Ordóñez-Parra Carlos A, Medeiros Natália F, Dayrell Roberta L C, Le Stradic Soizig, Negreiros Daniel, Cornelissen Tatiana, Silveira Fernando A O
Programa de Pós-Graduação em Biologia Vegetal, Departamento de Botânica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
Centro de Síntese Ecológica e Conservação, Departamento de Genética, Ecologia e Evolução, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, 31270-901, Brazil.
Ann Bot. 2025 Feb 19;135(3):371-386. doi: 10.1093/aob/mcae160.
Rock outcrop vegetation is distributed worldwide and hosts a diverse and unique flora that evolved under harsh environmental conditions. Unfortunately, seed ecology in such ecosystems has received little attention, especially regarding seed traits, germination responses to abiotic factors and the potential role of phylogenetic relatedness in shaping such features. Here, we provide the first quantitative and phylogenetically informed synthesis of the seed functional ecology of Brazilian rock outcrop vegetation, with a particular focus on quartzitic and ironstone campo rupestre.
Using a database of functional trait data, we calculated the phylogenetic signal for seven seed traits for 371 taxa and tested whether they varied among growth forms, geographic distribution and microhabitats. We also conducted meta-analyses that included 4252 germination records for 102 taxa to assess the effects of light, temperature and fire-related cues on the germination of campo rupestre species and explored how the aforementioned ecological groups and seed traits modulate germination responses.
All traits and germination responses showed a moderate to strong phylogenetic signal. Campo rupestre species responded positively to light and had maximum germination between 20 and 25 °C. The effect of temperatures beyond this range was moderated by growth form, species geographic distribution and microhabitat. Seeds exposed to heat shocks above 80 °C lost viability, but smoke accelerated germination. We found a moderating effect of seed mass for responses to light and heat shocks, with larger, dormant seeds tolerating heat better but being less sensitive to light. Species from xeric habitats evolved phenological strategies to synchronize germination during periods of increased soil water availability.
Phylogenetic relatedness plays a major role in shaping the seed ecology of Brazilian rock outcrop vegetation. Nevertheless, seed traits and germination responses varied significantly between growth forms, species geographic distribution and microhabitats, providing support to the regeneration niche hypothesis and the role of functional traits in shaping germination in these ecosystems.
岩石露头植被分布于全球，拥有在恶劣环境条件下进化而来的多样且独特的植物群。遗憾的是，此类生态系统中的种子生态学很少受到关注，尤其是关于种子性状、对非生物因素的萌发反应以及系统发育相关性在塑造这些特征方面的潜在作用。在此，我们首次对巴西岩石露头植被的种子功能生态学进行了定量且基于系统发育的综合研究，特别关注石英岩和铁矿石坎普鲁普斯群落。
利用功能性状数据数据库，我们计算了371个分类单元的7种种子性状的系统发育信号，并测试了它们在生长形式、地理分布和微生境之间是否存在差异。我们还进行了荟萃分析，其中包括102个分类单元的4252条萌发记录，以评估光照、温度和与火相关的线索对坎普鲁普斯物种萌发的影响，并探讨上述生态组和种子性状如何调节萌发反应。
所有性状和萌发反应均显示出中等至强烈的系统发育信号。坎普鲁普斯物种对光照反应积极，在20至25°C之间具有最大萌发率。超出此范围的温度影响受生长形式、物种地理分布和微生境的调节。暴露于80°C以上热激的种子失去活力，但烟雾可加速萌发。我们发现种子质量对光照和热激反应有调节作用，较大的休眠种子更能耐受高温，但对光照不太敏感。来自干旱生境的物种进化出物候策略，以便在土壤水分可用性增加的时期同步萌发。
系统发育相关性在塑造巴西岩石露头植被的种子生态学方面发挥着重要作用。然而，种子性状和萌发反应在生长形式、物种地理分布和微生境之间存在显著差异，这为更新生态位假说以及功能性状在这些生态系统中塑造萌发的作用提供了支持。
