Geoscience Reference
In-Depth Information
Tool
How it works
What it tells us
Advantages & disadvantages
Experiments
Manipulations of
temperature, water & CO
2
in laboratory and ield
conditions investigate
potential impacts and their
physiological basis. Free Air
Carbon Dioxide Enrichment
(FACE) experiments in
which natural communities
are treated with elevated
CO
2
concentrations have
been set up in many
different vegetation types
globally (although only
in northern savanna and
temperate grasslands in
Australia).
Increased atmospheric CO
2
has a fertilizer effect
on many plants, increasing photosynthetic rate and
growth, provided that nutrients, water and light
are not limiting. Many plants have greater water
use eficiency (WUE) at high CO
2
although this
varies between plants with different photosynthetic
pathways. Reductions in nitrogen content relative
to carbon in plants tissues affect nutritional and
defensive qualities of plant tissues, with low
on impacts to herbivores. Plants grown under
continuously elevated CO
2
may eventually acclimate,
with a leveling off of growth rate. Increased WUE
may mitigate drought stress up to a point. Differences
in CO
2
responsiveness between species will alter both
inter- and intra-speciic competition, changing both
the structure and function of plant communities.
Warming of plant and soil communities under ield
conditions alters many aspects of their structure,
composition, phenology, and function.
Elevated CO
2
experiments have increased our
understanding of how climate change could affect
many physiological and ecological processes. However,
most experiments have been performed on small
scales, on relatively young plants, over short time
periods, with non-limiting nutrients, light and water,
and in the absence of pathogens, herbivores and
competitors (Hovenden and Williams 2009). Scaling
up from these experiments to understand community
and ecosystem-level effects remains a challenge.
Impacts of elevated CO
2
have been investigated
for relatively few native plant species in Australia
(Hovenden & Williams 2009).
Gradient
studies
Quantifying turnover of
species distributions or
community traits along
naturally occurring
environmental gradients,
as a surrogate for future
climatic change (space for
time substitution).
Most ecological communities exhibit substantial
species turnover along ecological gradients, indicating
that climate change could result in rapid changes in
the community composition (Andrew and Hughes
2007).
Interpretation of species turnover along temperature
gradients can be confounded by other latitude-related
changes, such as photoperiod, and seasonality, or
elevation-related changes such as UV-radiation.
