Distinguishing the mechanisms driving multifaceted plant diversity in subtropical reservoir riparian zones

Abstract

Understanding the multifaceted plant diversity and its maintenance mechanisms is crucial for biodiversity conservation. Dam-induced water level fluctuations dramatically alter various aspects of riparian diversity, such as taxonomic (TD), phylogenetic (PD), or functional (FD) diversity. However, few studies simultaneously evaluated plant TD, FD, and PD, especially in the subtropical reservoir riparian zone. Here we sampled plant diversity and environmental drivers along inundation gradients of the Three Gorges Reservoir Region in China. We integrated multifaceted plant diversity to assess how distinct ecological processes affect the plant community assembly and how they respond to inundation gradients, spatial variability, climate, and soils in dam-regulated riparian zones. We found that alpha TD, PD, and FD diversity exhibited decreasing trends with increasing inundation gradients and significant positive correlations with soil organic matter. The number of clustering plant communities increases along the inundation gradients. Beta TD and PD diversity were mainly dominated by species turnover with fewer contributions from nestedness, while beta FD diversity was mainly dominated by nestedness with fewer contributions from species turnover. The explainable rates of different dimensions of beta diversity, turnover, and nestedness ranged from 11% to 61%, with spatial factors explaining the highest beta diversity in different dimensions, followed by inundation gradients, soil properties, and climate variables. Our results suggest dispersal limitations are more important for species turnover in dam-regulated riparian zones at regional scales, while inundation gradients and soil fertility are more critical in shaping plant community assemblages at the local scale. This study emphasizes that environmental and spatial gradients are critical for understanding the assembly mechanisms driving multifaceted plant communities at local and regional scales and reinforces the importance of protecting seed sources and dispersal pathways and maintaining river connectivity when implementing restoration projects.

Patterns and drivers of plant carbon, nitrogen, and phosphorus stoichiometry in a novel riparian ecosystem

“…One possible explanation is that prolonged inundation in the TGRR accelerates soil mineralization, facilitating N and P uptake by plants ( Ye et al., 2020 ). Furthermore, frequent summer precipitation in the TGRR may transport upland surface pollutants like N and P to the adjacent zone ( Zheng et al., 2023 ), enhancing nutrient recharge for riparian plant growth ( Huang et al., 2019 ). This underscores the conclusion that the newly formed riparian habitat in the TGRR shapes a distinctive ecological strategy for plants.…”

“…The study area is situated in the upper reaches of the Yangtze River (28°17′~ 32°05′N, 105°73′~ 111°12′E) ( Figure 1 ), covering a total area of 344.22 km 2 and spanning 639.38 km from the Three Gorges Dam to Jiangjin County, Chongqing Municipality ( Zheng et al., 2023 ). This region experiences a humid subtropical monsoon climate, boasting an average annual temperature of 18.22 ± 0.56°C and an average annual precipitation of 1110 ± 75.23 mm.…”

Effects of changing riparian topography on the decline of ecological indicators along the drawdown zones of long rivers in China

“…Freshwater resources face tremendous pressure due to climate change, intensive land-use, and increased population density worldwide (Rodrigues et al, 2018;Martins et al, 2021;Zheng et al, 2023). The variation in available water supplies has increased the necessity of freshwater conservation, particularly in limited and unstable water supply situations (Belete et al, 2020;Suwal et al, 2020;Arif et al, 2023).…”

“…Because the environment affects vegetation in different ways at varying elevations (Pompa-Garcia et al, 2021;Shahariar et al, 2021), topographical features (e.g., stream-channel width, riparian width, and elevation) may variably impact the river's other EIs. Hence, in the face of a shifting environment and its consequences on productivity, topographical features remain important measures of EIs (Tito et al, 2018;Zheng et al, 2023). It is hypothesized that changes in riparian topographical features affect ecological indicators along the drawdown zones of long rivers similarly or not.…”

Genetic variability and population divergence of Rhododendron platypodum Diels in China in the context of conservation

“…Human disturbances such as habitat fragmentation, deforestation, and land development are often the cause of it thriving in disturbed habitats (He et al, 2023). It is particularly vulnerable to the impacts of these anthropogenic activities due to its limited distribution and habitat requirements (Zheng et al, 2023). It is well known for its ornamental value, but habitat loss and overexploitation have threatened the species' survival.…”