Wang
Shu and Jia Hepeng
14 December
2007
Source: SciDev.Net
[BEIJING]
Climate change has helped plants in China become
more robust, according to a study by Chinese scientists.
Scientists
at the Beijing Normal University studied the link between climate
factors and changes in plants' net primary productivity — a term used
to evaluate the net reserve energy plants need during growth — between
1982 and 1999.
"If
the net primary productivity
of a plant
is high, it means the plant grows more healthily," says lead author Zhu
Wenquan of the College of Resources at the university.
Zhu
and colleagues analyzed climate-observation data for the period
alongside remote-sensing data on plantations in different regions in
China. They then determined the specific climate factors — sunshine,
temperature and precipitation — that had the biggest impact on plant
growth in these regions.
They
found that low
temperatures in northeast China and the Tibet–Qinghai highlands
contribute most to poor plant growth. In northwestern China it is
reduced precipitation. And in southern and eastern China it is lack of
sunshine that hinders growth.
But
over the
period studied,
temperature, precipitation or sunshine increased markedly in these
respective regions — effects that the scientists attribute to global
warming.
"We
are not denying the role of other
factors, but
the three factors (sunshine, temperature and precipitation) have played
a much more important role than others," Zhu told SciDev.Net.
As
a result, the net primary productivity of land plants in China grew by
11.5 per cent because of climate change, which the authors say is
consistent with the global trend of an increase of about six per cent
worldwide.
Zhu
says this does not contradict
the widely
believed negative impacts of global warming. "For crops, for example,
the growth in net primary productivity does not necessarily translate
into increased output. The plant stem may grow more than fruits, for
example."
He
adds that climate change could cause severe disasters in individual
regions, which would not be offset by increased plant productivity.
A
previous study, published in 2004 by Gao Zhiqiang and colleagues from
the Institute of Geographical Sciences and Nature Resources Research at
the Chinese Academy of Sciences, concluded that climate change between
1978 and 1998 had caused a decrease in plant productivity in northeast
China.
Referring
to Zhu's studies, Gao says
various aspects
of climate change could combine to complicate the impact on plant
growth, and it is difficult to associate a change in net primary
productivity with variation of a single "major" climate factor.
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