The MP divides this criterion into three subcriteria: ecosystem diversity, species diversity, and genetic diversity. The indicators in the criterion are organized accordingly, addressing first the extent, conservation status, and structure of different forest ecosystem types; then the number and status of forestassociated species along with related conservation efforts; and, finally, a similar set of indicators describing genetic diversity of forest-associated species. Several of the indicators in the species and genetic diversity subcriteria address “species at risk” in their titles, a category comparable to the concept of threatened or endangered species in the United States but more broadly defined (and lacking the same legal implications).
Current data allow us to present a relatively complete picture of the overall extent of forest ecosystem types and their conservation status. The total area of forests in the United States currently stands at 751 million acres. Overall, this number has been stable to slightly increasing in recent decades. Gains in broadleaved forests in the Southern and interior Northern Regions have been largely offset by declines in forest area in the more developed coastal regions, particularly in coniferous forests.
Although the size of forest area may be relatively stable, the other indicators in the criterion paint a more troubling picture about forest sustainability. Though the data on forest fragmentation presented in this report are not directly comparable to those in 2003, common knowledge and anecdotal evidence strongly suggests that the area of forests impacted by fragmentation has been increasing at a steady rate. Impacted areas include lands on the fringes of major population centers and in rural areas where growth in smaller centers and in the number of second homes continues to drive development and thereby fragmentation. This conclusion is supported by the information on the impacts of housing development on forest area included in Indicator 3.16.
Species richness and genetic diversity of forest-associated species are closely linked to the availability and quality of forest ecosystems. These ecosystems, in turn, are impacted by human and natural forces––such as development patterns, fire suppression, and climate change. As a result, species diversity and healthy populations of keystone species are viewed as crucial indicators of forest sustainability. The indicators covering species richness and genetic diversity do not yield a clear signal regarding changes in richness and diversity since 2003. The inability to compare current data with past data is due in large part to increased sampling intensity resulting in higher species counts and the identification of more species at risk during the past decade (the more you look, the more you find). In addition, changes in richness and diversity are highly variable across geographic regions and general species categories (vascular plants, mammals, birds, and so on), with declines in species counts in some areas or categories being offset by gains in others. Ideally, we will be able to develop more consistent ways of tracking these indicators over time, but changing taxonomy and improved sampling will remain a challenge. Currently, 28 percent of forest-related species have been determined to be presumed or possibly extinct (1 percent), or at risk of extinction (27 percent––includes imperiled, critically imperiled, or vulnerable).
In addition to the indicators in Criterion 1 that describe the extent and condition of forests and their biological components, three indicators in this criterion describe our society’s efforts to conserve these resources. Of these indicators, only Indicator 1.2, which measures the area of protected forests, was reported in 2003. The area of forests that are formally protected by government designation totals some 106 million acres; this number has changed little since 2003. At the same time, alternative ways of protecting forests through land trusts and conservation easements have been gaining popularity, accounting in total for more than 10 million acres in 2005 (http://www.landtrustalliance.org/). This acreage is small relative to the size of the officially designated protected areas, but it is an important addition to the U.S. portfolio of protected forest lands and has been growing rapidly. Indicator 6.27, which tracks payments for ecosystem services, including conservation easements, provides more information on this topic.
Indicators 1.6 and 1.9 describe U.S. efforts to conserve species and genetic resources respectively. These indicators are new, and, because they cover a broad spectrum of activities on the part of the Government, academia, and the private sector, they are not easy to measure. The information presented for these indicators in Part II provides a picture of the breadth of current activities in this area, ranging from experimental forests and wildlife conservation areas to zoos and seed banks. It does not, however, indicate whether these activities have increased, nor does it answer the crucial question of whether they are adequate to help secure the sustainability of biological diversity in our forests. Future editions of this report should be able to better answer these questions.