Response of central Amazon rainforest soil seed banks to climate change - Simulation of global warming

Isabela Maria Souza Silva, Geângelo Petene Calvi, Carol C. Baskin, Gisele Rodrigues dos Santos, Niwton Leal-Filho, Isolde Dorothea Kossmann Ferraz

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

The most severe global warming is predicted to occur in the Amazon region of Brazil, with an estimated temperature increase of 4 to 8 °C between 2071 and 2100. Our study evaluated the effects of increased temperatures on germination success of seeds in the soil seed bank of secondary forests in Central Amazonia. Soil samples (3-cm depth) were collected in six secondary forests with different land-use histories and ages of regrowth. Soils from all sites were sieved and mixed, and germination and seedling development were assessed during 4 months of incubation in germination chambers at (1) a constant temperature of 25 °C and a 12:12 h alternating temperature regime of 20:30 °C, considered as controls; (2) a simulated 5 °C temperature increase to 30 °C and 25:35 °C and (3) a 10 °C temperature increase to 35 °C and 30:40 °C. To determine the effect of light vs. dark on germination, germination was compared for samples in light (12 h daily photoperiod) vs. continuously dark for 1 month, followed by 3 months in light. Six temperature conditions were tested with 30 subsamples each. In the mixed soil seed bank, 3640 seeds germinated, of which 18 families, 28 genera and 41 species (grouped in 20 trees, 11 shrubs, eight herbs and two lianas) could be identified. A light requirement for germination was detected for 94–97% of the species. Alternating temperatures did not stimulate germination in the dark. Seedling density m−2 was 1.7 to 2.3 times higher at alternating (20:30 °C and 25:35 °C) than at constant temperatures (25 °C and 30 °C); but an increase of 10 °C decreased seedling density to 47% at 35 °C and 26% at 30:40 °C compared to control (100% at 25 °C and 20:30 °C); and furthermore increased seedling mortality. Thus, the secondary forest at the study area may maintain its integrity with a 5 °C but not with a 10 °C temperature increase. Species-specific sensitivities to temperature were detected. Temperature may function to fine-tune germination at a specific microsite, and the variety of germination requirements may enhance coexistence and maintenance of species diversity within the pioneer species subset. In general, seeds of tree species were more sensitive to increased temperatures than those of shrubs and herbs, supporting the hypothesis of replacement of the tropical forest by savanna-like vegetation in the Amazon region. Our results show that natural regeneration may be significantly affected by global warming and with potential to alter floristic composition.

Original languageEnglish
Article number119224
JournalForest Ecology and Management
Volume493
DOIs
StatePublished - Aug 1 2021

Bibliographical note

Funding Information:
This work is part of I.M.S.S. MSc. dissertation in the Tropical Forest Science Programme (PPG-CFT) of the National Institute for Amazonian Research – INPA, supported by a fellowship of Amazonas Research Foundation - FAPEAM. This work was supported by the National Council of Technological and Scientific Development of Brazil – CNPq (309 111/2013-7) and received additional support of INPA (PRJ 12.294), FAPEAM (PAPAC and Posgrad) and by Cooordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Financial code 001. I.D.K.F. is a research fellow of CNPq. We thank all collaborators who contributed directly and indirectly to this research, especially the assistance in the seed laboratory of Elzineide Moreira do Carmo, Itamara Gonçalves da Gama and Gina Janet Vargas Pinedo Moraes. This is publication number 812 of the technical series of Biological Dynamics of Forest Fragments Project (BDFFP- INPA/STRI).

Funding Information:
This work is part of I.M.S.S. MSc. dissertation in the Tropical Forest Science Programme (PPG-CFT) of the National Institute for Amazonian Research – INPA, supported by a fellowship of Amazonas Research Foundation - FAPEAM. This work was supported by the National Council of Technological and Scientific Development of Brazil – CNPq (309 111/2013-7) and received additional support of INPA (PRJ 12.294), FAPEAM (PAPAC and Posgrad) and by Cooordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Financial code 001. I.D.K.F. is a research fellow of CNPq. We thank all collaborators who contributed directly and indirectly to this research, especially the assistance in the seed laboratory of Elzineide Moreira do Carmo, Itamara Gonçalves da Gama and Gina Janet Vargas Pinedo Moraes. This is publication number 812 of the technical series of Biological Dynamics of Forest Fragments Project (BDFFP- INPA/STRI).

Publisher Copyright:
© 2021 Elsevier B.V.

Keywords

  • Amazonia
  • Germination
  • Regeneration
  • Secondary Forest
  • Tropical forest

ASJC Scopus subject areas

  • Forestry
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law

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