Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan, China.
Department of Geography, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Glob Chang Biol. 2018 Jan;24(1):536-551. doi: 10.1111/gcb.13860. Epub 2017 Sep 18.
Knowledge of nutrient storage and partitioning in forests is imperative for ecosystem models and ecological theory. Whether the nutrients (N, P, K, Ca, and Mg) stored in forest biomass and their partitioning patterns vary systematically across climatic gradients remains unknown. Here, we explored the global-scale patterns of nutrient density and partitioning using a newly compiled dataset including 372 forest stands. We found that temperature and precipitation were key factors driving the nutrients stored in living biomass of forests at global scale. The N, K, and Mg stored in living biomass tended to be greater in increasingly warm climates. The mean biomass N density was 577.0, 530.4, 513.2, and 336.7 kg/ha for tropical, subtropical, temperate, and boreal forests, respectively. Around 76% of the variation in biomass N density could be accounted by the empirical model combining biomass density, phylogeny (i.e., angiosperm, gymnosperm), and the interaction of mean annual temperature and precipitation. Climate, stand age, and biomass density significantly affected nutrients partitioning at forest community level. The fractional distribution of nutrients to roots decreased significantly with temperature, suggesting that forests in cold climates allocate greater nutrients to roots. Gymnosperm forests tended to allocate more nutrients to leaves as compared with angiosperm forests, whereas the angiosperm forests distributed more nutrients in stems. The nutrient-based Root:Shoot ratios (R:S), averaged 0.30 for R:S , 0.36 for R:S , 0.32 for R:S , 0.27 for R:S , and 0.35 for R:S , respectively. The scaling exponents of the relationships describing root nutrients as a function of shoot nutrients were more than 1.0, suggesting that as nutrient allocated to shoot increases, nutrient allocated to roots increases faster than linearly with nutrient in shoot. Soil type significantly affected the total N, P, K, Ca, and Mg stored in living biomass of forests, and the Acrisols group displayed the lowest P, K, Ca, and Mg.
森林养分储存和分配的知识对生态系统模型和生态学理论至关重要。储存在森林生物量中的养分（N、P、K、Ca 和 Mg）及其分配模式是否会随气候梯度系统地变化尚不清楚。在这里，我们使用新汇编的数据集（包括 372 个森林林分）探索了全球尺度养分密度和分配格局。我们发现，温度和降水是驱动全球森林生物量中养分储存的关键因素。在温暖的气候条件下，生活生物量中储存的 N、K 和 Mg 往往更多。热带、亚热带、温带和北方森林的活体生物量 N 密度分别为 577.0、530.4、513.2 和 336.7 kg/ha。生物量 N 密度的 76%左右可以通过结合生物量密度、系统发育（即被子植物、裸子植物）以及年平均温度和降水的相互作用的经验模型来解释。气候、林分年龄和生物量密度显著影响森林群落水平养分的分配。养分向根的分配分数随温度显著降低，表明寒冷气候下的森林将更多的养分分配给根。与被子植物林相比，裸子植物林更倾向于将更多的养分分配给叶子，而被子植物林则更多地将养分分配给茎。基于养分的根：茎比（R：S）平均为 0.30 用于 R：S，0.36 用于 R：S，0.32 用于 R：S，0.27 用于 R：S，0.35 用于 R：S，分别。描述根养分作为茎养分函数的关系的标度指数大于 1.0，表明随着分配给茎的养分增加，分配给根的养分以快于线性的速度与茎中的养分增加。土壤类型显著影响森林活体生物量中总 N、P、K、Ca 和 Mg 的储存，而灰壤组显示出最低的 P、K、Ca 和 Mg。
