310 



Interior V/esl — Our Living Rcsmirces 



is on timber-management sites. 



The last two articles focus on restoring 

 ecosystem integrity by reintroducing extiipated 

 species. Singer reports that the success of 

 restoration efforts of bighorn sheep (Oris 

 caiiMlensis) in the Rocky Mountains is influ- 

 enced negatively by their proximity to domestic 

 sheep and by small, translocated groups of 

 bighorn sheep that are too genetically similar. 

 McCutchen discusses the history and status of 

 deseil bighorn {O.c. iwlsoni) and shows that 

 sheep translocations have been fairly success- 

 ful, except in New Mexico and southern 

 California. 



It is important to note the overriding theme 

 in this section: modem humans continue to alter 

 ecosystem components and processes. To man- 

 age natural resources in a sustainable way to 

 meet the needs of the American people, we 

 must first understand the inseparable link of 

 human and resource ecology. The perpetuation 

 of biological diversity in the Interior West 

 depends largely on coordinated, multiscale 

 ecosystem science, and resource inventory and 

 monitoring efforts. 



Ecosystem 

 Trends in the 

 Colorado 

 Rockies 



by 

 Thomas J. Stohlgren 



Jill Baron 



National Biological Service 



Timothy G.F. Kittel 



University Corporation for 

 Atmospheric Research 



Dan Brinkley 

 Colorado State Universitv 





-.r....«i=: 



Fig. 1. Drastically increased 

 urbanization in Estes Park/Rocky 

 Mountain National Park. 1921 

 (above) to 1986 (below). The pho- 

 tographs also show, however, for- 

 est recovery from tum-of-the-cen- 

 tury logging and human-caused 

 fires (Veblen and Lorenz 1991 ). 



Biological conservation is increasingly mov- 

 ing toward an ecosystem and landscape 

 approach, recognizing the prohibitive cost and 

 difficulty of a species-by-species approach 

 (LaRoe 1993). Also, statewide (e.g.. Gap 

 Analysis Program) and national surveys (e.g.. 

 Environmental Monitoring and Assessment 

 Program or EMAP) are conducted at a scale and 

 level of resolution that do not meet the needs of 

 most small land-management units that require 

 detailed information at the ecosystem and land- 

 scape scale (Stohlgren 1994). The Colorado 

 Rockies are an ideal outdoor laboratory for 

 ecosystem science and management. The esca- 

 lating environmental threats described in this 

 article compelled us to design a landscape-scale 

 assessment of the status and trends of biotic 

 resources. 



Our guiding principle is that a strong ecosys- 

 tem science program provides crucial informa- 

 tion for ecosystem management and wise stew- 

 ardship. We define ecosystem science as the 

 long-term, interdisciplinary study of ecosystem 

 components and processes and their interac- 

 tions at multiple spatial, temporal, and organi- 

 zational scales, to meet management needs. 



About 76% of the land adjacent to Rocky 

 Mountain National Park is federal land. While 

 the area has not received as much attention as 

 the Greater Yellowstone Ecosystem, there may 

 be as many internal and external threats to the 

 natural resources in the area. The Colorado 

 Rockies are an archetypal ecosystem under 

 siege. Like many national parks, wilderness 

 areas, wildlife refuges, and other natural areas, 

 common threats include encroachment from 

 urbanization and development, habitat fragmen- 

 tation, fire suppression, nonindigenous species" 

 invasion, and global change (e.g., climate 

 change, bordering land-use changes, and air and 

 water pollution). Since all these threats tran- 

 scend ownership or stewardship borders, so 

 have interagency concerns for conservation, 

 inventory and monitoring, and research. 



Here we identify and quantify trends that 



threaten ecosystem integrity in Rocky Mountain 

 National Park and the Colorado Rockies. Our 

 specific objectives include presenting qualita- 

 tive information on vegetation change over the 

 past 65 years, documenting quantitative trends 

 of an ecosystem under siege, showing prelimi- 

 nary results of a long-term global change 

 research program, and discussing the role of 

 ecosystem science in assessing long-term trends 

 in ecosystem condition. 



Status and Trends 



There is little doubt that the ecosystems of 

 the Colorado Rockies have been altered signifi- 

 cantly by humans. The density of ponderosa 

 pine woodlands has increased (Fig. 1) as has 

 suburban development (Veblen and Lorenz 

 1991). These qualitative changes are suppoHed 

 by qualitative measures (Fig. 2). The response 

 of the forest from turn-of-the-century logging 

 and fires showed a 5-fold increase in ponderosa 

 pine bole (see glossary) biomass. In addition, 

 the human population in Estes Park and the 

 number of visitors in Rocky Mountain National 

 Park have almost doubled since 1960. Urban 

 development throughout the Front Range of 

 Colorado has resulted in increased air pollution. 

 Annual wet deposition values for nitrate, 

 ammonium, and sulfate in the Loch Vale water- 

 shed of Rocky Mountain National Park are sig- 

 nificantly greater than the average values of 2-4 

 kg/ha (about 2-4 lb/acre) in remote areas of the 

 world (Fig. 2). 



Elk and moose populations continue to 

 increase in the park (Fig. 2) for many reasons 

 including reduced predation (wolves have been 

 extirpated) and hunting as well as diminished 

 habitat and migratory comdors outside the 

 park. Researchers are now quantifying ungulate 

 (hooved herbivores) habitat relationships and 

 aspen-willow community conservation. 

 Although agricultural land use in Larimer 

 County has declined slightly in recent years 

 (Fig. 2). landscape and ecosystem integrity is 



