|Abstract or Summary
- Western juniper (Jun iperus occidentalis Hook) is a species of juniper native to arid regions of the Pacific Northwest. The western juniper tree has a number of competitive strategies that, in conjunction with an almost complete removal of fire from the ecosystem, have resulted in a significant expansion of its population in the last 150 years. This increase is of concern since western juniper have numerous negative impacts on the ecosystems upon which they encroach. Western juniper can cause increased erosion, decreased production of herbaceous vegetation, decreased streamflows and increased stream sedimentation, increased bare ground, and changes in wildlife diversity and species abundance. However, because western juniper is both expensive and difficult to kill or harvest, and because there is a limited market for its wood and other western juniper products, the expansion of western juniper populations throughout parts of the Pacific Northwest occurs largely unimpeded.
Within western juniper's range in central and eastern Oregon, much of the land is owned by and operated as beef cattle ranches. As western juniper encroach upon a site, the reduction in herbaceous vegetation causes a decrease in the number of livestock the site can support. As the ability of rangeland to support livestock declines, ranch profits will also likely diminish Despite this trend, clearing of western juniper has historically been limited.
This research presents discrete-time, dynamic economic models developed to depict various representative ranches located in the John Day Ecological Province of Oregon, the area of the greatest distribution of western jumper and where the majority of research regarding the western juniper has been conducted. The bioeconomic models are developed to examine optimal ranch management
practices. The optimization criterion is to maximize the net present value of gross
margins through decisions regarding herd size and composition, cattle sales, and the manipulation of forage production through juniper management practices. Comparisons are made to models in which juniper control is not a management option. Results indicate that it is indeed profitable for ranchers to practice juniper management on rangeland pastures. Models that included juniper management options consistently resulted in treatment of a minimum of seventy percent of
juniper-encroached rangelands, larger equilibrium herd sizes, and greater gross
margins. Erosion levels, and therefore potential stream sedimentation, was
substantially lower in the models that contained juniper management options. Other environmental externalities included increased quail densities, but lower deer and elk populations.