J Plant Ecol ›› 2022, Vol. 15 ›› Issue (1): 13-25 .DOI: 10.1093/jpe/rtab070

• Research Articles • Previous Articles     Next Articles

Seasonal fires shape the germinable soil seed bank community in eastern Mediterranean woodlands

Neta Manela1,2, *, Hagai Shemesh3, Yagil Osem4, Yohay Carmel5, Chanoch Soref6, Anat Tsafrir1, and Ofer Ovadia1,*   

  1. 1 Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel, 2 The National Herbarium, National Natural History Collections, The Hebrew University of Jerusalem, Jerusalem, Israel, 3 Department of Environmental Sciences, Tel-Hai College, Qiryat Shemona, Israel, 4 Department of Natural Resources, Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Rishon LeTsiyon, Israel, 5 Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa, Israel, 6 Judean Mountains Forest Region KKL, Givat Yeshiayah, Israel

    *Corresponding author. E-mail: Neta.manela@mail.huji.ac.il (N.M.); oferovad@bgu.ac.il (O.O.)
  • Received:2021-04-19 Revised:2021-04-29 Accepted:2021-05-22 Online:2021-06-26 Published:2022-02-01

Abstract:

We explored if and how seasonal fires interact with microhabitat type (i.e. under Pistacia shrub, under Cistus shrub or a canopy gap) to influence the composition of the germinable soil seed bank (GSSB) community in a typical eastern Mediterranean woodland. We conducted a field experiment, involving prescribed spring and autumn burns, and thereafter quantified the seed germination patterns using soil samples collected from both burned and adjacent unburned control plots. Soil temperature was significantly higher during autumn burns, while being more variable during spring burns. Fire caused overall reductions in GSSB density, richness and diversity. The reductions in GSSB richness and diversity were significantly stronger under Pistacia and Cistus shrubs located within plots subjected to autumn burns, and these patterns were mainly evident among annuals. GSSB density of dwarf shrubs was higher in samples collected from burned plots, and this pattern was more pronounced in samples collected under Pistacia and Cistus shrubs. Together with the appearance of unique species, seasonal fires led to significant changes in the composition of the GSSB community. Our results illustrate that seasonal fires interact with spatial heterogeneity to influence the composition of the GSSB community mostly via differential effects on the germination densities of annuals and dwarf shrubs. These findings imply that the increase in the frequency of seasonal fires, which has occurred in the eastern Mediterranean basin during the last few decades, may translate into a shift in eco-evolutionary selection pressures, operating on plants inhabiting this unique ecosystem.

Key words: fire season, germination, Mediterranean woodlands, microhabitat, soil seed bank

摘要:

季节性火烧塑造了东地中海地区林地的可萌发种子库群落

本研究探索了在典型东地中海林地中,季节性火烧是否以及如何与微生境类型(即黄连木属(Pistacia)灌木下、岩蔷薇属(Cistus)灌木下或林冠间隙)相互作用,从而影响可萌发种子库(germinable soil seed bank, GSSB)群落的组成。我们进行了一项野外实验,其中包括预定的春秋火烧,然后利用从火烧地块和相邻未火烧对照地收集的土壤样本对种子萌发的模式进行定量。研究结果表明,秋烧期间,土壤温度比春烧的要高,而春烧期间土壤温度则比秋烧的变化更大。火烧导致可萌发种子库整体的密度、丰富性和多样性降低。秋烧地块内黄连木属和岩蔷薇属灌木的可萌发种子库丰富性和多样性显著降低,这些模式主要表现在一年生植物中。在火烧样地收集的样本中,低矮灌木的可萌发种子库密度更高,在黄连木属和岩蔷薇属灌木下采集的样品中,这种模式更为明显。在季节性火烧与出现的独特物种会共同导致可萌发种子库的群落组成发生显著的变化。这些结果表明,季节性火烧与空间异质性互相作用,主要通过对一年生植物和低矮灌木的可萌发密度的差异效应来影响可萌发种子库群落的组成。这些研究发现意味着,过去几十年东地中海盆地的季节性火烧频率上升,可能转化为进化生态选择压力的变化,并对这一独特生态系统内的植物产生影响。

关键词: 火灾季节, 萌芽, 地中海地区林地, 微生境, 土壤种子库