Climate seasonality limits carbon assimilation and storage in tropical forests

Abstract

<p><strong>Abstract.</strong> The seasonal climate drivers of the carbon cycle in tropical forests remain poorly known, although these forests account for more carbon assimilation and storage than any other terrestrial ecosystem. Based on a unique combination of seasonal pan-tropical data sets from 89 experimental sites (68 include aboveground wood productivity measurements and 35 litter productivity measurements), their associate canopy photosynthetic capacity (enhanced vegetation index, EVI) and climate, we ask how carbon assimilation and aboveground allocation are related to climate seasonality in tropical forests and how they interact in the seasonal carbon cycle. We found that canopy photosynthetic capacity seasonality responds positively to precipitation when rainfall is < 2000 mm.yr<sup>−1</sup> (water-limited forests) and to radiation otherwise (light-limited forests); on the other hand, independent of climate limitations, wood productivity and litterfall are driven by seasonal variation in precipitation and evapotranspiration respectively. Consequently, light-limited forests present an asynchronism between canopy photosynthetic capacity and wood productivity. Precipitation first-order control indicates an overall decrease in tropical forest productivity in a drier climate.</p>

Growth and reproduction respond differently to climate in three Neotropical tree species

“…Woody productivity in tropical forests depends on multiple climatic factors, and therefore different growth responses to climate are expected depending on the most limiting factor for wood formation (Wagner et al 2016). Here, tree growth increased with precipitation and decreased with current-year wet season solar radiation (Fig.…”

“…This could indicate that stem radial growth is limited by water availability, since drought stress constrains wood formation in tropical forests probably through shorter growing seasons and stomatal closure (Phillips et al 2009, Wagner et al 2016. The importance of rainfall to growth is consistent with previous dendrochronological studies in Panama and other moist and dry tropical forests (Devall et al 1995;Worbes 1999;Brienen and Zuidema 2005;Rozendaal and Zuidema 2011;Mendivelso et al 2013Mendivelso et al , 2014, as well as with analyses of census data for multi-year intervals in permanent plots in Panama (Feeley et al 2007).…”

Equatorial Forests Display Distinct Trends in Phenological Variation: A Time-Series Analysis of Vegetation Index Data from Three Continents

“…That is, forest phenology in different regions may be synchronized to different factors, and the correlation analysis indicates that driving factors differ greatly between central Africa and South America. A recent study found that tropical photosynthetic activity is only bound to precipitation when precipitation is less than 2000 mm/year-only the case for central Africa, but not the Guiana Shield or Borneo [19]. Other studies suggest that in the Guiana Shield, the phenological cycle is matched to the availability of light [3], [5], [6], [20].…”

Climate seasonality and tree growth strategies in a tropical dry forest

“…The positive significant correlation between monthly temperature and rainfall over the study period, and the stronger response of monthly stem increments to temperature than to rainfall, support this interpretation. On the other hand, stronger responses to small variations in temperature might be explained by the fact that photosynthetic capacity increases with temperature when water is not limiting (i.e., in the absence of rainfall effects, as was considered in the partial correlations we performed; Koch, Amthor, & Goulden, ; Wagner et al, ), since maximal temperatures reflect available solar energy, and tropical trees tend to maximize water and radiation use while reducing drought susceptibility (Bi et al, ; Myneni et al, ). In fact, growth (annual tree ring widths) in Tabebuia chrysantha shows positive correlations with temperature in a similar SDTF (Espinosa, Camarero, & Gusmán, ).…”

“…At the intra‐annual level, however, little is known about seasonal growth strategies, cambial phenology and their relationships with climate (Borchert, ; García‐Cervigón, Camarero, & Espinosa, ). Given the limiting conditions for plant development in SDTFs, stem secondary growth is expected to be coupled with leaf development and persistence during the wet season or during the transitions from the dry to the wet seasons (Borchert, ; Wagner et al, ). However, the relationships between climate, secondary growth and leaf phenology are not always consistent among co‐existing tree species: some studies have detected species‐specific associations between leaf flushing, functional traits (e.g.…”