Australia: The Land Where Time Began |
||||||||||||||
Global Tropical Forests – Seasonality Constrained by Hydroclimate It is highly uncertain how tropical forests respond
to droughts (Huntingford et al., 2013). Photosynthesis in some tropical
forests can decline during the dry season, while others can maintain it
at the same or higher levels than they reach in the wet season
(Restrepo-Coupe, N. et
al.,
2013). It remains uncertain, however, to what extent declines of
productivity in the dry season is caused by the availability of water
(Restrepo-Coupe, N. et
al.,
2013; Saleska, de Rocha, Kruijt & Nobre, 2009). In this paper Guan et
al. investigate links between
hydroclimate and the productivity of tropical forests using global
satellite observations of 2 independent measures of the photosynthetic
properties of vegetation (enhanced vegetation index from 2002 to 2012,
and from 2007 to 2012, solar-induced chlorophyll fluorescence). They
found that the evergreen state is sustained during the dry season in
tropical forests worldwide above an annual rainfall threshold of about
2,000 mm/yr, though this is not the case below that threshold. Guan, et
al. used a water-budget
analysis of precipitation, potential evapotranspiration and satellite
measurements of changes in water storage to demonstrate that the
seasonally redistributed subsurface water storage from the wet season
can satisfy the demands for water in the subsequent dry season. Their
conclusion is that in tropical forests globally a first-order control is
exerted of the seasonality of vegetation. They also suggest that their
framework could also help in the identification of tropical forests that
may be vulnerable or resilient to Hydroclimate changes in the future.
|
|
|||||||||||||
|
||||||||||||||
Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |