biomass allocation
; carbon
; carbon cycle
; ecosystem function
; humid environment
; irradiance
; net primary production
; phenology
; precipitation intensity
; rainforest
; seasonality
; solar radiation
; trend analysis
; tropical forest
; Amazonia
英文摘要:
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. �2016. American Geophysical Union. All Rights Reserved.
Environmental Change Institute, School of Geography and the Environment, University of Oxford, Oxford, United Kingdom; Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden; School of Geosciences, Edinburgh University, Edinburgh, United Kingdom; Research School of Biology, Australian National University, Canberra, ACT, Australia; Department of Biology, Universidad Nacional de la Amazonia Peruana, Iquitos, Peru; Instituto de Investigaciones de la Amazonia Peruana, Iquitos, Peru; Museo de Historia Natural Noel Kempff Mercado, Universidad Aut�noma Gabriel Ren� Moreno, Santa Cruz, Bolivia; Centro de Geociencias, Universidade Federal do Par�, Belem, Brazil; Department of Biology, Universidad Nacional San Antonio Abad del Cusco, Cusco, Peru
Recommended Citation:
Girardin C,A,J,et al. Seasonal trends of Amazonian rainforest phenology, net primary productivity, and carbon allocation[J]. Global Biogeochemical Cycles,2016-01-01,30(5)