Seasonal production, allocation and cycling of carbon in two mid-elevation tropical montane forest plots in the Peruvian Andes

Abstract

Background: Tropical montane cloud forests (TMCF) are unique ecosystems with high biodiversity and large carbon reservoirs. To date there have been limited descriptions of the carbon cycle of TMCF. Aims: We present results on the production, allocation and cycling of carbon for two mid-elevation (1500-1750 m) tropical montane cloud forest plots in San Pedro, Kosñipata Valley, Peru. Methods: We repeatedly recorded the components of net primary productivity (NPP) using biometric measurements, and autotrophic (R a ) and heterotrophic (R h ) respiration, using gas exchange measurements. From these we estimated gross primary productivity (GPP) and carbon use efficiency (CUE) at the plot level. Results: The plot at 1500 m was found very productive, with our results comparable with the most productive lowland Amazonian forests. The plot at 1750 m had significantly lower productivity, possibly because of greater cloud immersion. Both plots had similar patterns of NPP allocation, a substantial seasonality in NPP components and little seasonality in R a . Conclusions: These two plots lie within the ecotone between lower and upper montane forests, near the level of the cloud base. Climate change is likely to increase elevation of the cloud base, resulting in shifts in forest functioning. Longer-term surveillance of the carbon cycle at these sites would yield valuable insights into the response of TMCFs to a shifting cloud base.

Amazonian functional diversity from forest canopy chemical assembly

“…Elevation-dependent increases in δ 13 C also suggest increased carboxylation efficiency when there also exists an associated higher N per unit leaf area (29,30), which did occur with increasing elevation. In turn, this finding suggests that the efficiency of C fixation is maintained, or perhaps increases at higher elevation, which would explain the relatively constant and high photosynthetic capacity recently reported along a similar Andes to Amazon elevation gradient (31)(32)(33). Such highgrowth rate environments likely create the conditions under which competition and defense are the most critical factors determining how maximum productivity is achieved and maintained.…”

“…Against this regional backdrop of community-scale adjustment to rock-derived nutrient availability, climatological growth conditions are generally good, even with increasing elevation (31)(32)(33)44), and foliar N is generally high everywhere. Such productive conditions go hand in hand with high pest and pathogen pressure on foliage (9,25,45).…”

Geomorphic regime modulates hydrologic control of chemical weathering in the Andes–Amazon

“…The mean annual air temperature in the Andean catchments ranges from $12 to 19°C, varying with the elevation (Girardin et al, 2013;Huasco et al, 2014), with an adiabatic air temperature lapse rate of 4.94°C km À1 (Girardin et al, 2013). Catchment-wide mean annual rainfall values of 2299 ± 115 mm year À1 (Way) and 2881 ± 124 mm year À1 (SP) were determined for the period from 1998 to 2012 using calibrated TRMM data .…”

Amazonian landscapes and the bias in field studies of forest structure and biomass

“…To assess the accuracy and precision of using TCH to predict EACD, we regressed LiDAR-based EACD against field plot-derived EACD obtained from recent published values (43,65,66). Using Eqs.…”