Towards a predictive framework for biocrust mediation of plant performance: A meta‐analysis

Abstract

1. Understanding the importance of biotic interactions in driving the distribution and abundance of species is a central goal of plant ecology. Early vascular plants likely colonized land occupied by biocrusts -photoautotrophic, surface-dwelling soil communities comprised of cyanobacteria, bryophytes, lichens and fungi -suggesting biotic interactions between biocrusts and plants have been at play for some 2,000 million years. Today, biocrusts coexist with plants in dryland ecosystems worldwide, and have been shown to both facilitate or inhibit plant species performance depending on ecological context. Yet, the factors that drive the direction and magnitude of these effects remain largely unknown.2. We conducted a meta-analysis of plant responses to biocrusts using a global dataset encompassing 1,004 studies from six continents. 3. Meta-analysis revealed there is no simple positive or negative effect of biocrusts on plants. Rather, plant responses differ by biocrust composition and plant species traits and vary across plant ontogeny. Moss-dominated biocrusts facilitated, while lichen-dominated biocrusts inhibited overall plant performance. Plant responses also varied among plant functional groups: C 4 grasses received greater benefits from biocrusts compared to C 3 grasses, and plants without N-fixing symbionts responded more positively to biocrusts than plants with N-fixing symbionts. Biocrusts decreased germination but facilitated growth of non-native plant species. S U PP O RTI N G I N FO R M ATI O N Additional supporting information may be found online in the Supporting Information section at the end of the article. How to cite this article: Havrilla CA, Chaudhary VB, Ferrenberg S, et al. Towards a predictive framework for biocrust mediation of plant performance: A meta-analysis. J

Biological soil crusts increase stability and invasion resistance of desert revegetation communities in northern China

“…, Havrilla and Barger , Havrilla et al. ). The authors of those studies argued that larger seeds or seeds with large awns may prevent the seeds from slipping into small cracks found in BSCs, leaving seeds on the soil surface vulnerable to predation and lacking sufficient moisture to germinate (Belnap et al.…”

“…, Zhang and Belnap , Havrilla et al. ). In this study, the size and morphology of the seeds of the two native plant species were not significantly different; therefore, the difference in germination percentage between E. poaeoides and A. capillaries may be related to their different strategies to adapt to the drought environment.…”

“…), which may be partially explained by physical interactions between non‐native seed morphological traits and BSCs (Havrilla and Barger , Havrilla et al. ). The results also suggested that BSCs can maintain native plant populations at a stable level due to their coevolutionary relationships (Belnap et al.…”

“…Therefore, the response of exotic species with differing traits to BSCs is different from that of native species (Havrilla et al. ). Other studies have also shown that the germination of the exotic annual grasses Bromus and Schismus was stimulated in broken crusts and inhibited on intact crusts (Larsen ).…”

“…Currently, as mentioned by Havrilla et al. () in their latest meta‐analysis, there have been a large number of experimental studies on the effects of BSCs on plant germination, growth, and other performance metrics. Among those studies, some have investigated the effects of BSCs on exotic plant species.…”