Photo:Rio Grande, Big Bend National Park. Saltcedar and Giant Cane dominate the vegetation. Copyright 2017 Delena Norris-Tull
Ecosystems Health
The goal of the management of ecosystems, such as that being done in weed management, will have to pay attention to the overall health of the entire ecosystem. When I began this project of examining how various State, local, and Federal Agencies were responding to the management of invasive plants, I had hopes that I would find a well-coordinated system. But the more I have examined the issues around managing invasive plants, the more I see disconnected and fragmented processes. While many agencies recognize the value of paying attention to ecosystems as a whole, poor funding usually results in a reductionist approach. For example, much of the funding at State and County levels is focused on herbicide applications, with little effort and funding going to replacing invasive plants with native plants, or paying attention to the impact that killing weeds has on the remaining ecosystem.
For example, while many States have one office, typically within the State Department of Agriculture, devoted to management of invasive plants, funding to assist in coordinating County and local agencies within the State is often minimal. And funding for coordination between State and Federal Agencies is also minimal, sometimes resulting in a lack of adequate coordination. Many Federal Agencies have an office that is responsible for managing weeds, and again, coordination between those agencies is minimal. The result is a reductionist approach to management, with the focus on eradication of individual species of plants, with little attention to the interactions between invasive species and between invasive species and native plants, and the effects of management practices, which often consists of little more than simply spraying herbicides, on the ecosystem as a whole.
“Health and the phenomenon of healing have meant different things in different ages… What is meant by health depends on one’s view of a living organism and its relation to its environment. As this view changes from one culture to another, and from one era to another, the notions of health also change. The broad concept of health that will be needed for our cultural transformation - a concept that includes individual, social, and ecological dimensions - will require a systems view of living organisms and, correspondingly, a systems view of health… In modern scientific terms we could say that the healing process represents the coordinated response of the integrated organism to stressful environmental influences” (Capra, 1982, p. 124-125).
Ecosystems Health along the Rio Grande
Research by Kelly & Finch (1999) is one of many studies of the impact of an invasive plant species within an ecosystem. They examined the impact of saltcedar (Tamarisk ramosissima), a large invasive tree, on the riparian habitat of the Rio Grande, which forms the border of Texas with Mexico. They "compared diversity, abundance and energetic condition of migrant landbirds captured in four different vegetation types in the Bosque del Apache National Wildlife Refuge." "Large numbers of en-route migrants use these riparian areas as stopover habitat and they likely represent a critical resource for successful migration... The bosque was historically dominated by cottonwood-willow vegetative associations." Two changes to the region have contributed to changes in the ecosystems in this region. Changes in the hydrograph (stream flow) of the river, and the introduction of saltcedar, which is now abundant there.
Over 240 species of birds breed in the Middle Rio Grande Valley, a number of whom are now endangered. As ecotourism has become a large source of income in this region, the reduction of biodiversity will have economic impacts.
In 1996 and 1997, Kelly & Finch (1999) carried out a mist netting project, to assess the numbers and condition of birds in the riparian vegetation. They combined that data with various other data sources. They assumed that if saltcedar provides poor habitat, they would find fewer numbers of birds, and their condition would be poorer, than in the native willows and cottonwoods in the region.
They captured 5,466 and banded individual birds, that represented118 species of birds. Five families accounted for 80% of capture, warblers, sparrows, flycatchers, thrushes and grosbeaks. They collected data on the condition of seven bird species, which represented greater than 200 individuals, three warblers, three sparrows, and the Ruby Crowned Kinglet.
"Rarefaction curves indicate that the diversity of migrants captured in saltcedar was lower than that captured in native cottonwood and willow in 3 of the 4 seasons examined...; the exception was spring 1997," when there was no significant differences in variation. "There was also a tendency for diversity of birds captured to be lower in agriculture edge than in native bosque vegetation."
Kelly & Finch found "lower species diversity among migrants caught in exotic saltcedar vegetation than in native willow or cottonwood." Contrary to their expectations, they found that, "In general, migrants were most abundant in agricultural edge and least abundant in cottonwood. There were no consistent patterns in energetic condition of common species among vegetation types. Ninety percent of statistical tests for variation in mass and fat score among vegetation types showed no significant difference. The few significant tests indicated that (1) Chipping Sparrows caught in saltcedar tended to be in poorer energetic condition than those caught in other vegetative types; (2) Ruby-crowned Kinglets captured in saltcedar tended to be in better energetic condition than those in other vegetative types; (3) The relationship between energetic condition of Wilson’s Warbler’s and vegetation types varied with year and season."
In attempting to understand potential causes for the lack of consistent variation in energetic condition, they looked at research conducted on arthropod diversity in the same net area. Several researchers found no significant variation in arthropod communities between vegetation types. Thus, some found that the main food source for many bird species is similar in each vegetation type. In contrast, other researchers found significant variation in arthropod communities, with fewer arthropods in saltcedar than in native vegetation.
A recent political development along the Rio Grande is the creation of a very tall wall on the southern border of Texas, used to discourage immigrants from Mexico and other Central American countries from entering the USA illegally. I recently went on a bird watching trip to several National Parks and National Wildlife Refuges, including the Bosque del Apache, that occur in South Texas along the Rio Grande. The Federal Government was able to build this large wall with little fanfare because they built it right through a series of Federal lands. Apparently no Environmental Impact Studies were conducted before the building of the wall. I feel confident that any such study would have highlighted the disruption of the wall to many species of animals, such as birds and mammals, that rely on the riparian habitat along the Rio Grande, for food and habitat.
Reference:
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Ecosystems Health
The goal of the management of ecosystems, such as that being done in weed management, will have to pay attention to the overall health of the entire ecosystem. When I began this project of examining how various State, local, and Federal Agencies were responding to the management of invasive plants, I had hopes that I would find a well-coordinated system. But the more I have examined the issues around managing invasive plants, the more I see disconnected and fragmented processes. While many agencies recognize the value of paying attention to ecosystems as a whole, poor funding usually results in a reductionist approach. For example, much of the funding at State and County levels is focused on herbicide applications, with little effort and funding going to replacing invasive plants with native plants, or paying attention to the impact that killing weeds has on the remaining ecosystem.
For example, while many States have one office, typically within the State Department of Agriculture, devoted to management of invasive plants, funding to assist in coordinating County and local agencies within the State is often minimal. And funding for coordination between State and Federal Agencies is also minimal, sometimes resulting in a lack of adequate coordination. Many Federal Agencies have an office that is responsible for managing weeds, and again, coordination between those agencies is minimal. The result is a reductionist approach to management, with the focus on eradication of individual species of plants, with little attention to the interactions between invasive species and between invasive species and native plants, and the effects of management practices, which often consists of little more than simply spraying herbicides, on the ecosystem as a whole.
“Health and the phenomenon of healing have meant different things in different ages… What is meant by health depends on one’s view of a living organism and its relation to its environment. As this view changes from one culture to another, and from one era to another, the notions of health also change. The broad concept of health that will be needed for our cultural transformation - a concept that includes individual, social, and ecological dimensions - will require a systems view of living organisms and, correspondingly, a systems view of health… In modern scientific terms we could say that the healing process represents the coordinated response of the integrated organism to stressful environmental influences” (Capra, 1982, p. 124-125).
Ecosystems Health along the Rio Grande
Research by Kelly & Finch (1999) is one of many studies of the impact of an invasive plant species within an ecosystem. They examined the impact of saltcedar (Tamarisk ramosissima), a large invasive tree, on the riparian habitat of the Rio Grande, which forms the border of Texas with Mexico. They "compared diversity, abundance and energetic condition of migrant landbirds captured in four different vegetation types in the Bosque del Apache National Wildlife Refuge." "Large numbers of en-route migrants use these riparian areas as stopover habitat and they likely represent a critical resource for successful migration... The bosque was historically dominated by cottonwood-willow vegetative associations." Two changes to the region have contributed to changes in the ecosystems in this region. Changes in the hydrograph (stream flow) of the river, and the introduction of saltcedar, which is now abundant there.
Over 240 species of birds breed in the Middle Rio Grande Valley, a number of whom are now endangered. As ecotourism has become a large source of income in this region, the reduction of biodiversity will have economic impacts.
In 1996 and 1997, Kelly & Finch (1999) carried out a mist netting project, to assess the numbers and condition of birds in the riparian vegetation. They combined that data with various other data sources. They assumed that if saltcedar provides poor habitat, they would find fewer numbers of birds, and their condition would be poorer, than in the native willows and cottonwoods in the region.
They captured 5,466 and banded individual birds, that represented118 species of birds. Five families accounted for 80% of capture, warblers, sparrows, flycatchers, thrushes and grosbeaks. They collected data on the condition of seven bird species, which represented greater than 200 individuals, three warblers, three sparrows, and the Ruby Crowned Kinglet.
"Rarefaction curves indicate that the diversity of migrants captured in saltcedar was lower than that captured in native cottonwood and willow in 3 of the 4 seasons examined...; the exception was spring 1997," when there was no significant differences in variation. "There was also a tendency for diversity of birds captured to be lower in agriculture edge than in native bosque vegetation."
Kelly & Finch found "lower species diversity among migrants caught in exotic saltcedar vegetation than in native willow or cottonwood." Contrary to their expectations, they found that, "In general, migrants were most abundant in agricultural edge and least abundant in cottonwood. There were no consistent patterns in energetic condition of common species among vegetation types. Ninety percent of statistical tests for variation in mass and fat score among vegetation types showed no significant difference. The few significant tests indicated that (1) Chipping Sparrows caught in saltcedar tended to be in poorer energetic condition than those caught in other vegetative types; (2) Ruby-crowned Kinglets captured in saltcedar tended to be in better energetic condition than those in other vegetative types; (3) The relationship between energetic condition of Wilson’s Warbler’s and vegetation types varied with year and season."
In attempting to understand potential causes for the lack of consistent variation in energetic condition, they looked at research conducted on arthropod diversity in the same net area. Several researchers found no significant variation in arthropod communities between vegetation types. Thus, some found that the main food source for many bird species is similar in each vegetation type. In contrast, other researchers found significant variation in arthropod communities, with fewer arthropods in saltcedar than in native vegetation.
A recent political development along the Rio Grande is the creation of a very tall wall on the southern border of Texas, used to discourage immigrants from Mexico and other Central American countries from entering the USA illegally. I recently went on a bird watching trip to several National Parks and National Wildlife Refuges, including the Bosque del Apache, that occur in South Texas along the Rio Grande. The Federal Government was able to build this large wall with little fanfare because they built it right through a series of Federal lands. Apparently no Environmental Impact Studies were conducted before the building of the wall. I feel confident that any such study would have highlighted the disruption of the wall to many species of animals, such as birds and mammals, that rely on the riparian habitat along the Rio Grande, for food and habitat.
Reference:
- Capra, F. (1982). The Turning Point: Science, Society, and the Rising Culture. New York: Bantam Books.
- Kelly, J.F., & Finch, D.M. (1999). Use of saltcedar vegetation by landbirds migrating through the Bosque del Apache National Wildlife Refuge, in Finch, et al., Rio Grande ecosystems: Linking land, water, and people. USDA.
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