Testing a GIS Model of Habitat Suitability for a Declining Grassland Bird

Demand for information that can be used to manage loggerhead shrikes has recently increased because of concern over declining populations and loss of open, non-forested habitat. A previously-developed habitat model was modified to predict shrike habitat quality on Fort Riley Military Reservation (FRMR) in Kansas. Shrike habitat suitability indices were calculated based on the amount of potential and usable foraging habitat, and the number of potential nesting sites within a specified area. Interpretation of high quality digital photographs was used to delineate land cover classes, hedgerows and tree counts. These data were entered into a geographic information system (GIS) as individual data sets. The shrike habitat model was then employed to produce a GIS database predicting low, moderate, and high quality shrike habitat throughout the Reservation. Model results indicated that 67% of the Reservation was suitable habitat for loggerhead shrikes. Although over 80% of FRMR was mapped as grassland, the presence of few to several isolated trees or hedgerows was identified as a key factor in modeling habitat suitability. The accuracy of the GIS model was 82% in predicting suitable (moderate and high quality) loggerhead shrike habitat using an independent set of 66 recent shrike observations. The number of potential nesting sites and percent cover of usable foraging habitat were significantly related to habitat suitability of the sites occupied by shrikes.     

Rough Set Rule Induction for Suitability Assessment

The data that characterize an environmental system are a fundamental part of an environmental decision-support system. However, obtaining complete and consistent data sets for regional studies can be difficult. Data sets are often available only for small study areas within the region, whereas the data themselves contain uncertainty because of system complexity, differences in methodology, or data collection errors. This paper presents rough-set rule induction as one way to deal with data uncertainty while creating predictive if–then rules that generalize data values to the entire region. The approach is illustrated by determining the crop suitability of 14 crops for the agricultural soils of the Willamette River Basin, Oregon, USA. To implement this method, environmental and crop yield data were spatially related to individual soil units, forming the examples needed for the rule induction process. Next, four learning algorithms were defined by using different subsets of environmental attributes. ROSETTA, a software system for rough set analysis, was then used to generate rules using each algorithm. Cross-validation analysis showed that all crops had at least one algorithm with an accuracy rate greater than 68%. After selecting a preferred algorithm, the induced classifier was used to predict the crop suitability of each crop for the unclassified soils. The results suggest that rough set rule induction is a useful method for data generalization and suitability analysis.     

Soil Fertility, Salinity and Nematode Diversity Influenced by Tamarix ramosissima in Different Habitats in an Arid Desert Oasis

The aim of this paper was to assess the influence of tamarisk shrubs on soil fertility, salinity and nematode communities in various habitats located in an arid desert-oasis region in northwest China. Three habitats were studied: sand dune, riparian zone and saline meadow, where tamarisk shrubs have been established in recent decades in order to vegetation restoration used as desertification control and saline land rehabilitation projects and become the dominant plant community. The parameters measured include soil organic carbon (SOC), total nitrogen, available phosphorus (P) and potassium (K), pH, salt component, and nematode community characteristics. Enrichment ratios (a comparison of the soil measurements between soils under canopy and in the open interspaces) for soil nutrients and salinity were used to evaluate fertility and salinity islands underneath the tamarisk shrubs. The soil nematode community was used as a biological indicator of soil condition. SOC and available P and K were higher beneath the plant canopy than in the open interspaces outside that canopy. The enrichment ratios for SOC and nutrients were highest for the sand dune habitat and tamarisk shrubs clearly created islands of greater salinity under the canopies. Nematode abundance per 100 g dry soil varied considerably between the locations and habitats, with the highest abundance found in sand dune and the lowest in saline meadow. A significantly higher nematode abundance and a lower trophic diversity were found in soils under the canopy compared to the soils in the open interspaces. With the exception of saline meadow, the abundance of bacterivores increased and fungivores decreased under the canopy relative to the open interspaces, and bacterivores dominated under the canopies in the sand dune and riparian habitats. The enrichment ratios for salinity were higher than for fertility, suggesting that improved soil fertility can not limit the impact of salinization beneath tamarisk shrubs. The adverse effect of salt accumulation on the soil environment should be taken into account when using tamarisk as restoration plant species, especially in saline meadow and controlling of tamarisk density should be considered when undertaking re-vegetation projects in the arid desert oasis regions.     

Resource Selection Probability Functions for Gopher Tortoise: Providing a Management Tool Applicable Across the Species’ Range

The gopher tortoise (Gopherus polyphemus) is protected by conservation policy throughout its range. Efforts to protect the species from further decline demand detailed understanding of its habitat requirements, which have not yet been rigorously defined. Current methods of identifying gopher tortoise habitat typically rely on coarse soil and vegetation classifications, and are prone to over-prediction of suitable habitat. We used a logistic resource selection probability function in an information-theoretic framework to understand the relative importance of various environmental factors to gopher tortoise habitat selection, drawing on nationwide environmental datasets, and an existing tortoise survey of the Ft. Benning military base. We applied the normalized difference vegetation index (NDVI) as an index of vegetation density, and found that NDVI was strongly negatively associated with active burrow locations. Our results showed that the most parsimonious model included variables from all candidate model types (landscape features, topography, soil, vegetation), and the model groups describing soil or vegetation alone performed poorly. These results demonstrate with a rigorous quantitative approach that although soil and vegetation are important to the gopher tortoise, they are not sufficient to describe suitable habitat. More widely, our results highlight the feasibility of constructing highly accurate habitat suitability models from data that are widely available throughout the species’ range. Our study shows that the widespread availability of national environmental datasets describing important components of gopher tortoise habitat, combined with existing tortoise surveys on public lands, can be leveraged to inform knowledge of habitat suitability and target recovery efforts range-wide.     

Effectiveness of Voluntary Habitat Stewardship in Conserving Grassland: Case of Operation Burrowing Owl in Saskatchewan

There have been no published performance evaluations of nongovernmental, voluntary habitat stewardship programs. The Operation Burrowing Owl (OBO) stewardship program, initiated in 1987, was evaluated for its effectiveness in conservation of grassland habitat during 1986–1993. The 108 OBO sites from 1987 to 88 and 98 randomly selected non-OBO sites that were grassland in 1986 in the Regina-Weyburn, Saskatchewan study area were classified by size and agricultural soil suitability. By 1993, 41 (38%) of the 108 OBO sites had been withdrawn from the program. The 1986 area of grassland was compared with grassland area calculated from digitized 1993 LANDSAT imagery. A correction for satellite inaccuracies was determined. Grassland retention in 1993 was significantly higher at OBO sites (66%) than at random sites (49%), demonstrating that the OBO voluntary program effectively conserved habitat. Also, grassland retention was significantly lower on sites with better agricultural soils, and for sites <12 ha in size. Site type (OBO or random), size and their interaction, followed by agricultural soil suitability, had the greatest effects on grassland retention. During an era of accelerated grassland loss, OBO strongly and positively (statistically significant) affected conservation of grassland sites most at risk: sites <12 ha in size and with good to excellent agricultural soils. This suggests that grassland conservation efforts focus on vulnerable sites (small size and/or good agricultural soils) to provide nesting habitat for burrowing owls. Our study demonstrates that a voluntary stewardship program can significantly increase conservation of habitat.     

Model-Based Selection of Areas for the Restoration of Acrocephalus paludicola Habitats in NE Germany

The global Aquatic Warbler (Acrocephalus paludicola, Vieillot, 1817) population has suffered a major decline due to the large-scale destruction of its natural habitat (fen mires). The species is at risk of extinction, especially in NE Germany/NW Poland. In this study, we developed habitat suitability models based on satellite and environmental data to identify potential areas for habitat restoration on which further surveys and planning should be focused. To create a reliable model, we used all Aquatic Warbler presences in the study area since 1990 as well as additional potentially suitable habitats identified in the field. We combined the presence/absence regression tree algorithm Cubist with the presence-only algorithm Maxent since both commonly outperform other algorithms. To integrate the separate model results, we present a new way to create a metamodel using the initial model results as variables. Additionally, a histogram approach was applied to further reduce the final search area to the most promising sites. Accuracy increased when using both remote sensing and environmental data. It was highest for the integrated metamodel (Cohen’s Kappa of 0.4, P < 0.001). The final result of this study supports the selection of the most promising sites for Aquatic Warbler habitat restoration.     

Reduced complexity models for regional aquatic habitat suitability assessment

Generalizable methods that identify suitable aquatic habitat across large river basins and regions are needed to inform resource management. Habitat suitability models intersect environmental variables to predict species occurrence, but are often data intensive and thus are typically developed at small spatial scales. This study estimated mean monthly aquatic habitat suitability throughout Utah (USA) for Bonneville Cutthroat Trout (Oncorhynchus clarkii utah) and Bluehead Sucker (Catostomus discobolus) with publicly available, geospatial datasets. We evaluated 15 habitat suitability models using unique combinations of percent of mean annual discharge, velocity, gradient, and stream temperature. Environmental variables were validated with observed conditions and species presence observations to verify habitat suitability estimates. Stream temperature, gradient, and discharge best predicted Bonneville Cutthroat Trout presence, and gradient and discharge best predicted Bluehead Sucker presence. Simple aquatic habitat suitability models outperformed models that used only streamflow to estimate habitat for both species, and are useful for conservation planning and water resources decision-making. This modeling approach could enable resource managers to prioritize stream restoration across vast regions within their management domain, and is potentially compatible with water management modeling to improve ecological objectives in management models.     

Biotic and abiotic degradation of CL-20 and RDX in soils

The caged cyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) is a new explosive that has the potential to replace existing military explosives, but little is known about its environmental toxicity, transport, and fate. We quantified and compared the aerobic environmental fate of CL-20 to the widely used cyclic nitramine explosive hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in surface and subsurface soil microcosms. Soil-free controls and biologically attenuated soil controls were used to separate abiotic processes from biologically mediated processes. Both abiotic and biological processes significantly degraded CL-20 in all soils examined. Apparent abiotic, first-order degradation rates (k) for CL-20 were not significantly different between soil-free controls (0.018 < k < 0.030 d(-1)) and biologically attenuated soil controls (0.003 < k < 0.277 d(-1)). The addition of glucose to biologically active soil microcosms significantly increased CL-20 degradation rates (0.068 < k < 1.22 d(-1)). Extents of mineralization of (14)C-CL-20 to (14)CO(2) in biologically active soil microcosms were 41.1 to 55.7%, indicating that the CL-20 cage was broken, since all carbons are part of the heterocyclic cage. Under aerobic conditions, abiotic degradation rates of RDX were generally slower (0 < k < 0.032 d(-1)) than abiotic CL-20 degradation rates. In biologically active soil microcosms amended with glucose aerobic RDX degradation rates varied between 0.010 and 0.474 d(-1). Biodegradation was a key factor in determining the environmental fate of RDX, while a combination of biotic and abiotic processes was important with CL-20. Our data suggest that CL-20 should be less recalcitrant than RDX in aerobic soils.     

Ecological Restoration of Coastal Sage Scrub and Its Potential Role in Habitat Conservation Plans

Extensive acreage loss of coastal sage scrub (CSS), isolation of surviving stands, and the federal listing of several animal species with obligate relationships to this plant community, particularly the threatened California gnatcatcher (Polioptila californica), have led to attempts to create CSS to mitigate habitat lost to urban development and other causes. Many of these creations lie within habitat conservation plan (HCP) sites, and they could play a more prominent role by being repositories for plants taken from a single site having site-specific genetics. Among others, one technique that increases initial resemblance to natural stands uses digitized, to-scale photography, which has been ground-truthed to verify vascular plant associations, which appear as mosaics on a landscape. A combination of placing patches of salvaged, mature canopy plants within larger matrices of imprinted or container plant plots appears to significantly enhance immediate use by CSS obligate bird species, accelerate "spread" or expansion of CSS, and can also introduce many epiphytic taxa that otherwise would be slow or unable to occupy developing CSS creations. Reptile, amphibian, butterfly, and rodent diversity in a salvaged canopy restoration case study at the University of California, Irvine, showed CSS species foraging and inhabiting transplanted canopy patches. Using restoration techniques to expand existing CSS stands has more promise than creating isolated patches, and the creation of canopies resembling CSS mid-fire cycle stands is now common. Gnatcatchers and other birds use restorations for foraging and occasional nesting, and in some cases created stands along "biological corridors" appear to be useful to bird movement. Patches of transplanted sage scrub shrubs along habitat edges appear to break up linear edge effects. There are no data on which long-term survival, succession, or postfire behavior can be predicted for CSS restoration sites, and postfire community changes are not part of either mitigation or restoration planning at present. Long-term planning including burning is needed so that a fire-adapted habitat will develop. Restoration is important in retaining genetic resources, for ameliorating edge effects, as habitat extenders in buffer zones around HCP sites, and by providing areas into which natural stands can expand.     

Maximizing Benefits from Riparian Revegetation Efforts: Local- and Landscape-Level Determinants of Avian Response

With limited financial resources available for habitat restoration, information that ensures and/or accelerates success is needed to economize effort and maximize benefit. In the Central Valley of California USA, riparian habitat has been lost or degraded, contributing to the decline of riparian-associated birds and other wildlife. Active restoration of riparian plant communities in this region has been demonstrated to increase local population sizes and species diversity of landbirds. To evaluate factors related to variation in the rate at which bird abundance increased after restoration, we examined bird abundance as a function of local (restoration design elements) and landscape (proportion of riparian vegetation in the landscape and riparian patch density) metrics at 17 restoration projects within five project areas along the Sacramento River. We developed a priori model sets for seven species of birds and used an information theoretic approach to identify factors associated with the rate at which bird abundance increased after restoration. For six of seven species investigated, the model with the most support contained a variable for the amount of riparian forest in the surrounding landscape. Three of seven bird species were positively correlated with the number of tree species planted and three of seven were positively correlated with the planting densities of particular tree species. Our results indicate that restoration success can be enhanced by selecting sites near existing riparian habitat and planting multiple tree species. Hence, given limited resources, efforts to restore riparian habitat for birds should focus on landscape-scale site selection in areas with high proportions of existing riparian vegetation.     

Competitive degradation between the fumigants chloropicrin and 1,3-dichloropropene in unamended and amended soils

The mixture of 1,3-dichloropropene (1,3-D) and chloropicrin (CP) is used as a preplant soil fumigant. In comparison with individual fumigants, application of a mixture may affect the environmental dissipation and fate of each chemical, such as emission and degradation. We investigated the degradation of CP, 1,3-D, and their mixture in fresh soils and sterile soils, and evaluated the competitive characteristic of fumigants in the mixture. The degradation of low concentrations of CP in fresh soil was accelerated at early times in the presence of 1,3-D, whereas the addition of CP reduced the degradation rate of trans-1,3-D, possibly by inhibiting the activity of trans-1,3-D degrading microorganisms. The potential of applying amendments to the soil to increase the rate of CP and 1,3-D degradation was also illustrated. The degradation of both fumigants was significantly enhanced in soils amended with ammonium thiosulfate (ATS) and sodium diethyldithiocarbamate (Na-DEDTC) compared with unamended soil. Competitive degradation was observed for CP in amended soils in the presence of 1,3-D. The degradation of cis-1,3-D in amended soils spiked as a mixture of 1,3-D and CP was repressed compared with the rate of degradation in samples spiked with 1,3-D only. This implied that in abiotic degradation, CP and cis-1,3-D competed for a limited number of reaction sites in amended soil, resulting in decreased degradation rates. No significant influence of fumigant mixtures was observed for trans-1,3-D in amended soil.     

Fuzzy assessment of land suitability for scientific research reserves

Evaluating the characteristics of a set of sites as potential scientific research reserves is an example of land suitability assessment. Suitability in this case is based upon multiple criteria, many of which can be linguistically imprecise and often incompatible. Fuzzy logic is a useful method for characterizing imprecise suitability criteria and for combining criteria into an overall suitability rating. The Ecosystem Management Decision Support software combined a fuzzy logic knowledge base we developed to represent the assessment problem with a GIS database providing site-specific data for the assessment. Assessment of sites as a potential natural reserve for the new University of California campus at Merced demonstrates the benefits of fuzzy suitability assessment. The study was conducted in three stages of successively smaller assessment regions with increasingly fine spatial resolution and specificity of criteria. Several sites were identified that best satisfy the suitability criteria for a reserve to represent vernal pool habitat.     

Estimating soil phosphorus requirements and limits from oxalate extract data

Excessive fertilizer and manure phosphorus (P) inputs to soils elevates P in soil solution and surface runoff, which can lead to freshwater eutrophication. Runoff P can be related to soil test P and P sorption saturation, but these approaches are restricted to a limited range of soil types or are difficult to determine on a routine basis. The purpose of this study was to determine whether easily measurable soil characteristics were related to the soil phosphorus requirements (P(req), the amount of P sorbed at a particular solution P level). The P(req) was determined for 18 chemically diverse soils from sorption isotherm data (corrected for native sorbed P) and was found to be highly correlated to the sum of oxalate-extractable Al and Fe (R2 > 0.90). Native sorbed P, also determined from oxalate extraction, was subtracted from the P(req) to determine soil phosphorus limits (PL, the amount of P that can be added to soil to reach P(req)). Using this approach, the PL to reach 0.2 mg P L(-1) in solution ranged between -92 and 253 mg P kg(-1). Negative values identified soils with surplus P, while positive values showed soils with P deficiency. The results showed that P, Al, and Fe in oxalate extracts of soils held promise for determining PL to reach up to 10 mg P L(-1) in solution (leading to potential runoff from many soils). The soil oxalate extraction test could be integrated into existing best management practices for improving soil fertility and protecting water quality.     

Assessing Restoration Potential of Semi-natural Grasslands by Landscape Change Trajectories

Species-rich semi-natural grasslands have rapidly declined and become fragmented in Northern Europe due to ceased traditional agricultural practices and animal husbandry. Restoration actions have been introduced in many places to improve the habitat conditions and increase the area to prevent any further losses of their ecological values. However, given the limited resources and long time span needed for successful restoration, it is essential to target activities on sites having a suitable initial state and where the effects of restoration are most beneficial for the habitat network. In this paper we present a conceptual framework for evaluating the restoration potential of partially overgrown and selectively managed semi-natural grasslands in a moderately transformed agricultural environment in south-western Finland. On the basis of the spatio-temporal landscape trajectory analysis, we construct potential restoration scenarios based on expected semi-natural grassland characteristics that are derived from land productivity, detected grassland continuum, and date of overgrowth. These scenarios are evaluated using landscape metrics, their feasibility is discussed and the effects of potential restoration are compared to the present extent of open semi-natural grasslands. Our results show that landscape trajectory analysis and scenario construction can be valuable tools for the restoration planning of semi-natural grasslands with limited resources. The approach should therefore be considered as an essential tool to find the most optimal restoration sites and to pre-evaluate the effects.     

Assessing Land-Use Impacts on Natural Resources

/ Much information is available on changes that occur in natural resources from both spatially-explicit data on environmental conditions and models of the interactions of these conditions and resources with human activities. The strategy for assessing land-use impacts on natural resources developed in this paper provides a framework for using relevant data and models to address questions of how management practices can promote both use and protection of resources. This assessment strategy integrates spatially explicit environmental data using geographic information systems (GIS) with computer models that simulate changes in land cover in response to land-use impacts. The computer models also simulate susceptibility of species to changes in habitat suitability and landscape patterns. The approach is applied to management of limestone barrens on the Oak Ridge Reservation in East Tennessee. Potential limestone barrens habitats are identified by overlaying appropriate soils, geology, slope, and land-use/land-cover conditions. Their validity is tested against known sites containing rare species that occur in these habitats. The location of habitats at risk in the aftermath of human activities is determined by using an available area model that identifies the size and proximity of sites that particular types of species can no longer use as habitat. The resulting risk map can be used in land management planning. The approach uses readily available in situ and remotely sensed data and is applicable to a wide range of locations and land-use scenarios. This approach can be refined based on needs identified by land managers and on the sensitivity of the results to the resolution of available resource information.KEY WORDS: Land management; Assessment; Habitat characterization; Limestone barrens; Ecological modeling; Geographic information systems     

Determining Ecological Equivalence in Service-to-Service Scaling of Salt Marsh Restoration

The amount of ecological restoration required to mitigate or compensate for environmental injury or habitat loss is often based on the goal of achieving ecological equivalence. However, few tools are available for estimating the extent of restoration required to achieve habitat services equivalent to those that were lost. This paper describes habitat equivalency analysis (HEA), a habitat-based “service-to-service” approach for determining the amount of restoration needed to compensate for natural resource losses, and examines issues in its application in the case of salt marsh restoration. The scientific literature indicates that although structural attributes such as vegetation may recover within a few years, there is often a significant lag in the development of ecological processes such as nutrient cycling that are necessary for a fully functioning salt marsh. Moreover, natural variation can make recovery trajectories difficult to define and predict for many habitat services. HEA is an excellent tool for scaling restoration actions because it reflects this ecological variability and complexity. At the same time, practitioners must recognize that conclusions about the amount of restoration needed to provide ecological services equivalent to those that are lost will depend critically on the ecological data and assumptions that are used in the HEA calculation.     

Differential Effects of Legume Species on the Recovery of Soil Microbial Communities, and Carbon and Nitrogen Contents, in Abandoned Fields of the Loess Plateau, China

Plant–soil interactions are known to influence a wide range of ecosystem-level functions. Moreover, the recovery of these functions is of importance for the successful restoration of soils that have been degraded through intensive and/or inappropriate land use. Here, we assessed the effect of planting treatments commonly used to accelerate rates of grassland restoration, namely introduction of different legume species Medicago sativa, Astragalus adsurgens, Melilotus suaveolens, on the recovery of soil microbial communities and carbon and nitrogen contents in abandoned fields of the Loess Plateau, China. The results showed effects were species-specific, and either positive, neutral or negative depending on the measure and time-scale. All legumes increased basal respiration and metabolic quotient and had a positive effect on activity and functional diversity of the soil microbial community, measured using Biolog EcoPlate. However, soil under Astragalus adsurgens had the highest activity and functional diversity relative to the other treatments. Soil carbon and nitrogen content and microbial biomass were effectively restored in 3–5?years by introducing Medicago sativa and Astragalus adsurgens into early abandoned fields. Soil carbon and nitrogen content were retarded in 3–5?years and microbial biomass was retarded in the fifth year by introducing Melilotus suaveolens. Overall, the restoration practices of planting legumes can significantly affect soil carbon and nitrogen contents, and the biomass, activity, and functional diversity of soil microbial community. Therefore, we propose certain legume species could be used to accelerate ecological restoration of degraded soils, hence assist in the protection and preservation of the environment.     

LANDSCAPE ATTRIBUTES AS CONTROLS ON GROITHD WATER NITRATE REMOVAL CAPACITY OF RIPARIAN ZONES1

ABSTRACT: Inherent site factors can generate substantial variation in the ground water nitrate removal capacity of riparian zones. This paper examines research in the glaciated Northeast to relate variability in ground water nitrate removal to site attributes depicted in readily available spatial databases, such as SSUIRGO. Linking site‐specific studies of riparian ground water nitrate removal to spatial data can help target high‐value riparian locations for restoration or protection and improve the modeling of watershed nitrogen flux. Site attributes, such as hydric soil status (soil wetness) and geomorphology, affect the interaction of nitrate‐enriched ground water with portions of the soil ecosystem possessing elevated biogeochemical transformation rates (i.e., biologically active zones). At our riparian sites, high ground water nitrate‐N removal rates were restricted to hydric soils. Geomorphology provided insights into ground water flowpaths. Riparian sites located on outwash and organic/alluvial deposits have high potential for nitrate‐enriched ground water to interact with biologically active zones. In till deposits, ground water nitrate removal capacity may be limited by the high occurrence of surface seeps that markedly reduce the time available for biological transformations to occur within the riparian zone. To fully realize the value of riparian zones for nitrate retention, landscape controls of riparian nitrate removal in different climatic and physiographic regions must be determined and translated into available spatial databases.     

Visible-near infrared reflectance spectroscopy for rapid, nondestructive assessment of wetland soil quality

Recent evidence supports using visible-near infrared reflectance spectroscopy (VNIRS) for sensing soil quality; advantages include low-cost, nondestructive, rapid analysis that retains high analytical accuracy for numerous soil performance measures. Research has primarily targeted agricultural applications (precision agriculture, performance diagnostics), but implications for assessing ecological systems are equally significant. Our objective was to extend chemometrics for sensing soil quality to wetlands. Hydric soils posed two challenges. First, wetland soils exhibit a wider range of organic matter concentrations, particularly in riparian areas where levels range from <1% in sedimentation zones to >90% in backwater floodplains; this may mute spectral responses from other soil fractions. Second, spectral inference of cation concentrations in terrestrial soils is for oxidized species; under reducing conditions in wetlands, oxidation state variability is observed, which strongly affects chroma. Riparian soils (n = 273) from western Florida exhibiting substantial target parameter variability were compiled. After minimal pre-processing, soils were scanned under artificial illumination using a laboratory spectrometer. A multivariate data mining technique (regression trees) was used to relate post-processed reflectance spectra to laboratory observations (pH, organic content, cation concentrations, total N, C, and P, extracellular enzyme activity). High validation accuracy was generally observed (r2(validation) > 0.8, RPD > 2.0, where RPD is the ratio of the standard deviation of an attribute to the observed standard error of validation); where accuracy was lower, categorical models (classification trees) successfully screened samples based on diagnostic functional thresholds (validation odds ratio > 10). Graphical models verified significant association between predictions and observations for all parameters, conditioning on biogeochemical covariates. Visible-near infrared reflectance spectroscopy offers both cost and statistical power advantages; hydric conditions do not appear to constrain application.     

An analytical platform for cumulative impact assessment based on multiple futures: the impact of petroleum drilling and forest harvesting on moose (Alces alces) and marten (Martes americana) habitats in northeastern British Columbia

The combined influence on the environment of all projects occurring in a single area is evaluated through cumulative impact assessments (CIA), which consider the consequences of multiple projects, each insignificant on its own, yet important when evaluated collectively. Traditionally, future human activities are included in CIA using an analytical platform, commonly based on complex models that supply precise predictions but with reduced accuracy. To compensate for the lack of accuracy in current CIA approaches, we propose a shift in the paradigm governing CIA. The paradigm shift involves a change in the focus of CIA investigations from the detailed analysis of one unlikely future to the identification of the patterns describing multiple potential future changes in the environment. To illustrate the approach, a set of 144 possible and equally likely futures were developed that aimed to identify the potential impacts of forest harvesting and petroleum drilling on the habitat suitability of moose and marten in northeast British Columbia, Canada. The evolution of two measures of habitat suitability (average habitat suitability index and surface of the stands with habitat suitability index >0.5) revealed that the human activities could induce cycles in the habitat dynamics of moose and marten. The planning period of 100 years was separated into three distinct periods following a sinusoidal pattern (i.e., increase - constant - decrease in the habitat suitability measures). The attributes that could induce significant changes in the assessment of environment are the choice of harvesting age and species.