Seasonal trends of Amazonian rainforest phenology, net primary productivity, and carbon allocation

Research output: Contribution to journalArticle

Abstract

The seasonality of solar irradiance and precipitation may regulate seasonal variations in tropical forests carbon cycling. Controversy remains over their importance as drivers of seasonal dynamics of net primary productivity in tropical forests. We use ground data from nine lowland Amazonian forest plots collected over 3 years to quantify the monthly primary productivity (NPP) of leaves, reproductive material, woody material, and fine roots over an annual cycle. We distinguish between forests that do not experience substantial seasonal moisture stress (“humid sites”) and forests that experience a stronger dry season (“dry sites”). We find that forests from both precipitation regimes maximize leaf NPP over the drier season, with a peak in production in August at both humid (mean 0.39 ± 0.03 Mg C ha−1 month−1 in July, n = 4) and dry sites (mean 0.49 ± 0.03 Mg C ha−1 month−1 in September, n = 8). We identify two distinct seasonal carbon allocation patterns (the allocation of NPP to a specific organ such as wood leaves or fine roots divided by total NPP). The forests monitored in the present study show evidence of either (i) constant allocation to roots and a seasonal trade-off between leaf and woody material or (ii) constant allocation to wood and a seasonal trade-off between roots and leaves. Finally, we find strong evidence of synchronized flowering at the end of the dry season in both precipitation regimes. Flower production reaches a maximum of 0.047 ± 0.013 and 0.031 ± 0.004 Mg C ha−1 month−1 in November, in humid and dry sites, respectively. Fruitfall production was staggered throughout the year, probably reflecting the high variation in varying times to development and loss of fruit among species.

Details

Authors
  • Cécile A J Girardin
  • Yadvinder Malhi
  • Christopher E. Doughty
  • Daniel B. Metcalfe
  • Patrick Meir
  • Jhon del Aguila-Pasquel
  • Alejandro Araujo-Murakami
  • Antonio C. L. da Costa
  • Javier E. Silva Espejo
  • Filio Farfán Amézquita
  • Lucy Rowland
Organisations
External organisations
  • University of Oxford
  • University of Edinburgh
  • Australian National University
  • Federal University of Paraná
  • Universidad Nacional de la Amazonia Peruana
  • Instituto de Investigaciones de la Amazonia Peruana (IIAP)
  • Gabriel René Moreno Autonomous University
  • National University of Saint Anthony the Abbot in Cuzco
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Ecology

Keywords

  • carbon allocation, ecosystem function, net primary productivity, phenology, seasonality, tropical forests
Original languageEnglish
Pages (from-to)700-715
Number of pages16
JournalGlobal Biogeochemical Cycles
Volume30
Issue number5
Publication statusPublished - 2016 May 1
Publication categoryResearch
Peer-reviewedYes