- When portions of a previously contiguous forest are carved away, so-called “fragmented forests” are created, and now-isolated species find it increasingly difficult to maintain a healthy and sustainable population. Species in fragmented forests start to head toward extinction within in less than a decade.
- Out of 25 global biodiversity hotspots – sites that contain unusually high numbers of endemic plant and animal species and have lost greater than 70 percent of their original habitat – a team of scientists analyzed two forests for habitat restoration study.
- The team calculated that the cost to regenerate the locations, two of the most fragmented biodiversity hotspots in the world, at less than $70 million. Under the advised approach, the overall projects could generate one of the highest returns on investment for biodiversity conservation in the world.
- The team also notes that the work “could dramatically postpone and likely prevent many forest bird extinctions in these two highly fragmented tropical biodiversity hotspots.”
We’ve all been there: you’re driving along a road lined with trees, when all of a sudden a squirrel or some such animal runs out in front of your vehicle. If it’s a happy day, you steer clear of the forest dweller.
Whatever the outcome of that particular encounter, it was a first-hand lesson on the dilemma species face when their habitat is lost because it was divided up. For the familiar tree squirrel, of which there are several species – they are accustomed to a home range of trees between 0.5-10 acres in natural forests. Those that live in parks have a range of 0.5 acres. Birds and other animals can have a much larger need for range. When the natural habitat is cut up, that squirrel and countless other creatures of the forest have to figure out if they can cross expanses like roads and other development or habitat-bare areas.
For a team of international scientists, there is a simple answer: reconnect fragmented forest habitat and see species thrive. The international team of researchers notes that it can be done in two of the world’s most important biodiversity hotspots in just a few years. The cost, they say, would be less than $70 million total.
The team studied two biodiversity hotpsots, one in South America and one in Africa, and determined that regenerating forests in those locales is highly feasible. Estimated conservation costs would be less than $21 million in Tanzania and $49 million in Brazil. According to their published calculations, the work “would require the development of a broad package of incentives focused on individuals and communities using matrix habitats to establish and conserve forest cover between existing protected fragments.”
Their paper, “Targeted habitat restoration can reduce extinction rates in fragmented forests,” will be published in the Aug. 25 edition of the journal of the Proceedings of the National Academy of Sciences. It was authored by William D. Newmark, Clinton Jenkins, Stuart Pimm, Phoebe McNeally, and John Halley, and partially inspired by a July 2016 paper on habitat loss and species extinction.
The term “fragmented forests” describes what happens when portions of a previously contiguous forest are carved away. Certain species become isolated and it’s difficult to maintain a healthy and sustainable population. Vulnerable species in fragmented forests that find themselves restricted to their portion of forest start to head toward extinction within in less than a decade.
Out of the world’s top 25 biodiversity hotspots, the team chose to analyze the Eastern Arc Mountains in Tanzania and the Atlantic Forest in Brazil. Both areas extend to other countries. Much of the land within the Eastern Arc-Atlantic forest fragments is already under federal or protected status of some kind, but not all protections are being legally enforced.
The cost in Africa is based on the per hectare cost of establishing a similar project in Tanzania, the Derema Forest Corridor. Similar plans of recently re-established forests in South America include the Fazenda Dourada and Rosanela linkages in Brazil. Observation after regeneration in these areas have shown that extinction-prone species in South America such as the golden lion tamarins (Leontopithecus rosalia) and panthers (Puma concolor) can travel through forest linkages in less than ten years.
The scientists identified 11 study locations, nine in the Eastern Arc Mountains of Tanzania and two in the Atlantic Forest of Brazil. They targeted the areas where financial and social costs could be minimized, with the highest potential return on investment. They note there is also a significant backlog of legally required restoration to be done in the region.
According to their research, by regenerating a total of less than 15,000 hectares of forest, 567,000 hectares of contiguous forest would be created.
“This paper looks at the solutions,” said Clinton Jenkins, one of the report authors. “We invest some money in developing a corridor.” His institution, the Instituto de Pesquisas Ecológicas (IPE) in Brazil has established a corridor more than 7.5 miles (12 km) long in Brazil that is now regrowing.
Based on his institution’s experience with that project, Jenkins states confidently that the Tanzania-Brazil projects “can be done.” That’s important for many species that live in these areas.
Fragmented habitat that gets carved up by logging, development, or other land use causes many complications for species, namely survival.
“If it’s a small fragment, the populations are often too small to survive in the long term,” Jenkins said. “So over decades or 100 years, they just wink out. Related to that, you rapidly start losing genetic diversity. Even if you don’t lose the species, it becomes less and less diverse and there’s inbreeding and things like that. They end up having genetic problems.”
The good news for the tracts of land between habitat fragments analyzed in the study: current population density and land use in both areas is minimal, and in some areas secondary forest has already started to regenerate.
Others who work in targeted habitat restoration agree that it is a highly effective approach. But it requires patience.
“It does make a difference, but it takes a long time,” said Pat Monatanio, director of NOAA’s Office of Habitat Conservation in an interview. “If you work with partners and follow the science, it has huge benefits and payoff.”
NOAA is a US government entity that focuses on the condition of the oceans and the atmosphere. It started working in targeted habitat restoration 25 years ago with oil spills. Today, the Office of Habitat Conservation oversees projects in 10 habitat focus areas in areas ranging from Michigan, to Guam, Hawai’i and elsewhere. Many of their projects require minimal funding that goes directly to local partners, such as in the Great Lakes and the Choptank River in Maryland and Delaware.
It is also being done in other parts of the world on a smaller scale.
In Scotland, Alan Watson Featherstone’s habitat conservation charity Trees for Life has worked to restore the fragmented Scottish Caledonian Forest since 1989. Featherstone is the organization’s founder and says restoring connections is a boon to the health of the forest. The Caledonian Forest once spanned the iconic Scottish Highlands.
“We’re taking a targeted approach to extend existing woodland areas to provide connectivity,” Featherstone said. He notes that “connectivity is crucial” for the migration of species and to support larger species that need more range. They use targeted tree planting to establish islands of healthy forest, which they hope will eventually lead to larger connections.
He notes that even with their efforts, though, “many of these small areas of woodland in Scotland” have already lost their ecology.
Banner image: A golden tamarin monkey, a species known to use forest corridors. Photo courtesy of Stuart Pimm/SavingSpecies.
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