Scientists are still searching for possible unifying mechanisms
to explain this range of spatial patterns (Tongway
and Ludwig 2001), and an important question of this research
is whether this range is the result of preexisting
environmental heterogeneity, the result of spatial selforganization,
or both (Klausmeier 1999; Couteron and
Lejeune 2001; HilleRisLambers et al. 2001; Von Hardenberg
et al. 2001). Here, we contribute to the ongoing debate
about vegetation pattern formation in arid ecosystems
by presenting novel, spatially explicit model analyses and
results, extending on the work of HilleRisLambers et al.
(2001). Our results show that these different vegetation
patterns observed in arid ecosystems might all be the result
of spatial self-organization, caused by one single mechanism:
water infiltrates faster into vegetated ground than
into bare soil, leading to net displacement of surface water
to vegetated patches. This model differs from earlier model
results (Klausmeier 1999; Couteron and Lejeune 2001;
HilleRisLambers et al. 2001; Von Hardenberg et al. 2001) primarily in two ways: it is fully mechanistic, and it treats
the lateral flow of water above and below the soil as separate,
not independent, variables. Although the current
model greatly simplifies the biophysics of arid systems, it
can reproduce the whole range of distinctive vegetation
patterns as observed in arid ecosystems, indicating that
the proposed mechanism might be generally applicable.
We further show that self-organized vegetation patterns
can persist far into regions of high aridity, where plants
would become extinct if homogeneously distributed,
pointing to the importance of this mechanism for maintaining
productivity of arid ecosystems (Noy-Meir 1973).
Our analyses are based on the model first developed in
HilleRisLambers et al. (2001