Germination niche of campo rupestre plants: effects of increased temperature and darkness

Anthropogenic disturbances are causing significant impacts on plant distribution worldwide, and many of these effects are driven by changes in the recruitment patterns of plant species. Global warming and land-use change are two major disturbances leading to changes in germination strategies by changing both soil temperature regimes and light quality reaching the seeds due to soil disturbance. Investigating the range, overlap, and redundancy of niche germination of co-occurring plant species allows us to understand whether endemic species are threatened either by native non-endemic or by alien species, especially in an ecosystem of restricted distribution such as the campo rupestre. Employing a systematic review, this study aimed to evaluate the effect of temperature increase and seed burial on the germination of endemic and non-endemic species in the campo rupestre in Brazil. We performed a meta-analysis using increased temperature and darkness as proxies for the impact of disturbance on germination patterns. In this context, we hypothesized that: increased temperature and darkness negatively influence the germination of native species and positively influence the germination of alien species in the campo rupestre. Specifically, we expect the negative effect to be more pronounced in endemic species than in native non-endemic species. Moreover, we intend to describe the role of seed size in the germination of native and alien species from campo rupestre in the context of increased temperature and darkness. Our analysis showed that increased temperature influenced the germination of alien species by ca. 55%, while it did not influence the germination of endemic or native non-endemic species. Furthermore, the germination of alien species under higher temperatures was promoted by increasing seed size. Darkness negatively influenced seed germination of native species, independent of their distribution. Moreover, under darkness conditions, the germination of endemic seeds decreased with seed size. Through their direct effects on germination strategies, we conclude that warming temperatures and land-use change can lead to a long-term displacement of endemic species by native non-endemic and alien species in campo rupestre, thus compromising ecosystem services and conservation of these fragile physiognomies in the near future.