略。我们在中国黄土高原收集了64个植物根系和81个土壤水分剖面，深度达10米，植物年龄达40年，然后拟合其形状和消光系数（β），并提出D95/D50（总生物量95%对应的深度与总生物量50%对应的深度之比）与β的关系来表征生根策略。从浅根植物到深根植物，以及从降水量>550毫米到<450毫米的梯度，根系生物量累积增加。根系系统参数具有较大的空间变异性，主要受植被类型影响，但也受气候影响。D95/D50与β之间的负相关表明生根深度和根系生物量之间存在权衡。当林分年龄和土壤水分消耗程度分别>25.7±3.6年和35.7%±15.1%时，植物会将生根策略从增加根系生物量转变为增加生根深度。这些结果揭示了一种明确的植物生根策略，即由关键年龄和土壤水分消耗引发的根系向更深层延伸而非增加根系生物量。
