Fine root biomass and morphology in a temperate forest are influenced more by canopy water addition than by canopy nitrogen addition
Wen Li, Chuang Wang, Haowei Liu, Wenqian Wang, Ruomin Sun, Mengke Li, Yifei Shi, Dandan Zhu, Wenzhi Du, Lei Ma, Shenglei Fu
Abstract
Introduction Increasing atmospheric N deposition and changes in precipitation patterns could profoundly impact forest community structure and ecosystem functions. However, most N and water (W) addition experiments have focused on direct N application to leaf litter or soil, neglecting canopy processes such as leaf evaporation and absorption. Methods In this study, we aimed to assess the effects of atmospheric N deposition and increased precipitation on the fine root biomass and morphology of plants in a temperate deciduous forest. To achieve this, we applied N and W above the forest canopy and quantified the seasonal dynamics (January, July, and October) of fine root biomass and morphology. Results Our results revealed that only canopy W addition significantly increased the biomass of fine roots in January compared to that in other seasons ( p < 0.05). We observed no significant interaction effect of N and W on fine root biomass. However, we found that the different growth seasons had a significant impact on the fine root biomass ( p < 0.001). The combined application of N and W significantly affected the root tip density ( p = 0.002). Although canopy N addition was significantly positively correlated with available soil N ( p < 0.05), we detected no significant association with fine root biomass or morphology. Discussion The findings of this study indicated that fine root biomass and morphology, are affected to a greater extent by the provision of W than by N application. These findings provide a new perspective and a more precise understanding of the effects of the actual N deposition and precipitation on the dynamics of plant fine roots in forest ecosystems.