Treesearch

We review research on surface water hydrology and soil erosion at the Santa Rita Experimental Range (SRER). Almost all of the research was associated with eight small experimental watersheds established from 1974 to 1975 and operated until the present. Analysis of climatic features of the SRER supports extending research findings from the SRER to broad areas of the Southwest with similar climates. Conceptual models for annual water balance and annual sediment yield at the SRER were developed and supported by data from four very small experimental watersheds. The impacts of rotation and...

The Santa Rita Experimental Range (SRER) is both an archive of past ecological research and a laboratory for continuing research embedded in the southern Arizona landscape. The scientific questions being asked there have changed over the last 100 years, but SRER with its monitoring stations and its legacy of repeat photography still offers a unique opportunity to study environmental change through time. Now that it belongs to the State of Arizona, however, the Arizona State Land Department (ASLD) could conceivably sell it for commercial development if the Arizona legislature were to revoke...

Climatic variability is reflected in differential establishment, persistence, and spread of plant species. Although studies have investigated these relationships for some species and functional groups, few have attempted to characterize the specific sequences of climatic conditions at various temporal scales (subseasonal, seasonal, and interannual) associated with proliferation of particular species. Research has primarily focused on the climate conditions concurrent with or occurring just prior to a vegetation response. However, the cumulative effect of antecedent conditions taking place...

At the centennial of the Santa Rita Experimental Range, historical analysis is called for on two levels. First, as a major site in the history of range ecology, the Santa Rita illuminates past successes and failures in science and management and the ways in which larger social, economic, and political factors have shaped scientific research. Second, with the turn away from equilibrium-based models in range science - a turn prompted in part by research at the Santa Rita - there is a growing need for history in range ecology itself. I discuss the needs, premises, and events underlying...

With the advent of satellite remote sensing and computing technology, mapping land cover over extensive regions of the earth has become practical and cost effective. For example, land-cover maps have been produced covering pan-Europe (Mucher et al., 2000), Great Britain (Fuller et al., 1994), Canada (Cihlar et al., 1999), Mexico (Mas et al., 2002) the United States (Vogelmann et al., 2001), and the globe (Belward et al., 1999). Franklin and Wulder (2002) assemble a diverse array of other examples of large-area, land-cover maps. Land-cover maps are typically an intermediate product, used,...

The growing literature on ecosystem management describes an adaptive system in which monitoring measures progress toward goals, increases our knowledge, and improves our plans (e.g., Holling 1978; Walters 1986; Duffus III 1994; Everett et al. 1994; Grumbine 1994; Bormann et al. 1995; Gunderson et al. 1995; Interagency Ecosystem Management Task Force 1995; Montgomery et al. 1995; Christensen et al. 1996; Yaffee et al. 1996). Adaptive management acknowledges that action is necessary or appropriate, although knowledge may be imperfect (Raiffa 1968; Holling 1978; Walters 1986; Everett et al....

The performance of three classes of weighted average estimators is studied for an annual inventory design similar to the Forest Inventory and Analysis program of the United States. The first class is based on an ARIMA(0,1,1) time series model. The equal weight, simple moving average is a member of this class. The second class is based on an ARIMA(0,2,2) time series model. The final class is based on a locally weighted least-squares regression prediction. The estimator properties were tested using a simulation population created from Forest Inventory and Analysis (FIA) data from northeastern...

While the importance of canopy structure in open woodlands and savannas on regulating the flow of energy and matter is well known, few studies have investigated how variation in overstory abundance influences canopy light transmission and the extent that estimates vary in their ability to characterize the light environment in these ecosystems. Canopy light transmittance (% photosynthetic photon flux density, or %PPFD) was measured with gallium arsenide phosphide (GaAsP) photodiodes and was monitored throughout the growing season in an open-canopy longleaf pine (Pinus palustris Mill.)...

Body mass is routinely used as an index of physical condition for comparing small-mammal populations. However, trapping effects on animals may undermine the effectiveness of body mass as an index of population health. We examined the effects of live-trapping on body mass of 3 small-mammal species: deer mice (Peromyscus maniculatus), southern red-backed voles (Clethrionomys gapperi), and red-tailed chipmunks (Tamias ruficaudus). We found that live-trapping resulted in significant trap-induced body mass declines (TMDs) that varied by species, age, and sex. Longer rest intervals between...

Establishing cause-effect is critical in the field of natural resources where one may want to know the impact of management practices, wildfires, drought, etc. on water quality and quantity, wildlife, growth and survival of desirable trees for timber production, etc. Yet, key obstacles exist when trying to establish cause-effect in such contexts. Issues involved with identifying a causal hypothesis, and conditions needed to estimate a causal effect or to establish cause-effect are considered. Ideally one conducts an experiment and follows with a survey, or vice versa. In an experiment, the...