Contrasting Net Ecosystem Production Across Ecological Succession at
Subtropical Dry Forest of Northwestern Mexico
Abstract
Forests are under major pressures due to contemporary land-use, which
creates mosaics of stand-stage development that follow different
successional paths, that imply ecosystem complexity. The interplay of
carbon and water dynamics across succession involves physical and
biological interactions that shape net ecosystem production (NEP) and
water use efficiency. Here we present 13 years-site of eddy covariance
data (2016-2020) from a seasonally dry tropical forest in Northwestern
Mexico to elucidate the environmental controls on ecosystem fluxes and
explore the interactions with changes in resource availability. Across a
successional gradient, an early (9 years since abandonment) and a
mid-successional (about 45 years with natural recruitment and regrowth)
sites were net carbon sinks (in the order of 100 to 500 g C m-2 y-1)
while an old- growth forest was a chronic net source over the 5 years
studied (losing between 100 and 300 g C m-2 y-1). In contrast
evapotranspiration was alike at sites and close to the precipitation
input. Ecosystem water use efficiency tended to be higher at the
old-growth forest site (ca. 3.0 g C m-2 /mm H2O vs. ca. 2.0 g C m-2 / mm
H2O at the secondary sites). Water availability and radiation where
clearly dominant environmental controls across sites, but notably vapor
pressure deficit was not a controlling factor for gas exchange at the
old-growth forest. Surface characteristics, canopy structure and species
composition may explain differences in NEP across succession in TDF at
its northernmost extent.