The purpose of this paper is to propose a measurable terrestrial ecosystem boundary to answer the question: what extent of landscapes, bioregions, continents, and the global Earth System must remain as connected and intact core ecological areas and agro-ecological buffers to sustain local and regional ecosystem services as well as the biosphere commons?
This observational study reviews planetary boundary, biosphere, climate, ecosystems, and ecological tipping point science. It presents a refinement to planetary boundary science to include a measurable terrestrial ecosystem boundary based on landscape ecology and percolation theory. The paper concludes with discussion of the urgency posed by ecosystem collapse.
A new planetary boundary threshold is proposed based on ecology's percolation theory: that across scales 60 percent of terrestrial ecosystems must remain, setting the boundary at 66 percent as a precaution, to maintain key biogeochemical processes that sustain the biosphere and for ecosystems to remain the context for human endeavors. Strict protection is proposed for 44 percent of global land, 22 percent as agro-ecological buffers, and 33 percent as zones of sustainable human use.
It is not possible to carry out controlled experiments on Earth's one biosphere, removing landscape connectivity to see long-term effects results upon ecological well-being.
Spatially explicit goals for the amount and connectivity of natural and agro-ecological ecosystems to maintain ecological connectivity across scales may help in planning land use, including protection and placement of ecological restoration activities.
This paper proposes the first measureable and spatially explicit terrestrial ecosystem loss threshold as part of planetary boundary science.
I would like to acknowledge the love and support of my wife Julie, daughter Talita, and golden retriever Ginger who sustain me. Paul Hawley provided much appreciated editing, and Nagaraj Kla's presented the opportunity for an earlier draft to be discussed at the Kerala Law Academy's conference in India. All errors and omissions remain my own.
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