J Plant Ecol ›› 2020, Vol. 13 ›› Issue (4): 470-477.DOI: 10.1093/jpe/rtaa035

• Research Articles • Previous Articles     Next Articles

Germination strategies under climate change scenarios along an aridity gradient

Alexander Zogas1,2, Evsey Kosman3, and Marcelo Sternberg2, *   

  1. 1 Porter School of Environmental Studies, Tel Aviv University, Tel Aviv, Israel, 2 School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel, 3 Institute for Cereal Crops Improvement, School of Plant Sciences and Food Security, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel

    *Corresponding author. E-mail: marcelos@tauex.tau.ac.il
  • Received:2019-08-05 Revised:2020-06-01 Accepted:2020-06-23 Online:2020-06-29 Published:2020-08-01

Abstract:

Aims

Climate change in the eastern Mediterranean region will have a strong impact on ecosystem functioning and plant community dynamics due to a reduction in annual rainfall and increased variability. We aim to understand the role of seed banks as potential buffers against climatic uncertainty determined by climate change.

Methods

We examined germination strategies of 18 common species present along an aridity gradient. Data were obtained from soil seed banks germinated during nine consecutive years from arid, semi-arid, Mediterranean and mesic Mediterranean ecosystems. At the semi-arid and Mediterranean sites, rainfall manipulations simulating 30% drought and 30% rainfall increase were applied. Germination strategies were tested under optimal irrigation conditions during three consecutive germination seasons to determine overall seed germinability in each soil sample. Changes in germination strategy were examined using a novel statistical approach that considers the climatic and biotic factors that may affect seed germinability.

Important Findings

The results showed that dominant species controlled their germination fractions by producing seeds with a different yearly germination fraction probability. The amount of rainfall under which the seeds were produced led to two major seed types with respect to germinability: high germinability, seeds leading to transient seed banks, and low germinability, seeds leading to persistent seed banks. We conclude that differential seed production among wet and dry years of both seed types creates a stable balance along the aridity gradient, enabling the soil seed bank to serve as a stabilizing mechanism buffering against rainfall unpredictability. Additionally, we present a general model of germination strategies of dominant annual species in Mediterranean and arid ecosystems that strengthens the notion of soil seed banks as buffers against climatic uncertainty induced by climate change in the region.

Key words: climate change, desert, drought, Mediterranean, rainfall manipulations, seed bank

摘要:
由于年降雨量减少和变异性的增加,地中海东部地区的气候变化将对生态系统功能和植物群落动态产生重大影响。我们旨在了解种子库作为应对气候变化所导致的气候不确定性的潜在缓冲作用。我们研究了沿干旱梯度出现的18种常见物种的萌发策略。数据由干旱、 半干旱、地中海和中等地中海生态系统连续九年内萌发的土壤种子库获得。在半干旱和地中海地区,采用了模拟30%干旱和30%降雨增加的降雨处理方法。在连续三个萌发季的最佳灌溉条件下检测了萌发策略,以确定每种土壤样品的总体种子萌发能力。使用一种新颖的统计方法研究了萌发策略的变化,该方法考虑了可能影响种子发芽性的气候和生物因素。研究结果表明,优势种通过产生具有不同年度发芽率概率的种子来控制其发芽率。可产生种子的降雨量导致了关于可萌发性的两种主要种子类型:高萌发性(可形成短暂种子库的种子)和低萌发性(可形成持久种子库的种子)。我们得出的结论是,两种类型的干湿年之间种子产生的差异沿干旱梯度建立了一个稳定的平衡,使土壤种子库可以充当稳定机制,以防止降雨的不可预测性。此外,我们提出了地中海和干旱生态系统中占主导地位的一年生物种萌发策略的一般模型,该模型加强了土壤种子库可以作为应对该地区气候变化引起的气候不确定性的缓冲剂的概念。

关键词: 气候变化, 沙漠, 干旱, 地中海, 降雨控制, 种子