Abstract:
The Chir-Pine (Pinus roxburghii) and
Banj-Oak (Quercus leucotrichophora)-dominated
ecosystems of central Himalaya provide significant
green services. However, responses of these ecosystems,
with respect to ecosystem carbon flux variability,
to changing microclimate are not yet studied.
Since quantification of ecosystem responses to
fluctuation in the microclimate, particularly rainfall,
is expected to be beneficial for management of
these ecosystems, this study aims (i) to quantify and
compare amplitude of rainfall-induced change in
the carbon fluxes of Chir-Pine and Banj-Oak-dominated
ecosystems using wavelet methods, and (ii)
to quantify and compare dissimilarities in the ecosystem
exchanges due to varying rainfall spell and
amount. Eddy covariance–based continuous daily
micrometeorological and flux data, during the 2016–
2017 monsoon seasons (total 244 days, 122 days of
June–September), from two sites in Uttarakhand,
India, are used for this purpose. We find that both
Chir-Pine and Banj-Oak-dominated ecosystems are
the sinks of carbon, and Chir-Pine-dominated ecosystem
sequesters around 1.8 times higher carbon
than the Banj-Oak. A systematic enhancement in the
carbon assimilation of the Chir-Pine-dominated ecosystem
is noted with increasing rainfall spell following
a statistically significant power-law relationship.
We have also identified a rainfall amount threshold
for Chir-Pine and Banj-Oak-dominated ecosystems
(10 ± 0.7 and 17 ± 1.2 mm, respectively) that resulted
in highest ecosystem carbon assimilation in monsoon.
The general inference of this study accentuates that
Banj-Oak-dominated ecosystem is more sensitive to
maximum rain within a spell whereas the Chir-Pinedominated
ecosystem is more responsive to increasing
rainfall spell duration.
