Proposing a planetary boundary for
terrestrial ecosystem loss
By
Dr. Glen Barry, December 16, 2012
Theme
- The Legal Regime and Measures for Conservation of Bio Diversity and
Protection of Ecological Balance of Western Ghats
“Earth
provides enough to satisfy every man's need, but not every man's greed.” –
Mahatma Gandhi
"How
wonderful it is that nobody need wait a single moment before starting to
improve the world." – Anne Frank
*Version
1.0, not
yet peer reviewed, or final edits for publication in conference proceedings
Review Paper Abstract
Planetary
boundary science continues the study of requirements to avoid ecosystem
collapse and to achieve global ecological sustainability, by defining key
thresholds in the Earth System's ecological conditions that threaten human
well-being. Terrestrial ecosystems do not enter into the nine originally
defined boundaries ranging from climate change to water availability, except
peripherally through other boundaries such as land use and biodiversity. A
rigorous research agenda is necessary to determine what quantity and quality of
terrestrial ecosystems are required across landscapes so as to sustain the
biosphere. This includes a spatially explicit way of indicating what extent of
a landscape, bioregion, continent and global Earth System must remain in the
form of connected and intact core ecological areas and semi-natural
agroecological buffers, in order to sustain local ecosystem services as well as
the biosphere commons. Connectivity of large ecosystem patches which remain the
matrix for the landscape is a preeminent consideration. When ~60% of a natural
ecosystem habitat remains, after just under 40% of the ecosystem has been
destroyed, the landscape is said to percolate, and we see critical collapse of the
"percolating cluster" – the dominant large habitat patch constituting
the matrix of the landscape – into smaller, more distant habitat, in a sea of
human development. This critical deterioration of habitat connectivity
continues so that at or near 50% loss of a landscape or bioregon's natural
vegetation, the natural habitat percolates from people within ecosystems, to
natural islands surrounded by human works. This transition is likely to be
similar at a continental and global scale.
A
new planetary boundary threshold is proposed: that 60% of terrestrial
ecosystems must be maintained across scales – with the boundary set at 66% as a
precaution – as a safe space not only for humanity but for all life and to
maintain the long-term viability of the biosphere. It is thought that loss and
diminishment of terrestrial ecosystems aggregates from the local and regional
scale, yet disrupts planetary process with this global scale threshold. It is hypothesized
that ensuring natural ecosystems and their biogeochemical flows remain the
context for human endeavors is a requirement to sustain the biosphere for the
long term, and that fundamentally this requires large core ecological areas,
and the critical connectivity of ecosystem processes and patterns, as the
global and fractal landscape matrix. It is further proposed on the basis of
ecology's percolation theory that two-thirds of the 66% of terrestrial
ecosystems must be protected as ecological core areas (in total 44% of the global
land mass as intact ecological cores, 22% as agroecological, agroforestry and
managed forest buffers, and transition zones), to ensure the ecological
integrity of the semi-natural agroecological landscapes, to maintain critical
ecosystem connectivity across scales, and encompass semi-natural landscapes and
bioregions within a matrix of intact nature to ensure that their own ecological
patterns and processes are sustainable. Up to 50% of Earth's land surface has already
been transformed from mostly wild to mostly anthropocentric, so the biosphere is
likely to have already lost its global percolating cluster. If indeed
bioregional and global scaled landscapes are similar to landscape and
bioregional pattern, terrestrial ecosystem connectivity is already critically
lacking, and the global ecosystem now exists as patches of nature within a sea
of humanity. It is urgent to protect most of what remains and to begin
reconstructing connected ecological landscape matrixes of intact ecosystems
across scales, so that globally the biosphere can percolate back to connected
nature as the provider of top-down context to human and all life.
To
have meaning in guiding global ecological sustainability policy, these continental
and global observations – and proposed 66% presence / 44% protected –
planetary boundary for terrestrial ecosystem loss must be grounded in real-life
landscape and bioregional conservation considerations. An example are efforts
to achieve ecological sustainability, including maintaining continued viable
populations of Asian elephants in the Western Ghats bioregion of India, particularly
within Kerala state, as an umbrella species. The Asian elephant requires
extensive and adequate natural habitat for its survival, and the Western
monsoon depends upon forest-dependent pressure gradients – and thus the
provision of both provides for water, clean air, soil, pollinators, and other
ecosystem services for the region, nation, and biosphere. An initial expansive regional
ecosystem mapping exercise that seeks to identify natural gradients in
ecological importance has taken place in Kerala, but its largely top-down
processes have faced organized socio-political resistance, it is not clear the
scientifically valid mapping processes have enough understanding and support, and
the legal structure is not in place to tie its requirements for local and
regional sustainability to laws. As a real-world example, elephants moving
across landscapes are emblematic and widely visible examples of the myriad types
of flows that continue on a connected landscape, making life possible. It is
suggested that as go the Western Ghats' and Kerala's Asian elephants and their
habitat, so shall go the biosphere, and that it is crucial to build awareness that
healthy ecosystems are essential to both local advancement and global
sustainability. On the basis of taking such an ecosystem and landscape approach
to the needs of Earth System sustainability, and given pernicious trends of
ecosystem loss and decline, it is concluded that more attention is needed to
prevent worst-case outcomes including biosphere collapse and a lifeless Earth,
particularly because of abrupt climate change and ecosystem loss. A massive and
global program to protect and restore natural ecosystems – funded by a carbon
tax on fossil fuels – is presented as the sort of policy approach necessary at
this time to avoid biosphere collapse. Humanity is now the major force shaping
the biosphere, which, if current trends in ecological loss and diminishment
continue, may collapse or die as a result.
