Climatic Factors Determine the Distribution Patterns of Leaf Nutrient Traits at Large Scales

Abstract

Leaf nutrient content and its stoichiometric relationships (N/P ratio) are essential for photosynthesis and plant growth and development. Previous studies on leaf nutrient-related functional traits have mainly focused on the species level and regional scale, but fewer studies have investigated the distribution patterns of the leaf N and P contents (LN, LP) and N/P ratios (N/P) in communities and their controlling factors at a large scale; therefore, we used LN, LP, and N/P data at 69 sites from 818 forests in China. The results showed significant differences (P < 0.05) in the LN, LP, and N/P at different life forms (tree, shrub, and herb). Neither LN, LP, nor N/P ratios showed significant patterns of latitudinal variation. With the increase in temperature and rainfall, the LN, LP, and leaf nutrient contents increased significantly (P < 0.001). Across life forms, LN at different life forms varied significantly and was positively correlated with soil P content (P < 0.001). The explanatory degree of climatic factors in shaping the spatial variation patterns of LN and N/P was higher than that of the soil nutrient factors, and the spatial variation patterns of the leaf nutrient traits of different life forms were shaped by the synergistic effects of climatic factors and soil nutrient factors.

Effects of Soil Nutrients on Plant Nutrient Traits in Natural Pinus tabuliformis Forests

“…The “community construction theory” based on nutrient traits explains that, in a local community, competition may lead to divergence between traits, but habitat screening may lead to the convergence of traits [ 33 ]. Often, the habitat selection effect causes different species to form more consistent characteristics so as to adapt to the same environment [ 3 ].…”

“…In the past century, aboveground ecology has attracted extensive attention. However, the ecological links between aboveground and underground components remain unclear [ 2 , 3 ]. This knowledge gap hampers our ability to understand and predict the comprehensive responses of an ecosystem to environmental stresses [ 2 , 3 ].…”

“…Nutrient traits refer to traits related to nutrient characteristics (e.g., N mass and P mass ), reflecting the survival strategies of plants in response to global warming, and are widely used in ecology [ 1 , 2 , 3 ]. Nitrogen (N) and phosphorus (P) are basic components of plant genetic material and nutrients, and their stoichiometric relationships significantly influence the process of plant growth and reproduction [ 4 , 5 ].…”

“…Meanwhile, phosphorus drives the generation and maintenance of proteins and is also limiting in most environments [ 6 ]. The absence of nitrogen and phosphorus in leaves will affect the formation of chlorophyll, further reduce the productivity of forest communities and regulate carbon cycling [ 3 ]. The ratio of nitrogen to phosphorus (N/P) in plants reflects environmental factors, especially the nutrient supply of soil-to-plant growth [ 7 , 8 ].…”

“…It can clarify which elements restrict the plant’s productivity. In other words, in a habitat where P is scarce and N is relatively abundant, plant N/P is relatively high, while in the habitat where N is scarce and P is relatively rich, plant N/P is relatively low and plant P content is significantly increased [ 3 ]. Soil nutrient limitation not only affects the nutrient structure of species but also affects the composition of community species and the direction of community succession [ 9 ].…”