FEATURE
Figure 4: A functionally healthy valley sequence to its floodplain and then how the
whole drainage ecosystem can become essentially a ”tiled roof with drain pipes”,
etching out all the critical habitats in the process (Pringle & Tinley, 2003).
Prevention is better than cure: If one
believes that prevention is better than
cure, it is imperative that all activities that
involve the unnatural cutting of the nat-
ural landscape are stopped, or planned
very carefully. In particular, the sills that
hold up the ponding of local wetlands
should be protected on-site. For in-
stance, by locating artificial watering
points across slope rather than above or
below wetland sills and avoiding track
alignment near these fragile areas can
minimise the threat of initiating gully
head cuts into them from downslope or
the diversion of flows elsewhere from
upslope areas (Pringle et al., 2019). The
key issue is to maintain critical natural
landscape base levels that enable water
retention, thereby supporting all of the
key biodiversity values that result from
nested patterns of small to very large
wetlands, the “jewels in the crown” of
any drainage ecosystem.
Concluding comment: Landscape inci-
sion is episodic but fast. It often works
against natural, slow landscape succes-
sion processes that create areas of great-
er soil moisture balance and landscape
productivity (Noy Meir, 1980) as well as
critical, nested, drought buffering habi-
tats (Newsome, 1980; McNaughton,
1983; Illius & O'Connor, 2000). Human-
induced gullies and their devastating
effects of landscape droughting and
ecosystems’ drought buffering are not
an issue specific to commercial land use
as causative processes also affect lands
set aside for biodiversity conservation.
Gully development adheres to the laws
of physics everywhere and can affect
any land where a nick point is created
by the cutting of the natural land sur-
face. Generally, the effects of gully de-
Figure 5: The unplugging of a wetland
(Ken Tinley).
velopment and expansion are at odds
with most land management objectives,
especially in relation to wetlands in their
wide, arid context. Most importantly,
gully head cuts are usually expanding
their “stealing” of rangeland ecosys-
tems’ most valuable resource: soil mois-
ture.
Acknowledgements
Ken Tinley (D.Sc.) opened my eyes to
the importance of physical landscape
succession processes in ecological land
management whatever the primary and
other objectives of those managing the
land. He also drew all the diagrams in
this article, in cases with help from his
wife Lynne. The Tinleys and Russell
Grant kindly reviewed the initial drafts
in detail.
References
1. Clements, F.E. (1916) Plant Succession: An Analysis of the Development of Vegetation. In. Carnegie Institute of Washing-
ton
2. Cole, M. (1963) Vegetation and geomorphology in northern Rhodesia: An aspect of the distribution of savanna of Cen-
tral Africa. Geography Journal, 129, 290-310.
3. Cooke, R.U. & Reeves, R.W. (eds) (1976) Arroyos and Environmental Change in the American South-West. Clarendon
Press, Oxford.
4. Cowles, C.C. (1901) The physiographic ecology of Chicago and vicinity: A study of the origin, development and classifi-
cation of plant societies. Botanical Gazette, 31, 73-108.
5. Duguid, A., Barnetson, J., Clifford, B., Pavey, C., Albrecht, D., Risler, J. & McNellie, M. (2005) Wetlands in the North-
ern Territory vol. 1. A report to the Austraian Government Department of Environment and Heritage on the inventory
and significance of wetlands in the Northern Territory. In. Department of Natural Resources, Environment and the Arts,
Northern Territory Government, Darwin.
6. Fanning, P. (1994) Long-term contemporary erosion rates in an arid rangelands environment in western New South
Wales, Australia. Journal of Arid Environments, 28, 173-187.
7. Fynn, R.S. (2012) Functional resource heterogeneity increases livsetock and rangeland productivity. Rangeland Ecology
05
Grassroots
Vol 20
No 1
March 2020