Alternative Land Management Research Articles

Assessment of alternative land management practices using hydrological simulation and a decision support tool: Arborea agricultural region, Sardinia

Abstract. Quantifying the impact of land use on water supply and quality is a primary focus of environmental management. In this work we apply a semidistributed hydrological model (SWAT) to predict the impact of different land management practices on water and agricultural chemical yield over a long period of time for a study site situated in the Arborea region of central Sardinia, Italy. The physical processes associated with water movement, crop growth, and nutrient cycling are directly modeled by SWAT. The model simulations are used to identify indicators that reflect critical processes related to the integrity and sustainability of the ecosystem. Specifically we focus on stream quality and quantity indicators associated with anthropogenic and natural sources of pollution. A multicriteria decision support system is then used to develop the analysis matrix where water quality and quantity indicators for the rivers, lagoons, and soil are combined with socio-economic variables. The DSS is used to assess four options involving alternative watersheds designated for intensive agriculture and dairy farming and the use or not of treated wastewater for irrigation. Our analysis suggests that of the four options, the most widely acceptable consists in the transfer of intensive agricultural practices to the larger watershed, which is less vulnerable, in tandem with wastewater reuse, which rates highly due to water scarcity in this region of the Mediterranean. More generally, the work demonstrates how both qualitative and quantitative methods and information can assist decision making in complex settings.

Using conservation value to assess land restoration and management alternatives across a degraded oak savanna landscape

Summary Managers considering restoration of landscapes often face a fundamental challenge – what should be the habitat composition of the restored landscape? We present a method for evaluating an important conservation trade‐off inherent in making that decision. Oak savannas and grasslands were historically widespread across central North America but are now rare. Today, in north‐west Indiana, USA, habitats spanning a range of woody vegetation density, from nearly treeless open habitats to forests, occur across the conserved landscape where savannas probably once dominated. To understand the benefits of different potential landscape compositions, we evaluated how different proportions of five habitats – open, savanna, woodland, scrub and forest – might affect the conservation value of the north‐west Indiana landscape for birds. Two variables of potential conservation importance were examined: species diversity, a measure of avian community richness, and conservation index, the percentage of a bird species’ global population occurring on a hectare of landscape, summed across all bird species present. Higher values of conservation index were associated with higher local densities of globally more rare and more threatened species. Conservation index and species diversity were correlated negatively across hypothetical landscapes composed of different proportions of the five habitats. Therefore, a management trade‐off existed between conservation index and species diversity because landscapes that maximized species diversity differed from landscapes that maximized conservation index. A landscape of 50% open, 22% savanna, 15% scrub and 13% forest was predicted to represent a compromise at which conservation index and species diversity reached the same percentage of their maxima. In contrast, the current landscape is dominated by forest. Synthesis and applications. We quantified the trade‐off between two potential aspects of a landscape's conservation value for birds – the landscape's ability to promote avian species diversity and the landscape's use by threatened avian species. This quantification allowed us to evaluate the ability of different landscape compositions to achieve preferable trade‐off compromises, such as maximizing diversity for a given level of landscape use by threatened species. Managers can use these trade‐off results to determine which landscape compositions are associated with particular conservation and management priorities.

Impact of Alternative Land Management Options on Soil Fertility and Erosion in Uganda

Using a data set collected in eight districts of Uganda, this study investigates how investment in soil fertility management (SFM) and conservation practices may affect natural resource outcomes, particularly the extent and level of soil erosion and soil nutrient loss. The study used ordered probit models and the results suggest that investment in SFM and conservation practices greatly improves soil fertility and reduces soil erosion. From a policy perspective, public investment to encourage use of SFM and conservation technologies would help the country achieve sustainable agricultural production.

COMPILATION OF MEASURED NUTRIENT LOAD DATA FOR AGRICULTURAL LAND USES IN THE UNITED STATES1

ABSTRACT: Measured field scale data are increasingly used to guide policy and management decisions based on comparative pollutant load information from various land management alternatives. The primary objective of this study was to compile measured annual nitrogen (N) and phosphorus (P) load data representing field scale transport from agricultural land uses. This effort expanded previous work that established an initial nutrient export coefficient dataset. Only measured annual N and P load data published in scientific peer‐reviewed studies were included in the present compilation. Additional criteria for inclusion were: spatial scale (field scale or farm scale, minimum 0.009 ha); land use (homogeneous, either cultivated agriculture or pasture/rangeland/hay); natural rainfall (not rainfall simulation); and temporal scale (minimum one year). Annual N and P load data were obtained from 40 publications, resulting in a 163‐record database with more than 1,100 watershed years of data. Basic descriptive statistics in relation to N and P loads were tabulated for tillage management, conservation practices, fertilizer application, soil texture, watershed size, and land use (crop type). The resulting Measured Annual Nutrient loads from A Circumlittoral Environments (MANAGE) database provides readily accessible, easily queried watershed characteristic and nutrient load data and establishes a platform suitable for input of additional project specific data.

Modeled carbon sequestration variation in a linked erosion–deposition system

Unraveling the consequences of hydrologic transport on carbon (C) storage will help identify feedbacks between land management alternatives, climate change, and soil-vegetation-atmospheric-transfers (SVATs) of C. There is a need for theoretically driven models of erosion and deposition that includes transport induced mineralization to better understand the controls on SVATs of C. Here we present a model developed using a systems-dynamic approach that coupled C-SVATs at a 2-day resolution with a discrete event erosion–deposition model occurring with a prescribed return interval. Five possible mass-balance transformations of C occurring between the two patches were explicitly modeled: net primary production (NPP), decomposition, erosion, transport induced mineralization, and deposition. The net C-SVAT, NPP minus decomposition, exhibited three stable points of no net C flux. Starting with arbitrary initial C pool in each patch above the bifurcation point, the model approached a quasi-steady state, which included both the short-term and longer term consequences of erosion; in the baseline simulation 5080 g C m −2 was stored prior to erosion and 100 years of low intensity erosion 4840 g C m −2 SOC remained. Low intensity erosion also generated spatial heterogeneity; from an initial homogeneous distribution to 40% of the C stored in the eroded patch and 60% of the C stored in the deposition patch. Erosion reduction resulted in a corresponding increase in total soil C content that was positively related to the magnitude of erosion reduction. In conjunction with providing a modeling framework for reducing the uncertainty in C-SVAT, this model is a prototype of a growing theory of ecosystem processes within spatially explicit landscapes, a meta-ecosystem model.

Switchgrass simulation by the ALMANAC model at diverse sites in the southern US

Simulation models for plant species important for biofuel such as switchgrass (Panicum virgatum L.) can be used to make management decisions related to biomass productivity and related to environmental impacts such as soil erosion and changes in surface and groundwater quality. The present study was designed to evaluate the accuracy of simulation of switchgrass biomass production by the ALMANAC (Agricultural Land Management Alternatives with Numerical Assessment Criteria) model at sites in Texas, Arkansas, and Louisiana. We used multi-year field data for Alamo switchgrass yields at each of five sites to evaluate ALMANAC. The model realistically simulated mean switchgrass yields at each of the locations and the total variability of all the data pooled, but did not perform as well in accounting for the year-to-year variability within some locations. Sensitivity analysis showed that changes in runoff curve number (CN) and changes in maximum stomatal conductance (GSI) had variable impacts on simulated values among the sites. A 15% change in CN changed mean annual biomass yield from 0% to 16% depending on location. Changing GSI from 4 to 8 mm s−1 changed mean annual biomass from 1% to 31% depending on location. ALMANAC shows promise as a tool to realistically simulate mean biomass yields and variability around the mean for multi-year runs of switchgrass at these diverse sites. Further research, with more extensive measurements of soil parameters including soil nutrients is needed to determine why the model reasonably simulated individual years’ yields at Stephenville, TX and Dallas, TX, but had difficulty at other sites.

Maize yield potential: critical processes and simulation modeling in a high-yielding environment

Understanding processes of maize ( Zea mays L.) growth and production of grain in high-yielding, irrigated conditions offers hope to understand yield potential in many other environments. In this study we investigated such processes at the plant level, and attempted to simulate maize yields at the field level and county level in the high yielding region of the High Plains of Texas. In addition, we used the normalized difference vegetation index (NDVI) from satellite data of year 2000 to update leaf area index for yield simulation in three counties. In the field study, we measured maize leaf area index (LAI), the fraction of photosynthetically active radiation intercepted (FIPAR), and the harvest index (HI) in irrigated plots near Dumas, Texas. The light extinction coefficient ( k) for Beer's law was calculated with the FIPAR and the LAI. The radiation use efficiency (RUE) was determined with sequential measurements of the fraction of photosynthetically active radiation (PAR) intercepted and biomass harvests. The RUE was 3.98 g of above-ground biomass per MJ of intercepted PAR in 1999 and 3.41 in 2000 for three sampling dates prior to silking. These values are 106 and 93% of the expected RUE values at the measured vapor pressure deficits, using a previously published response function. The mean k value was −0.46 in 1999 and −0.47 in 2000, similar to the expected value of −0.43 reported in the literature for this row spacing. The mean HI measured in 2000 was 0.52, similar to values of 0.53 and 0.54 in the literature. Application of these parameters to maize simulation with the Agriculture Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) model for 13 center pivot irrigated fields near Dumas in 1999 provided simulations within 1.0 Mg ha −1 with a mean error of 0.03 Mg ha −1 and a mean square error of 0.10. For five years of grain yields reported for each of four counties in this region of Texas, ALMANAC simulations were within 5% of the mean measured yields. Introduction of PAR interception, based on the satellite-derived normalized difference vegetation index (NDVI), into ALMANAC resulted in slight increases in accuracy of yield prediction for two counties and a slight decrease in accuracy in one county for year 2000. Consistency in values of RUE, k, and HI in this study as compared with values reported in the literature will aid modelers simulating maize growth and grain yields in similar high-yielding, irrigated conditions.

Appropriate measures for conservation of terrestrial carbon stocks—Analysis of trends of forest management in Southeast Asia

The 21st century has brought new challenges for forest management at a time when global climate change is becoming increasingly apparent. Additional to various goods and services being provided to human beings, forest ecosystems are a large store of terrestrial carbon and account for a major part of the carbon exchange between the atmosphere and the land surface. Depending on the management regime, forests can thus be either a sink, or a source of atmospheric carbon. Southeast Asia or ASEAN comprises 10 countries of different cultures and political background. Rapid economic development and fast-growing population in the region have raised much concern over the use of natural resources, especially forest resources. This study aims at finding the appropriate measures for sustainable use and management of tropical forests on a long-term basis. Between 1990 and 2000, about 2.3 million ha of forest were cleared every year and lost to other forms of land use. In terms of carbon emissions, a net amount of approximately 465 million t per year were released to the atmosphere over the same period, which amounts to 29% of the global net carbon release from deforestation worldwide. This study provides an approach to analyzing the implications of alternative forest and land management options on forest carbon stocks. This is done in three steps: First, observed trends in land use are expressed in terms of a model in order to create a scenario for the period 1980–2050. Second, forest management practices and timber production rates are analyzed and three management scenarios are created: (1) continuing the current rate of exploitation, (2) management for long-term economic gains, and (3) climate-beneficial management. Third, the impact of the three scenarios on regional carbon storage is estimated on the basis of a carbon balance model. Comparing the additional rate of carbon sequestration of scenario (3) over scenario (2), and taking into account differing management costs, we also discuss a framework for industrialized countries to invest in carbon credits in the region in order to fulfil their commitments under present and future climate protection agreements.

Gliricidia sepium Carbon Inputs and Soil Carbon Pools in a Costa Rican Alley Cropping System

Alternative land management practices, including agroforestry, help to maintain levels of soil organic matter (SOM) and can facilitate soil carbon (C) sequestration for mitigating atmospheric CO2 emissions. This study quantified C inputs and determined the changes of the soil C pool in a 19-year-old Gliricidia sepium alley cropping system, studied at two fertiliser levels (tree prunings only [− N], and tree prunings plus chicken manure [+ N]), and was compared to a sole crop system. Carbon input from tree prunings ranged from 455 to 457 g C m− 2 y− 1, whereas C inputs from crop residues were similar between alley- and sole crops ranging from 121 to 159 g C m− 2y− 1. The soil organic C (SOC) pool in the alley crop was 16–23% higher than the sole crop. In the 19th year of alley farming, SOC was significantly higher (p < 0.05) in the alley crop (3.2%) compared to the sole crop (2.4%), and was also greater compared to that at the time of establishment of the agroforestry system (2.8%). Gross SOC turnover to a 20-cm depth ranged from 12 to 14 years in the + N and −N alley crops compared to 49 and 50 years in the + N and −N treatments for the sole crops. Residue stabilisation efficiency in the alley crops was 39% and 55% in + N and −N treatments respectively.

From landscapes to waterscapes: A PSE for landuse change analysis

We describe the design and implementation of L2W – a Problem Solving Environment (PSE) for landuse change analysis. L2W organizes and unifies the diverse collection of software typically associated with ecosystem models (hydrological, economic and biological). It provides a web-based interface for potential watershed managers and other users to explore meaningful alternative land development and management scenarios and view their hydrological, ecological, and economic impacts. A prototype implementation for the Upper Roanoke River Watershed in Southwest Virginia, USA is described.

Effects of floristics, physiognomy and non‐native vegetation on riparian bird communities in a Mojave Desert watershed

Summary In the deserts of the south‐western United States of America, as in many ecoregions around the world, invasion of non‐native plants is modifying the structure and composition of riparian vegetation. Restoration of native plant species frequently proves to be ecologically and economically difficult. In the Muddy River drainage in the Mojave Desert (Nevada, USA), eradication of one the most aggressive invasive plants, Tamarix ramosissima (salt‐cedar), often reduces the structural and compositional diversity of the remaining vegetation. This can have negative effects on native animals, including birds. The objectives of our work were (i) to examine relationships between avian diversity and measures of vegetational diversity (species richness, dominance of non‐native plants and vegetation structure [total vegetation volume]), (ii) to explore the extent to which avian community composition was associated with vegetation composition (floristics) or vegetation structure (physiognomy), and (iii) to consider the potential effects of alternative land management and ecological restoration strategies on the biodiversity of birds and other native fauna in watersheds in the arid south‐western USA. Species richness of all birds and of breeding birds was best modelled by total vegetation volume alone. Neither species richness of plants nor dominance of non‐native plants had a statistically significant effect on species richness, abundance or evenness of birds. Species composition of birds between sites was more similar when floristics was more similar, and vice versa. Species composition of birds was not correlated with physiognomy. Species richness of native birds in the Muddy River drainage appears not to suffer from invasion of non‐native plants, provided that the vegetational community retains sufficient structural diversity. The composition of the bird community is closely related to floristics, and other taxonomic groups may exhibit different responses to vegetation structure and composition. Therefore, explicit strategies for landscape‐scale management, restoration and maximization of native faunal diversity should consider how removal of invasive plants may affect physiognomy and floristics of the vegetational community as a whole.

The ALMANAC model's sensitivity to input variables

Crop models often require extensive input data sets to realistically simulate crop growth. Development of such input data sets can be difficult for some model users. The objective of this study was to evaluate the importance of variables in input data sets for crop modeling. Based on published hybrid performance trials in eight Texas counties, we developed standard data sets of 10-year simulations of maize and sorghum for these eight counties with the Agricultural Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) model. The simulation results were close to the measured county yields with bias values and root mean square errors less than 1.0 Mg ha −1 in each county. We then analyzed the sensitivity of grain yield to solar radiation, rainfall, soil depth, soil plant available water, and runoff curve number, comparing simulated yields with those with the original, standard data sets. Runoff curve number [US Department of Agriculture, Soil Conservation Service (1972) National Engineering Handbook, Hydrology Section 4, chapters 4–10] changes had the greatest impact on simulated maize and sorghum yields for all the counties. The next most critical input was rainfall, and then solar radiation for both maize and sorghum, especially for dryland conditions. For irrigated sorghum, solar radiation was the second most critical input instead of rainfall. The degree of sensitivity of yield to all variables was larger for maize than for sorghum except for solar radiation. Many models use a USDA curve number approach to represent soil water redistribution, so it will be important to have accurate curve numbers, rainfall, and soil depth to realistically simulate yields.

Modeling the relationship between land use and surface water quality

It is widely known that watershed hydrology is dependent on many factors, including land use, climate, and soil conditions. But the relative impacts of different types of land use on the surface water are yet to be ascertained and quantified. This research attempted to use a comprehensive approach to examine the hydrologic effects of land use at both a regional and a local scale. Statistical and spatial analyses were employed to examine the statistical and spatial relationships of land use and the flow and water quality in receiving waters on a regional scale in the State of Ohio. Besides, a widely accepted watershed-based water quality assessment tool, the Better Assessment Science Integrating Point and Nonpoint Sources (BASINS), was adopted to model the plausible effects of land use on water quality in a local watershed in the East Fork Little Miami River Basin. The results from the statistical analyses revealed that there was a significant relationship between land use and in-stream water quality, especially for nitrogen, phosphorus and Fecal coliform. The geographic information systems (GIS) spatial analyses identified the watersheds that have high levels of contaminants and percentages of agricultural and urban lands. Furthermore, the hydrologic and water quality modeling showed that agricultural and impervious urban lands produced a much higher level of nitrogen and phosphorus than other land surfaces. From this research, it seems that the approach adopted in this study is comprehensive, covering both the regional and local scales. It also reveals that BASINS is a very useful and reliable tool, capable of characterizing the flow and water quality conditions for the study area under different watershed scales. With little modification, these models should be able to adapt to other watersheds or to simulate other contaminants. They also can be used to study the plausible impacts of global environmental change. In addition, the information on the hydrologic effects of land use is very useful. It can provide guidelines not only for resource managers in restoring our aquatic ecosystems, but also for local planners in devising viable and ecologically-sound watershed development plans, as well as for policy makers in evaluating alternate land management decisions.

Integrated Computing Environments for Watershed Management

This paper describes a new computing paradigm known as a problem solving environment (PSE), explores the role this new paradigm might play in watershed management and land use change analysis, and compares PSEs to similar technologies such as decision support systems and geographic information systems. A prototypical watershed management PSE organizes and unifies the diverse collection of software typically associated with ecosystem models (hydrological, economic, and biological). A PSE provides a Web-based interface for potential watershed managers and other users to explore meaningful alternative land development and management scenarios and view their hydrological, ecological, and economic impacts. A brief description of a land use change analysis PSE being developed (called L2W, landscapes to waterscapes) is presented.

Models for Mapping Potential Habitat at Landscape Scales: An Example Using Northern Spotted Owls

Abstract We are assessing the potential for current and alternative policies in the Oregon Coast Range to affect habitat capability for a suite of forest resources. We provide an example of a spatially explicit habitat capability model for northern spotted owls (Strix occidentalis caurina) to illustrate the approach we are taking to assess potential changes in habitat capability for vertebrates across the Coast Range. The model was based on vegetation structure at five spatial scales: the potential nest tree, a 0.5 ha potential nest patch, 28 ha around a potential nest patch, 212 ha around a potential nest patch, and a 1,810 ha home range area around a potential nest patch. Sensitivity analyses indicated that the proportion of the 28 ha patch in large trees around a potential nest patch, and the number of potential nest trees per ha in the nest patch, had the greatest influence on habitat capability estimates. The model was verified using georeferenced locations of spotted owl nests from systematically surveyed areas. Logistic regression analysis indicated that habitat capability scores were significantly associated with the probability of a site having a nest. Alternative model structures were tested during verification to test assumptions associated with four variables. The final model allowed development of a map of habitat capability for spotted owl nesting. The model will be linked to a model of forest dynamics to project changes in habitat capability under alternative land management policies. FOR. SCI. 48(2):203–216.

Evaluation of potential effects of federal land management alternatives on trends of salmonids and their habitats in the interior Columbia River basin

Aquatic species throughout the interior Columbia River basin are at risk. Evaluation of the potential effects of federal land management on aquatic ecosystems across this region is an important but challenging task. Issues include the size and complexity of the systems, uncertainty in important processes and existing states, flexibility and consistency in the analytical framework, and an ability to quantify results. We focused on salmonid fishes and their habitats as indicators of conditions in aquatic ecosystems and used Bayesian belief networks as a formal, quantitative framework to address the issues in our evaluation of land management alternatives proposed for the interior Columbia River basin. Because empirical information is limited at the scales relevant to our analysis, an ability to combine both empirical and more subjective information was key to the analysis. The representation of linkages through conditional probabilities made uncertainty explicit. We constructed two general networks. One represented the influence of landscape characteristics and existing and predicted management activities on aquatic habitats. A second represented the influence of habitat, existing biotic conditions, and for two anadromous species, ocean and migratory conditions, on the status of six widely distributed salmonid fishes. In the long term (100 years) all three land management alternatives were expected to produce positive changes in the status and distribution of the salmonids and their habitats. Trends were stronger for habitat than for the status of salmonids because of greater uncertainty in linking the fish and habitat networks and constraints outside spawning and rearing habitat on federal lands in the study area. Trends were stronger for resident salmonids than anadromous forms because of additional effects of the migratory corridor assumed for the latter. Alternative S2, which approached ecosystem restoration more conservatively, generally produced the strongest positive changes, and alternative S3, designed to promote more aggressive restoration, the weakest. Averaged across the basin, differences among the alternatives were small. Differences were greater at finer temporal and spatial scales. In the short term (10 years) alternative S3 was expected to lead to further degradation in some areas. By formalizing our understanding and assumptions in these networks, we provided a framework for exploring differences in the management alternatives that is more quantifiable, spatially explicit, and flexible than previous approaches.

Using Bayesian belief networks to evaluate fish and wildlife population viability under land management alternatives from an environmental impact statement

We developed procedures for using Bayesian belief networks (BBNs) to model habitat and population viability of selected at-risk fish and wildlife species. The BBN models represent the ecological causal web of key environmental correlates (KECs) that most influence habitat capability, potential population response for each species, and influence of habitat planning alternatives. BBN models represent site-specific KECs, habitat capability at the subwatershed level, and pattern of habitat capability across all subwatersheds. BBNs use Dirichlet prior probability distributions and standard Bayesian updating of posterior probabilities. We derived estimates of prior and conditional probabilities from a mix of empirical data and expert judgment, mostly the latter. Sensitivity analyses identified planning decisions and KECs that most influence species outcomes, and can help prioritize monitoring activities. BBN models, however, substitute for neither field studies nor empirical, quantitative population viability analyses of population demography and genetics.

Status and trends of habitats of terrestrial vertebrates in relation to land management in the interior Columbia river basin

We analyzed effects of three land management alternatives on 31 terrestrial vertebrates of conservation concern within the interior Columbia river basin study area. The three alternatives were proposed in a Supplemental Draft Environmental Impact Statement (SDEIS) that was developed for lands in the study area administered by the US Department of Agriculture (USDA) Forest Service (FS) and US Department of Interior (USDA) Bureau of Land Management (BLM). To evaluate effects of these alternatives, we developed Bayesian belief network (BBN) models, which allowed empirical and hypothesized relations to be combined in probability-based projections of conditions. We used the BBN models to project abundance and distribution of habitat to support potential populations (population outcomes) for each species across the entire study area. Population outcomes were defined in five classes, referred to as outcomes A–E. Under outcome A, populations are abundant and well distributed, with little or no likelihood of extirpation. By contrast, populations under outcome E are scarce and patchy, with a high likelihood of local or regional extirpation. Outcomes B–D represent gradients of conditions between the extremes of classes A and E. Most species (65%, or 20 of 31) were associated with outcome A historically and with outcomes D or E currently (55%, or 17 of 31). Population outcomes projected 100 years into the future were similar for all three alternatives but substantially different from historical and current outcomes. For species dependent on old-forest conditions, population outcomes typically improved one outcome class — usually from E or D to D or C — from current to the future under the alternatives. By contrast, population outcomes for rangeland species generally did not improve under the alternatives, with most species remaining in outcomes C, D, or E. Our results suggest that all three management alternatives will substantially improve conditions for most forest-associated species but provide few improvements for rangeland-associated vertebrates. Continued displacement of native vegetation by exotic plants, as facilitated by a variety of human-associated disturbances, will be an on-going challenge to the improvement of future conditions for rangeland species.

Trends in terrestrial plant communities and landscape health indicate the effects of alternative management strategies in the interior Columbia River basin

Current and potential future conditions of terrestrial plant communities and landscape health were modeled for three alternative public land management strategies in the interior Columbia River basin. Landscape health was defined as an integration of the degree to which vegetation and disturbance conditions resemble native patterns and support levels of human activity. The range of vegetation and disturbance variability for a period before the middle 19th century was used as a basis for comparison of current and future regimes to the “historical” system. Departure from the “historical” regime in wildland environments was found to be related to altered disturbance patterns, especially changed fire regimes, forest insect and disease levels and excessive livestock grazing effects. Overall, mid-seral forests are currently more prevalent than they were in the past and old forests, especially single-layer structural types, are less abundant. Non-native plant species and altered plant community composition conditions exist across broad areas of rangelands. Landscape health has declined substantially in many areas. Proposed management strategies that emphasize maintenance and restoration activities in a hierarchical landscape approach should generate improved landscape health conditions over the next 100 years. However, the massive scale of changes to disturbance and vegetation patterns from historical to current times and the cost of implementing restoration activities make dramatic improvement unlikely.

Science and ecosystem management in the interior Columbia basin

Significant changes over the past 150 years in aquatic, terrestrial, landscape, and socioeconomic systems have altered biophysical systems in the interior Columbia basin. Changes and conflict in public policy concerns, such as resource use vs. restoration vs. conservation are especially evident in more than 34% of total forest and rangeland in the United States that are federally administered. In the last decade, design and implementation of complex land management strategies has become an issue for public land managers. In turn, the scientific community is often challenged to develop approaches for management of complete ecosystems. This paper discusses the use of science in the assessment and evaluation phases of one large-scale (multi-region) ecosystem management effort on federal lands in the Columbia river basin, the Interior Columbia Basin Ecosystem Management Project (ICBEMP), and briefly describes the evaluations of three alternative management strategies which are detailed by other papers in this issue. This paper contends that understanding the context of land management decisions is essential to defining the veracity or applicability of alternative land management strategies. Evaluating the alternatives is a complicated science process, which requires understanding the effects of each set of direction over both the short and long term, projecting the effects of those directions, making assumptions about pieces not yet developed, and modeling resource change.