TY - JOUR
T1 - The Role of Plants as Ecosystem Engineers in Resilience to Climate Change
AU - Shachak, Moshe
AU - Arbel, Shmuel
AU - Boeken, Bertrand
AU - Segoli, Moran
AU - Ungar, Eugene
AU - Zaady, Eli
PY - 2010/5/1
Y1 - 2010/5/1
N2 - In drylands landscape structure is controlled by two ecosystem
engineers, soil microphytes and shrubs. Soil microphytes adhere the
soil particles by secreting polysaccharides, thus forming biogenic soil
crusts. Shrubs engineer the environment above and below ground. Above
ground they can form soil mounds and below ground modulate the soil
properties by their roots. The two engineering modes create shrub
patches in the landscape. The two phase mosaic formed by the engineers
creates a source-sink system where the crust is a source of soil, water,
organic matter and nutrients while the shrub patch is the sink. Most of
the productivity and diversity of the system is concentrated in the sink
patches. Climate change such as the increase in frequency and severity
of droughts may affect the function of the two phase mosaic by causing
shrub dieback. This can transform a shrub land into crust land by
increasing leakage of resources and decreasing productivity and
diversity (desertification). Based on our long term research at LTER
sites in the Northern Negev, Israel, we present two models depicting how
climate change can cause state changes from shrub land to crust land and
how the mode of shrub engineering can prevent this transition. Our main
proposition is that the resilience of a two phase mosaic to drought
depends on whether the engineering is by mound formation or by
subsurface soil modulation. When the engineering mode is mound
formation, shrubs dying due to drought expose the underlying mound to
erosion by rainfall and runoff. The eroded patch is then colonized by
microphytes which form soil crusts. This process takes between five to
ten years. To rebuild the soil mound by a shrub takes hundreds of years.
Therefore, once the soil mound is eroded the area will then be
transformed from shrub land to crust land and the recovery time is long.
When the engineering is through the roots the system is more resilient
to drought. Even if the canopy dies back the shrub patch continues to
function as a sink because the roots function as tubes that channel the
water to deeper soil. The patch continues to function as a shrub patch
even though the shrub has been decimated. The enriched patch prevents
crust encroachment and stimulates regrowth of the shrub. In this case
there isn't a transformation from shrub land to crust land and the
recovery rate is rapid. Based on the two case studies we present a
general model on state changes in shrub lands due to climate change. We
demonstrate that a main factor in gauging state transition due to
climate change is the mode by which plants engineer their environment.
AB - In drylands landscape structure is controlled by two ecosystem
engineers, soil microphytes and shrubs. Soil microphytes adhere the
soil particles by secreting polysaccharides, thus forming biogenic soil
crusts. Shrubs engineer the environment above and below ground. Above
ground they can form soil mounds and below ground modulate the soil
properties by their roots. The two engineering modes create shrub
patches in the landscape. The two phase mosaic formed by the engineers
creates a source-sink system where the crust is a source of soil, water,
organic matter and nutrients while the shrub patch is the sink. Most of
the productivity and diversity of the system is concentrated in the sink
patches. Climate change such as the increase in frequency and severity
of droughts may affect the function of the two phase mosaic by causing
shrub dieback. This can transform a shrub land into crust land by
increasing leakage of resources and decreasing productivity and
diversity (desertification). Based on our long term research at LTER
sites in the Northern Negev, Israel, we present two models depicting how
climate change can cause state changes from shrub land to crust land and
how the mode of shrub engineering can prevent this transition. Our main
proposition is that the resilience of a two phase mosaic to drought
depends on whether the engineering is by mound formation or by
subsurface soil modulation. When the engineering mode is mound
formation, shrubs dying due to drought expose the underlying mound to
erosion by rainfall and runoff. The eroded patch is then colonized by
microphytes which form soil crusts. This process takes between five to
ten years. To rebuild the soil mound by a shrub takes hundreds of years.
Therefore, once the soil mound is eroded the area will then be
transformed from shrub land to crust land and the recovery time is long.
When the engineering is through the roots the system is more resilient
to drought. Even if the canopy dies back the shrub patch continues to
function as a sink because the roots function as tubes that channel the
water to deeper soil. The patch continues to function as a shrub patch
even though the shrub has been decimated. The enriched patch prevents
crust encroachment and stimulates regrowth of the shrub. In this case
there isn't a transformation from shrub land to crust land and the
recovery rate is rapid. Based on the two case studies we present a
general model on state changes in shrub lands due to climate change. We
demonstrate that a main factor in gauging state transition due to
climate change is the mode by which plants engineer their environment.
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VL - 12
SP - 1695
JO - Geophysical Research Abstracts
JF - Geophysical Research Abstracts
SN - 1029-7006
ER -