Stoichiometric Characteristics and Influencing Factors of Different Components of Karst Forest Plants at the Microtopography and Microhabitat Scale in Maolan National Nature Reserve, Guizhou, China

The main dominant tree species of karst forest at the microtopography and the microhabitat scale were taken as the research object in this study, and the stoichiometric characteristics of different components and their influencing factors were analyzed in order to reveal the survival strategy of karst forest plants in harsh habitats and their mechanism of adaptation to complex terrain. The results showed that the nutrient distribution among different components of the plant was closely related to its organizational structure and functional attributes. The microtopography had a significant effect on plant nutrient accumulation. However, the effect of the microhabitat on plant stoichiometric characteristics was relatively small. Different ecological factors had various regulatory effects on the stoichiometric characteristics of plant components, among which the specific leaf area (SLA) was the most critical biological factor affecting the stoichiometric characteristics of new leaves. Leaf dry matter content (LDMC) had the greatest effect on mature leaves, litter, and branches, and the trunks were mainly affected by plant species. There are synergistic tradeoffs between different plant components, and the interaction between each element mainly shows antagonistic and synergistic effects. Plants adapt to the changes in the karst microtopography and microhabitat by adjusting resource allocation and structural and functional traits. In the upslope, shady slope, and semi-shady slope regions and slopes above 25°, the plants adopted a conservative strategy. In depressions, on sunny slopes, and on flat land, as well as on slopes below 25°, the resource acquisition strategy was adopted. This is the result of the interaction of biological and abiotic factors, which reflects the resource acquisition and nutrient allocation strategies of plants in different habitats, and it is also an mechanism of adaptation to a complex and changeable environment.