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Fairfax Cross County Trail, 41 miles: completed 2 July 2010.
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Category Archives: Biodiversity
Preserving trash habitat
As a class assignment, I put together a short essay about unattractive habitat and butterfly conservation.
Swaps
Richard A. Fuller et al. make a provocative proposal in a recent latter to Nature. Working with a data set of the protected areas of Australia, the authors make a quantitative assessment of each preserve’s contribution to conserving vegetation types in the country. They then divide that contribution by the cost of continuing to protect the land (its estimated market value plus management costs), thereby deriving a benefit-cost ratio for each property. Fuller and his team find that about 1% of Australia’s protected areas are not pulling their weight in terms of conserving diversity, and propose that selling these lands (the local term of art is “degazettement”) and using the funds to acquire alternative lands leads to an overall increase in protection with no net impact on public spending.
There are certainly points to argue with in this work. The authors use conservation of vegetation types as their benefit measure, adjusted for the amount of each type found in the protected area and the percentage of each type remaining countrywide since the arrival of Europeans in the mid-eighteenth century. Another measure might yield different results. There are some benefits to protection—a visually attractive viewshed, for instance—that don’t appear to fit into this analysis. Along the same lines of thought, the importance of keystone or indicator species is discounted. If old-growth temperate rain forest is preserved specifically to protect Spotted Owl (Strix occidentalis), there may be knock-on effects. Also, the work assumes that protection can be acquired at market rates, either through outright land purchase or through conservation easements.
Nevertheless, I think it’s a good step toward quantifying the tradeoffs that are an inevitable part of conservation. It’s also worth noting that nearly all the benefit gains are achieved by degazetting the “dogs,” the bottom 1%. Beyond that, the bang (as measured by number of vegetation types protected) doesn’t increase.
Meanwhile, the U.S. federal government is under pressure from the State of Wyoming over two parcels of state-owned land adjacent to Grand Teton National Park, as Bob Beck reports. The high-value properties are held by the state in order to produce revenue, but the lands are yielding little, due to federal restrictions on their use. Wyoming is looking to exchange the land for other lots that can be developed, say for coal mining.
Plenty
The online version of Maya Lin’s What Is Missing? project launches for Earth Day.
Upcoming: 17
Via Round Robin, something worth a side trip to San Francisco on my next California trip: Maya Lin’s gramophone horn-influenced installation What Is Missing?, a plea for habitat and biodiversity conservation. A short video gives an idea of the experience.
Squeezed in Panama
Elisabeth Rosenthal reports on the controversial findings of Joe Wright, a senior scientist at the Smithsonian Tropical Research Institute in Panama, that the rate of secondary rain forest formation (through abandonment of farms via urbanization, and other causes) is outpacing the rate of primary rain forest destruction. The arguments critical of Wright and those in his support tend to tangle together the function of rain forests as a carbon sink with their role as a refuge for biodiversity.
Regenerated forests in the tropics appear to be especially good at absorbing emissions of carbon, but that ability is based on location and rate of growth. A field abandoned in New York in 1900 will have trees shorter than those growing on a field here [in Central America] that was abandoned just 20 years ago.
For many biologists, a far bigger concern is whether new forests can support the riot of plant and animal species associated with rain forests. Part of the problem is that abandoned farmland is often distant from native rain forest. How does it help Amazonian species threatened by rain-forest destruction in Brazil if secondary forests grow on the outskirts of Panama City?
Here in the East, you can observe the results of old field succession by taking a short drive to the Blue Ridge. Much of the now-protected parkland in the Appalachians was once in agricultural production, as the evidence of a family cemetery in the woods will attest.
Invaders from Europe, invaders from Asia
Recent publications by Steven D. Gaines and Dov Sax challenge the conventional wisdom that invasive, exotic species inevitably lead to extinctions and loss of biodiversity, as reported by Carl Zimmer.
More conservation tradeoffs
Emma Marris reviews the range of schemes for making choices in conservation biology and even uses the charged word “triage” for Nature‘s 8 November 2007 issue (paywall-protected link).
The EDGE program (Evolutionarily Distinct and Globally Endangered) of the Zoological Society of London gives priority to species that are taxonomically distinct, “far out on their own on the tree of life,” if you will. The reasoning is that a distinct taxon, now endangered, one that branched tens of millions of years ago from the tree, represents a unique chapter of evolutionary history that can’t be rewritten once lost. Priority amphibians include Chinese Giant Salamander (Andrias davidianus) (up to 1.8 meters long!), Sagalla Caecilian (Boulengerula niedeni), a worm-like burrower with an extremely restricted range in Kenya, and Purple Frog (Nasikabatrachus sahyadrensis), only described in 2003; top mammals are Yangtze River dolphin (Lipotes vexillifer) (perhaps already extinct), Long-beaked Echidna (Zaglossus bruijni), and Riverine Rabbit (Bunolagus monticularis) of South Africa. The system doesn’t appear to have been applied to other orders. A paper by Isaac et al., “Mammals on the EDGE: Conservation Priorities Based on Threat and Phylogeny” documents the EDGE metrics as applied to mammals.
The majority opinion among conservation biologists today is that they still understand too little about ecosystem functions to say for sure which species are the ‘load-bearing’ ones whose presence keeps a complex, multi-tiered ecosystem from collapsing into some worst case dull scenario of rats, roaches and invasive grass. “We are so fundamentally ignorant,” says Norman Myers, a fellow of the University of Oxford, UK, and adjunct professor at Duke University in Durham, North Carolina. “We cannot afford, by a long, long way, to say which species are dispensable.”
Thus Myers pioneered the concept of habitat hotspots, and a number of overlapping hotspot maps have proliferated. Birders may be familiar with catalogues of Important Bird Areas, Birdlife International’s Endemic Bird Areas, or Conservation International’s biodiversity hotspots. The problem for conservation biology is that each hotspot schema starts with different assumptions, chief among them the metric that is to be optimized. Do we seek to minimize extinctions of species or taxa, maximize land area preserved, maximize taxonomic diversity, or optimize some other measure? Marris writes that the work of Hugh Possingham of the University of Queensland in this area is getting a lot of attention: Possingham seeks to maximize the number of species conserved (vascular plants and vertebrates, in the paper cited below), trading off against the real-world costs of conservation efforts—land acquisition, invasive predator extirpation on islands, fire management, replanting, what have you. A paper by Kerrie A. Wilson et al., “Conserving Biodiversity Efficiently: What to Do, Where, and When,” explains the methodology and applies it as an example to 17 of the world’s 39 Mediterranean ecoregions.
What I find notable about the paper’s approach are the tools of economic analysis that are brought to bear on the problem. An expenditure in conservation activity is modelled as a financial investment. Different activities (“ecoactions”) show different expenditure streams: compare the one-time cost of land acquisition, for example, to the ongoing cost of fire management. The paper uses standard discounting methods and Net Present Value calculations to make investment choices comparable. The model reflects that the impact on species preservation will show diminishing marginal returns as investment is increased. The investment allocation algorithm is dynamic over time: it accounts for positive effects in the ecosystem as investments are made, and adjusts allocations year by year in response.
Wilson et al. acknowledge that the methodology does not yet account for uncertainty, a keystone of modern financial analysis. Also, it would be fruitful—albeit computationally more complicated—to consider the interaction effects of various conservation activities, rather than assuming that each activity acts independently of others.
A worked example chooses between three ecoactions in the Swan Coastal Plain region of Australia: revegetation to counteract habitat fragmentation, invasive predator control, and management of a soil-borne pseudo-fungus, Phytophthora cinnamomi). Even though Phytophthora management is the most expensive per square kilometer ($514K versus $301K for replanting and $7K for predator control), it is nevertheless the most cost-effective: a marginal $2 million spent controlling the pseudo-fungus, in this computation, will protect 49 species, versus 4 for predator management and effectively zero for revegetation.
