Sensitivity of tropical forest aboveground productivity to climate anomalies in SW Costa Rica

Abstract

The productivity of tropical forests is driven by climate (precipitation, temperature, and light) and soil fertility (geology and topography). While large-scale drivers of tropical productivity are well established, knowledge on the sensitivity of tropical lowland net primary production to climate anomalies remains scarce. We here analyze seven consecutive years of monthly recorded tropical forest aboveground net primary production (ANPP) in response to a recent El Niño-Southern Oscillation (ENSO) anomaly. The ENSO transition period resulted in increased temperatures and decreased precipitation during the El Niño dry period, causing a decrease in ANPP. However, the subsequent La Niña wet period caused strong increases in ANPP such that drought-induced reductions were overcompensated. Most strikingly, the climatic controls differed between canopy production (CP) and wood production (WP). Whereas CP showed strong seasonal variation but was not affected by ENSO, WP decreased significantly in response to a 3°C increase in annual maximum temperatures during the El Niño period but subsequently recovered to above predrought levels during the La Niña period. Moreover, the climate sensitivity of tropical forest ANPP components was affected by local topography (water availability) and disturbance history (species composition). Our results suggest that projected increases in temperature and dry season length could impact tropical carbon sequestration by shifting ANPP partitioning toward decreased WP, thus decreasing the carbon storage of highly productive lowland forests. We conclude that the impact of climate anomalies on tropical forest productivity is strongly related to local site characteristics and will therefore likely prevent uniform responses of tropical lowland forests to projected global changes.

Temperature and rainfall interact to control carbon cycling in tropical forests

“…Unmeasured climatic effects, such as dry season length and cloudiness, also likely play a role (Hofhansl et al . ), as well as variation in other state factor controls. Soil fertility, forest composition, topography and disturbance history can also strongly influence forest C cycling (e.g.…”

Bromeliad tanks are unique habitats for microbial communities involved in methane turnover

“…; Hofhansl et al 2014). The area around the field station is dominated by tank bromeliads of the genus Werauhia (syn.…”

Topographic distributions of emergent trees in tropical forests of the Osa Peninsula, Costa Rica

“…Forests on ridges, which have shallow soils prone to desiccation, are more sensitive to drought stress, experienced during El Niño periods, than ravine forests. Ravine forest soils are deeper and have greater clay and organic matter content, enhancing water‐holding capacity, which may underpin greater rates of wood production during drier periods by reducing hydraulic stress (Hofhansl et al ). This notion aligns with recent observations that wood growth increases with greater water availability at both seasonal and interannual timescales (Doughty et al , Hofhansl et al , Wagner et al ).…”