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Landuse Indicators |
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Introduction
Changes in landscape due to such activities as agriculture, silviculture, fishing, urban sprawl and transportation infrastructure have been recognized for some time as one of the major causes of the loss of biodiversity planet-wide.
There have been several efforts at all levels from the local to the global to develop indicators for land use that would capture the effects of changing land use patterns on biodiversity (Oregon Biodiversity Project; Heinz Center Project; WWF project; TNC and Natural Heritage efforts). However, there is no consensus framework for measuring or tracking these impacts. In addition, there has been little work that attempts to link indicators of land use that are valid at the local level (i.e. the level of the individual land owner) and the regional and national level indicators that are important to the public policy debate.
The lack of a consistent measurement tool or tools (i.e., indicators) makes it difficult to assess relative impacts and direct programs towards better conservation practices. It makes it difficult for the individual decision maker to tell what steps should be taken on a particular piece of land to promote biodiversity.
Recognizing this need, the Defenders of Wildlife and the Institute for Environmental Research and Education (IERE) organized a workshop at the Defenders of Wildlife's national offices in Washington D.C. held on 13 July 2000. The workshop was attended by representatives of environmental NGO's, the U.S. Government, university researchers and business. Interests ranged widely, but most of the participants had direct experience in developing or using indicators or standards for environmental performance. A list of attendees can be viewed here. This workshop was envisioned as a first of several, beginning the dialog towards some consensus. Future workshops should include international input. The ultimate goal is to have indicators that can be used anywhere in the world, and that could aggregate impacts in multiple locations.
One of the drivers for this workshop was the need of IERE to have indicators for land use that can be used for a life cycle impact assessment of agricultural products. IERE is developing an ecolabel based on life cycle assessment that will provide agricultural porducers with an incentive for improved environmental performance, including protecting biodiversity values (see the slides from Rita's Presentation).
The following sections summarize the discussion carried out throughout the day. Many topics were presented and revisited during the day, so the summary is organized by topic, rather than chronologically.
Workshop Discussion
Indicators
The attendees of the workshop came from very different backgrounds, and some time was spent discussing and clarifying concepts. Conceptually, indicators can be seen to fall along a continuum form pressure to state indicators. Pressure indicators are those relating to actions taken by human beings, for example, building roads or plowing fields. State indicators are measures of the condition of the environment, for example, diversity of animals and plants, or the fragmentation of ecosystems.
After some discussion, there was a clear desire to prefer measurement of the environmental state over environmental pressure indicators. However, there was some recognition that pressure indicators are generally easier to obtain, and represent leading rather than trailing indicators. As a practical matter they may be the best option until better data becomes available.
Although there is an immediate need for land use indicators that can be applied to agricultural areas, such indicators should be applicable to other landscapes, such as forestland, urban, and industrial environments. Further, the focus of this effort was on direct land use impacts, not on issues such as pesticide use or nutrient management. That is to say, that physical rather than chemical alterations were the topic of interest.
Aggregation
One important aspect of environmental indicators is how well they can be aggregated. It is important that the information that is gathered can be rolled up to higher levels to meet different needs. For example, although land use decisions are made on a field by field basis on farms, policy makers need to look at the aggregated land use over many farms. In addition, one may wish to look at aggregation of land use decisions over time as well as space. Time trend analysis is one way to think about this, but also, the data sampled at different times should be comparable: randomized methodologies will sample different points at different times.
In addition, we may wish to aggregate different measures of land use to achieve a single indicator of impacts. For example, one might want to aggregate landuse decisions on farms with use decision for forests. One participant likened this to adding up apples and oranges to get fruit. Very often, policy makers need to know the size of the total fruit basket, not the individual apples and oranges.
Several participants raised questions about temporal trends issues. The U.S. Government has several reserve programs, including the Conservation Reserve Program, and the Wetlands Reserve Program. Many of these programs have a time limit on their reserve status. For example after a ten-to-fifteen year contract period, land in the conservation reserve program (CRP) may come out of reserve status, depending on the decision of the producer. At the moment, no one is tracking what happens to those lands once they leave the program. This raises the issue of the value of temporary reserves. However, further discussion of this important issue was tabled for later meetings.
Issues of Scale and System Integrity
If we wish to have indicators of land use, they must provide useful guidance to decision-makers on actions that should be taken. In this context, the group discussed the issues of ecosystem integrity and scale. Ecologists have known for decades that the fragmentation of environments leads to the loss of species diversity. So the question arises: how large a piece of land must be preserved in order to preserve biodiversity values?
One attendee suggested that units of 25,000 acres were appropriate units to evaluate, especially in a grasslands/prairie ecosystem. This size of planning unit permits management of mammals and birds. If at least 30% the land is being managed for biodiversity values, then bird populations seem quite healthy. Another attendee notes that quite small units, on the order of one acre can be important for the preservation of amphibians and reptiles. There was general consensus that the appropriate planning size depends on the species one is interested in preserving and that progress can be made on all scales.
Possibly the most important issue of preserving systems integrity is access to open waters. The interface between water and land is important to all animals, and protecting this area may well be the best first step towards preserving wildlife.
There was also general recognition that the focus on animals was less useful than the focus on plants. Animals are entirely dependent on the primary production and the physical environment provided by plants, and being mobile, they have the opportunity to leave undesirable habitats. Animals are also often flexible with respect to the actual plants they associate with. For example, cornfields have replaced native grasses as a source of protective habitat and to a lesser extent, food for some birds. In a similar fashion, flooded rice fields provide habitat for migrating water birds. As a practical matter, the rooted nature of plants makes them much better subjects for sampling by remote sensing.
Another approach for indicators of biodiversity and land use is to focus on the issue of the functions of the ecosystem, rather than its specific components. In looking at system function, we might look at ground cover, soil fertility, the interaction of land and water and so forth. Focusing on these issues, especially as they pertain to plant species coverage might give good indicators of the environmental state of the system.
Brainstorming Indicators
The group undertook a brainstorming effort to identify potentially useful indicators. After consolidation of similar ideas, the following list was developed.
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Data Sources
Throughout the day, many potential sources of data for evaluating the environmental state of various locations were mentioned. These were augmented by discussions after the workshop. A brief list is shown below.
Summary Conclusions and Further Work
The workshop brought together individuals with the background and interest necessary to begin the process of developing useful indicators for land use/biodiversity that can be used at all scales. These preliminary discussions identified several areas of concurrence that should be evaluated to measure the impacts of land use. Considering the diverse backgrounds of the individuals at this workshop, the convergence of thought towards a few indicators was very encouraging.
We anticipate that developing good indicators will take several years, and it will be important to bring in our colleagues from other countries, in order to develop a global perspective. Over the next several months, we will be contacting our colleagues overseas to inform them of our efforts and to invite them to participate in our efforts.
IERE will be testing these indicators in the field over the next year. IERE is working with farmers in the Midwest to improve their overall environmental performance, as measured by a life cycle assessment. In addition to land use indicators, IERE will be measuring a comprehensive group of environmental indicators including:
To evaluate land use decisions, IERE will be measuring the parameters described in the table below, and will report back to this group the results of that effort.
IERE's efforts need to be complemented by the efforts of others in different environments. While the primarily agricultural/prairie one that they are studying is an important one from the point of view of the landuse impacts of agricultural practice, other landscapes, such as urban and forest landscapes are equally important.
| Biodiversity Indicators | Proposed Measures | |
| 1 | Protection of priority habitats/species |
Acreage of habitat that is physically protected (i.e.; through fencing or other methods); habitat to be identified as including
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| 2 | Soil characteristics: soil health | Concentration of organic carbon in the soil |
| 3 | Proximity to & protection of high priority vegetative communities | Acreage of habitat set aside (not farmed) that is identified as "high priority" in TNC vegetative maps |
| 4 | Interface between water and terrestrial habitats/buffer zones | Total linear space of aquatic habitat (i.e. river, lakeshore, etc) protected via physical means vs. total area managed |
| 5 | Assimilative capacity of water and land (TMDL process); hydrological function; | Depletion of water resources (annual use versus recharge rate) |
| 6 | Percent coverage of invasive species (within protected areas) | For physically protected areas, density of non-native vegetation (area percent) |
| 7 | Road density | Miles of road per square mile |
| 8 | Percent native-dominated vegetation | Acreage in native species dominated areas/total area managed |
| 9 | Restoration of native vegetation | Acreage newly returned (in last 12 months) to native habitat |
| 10 | Adoption of BMP’s linked to biodiversity objectives | Number of BMP's adopted |
| 11 | Distribution (patchiness; evenness, etc.) |
Size of native-managed acres vs. total acres managed Size of native-managed acres vs. average field size |
| 12 | Connectivity of native habitat | On managed acres, percent of native-managed land units that has at least one adjacency to other native-managed land |