K. Bruce Jones

Predicting nutrient and sediment loadings to streams from landscape metrics: A multiple watershed study from the United States Mid-Atlantic Region

There has been an increasing interest in evaluating the relative condition or health of water resources at regional and national scales. Of particular interest is an ability to identify those areas where surface and ground waters have the greatest potential for high levels of nutrient and sediment loadings. High levels of nutrient and sediment loadings can have adverse effects on both humans and aquatic ecosystems. We analyzed the ability of landscape metrics generated from readily available, spatial data to predict nutrient and sediment yield to streams in the Mid-Atlantic Region in the United States. We used landscape metric coverages generated from a previous assessment of the entire Mid-Atlantic Region, and a set of stream sample data from the U.S. Geological Survey. Landscape metrics consistently explained high amounts of variation in nitrogen yields to streams (65 to 86% of the total variation). They also explained 73 and 79% of the variability in dissolved phosphorus and suspended sediment. Although there were differences in the nitrogen, phosphorus, and sediment models, the amount of agriculture, riparian forests, and atmospheric nitrate deposition (nitrogen only) consistently explained a high proportion of the variation in these models. Differences in the models also suggest potential differences in landscape-stream relationships between ecoregions or biophysical settings. The results of the study suggest that readily available, spatial data can be used to assess potential nutrient and sediment loadings to streams, but that it will be important to develop and test landscape models in different biophysical settings.

Global-Scale Patterns of Forest Fragmentation

We report an analysis of forest fragmentation based on 1-km resolution land-cover maps for the globe. Measurements in analysis windows from 81 km 2 (9 x 9 pixels, “small” scale) to 59,049 km 2 (243 x 243 pixels, “large” scale) were used to characterize the fragmentation around each forested pixel. We identified six categories of fragmentation (interior, perforated, edge, transitional, patch, and undetermined) from the amount of forest and its occurrence as adjacent forest pixels. Interior forest exists only at relatively small scales; at larger scales, forests are dominated by edge and patch conditions. At the smallest scale, there were significant differences in fragmentation among continents; within continents, there were significant differences among individual forest types. Tropical rain forest fragmentation was most severe in North America and least severe in Europe–Asia. Forest types with a high percentage of perforated conditions were mainly in North America (five types) and Europe–Asia (four types), in both temperate and subtropical regions. Transitional and patch conditions were most common in 11 forest types, of which only a few would be considered as “naturally patchy” (e.g., dry woodland). The five forest types with the highest percentage of interior conditions were in North America; in decreasing order, they were cool rain forest, coniferous, conifer boreal, cool mixed, and cool broadleaf.

Fragmentation of Continental United States Forests

AbstractWe report a multiple-scale analysis of forest fragmentation based on 30-m (0.09 ha pixel−1) land-cover maps for the conterminous United States. Each 0.09-ha unit of forest was classified according to fragmentation indexes measured within the surrounding landscape, for five landscape sizes including 2.25, 7.29, 65.61, 590.49, and 5314.41 ha. Most forest is found in fragmented landscapes. With 65.61-ha landscapes, for example, only 9.9% of all forest was contained in a fully forested landscape, and only 46.9% was in a landscape that was more than 90% forested. Overall, 43.5% of forest was located within 90 m of forest edge and 61.8% of forest was located within 150 m of forest edge. Nevertheless, where forest existed, it was usually dominant—at least 72.9% of all forest was in landscapes that were at least 60% forested for all landscape sizes. Small (less than 7.29 ha) perforations in otherwise continuous forest cover accounted for about half of the fragmentation. These results suggest that forests are connected over large regions, but fragmentation is so pervasive that edge effects potentially influence ecological processes on most forested lands.

Monitoring environmental quality at the landscape scale

ver the past century, technological advances have greatly improved the standard of living in the United States. But these same advances have caused sweeping environmental changes, often unforeseen and potentially irreparable. Ethical stewardship of the environment requires that society monitor and assess environmental changes at the national scale with a view toward the conservation and wise management of our natural resources. Some of the most important environmental changes occur a t the spatial scale of landscapes. Obvious examples include clearcutting for lumber, urbanization, the loss of wetlands, and the conversion of forest and prairies into crop and grazing systems. Decisions about how to change land cover may be made by individual landowners, but their im-

Scaling and uncertainty analysis in ecology: Methods and applications

Dedication. Preface J. Wu et al. List of Contributors.- Part I. Concepts and Methods. 1. Concepts of scale and scaling J. Wu, H. Li. 2. Perspectives and methods of scaling J. Wu, H. Li. 3. Uncertainty analysis in ecological studies: An overview H. Li, J. Wu. 4. Multilevel statistical models and ecological scaling R.A. Berk , J. De Leeuw. 5. Downscaling abundance from the distribution of species: Occupancy theory and applications F. He, W. Reed. 6. Scaling terrestrial biogeochemical processes: Contrasting intact and model experimental systems M.A. Bradford, J.F. Reynolds. 7. A framework and methods for simplifying complex landscapes to reduce uncertainty in predictions D.P.C. Peters et al. 8. Building up with a top-down approach: The role of remote sensing in deciphering functional and structural diversity C.A. Wessman, C.A. Bateson.- Part II. Case studies. 9. Carbon fluxes across regions: Observational constraints at multiple scales B.E. Law et al. 10. Landscape and regional scale studies of nitrogen gas fluxes P.M. Groffman et al. 11. Multiscale relationships of landscape characteristics and nitrogen concentrations in streams K.B. Jones et al. 12. Uncertainty in scaling nutrient export coefficients J.D. Wickham et al. 13. Causes and consequences of land use change in the North Carolina Piedmont: The scope of uncertainty D.L. Urban et al. 14. Assessing the influence of spatial scale on the relationship between avian nesting success and forest fragmentation P. Lloyd et al. 15. Scaling issues in mapping riparian zones with remote sensing data: Quantifying errors andsources of uncertainty T.P. Hollenhorst et al. 16. Scale issues in lake-watershed interaction: Assessing shoreline development, impacts on water clarity C.A. Johnston, B.A. Shmagin. 17. Scaling and uncertainty in region-wide water quality decision-making O.L. Loucks et al.- Part III. Synthesis. 18. Scaling with known uncertainty: A Synthesis J. Wu et al.- Index.

Distribution and Causes of Global Forest Fragmentation

Because human land uses tend to expand over time, forests that share a high proportion of their borders with anthropogenic uses are at higher risk of further degradation than forests that share a high proportion of their borders with non-forest, natural land cover (e.g., wetland). Using 1-km advanced very high resolution radiometer (AVHRR) satellite-based land cover, we present a method to separate forest fragmentation into natural and anthropogenic components, and report results for all inhabited continents summarized by World Wildlife Fund biomes. Globally, over half of the temperate broadleaf and mixed forest biome and nearly one quarter of the tropical rainforest biome have been fragmented or removed by humans, as opposed to only 4% of the boreal forest. Overall, Europe had the most human-caused fragmentation and South America the least. This method may allow for improved risk assessments and better targeting for protection and remediation by identifying areas with high amounts of human-caused fragmentation.

Modeling runoff response to land cover and rainfall spatial variability in semi-arid watersheds.

Hydrologic response is an integrated indicator of watershed condition, and significant changes in land cover may affect the overall health and function of a watershed. This paper describes a procedure for evaluating the effects of land cover change and rainfall spatial variability on watershed response. Two hydrologic models were applied on a small semi-arid watershed; one model is event-based with a one-minute time step (KINEROS), and the second is a continuous model with a daily time step (SWAT). The inputs to the models were derived from Geographic Information System (GIS) theme layers of USGS digital elevation models, the State Soil Geographic Database (STATSGO) and the Landsat-based North American Landscape Characterization classification (NALC) in conjunction with available literature and look up tables. Rainfall data from a network of 10 raingauges and historical stream flow data were used to calibrate runoff depth using the continuous hydrologic model from 1966 to 1974. No calibration was carried out for the event-based model, in which six storms from the same period were used in the calculation of runoff depth and peak runoff. The assumption on which much of this study is based is that land cover change and rainfall spatial variability affect the rainfall-runoff relationships on the watershed. To validate this assumption, simulations were carried out wherein the entire watershed was transformed from the 1972 NALC land cover, which consisted of a mixture of desertscrub and grassland, to a single uniform land cover type such as riparian, forest, oak woodland, mesquite woodland, desertscrub, grassland, urban, agriculture, and barren. This study demonstrates the feasibility of using widely available data sets for parameterizing hydrologic simulation models. The simulation results show that both models were able to characterize the runoff response of the watershed due to changes of land cover.

Effects of Grazing on Lizard Abundance and Diversity in Western Arizona

-Lizard populations sampled on heavily grazed chaparral, desert grassland, mixed riparian scrub, and cottonwood-willow vegetative communities were characterized by lower relative abundance and species diversity indices than those of similar, lightly grazed sites. Lower relative abundance and diversity at heavily grazed sites were a result of vegetative structures that favored lizards who forage while roosting on trees, downed tree limbs, or under trees. Lightly grazed sites were characterized by vegetative structures that favored a wide variety of foraging styles. There were no differences in lizard abundance and diversity between lightly and heavily grazed Sonoran Desertscrub. Similarities in lizard abundance and diversity of lightly and heavily grazed Sonoran Desertscrub were attributed to similarities in vegetative structure. Many natural factors limit species distribution-competition, topography, climate, and vegetation to name a few. Recently we have become concerned with the way in which human activities, such as off-road vehicle use, road construction, and livestock grazing may affect species distribution. Few studies have addressed these effects on lizards. Bury and Busack (1974) found an inverse relationship between sheep grazing and lizard population density: an ungrazed study plot had twice the number of lizards and three times the biomass of a grazed plot. They related reduction in biomass on the grazed plot to the loss of cover, loss of social structure, invertebrate faunal degradation, and direct casualties. Although Bury and Busack (1974) related grazing-caused vegetative degradation to declines in lizard biomass, they made no attempt to relate the decline in numbers of individual species to changes in vegetative structure. Pianka (1966) discussed the importance of vegetative structure in determining the diversity of lizards in a given vegetative community. In most cases he found vegetative communities with increased plant structures supported more lizard species than those with fewer plant structures. He correlated this finding to increases in both structure of vegetative communities and foraging niches. Based on vegetative structural and foraging requirements, Pianka placed lizards into foraging styles: widely foraging species; sit-and-wait species who forage while sitting on rocks, trees and downed tree limbs; sit-and-wait species who forage in open spaces between shrubs; herbivorous species; and nocturnal species. Studies on the effects of livestock grazing on vegetation have been related primarily to changes in plant species composition. Ellison (1960), Laycock (1967), Potter and Krenetsky (1967), Brown and Schuster (1969), Turner (1971), and Blydenstein et al. (1957) indicated that heavy livestock use reduced biomass and diversity of annual forbs and grasses and changed composition of shrub species. However, there have been no studies relating plant compositional changes, due to livestock grazing, with vegetative structure. T E SO T ESTERN NATURALIST 26(2):107-115 MAY 21, 981 This content downloaded from 157.55.39.186 on Sun, 09 Oct 2016 06:27:18 UTC All use subject to http://about.jstor.org/terms The Southwestern Naturalist The objective of this study was to document how vegetative structural changes observed under lightly grazed as compared to heavily grazed situations affect lizard species abundance and diversity. Concern of various interest groups on the effects of human activities on vertebrate species has led to legislation dictating evaluation of these activities and their effect on wildlife (ie., National Environmental Policy Act). Due to these mandates, and other factors, the Bureau of Land Management, Phoenix District, conducted inventories in western Arizona to determine the effects of grazing on lizards. METHODS.-Field work was conducted in three planning areas of the Bureau of Land Managements Phoenix District: Black Canyon, Hualapai-Aquarius, and Lower Gila North (Fig. 1), encompassing approximately three million acres of federal, state, and patented lands. Fourteen sample sites, seven heavily and seven lightly grazed, were established in each of five vegetative communities: chaparral, desert grassland, mixed riparian scrub, cottonwood-willow riparian, and Sonoran Desertscrub (Brown and Lowe, 1974). Chaparral and desert grassland occurred at elevations from 1143 to 1571 m, with the former occurring on broken, hilly topography and the latter on mesa tops where slopes were less than 10°. Precipitation ranged from 0.31 to 0.41 m annually at chaparral and desert grassland sites. Sonoran Desertscrub occurred at elevations from 343 to 657 m where precipitation ranged from 0.18 to 0.26 m. Topography of Sonoran Desertscrub communities ranged from slopes in excess of 45° on mountain terrain to valleys of less than 10°. Mixed riparian scrub and cottonwood-willow riparian communities occurred in sand bottom drainages with the former at elevations from 314 to 629 m, annual precipitation from 0.18 to 0.26 m, and no surface water, and the latter at elevations from 571 to 1429 m, annual precipitation ranging from 0.18 to 0.41 m, and water at or near the surface. While mixed riparian scrub communities were found exclusively in open, broken topography, many of the cottonwood-willow sites were in deep, narrow canyons. Heavily grazed sites were characterized by existence of cattle trails, presence of livestock, and poor range condition (Davis, 1976). Lightly grazed sites were characterized by absence of livestock and good to excellent range condition (Davis, 1976). Deer and other wild ungulates were in low abundance throughout the study area and had little effect on range condition. Heavily and lightly grazed sites of a given vegetative community possessed similar topography, rainfall, and elevation to minimize the effects of natural environmental factors on vegetative structure. With the exception of Sonoran Desertscrub, lightly grazed sites were structurally more diverse than heavily grazed sites. Lightly grazed sites also possessed greater percentages of structure at heights of less than 1 m. Percent live vegetative cover also was greater at lightly grazed sites with the exception of chaparral and Sonoran Desertscrub communities. Dead plant cover in the form of tree limbs was greater at all heavily grazed sites with the exception of Sonoran Desertscrub. Relative lizard abundance and species diversity of lizards were estimated by use of an Array trapping method during the periods March-June and September-November 1978, and MarchOctober 1979. The Array trapping scheme (Campbell and Christman, 1977) consisted of a series of 18.3 1 buckets buried in the ground and connected by aluminum fences. Campbell and Christman (1977) used eight can traps with an open-center configuration. A four-bucket scheme was used in this study to reduce material cost and time constructing sampling equipment. Each Array consisted of a center bucket and three evenly dispersed (120°) peripheral buckets, 7.14 m from the center. Buckets were connected by 0.41 m high aluminum drift fence anchored by stakes and wire. Seventy Arrays were constructed, seven at each heavily and lightly grazed site in each vegetative community. Arrays were checked every 3 days during the study period. Lizards trapped were measured (mm), toe-clipped, sexed, and released not less than 3 m from the nearest bucket. Relative abundance was calculated as the number of lizards caught in 24 hours by one Array (lizards/Array/night). Mean relative abundance ± one standard deviation was calculated for each species on heavily and lightly grazed study sites. Total relative abundance for each heavily and lightly grazed vegetative community was compiled ± one standard deviation and tested (students t) for difference at p < 0.05. Species diversity indices were calculated for heavily and lightly grazed sites by a modified 108 vol. 26, no. 2 This content downloaded from 157.55.39.186 on Sun, 09 Oct 2016 06:27:18 UTC All use subject to http://about.jstor.org/terms Jones-Effects of Grazing on Lizards

A note on contagion indices for landscape analysis

The landscape contagion index measures the degree of clumping of attributes on raster maps. The index is computed from the frequencies by which different pairs of attributes occur as adjacent pixels on a map. Because there are subtle differences in the way the attribute adjacencies may be tabulated, the standard index formula may not always apply, and published index values may not be comparable. This paper derives formulas for the contagion index that apply for different ways of tabulating attribute adjacencies — with and without preserving the order of pixels in pairs, and by using two different ways of determining pixel adjacency. When the order of pixels in pairs is preserved, the standard formula is obtained. When the order is not preserved, a new formula is obtained because the number of possible attribute adjacency states is smaller. Estimated contagion is also smaller when each pixel pair is counted twice (instead of once) because double-counting pixel adjacencies makes the attribute adjacency matrix symmetric across the main diagonal.

Informing landscape planning and design for sustaining ecosystem services from existing spatial patterns and knowledge

Over the last decade we have seen an increased emphasis in environmental management and policies aimed at maintaining and restoring multiple ecosystem services at landscape scales. This emphasis has resulted from the recognition that management of specific environmental targets and ecosystem services requires an understanding of landscape processes and the spatial scales that maintain those targets and services. Moreover, we have become increasingly aware of the influence of broad-scale drivers such as climate change on landscape processes and the ecosystem services they support. Studies and assessments on the relative success of environmental policies and landscape designs in maintaining landscape processes and ecosystem services is mostly lacking. This likely reflects the relatively high cost of maintaining a commitment to implement and maintain monitoring programs that document responses of landscape processes and ecosystem services to different landscape policies and designs. However, we argue that there is considerable variation in natural and human-caused landscape pattern at local to continental scales and that this variation may facilitate analyses of how environmental targets and ecosystem services have responded to such patterns. Moreover, wall-to-wall spatial data on land cover and land use at national scales may permit characterization and mapping of different landscape pattern gradients. We discuss four broad and interrelated focus areas that should enhance our understanding of how landscape pattern influences ecosystem services: (1) characterizing and mapping landscape pattern gradients; (2) quantifying relationships between landscape patterns and environmental targets and ecosystem services, (3) evaluating landscape patterns with regards to multiple ecosystem services, and (4) applying adaptive management concepts to improve the effectiveness of specific landscape designs in sustaining ecosystem services. We discuss opportunities as well as challenges in each of these four areas. We believe that this agenda could lead to spatially explicit solutions in managing a range of environmental targets and ecosystem services. Spatially explicit options are critical in managing and protecting landscapes, especially given that communities and organizations are often limited in their capacity to make changes at landscape scales. The issues and potential solutions discussed in this paper expand upon the call by Nassauer and Opdam (Landscape Ecol 23:633–644, 2008) to include design as a fundamental element in landscape ecology research by evaluating natural and human-caused (planned or designed) landscape patterns and their influence on ecosystem services. It also expands upon the idea of “learning by doing” to include “learning from what has already been done.”