# Beta Diversity Patterns and Drivers of Macroinvertebrate Communities in Major Rivers of Ningxia, China

## TL;DR

This study examines how macroinvertebrate communities in Ningxia's rivers are shaped by environmental and spatial factors, aiming to improve biodiversity conservation.

## Contribution

The study integrates Generalized Dissimilarity Modelling with the Normalized Stochasticity Ratio to determine drivers of beta diversity in macroinvertebrates.

## Key findings

- Environmental variability, not spatial factors, mainly drives beta diversity in most regions studied.
- Deterministic processes dominate community assembly of benthic macroinvertebrates.
- Optimizing landscape structure can improve water quality and biodiversity.

## Abstract

Elucidating the community assembly mechanisms of macroinvertebrates and their relative contributions to the formation of beta diversity is a central issue in aquatic ecology. In this study, we employed Generalized Dissimilarity Modelling to quantify the relative importance of explanatory variables in shaping community beta diversity. We further identified the dominant assembly processes by integrating Generalized Dissimilarity Modelling with the Normalized Stochasticity Ratio and determined the most appropriate beta diversity metric for the study region. The findings provide a scientific basis for optimizing land use configurations and guiding aquatic biodiversity assessment and conservation.

The clarification of community assembly mechanisms in benthic macroinvertebrates and their respective contributions to the development of beta diversity is a fundamental concern in aquatic ecology. Nonetheless, the intrinsic complexity of community alterations and their non-linear reactions to gradients of explanatory variables present considerable obstacles to measuring the determinants of beta diversity. Fifty sampling points were set up along the major rivers of the Yellow River Irrigation Area (YRIA), the Central Arid Zone (CAZ), and the Southern Mountainous Area (SMA) in Ningxia in April, July, and October 2023. The findings demonstrate that the optimal parameter-based geographical detector (OPGD) model identified a 3000 m circular buffer as the spatial scale at which landscape structure most significantly influences water quality. A degradation in water quality presumably results in diminished differences in species composition among communities. The Sørensen index was determined to be more appropriate for this investigation, and the total beta diversity of the communities was relatively high (βSOR ≥ 0.82), with no identifiable nested spatial patterns detected. Except in the YRIA, environmental variability contributed more significantly to the variance in beta diversity than spatial factors, and deterministic mechanisms dominated the community assembly of benthic macroinvertebrates across all three months. To improve biodiversity and aquatic ecosystem health, the study region should optimize its landscape structure by reducing the amount of bare land and increasing the percentage of forest land within buffer zones. Additionally, a multi-site conservation strategy should be put into place.