Field season has not yet truly begun here in New England (we're still anxiously awaiting budburst!), but I have been spending some time in the field, investigating barnacle recruitment in Narragansett Bay. Here, the intertidal barnacle Semibalanus balanoides reproduces in the fall and broods its larvae until the winter. Larvae are released in January and develop in the water column for about a month and begin to settle in February and March. They settle as cyprids, a larval stage that looks an awful lot like a sesame seed (see photos). In the cyprid stage, the barnacles decide where on the shore to settle and attach, based on chemical cues from adult barnacles and surface texture. This is a critical moment in a barnacle's life - after metamorphosis, it will be stuck in the same place for the rest of its sessile adult life.
Click here for full size photos.
Sunday, March 29, 2009
Friday, March 13, 2009
Mangrove restoration suggestion
My collaborator, Brian Silliman, and I published a comment this month in the British scientific journal Ambio about incorporating into mangrove restoration design plans the natural capacity of wetland plants to reduce environmental stress for them and their neighbors . Here is an excerpt (references omitted):
Using Facilitation Theory to Enhance Mangrove Restoration
Most mangrove restorations around the world, including the Philippines example, plant mangroves as single seedlings, evenly spaced, in rows. This configuration is based on the assumption that competition among seedlings needs to be minimized to foster establishment and growth. Thus seedlings need to be spaced well away from each other to maximize light availability and minimize competition between neighbors. However, whereas light availability can be a limiting factor at later stages in mangrove forest development, the limiting growth factors at the initial stages of mangrove establishment are edaphic stressors, such as low redox potential and high soil salinity, as recognized by the Samson and Rollon. Because coastal wetland plants engineer the substrate to ameliorate these harmful conditions, an effect that increases with wetland plant density, seedlings are likely to exhibit positive, not negative, density dependence because of the facilitative effects of neighbors on ameliorating anoxic soil conditions.
Ecological theory and wetland experiments both predict that mangrove seedlings have a far better chance of survival if they are planted in clusters of several seedlings rather than plantation style. Planting seedlings in clusters will likely allow the necessary positive feedbacks to take root in the absence of adult plant roots or pneumatophores. For example, a black mangrove restoration in Mexico that planted five-seedling clusters resulted in notably high survival of planted seedlings (74%) after 4 years, despite being planted in a mudflat environment. Mangrove seedlings frequently suffer high rates of mortality, and clustered or redundant plantings allow surviving seedlings to compensate for lost neighbors. Nurse plants, which can serve the same purpose in a restoration as seedling clusters, promoting the facilitative species interactions that ameliorate abiotic stress, have also been found to improve mangrove restoration success. Higher plant densities have also been found to reduce herbivory on susceptible, young plants in other saline wetland environments.
Saturday, February 21, 2009
Punta del Diablo fishery
My husband, Benjamin Gedan, author of the small state blog, made this short video about the fishermen and seafood we saw (and ate!) in Punta del Diablo, Uruguay, a small fishing village on the South American Atlantic coast. I loved seeing the fisherman haul their boats ashore and peeking at their fresh catch. However, I was dismayed to see that several small hammerhead sharks were caught as bycatch (non-target catch). Shark populations are in decline worldwide, largely due to sharkfin fisheries. The sharks are not eaten in Uruguay. The bycatch hammerheads were tossed off to some young boys to play with.
Friday, February 20, 2009
Small mammals control invasive plant colonization
My research was published in the most recent issue of Ecology. Very little is known about the role of small rodents in New England tidal marshes, a heavily researched ecosystem. Yet I found that these small rodents, mice and voles primarily, had an astonishingly large effect in tidal marsh plant communities.
Phragmites australis, the common reed, and Typha angustifolia, cattails, are major nuisance species in New England tidal wetlands, which are already heavily degraded by tidal restriction and land reclamation. Both plant species propogate clonally, can takeover entire communities, and disrupt wetland hydrodynamic processes. In my research in New England tidal marshes, I found that rodent herbivory has a strong effect on colonization and establishment of Phragmites and Typha in brackish and fresh tidal marsh systems. In caged areas, where rodents were excluded, plant species composition was drastically changed and Phragmites and Typha clones were established within three years, whereas these nuisance species were consumed by rodents in uncaged areas. This research tells us that small mammal populations are a necessity for New England tidal marshes in order to maintain healthy communities of native plants.
Read the research abstract here.
Phragmites australis, the common reed, and Typha angustifolia, cattails, are major nuisance species in New England tidal wetlands, which are already heavily degraded by tidal restriction and land reclamation. Both plant species propogate clonally, can takeover entire communities, and disrupt wetland hydrodynamic processes. In my research in New England tidal marshes, I found that rodent herbivory has a strong effect on colonization and establishment of Phragmites and Typha in brackish and fresh tidal marsh systems. In caged areas, where rodents were excluded, plant species composition was drastically changed and Phragmites and Typha clones were established within three years, whereas these nuisance species were consumed by rodents in uncaged areas. This research tells us that small mammal populations are a necessity for New England tidal marshes in order to maintain healthy communities of native plants.
Read the research abstract here.
Wednesday, February 18, 2009
10,000 lakes...in Florida?
There has been debate about the value of secondary forest, and I have read similar debate about the equivalency of restored ecosystems to their natural counterparts. But what about another common semi-natural system, artificial lakes?
My grandmother lives in Florida in a condo development with an artificial lake behind her building. I’ve observed that, in Florida, there are many, many grandmothers who live adjacent to many, many artificial lakes. I’m not sure if the lakes are usually stocked with fish or not, but I’ve seen a good deal of birds around these lakes, such as the pictured group of white ibises, Eudocimus albus, and the cattle egret, Bubulcus ibis, below.
The abundance of waterbirds suggests some ecosystem value from artificial lakes. Some ecologists argue that birds are good indicators of community health (though probably not these birds, which are quite common in disturbed systems).
However, these lakes must be quite eutrophied. They are generally adjacent to well-trimmed lawns and golf courses that I presume are well-fertilized. A close-up photo of the lakewater nearshore shows a thick algal slime in the lake. To sum up: These artificial lakes are probably crappy habitat, but at least there are a lot of them…
My grandmother lives in Florida in a condo development with an artificial lake behind her building. I’ve observed that, in Florida, there are many, many grandmothers who live adjacent to many, many artificial lakes. I’m not sure if the lakes are usually stocked with fish or not, but I’ve seen a good deal of birds around these lakes, such as the pictured group of white ibises, Eudocimus albus, and the cattle egret, Bubulcus ibis, below.
The abundance of waterbirds suggests some ecosystem value from artificial lakes. Some ecologists argue that birds are good indicators of community health (though probably not these birds, which are quite common in disturbed systems).
However, these lakes must be quite eutrophied. They are generally adjacent to well-trimmed lawns and golf courses that I presume are well-fertilized. A close-up photo of the lakewater nearshore shows a thick algal slime in the lake. To sum up: These artificial lakes are probably crappy habitat, but at least there are a lot of them…
Friday, February 6, 2009
Avoiding the mistakes of FDR's CCC
I published an oped in today's Providence Journal:
PRESIDENT Franklin D. Roosevelt took dramatic action in his first 100 days in office in 1933, establishing New Deal agencies that arguably saved our economy and completed valuable arts and public-works projects. Among Roosevelt’s most deeply felt contributions were those in environmental conservation, one of the president’s most enduring legacies.
As we face this new economic crisis, our new president is reading FDR’s playbook on how to rescue a floundering economy. President Obama’s new New Deal will likely mimic FDR’s strong commitment to conservation, and it should.
But as the president plans the next great environmental leap forward, and Rhode Island officials prepare lists of “shovel-ready” projects to be funded with economic-stimulus money, it is important we learn the lessons not only of FDR’s successes, but also of the programs that bequeathed serious environmental challenges to future generations.
Read on at the ProJo...Tuesday, February 3, 2009
forests, new and old: one is silver and the other's gold
Last week, The New York Times published an article (“New jungles prompt a debate on rainforests”), positing that saving old growth rainforest may be less important than previously thought because:
1) "By one estimate, for every acre of rain forest cut down each year, more than 50 acres of new forest are growing in the tropics on land that was once farmed, logged or ravaged by natural disaster."
2) "Globally, one-fifth of the world’s carbon emissions come from the destruction of rain forests, scientists say. It is unknown how much of that is being canceled out by forest that is in the process of regrowth."
I think this article has done a severe disservice to rainforest conservation, by giving legitimacy to uncertain ideas and unresolved hypotheses.
I consent that secondary forest likely has conservation value, in terms of both carbon sequestration capacity and wildlife habitat. Indeed, secondary forest clearly has a large conservation value when compared to cultivated land. However, it does not necessarily when compared with old growth forest. "[Dr. Wright, a STRI senior scientist] says new research suggests that 40 to 90 percent of rain-forest species can survive in new forest." A 60% loss of biodiversity, or anything close, is unacceptable, particularly in rainforests, where we have yet to discover the wonder, scientific mysteries, and human value of many of the species that reside there.
Despite reports that deforestation rates are declining, massive tracts of primary forest continue to be cut down or burned in many parts of the world. Although many small farmers are moving to cities, as the article points out, industrial agriculture has transformed the amount of clearing that can be accomplished by a small labor force. A colleague of mine, Shelby Hayhoe, works in Mato Grosso in Brazil, and tells me of soybean plantations as far as the eye can see, and expanded every year. Another colleague, Noé de la Sancha, studies the ever-disappearing forest fragments that remain between soybean fields in Paraguay. Even if secondary forest in Panama can support high diversity, I worry for the species endemic to these South American regions, where forest is still rapidly disappearing.
Although The New York Times’ article gives voice to dissenting opinions and recognizes that the equivalency of secondary forest is still in question, I am not sure all readers will get past the photo caption, describing a former farm as “land now reverting to nature, a trend dimming the view of primeval forests as sacred.”
Old growth and new growth and everything in between. A canopy walk in Belize, where forests have been growing back for centuries, but are still heavily influenced by local Maya.
1) "By one estimate, for every acre of rain forest cut down each year, more than 50 acres of new forest are growing in the tropics on land that was once farmed, logged or ravaged by natural disaster."
2) "Globally, one-fifth of the world’s carbon emissions come from the destruction of rain forests, scientists say. It is unknown how much of that is being canceled out by forest that is in the process of regrowth."
I think this article has done a severe disservice to rainforest conservation, by giving legitimacy to uncertain ideas and unresolved hypotheses.
I consent that secondary forest likely has conservation value, in terms of both carbon sequestration capacity and wildlife habitat. Indeed, secondary forest clearly has a large conservation value when compared to cultivated land. However, it does not necessarily when compared with old growth forest. "[Dr. Wright, a STRI senior scientist] says new research suggests that 40 to 90 percent of rain-forest species can survive in new forest." A 60% loss of biodiversity, or anything close, is unacceptable, particularly in rainforests, where we have yet to discover the wonder, scientific mysteries, and human value of many of the species that reside there.
Despite reports that deforestation rates are declining, massive tracts of primary forest continue to be cut down or burned in many parts of the world. Although many small farmers are moving to cities, as the article points out, industrial agriculture has transformed the amount of clearing that can be accomplished by a small labor force. A colleague of mine, Shelby Hayhoe, works in Mato Grosso in Brazil, and tells me of soybean plantations as far as the eye can see, and expanded every year. Another colleague, Noé de la Sancha, studies the ever-disappearing forest fragments that remain between soybean fields in Paraguay. Even if secondary forest in Panama can support high diversity, I worry for the species endemic to these South American regions, where forest is still rapidly disappearing.
Although The New York Times’ article gives voice to dissenting opinions and recognizes that the equivalency of secondary forest is still in question, I am not sure all readers will get past the photo caption, describing a former farm as “land now reverting to nature, a trend dimming the view of primeval forests as sacred.”
Old growth and new growth and everything in between. A canopy walk in Belize, where forests have been growing back for centuries, but are still heavily influenced by local Maya.
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