Riparian Habitat

The conservation of biological diversity in landscapes dominated by human use is emerging as an increasingly significant challenge, given the rate at which the Earth's remaining vegetation resources are being lost. Whilst traditional approaches to conservation have relied upon the ability of species to persist within the scattered fragments to which they have been confined, recent scientific evidence suggests that the long-term viability of fragmented populations may only be secured through the establishment of ecological connectivity between existing fragments.In the absence of a suitable methodology within which to design connective habitat configurations, a conceptual approach to landscape design was devised for a highly urbanised environment within the Shellharbour Local Government Area (LGA), New South Wales (NSW). This approach utilises beneficial landscape attributes advocated in the literature, and tailors existing rapid assessment methodologies traditionally used to provide simple measures of ecosystem health. Using this methodology, conservationally significant stepping-stone sites were identified between selected terminal habitat patches. The determination of an optimal corridor configuration linking these patches was found to heavily utilise riparian habitat and adjacent residential yard space. Planting endemic species in these areas will support ecological flow by increasing the area of core habitat relative to edge habitat.

The southern sector of the Guadiana River basin (GRB) drains the central-western part of the Iberian Pyrite Belt, an area with many polymetallic sulfide deposits and residues of mining activities that under oxidizing conditions generate an acidic leachate with large quantities of sulfates, metals, and metalloids in solution. These acidic leachates seep into the fluvial system contaminating the surface water bodies and increasing the contamination risk for local populations and riparian habitats. The present study was carried out both in Portugal and Spain with the main aim of identifying the principal contamination sources that produce acid mine drainage (AMD) in the southern part of the GRB and to evaluate the seasonal variations of water quality affected by AMD. The physicochemical parameters determined in the field (temperature, electrical conductivity, pH, redox potential, and dissolved oxygen) are discussed and interpreted together with the hydrochemical analysis of surface water samples collected at 79 points of observation. The data show a strong seasonal variation of surface water quality with poorer water quality standards during the dry season. It is also possible to observe that there is a natural decrease in pollution levels with increasing distance from the pollution source (mining areas). Acidic leachates are gradually neutralized as they drain away from the mining areas depositing Fe-(Cu-Al) bearing secondary minerals. There is also an important contaminant load reduction in the estuary area as a result of the mixing process with seawater. This contributes to a loss of the metals in solution due to both dilution and precipitation, as a result of pH increase.

Riparian forests of northwestern Pennsylvania’s Allegheny High
Plateau are often dominated by eastern hemlock, Tsuga canadensis, a tree
species under threat from the introduced hemlock woolly adelgid (Adelges
tsugae). It is vital to document the structure and composition of these forests
beforeadelgidinvasiontounderstandhowtheymayrespondtothis
disturbance and to provide information useful for future restoration and
management efforts. To meet these goals, we compared the composition and
structure of old-growth and second-growth stands in a T. canadensis-dominated
riparian forest along Henry Run, Cook Forest State Park, Pennsylvania. Tsuga
canadensis strongly dominated the large tree stratum of the old-growth stand,
followed by Betula lenta and Fagus grandifolia. Tsuga canadensis and Pinus
strobus were codominant in the second-growth stand with B. lenta, Fraxinus
americana, and Acer rubrum as secondary species. Seedlings and saplings of
dominant tree species in both old-growth and second-growth stands were under
represented relative to small and large trees, indicating regeneration difficulties.
The alien shrub Berberis thunbergii was the only sapling species to occur in the
second-growth stand, perhaps a land-use legacy, but was absent from the
seedling stratum. We predict that the potential loss of T. canadensis from the
canopy at Henry Run may cause a shift in composition to B. lenta and/or P.
strobus as these species capture gaps created by dead and dying T. canadensis.
However, browsing pressure by white-tailed deer (Odocoileus virginianus) and
competition with B. thunbergii may affect regeneration success of specific tree
species and ultimately, future forest canopy composition.

The Allegheny River Islands Wilderness (ARIW) consists of seven islands located along 90 km of the Allegheny National Wild and Scenic River in northwestern Pennsylvania. I surveyed riparian plant communities in the ARIW to provide an inventory of the species composition and distribution of the alien flora and to identify species of potential management concern. Forty-one alien plant species were tallied from 42 survey sites across the seven islands of the ARIW. The largely herbaceous floodplain scour community supported the greatest number of alien plant species (36 species; 18.9% of the community flora), followed by the Acer saccharinum L. – Platanus occidentalis L. floodplain forest community (23 species; 16.8% of the community flora) and the P. occidentalis  - Carya cordiformis (Wang.) K. Koch – Ulmus rubra Muhl. floodplain forest community (14 species; 12.4% of the community flora). Ten alien plant species (24.4% of the alien flora) occurred across all three community types. The alien flora of the ARIW included a range of species with varied ecological impact potential, distribution across plant communities, and difficulty of control. Potential control strategies for alien plant species in the ARIW must address the influence of an altered hydrologic regimen as well as control protocols for specific species on the islands and surrounding river corridor.

Macroinvertebrates are one of the key components of lake ecosystems and are required to be monitored alongside other biological groups to define ecological status according to European Union legislation. Macroinvertebrate communities are highly variable and complex and respond to a diverse series of environmental conditions. The purpose of this study was to examine the relative importance of environmental variables in explaining macroinvertebrate abundance. A total of 45 sub-alpine lakes were sampled for macroinvertebrates in the shallow sublittoral. Environmental variables were grouped into four types: (1) aquatic physical and chemical parameters, (2) littoral and riparian habitat, (3) lake morphometric parameters and (4) sediment chemical characteristics. Nonparametric multiplicative regression (NPMR) was used to model the abundance of individual macroinvertebrate taxa. Significant models were produced for nine out of the 24 taxa examined. Sediment characteristics were the group most frequently included in models and also the factors to which taxa abundance was the most sensitive. Aquatic physical and chemical variables were the next group most frequently included in models although chlorophyll a was not included in any of the models and total phosphorus in only one. This indicates that many taxa may not show a direct easily interpretable response to eutrophication pressure. Lake morphometric factors were included in several of the models although the sensitivity of macroinvertebrate abundance tended to be lower than for sediment and aquatic physical and chemical factors. Habitat factors were only included in three models although riparian vegetation was found to have a significant influence on the abundance of Ephemera danica indicating that ecotone integrity is likely to play a role in its ecology. Overall, the models tended to be specific for species with limited commonality across taxa. Models produced by NPMR indicate that the response of macroinvertebrates to environmental variables can be successfully described but further research is required focussing in more detail on the response of key taxa to relevant environmental parameters and anthropogenic pressures.

Keywords Lake macroinvertebrates - Sub-alpine lakes - Nonparametric multiplicative regression - Water Framework Directive

Abstract: We developed three black bear (   Ursus americanus) habitat models in the context of a geographic information system to identify linkage areas across a major transportation corridor. One model was based on empirical habitat data, and the other two (opinion- and literature-based) were based on expert information developed in a multicriteria decision-making process. We validated the performance of the models with an independent data set. Four classes of highway linkage zones were generated. Class 3 linkages were the most accurate for mapping cross-highway movement. Our tests showed that the model based on expert literature most closely approximated the empirical model, both in the results of statistical tests and the description of the class 3 linkages. In addition, the expert literature–based model was consistently more similar to the empirical model than either of two seasonal, expert opinion–based models. Among the expert models, the literature-based model had the strongest correlation with the empirical model. Expert-opinion models were less in agreement with the empirical model. The poor performance of the expert-opinion model may be explained by an overestimation of the importance of riparian habitat by experts compared with the literature. A small portion of the empirical data to test the models was from the pre-berry season and may have affected how well the model predicted linkage areas. Our empirical and expert models represent useful tools for resource and transportation planners charged with determining the location of mitigation passages for wildlife when baseline information is lacking and when time constraints do not allow for data collection before construction.Resumen: Desarrollamos tres modelos para el hábitat del Oso Negro (   Ursus americanus) en el contexto de un sistema de información geográfico para identificar las áreas de conexión a lo largo de un corredor de transporte grande. Un modelo estuvo basado en datos empíricos del hábitat y los otros dos (basados en opinión y en literatura) estuvieron basados en información de expertos desarrollada mediante un proceso de criterios múltiples y de toma de decisiones. Validamos el funcionamiento de los modelos con un juego de datos independiente. Se generaron cuatro clases de zonas de conexión en carreteras. Las conexiones clase 3 fueron las más precisas para el mapeo de movimientos de cruce de carreteras. Nuestras pruebas muestran que el modelo basado en literatura de expertos fue el que se aproximó más al modelo empírico, tanto en los resultados de las pruebas estadísticas, como en la descripción de las conexiones de clase 3. Aunado a esto, el modelo basado en la literatura de expertos fue consistentemente más similar al modelo empírico que cualquiera de los dos modelos estacionales basados en la opinión de los expertos. Entre los modelos de expertos, el modelo basado en la literatura tuvo la correlación más alta con el modelo empírico. Los modelos de opinión de expertos tuvieron menos concordancia con el modelo empírico. El bajo rendimiento de los modelos basados en la opinión de los expertos puede ser explicado por una sobrestimación de los expertos de la importancia del hábitat ripario comparado con lo que se establece en la literatura. Una pequeña porción de los datos empíricos usados para probar los modelos correspondió a la estación previa a las bayas y pudo haber afectado la eficacia de los modelos para predecir las áreas de conexión. Nuestros modelos empíricos y de expertos representan herramientas útiles para los encargados del manejo de recursos y la planeación de la transportación y los que necesitan determinar la ubicación de pasajes de mitigación para la vida silvestre, cuando se carece de información base y cuando las limitantes de tiempo no permiten la recolección de datos antes de iniciar la construcción.Resumen: Desarrollamos tres modelos para el hábitat del Oso Negro (   Ursus americanus) en el contexto de un sistema de información geográfico para identificar las áreas de conexión a lo largo de un corredor de transporte grande. Un modelo estuvo basado en datos empíricos del hábitat y los otros dos (basados en opinión y en literatura) estuvieron basados en información de expertos desarrollada mediante un proceso de criterios múltiples y de toma de decisiones. Validamos el funcionamiento de los modelos con un juego de datos independiente. Se generaron cuatro clases de zonas de conexión en carreteras. Las conexiones clase 3 fueron las más precisas para el mapeo de movimientos de cruce de carreteras. Nuestras pruebas muestran que el modelo basado en literatura de expertos fue el que se aproximó más al modelo empírico, tanto en los resultados de las pruebas estadísticas, como en la descripción de las conexiones de clase 3. Aunado a esto, el modelo basado en la literatura de expertos fue consistentemente más similar al modelo empírico que cualquiera de los dos modelos estacionales basados en la opinión de los expertos. Entre los modelos de expertos, el modelo basado en la literatura tuvo la correlación más alta con el modelo empírico. Los modelos de opinión de expertos tuvieron menos concordancia con el modelo empírico. El bajo rendimiento de los modelos basados en la opinión de los expertos puede ser explicado por una sobrestimación de los expertos de la importancia del hábitat ripario comparado con lo que se establece en la literatura. Una pequeña porción de los datos empíricos usados para probar los modelos correspondió a la estación previa a las bayas y pudo haber afectado la eficacia de los modelos para predecir las áreas de conexión. Nuestros modelos empíricos y de expertos representan herramientas útiles para los encargados del manejo de recursos y la planeación de la transportación y los que necesitan determinar la ubicación de pasajes de mitigación para la vida silvestre, cuando se carece de información base y cuando las limitantes de tiempo no permiten la recolección de datos antes de iniciar la construcción.

The species composition and richness of the summer riparian vegetation of four small  streams in the nonglaciated  Allegheny  Plateau  of northwestern Pennsylvania  (Forest,  Warren and McKean Counties) were examined. The arboreal stratum  (stems  > 2.5 cm dbh) of the four streams  consisted of twenty species with Fagus grandifolia,  Betula  alleghaniensis,  and  Tsuga  canadensis  dominant  (mean number of arboreal species  across sites  = 9.8 ± 0.9 SE).  Ninety-nine  species  were recorded from the ground-layer  stratum  (all  vascular plants >  2 m tall) of the four streams with forbs as the dominant growth form. Four species, Dryopteris intermedia, Maianthemum  canadense,  Pilea pumila,  and  Viola blanda,  were  common  to  the ground-layer vegetation associated with all streams. Species of upland affinity were more prevalent  in the riparian vegetation across streams than were wetland  species. Several  of the  plant  species  recorded  are  indicators  of rich  and/or  subacid  to circumneutral  soils, an edaphic medium of limited occurrence  in the region. Mean ground-layer  species richness  and cover differed significantly among streams  and ranged from 3.7 to 10.5 species/m2  (mean number of species/m2  across sites= 7 .9 ± 1.5 SE) and 8.3 to 43.0% (mean percent cover across sites= 30.4 ± 7.7 SE), respectively. Similarity  in  ground-layer  species  composition among streams  ranged from 33.3  to 54.1% (mean  similarity  across sites  = 38.9 ± 3.7%  SE  ).  Although compositionally distinct, the small stream riparian flora documented by this study compares favorably in richness to other riparian habitats in northwestern Pennsylvania.

Assessing the impacts of projects that affect aquatic resources is an integral part of regulatory programs. The time, resource, and technical requirements of existing assessment methods often prohibit their routine use by regulatory staff. Consequently, many evaluations are based on area affected and best professional judgment. In this paper, we present a Rapid Impact Assessment Method (RIAM) that can be used to assess impacts to aquatic resources in a manner that is scientifically defensible, yet easy to implement by regulators, planners, and resource managers. The RIAM provides a framework for assessing impacts while allowing for specialization of evaluation criteria based on the habitat type, region of interest, and specific regulatory, planning, or management goal. Site-specific impacts are assessed, by comparing the conditions present at each site prior to project implementation to conditions present after implementation of the project. A set of evaluation criteria is defined to reflect the important ecological characteristics to be evaluated. Each project site is given a pre- and post-project rating for each evaluation criterion, ranging from A for site conditions similar to those present at reference sites to E for the most degraded condition. Impact scores for each criterion, ranging from −4 to +4, are based on the difference between the pre- and post-project rating levels at each site. We demonstrate the application of the RIAM by using it to assess the impacts of projects permitted under Section 404 of the Clean Water Act on the following six evaluation criteria: endangered species habitat, structural diversity of habitat, spatial diversity of habitat, open space habitat, linear contiguity of habitat, and adjacent habitats. In the future, the method developed in this study can be used as a predictive tool to help monitor impacts on an ongoing basis.