Year effects drive beta diversity, but unevenly across plant community types

Abstract

Year of establishment can be a critical driver of plant communities with the establishment stage of community development particularly susceptible to factors including ambient rain, temperature, and other temporally variable drivers (e.g., seed and seedling predators). However, while year effects have been shown to drive community structure at local (patch) scales, it is yet unexplored how these within‐patch effects scale up to drive landscape‐level patterns of biodiversity. These dynamics are likely critical but overlooked in many systems, including those with high‐frequency disturbance regimes or active management. Here we leveraged a series of field‐based grassland mesocosms established identically at three sites across five years, and each monitored for four to eight years. We compared the strength of these temporal and spatial drivers (year effects and site effects) on consequent patterns of spatial and temporal variability (beta diversity and turnover) between plots seeded with native perennial species versus those seeded with non‐native annual species. Composition of plots seeded with perennial species showed strong effects of planting year and consequently exhibited higher beta diversity within sites (across mesocosms established in five different years within sites), while plots seeded with annual species had higher between‐site variation but low beta diversity within sites. Plots with annual species were also more temporally variable than plots with perennial species. These findings have important implications for our understanding of key drivers of biodiversity across landscapes. Specifically, we show that variable trajectories in community composition generated by site and year effects during establishment can promote beta diversity across landscapes dominated by perennial species, but are considerably less impactful in annual‐dominated systems. These findings further our understanding of the importance of assembly dynamics on landscape‐scale patterns of diversity, and have important management implications for restoration efforts.This article is protected by copyright. All rights reserved.

Soil climate underpins year effects driving divergent outcomes in semi-arid cropland to grassland restoration

“…Our results suggest obvious 'year effects' (Werner et al, 2020;Werner, Young and Stuble, 2024) from interannual climate variability in the species composition outcomes after restoration that had greater impact than landscape effects on community assemblage. We found that these year effects were explained by soil temperature and moisture before and after planting .…”