Environmental Site Characteristics Research Articles

Physiological trait coordination and variability across and within three Pinus species.

Studies have explored how traits separate plants ecologically and the trade-offs that underpin this separation. However, uncertainty remains as to the taxonomic scale at which traits can predictably separate species. We studied how physiological traits separated three Pinus (Pinus banksiana, Pinus resinosa, and Pinus strobus) species across three sites. We collected traits from four common leaf and branch measurements (light-response curves, CO2-response curves, pressure-volume curves, and hydraulic vulnerability curves) across each species and site. While common, these measurements are not typically measured together due to logistical constraints. Few traits varied across species and sites as expected given the ecological preferences of the species and environmental site characteristics. Some trait trade-offs present at broad taxonomic scales were observed across the three species, but most were absent within species. Certain trade-offs contrasted expectations observed at broader scales but followed expectations given the species' ecological preferences. We emphasize the need to both clarify why certain traits are being studied, as variation in unexpected but ecologically meaningful ways often occurs and certain traits might not vary substantially within a given lineage (e.g. hydraulic vulnerability in Pinus), highlighting the role a trait selection in trait ecology.

Can we predict visitor movement? Using step selection function analysis to map high probability camping areas in a remote Alaskan wilderness

Recreational use of parks and protected areas (PPAs) can have significant impacts to resources that can be difficult to mitigate. Cost-effective planning tools are needed to help managers anticipate where recreation disturbance is likely to occur. Tools from wildlife ecology may be helpful in meeting this information need, especially for large, remote PPA that experience sporadic use. We employed step selection function (SSF) analysis as a novel and flexible tool to identify areas with high probabilities of recreational disturbance. We fit SSFs to model environmental and experiential factors associated with campsite selection among backcountry kayakers in two regions of Glacier Bay National Park and Preserve (GLBA) in Alaska, USA. We hypothesized campers would select sites that offer bare, flat ground, are close to freshwater sources, and maximize experience-related attributes of glacier and scenic viewing while minimizing exposure to large vessels. Campers in both regions selected sites offering a combination of experiential and environmental site characteristics; however, not all factors were significant in the best fitting models. Site selection probabilities increased with increases in bare, flat ground and as distance to the nearest glacier decreased. In one region, selection probability also increased with increases in scenic viewshed. Using modeled relationships, we generated predictive maps of relative selection strength to locate areas within GLBA with high potential for camping based on site characteristics. Our results can be used to prioritize monitoring, target restoration efforts, or implement management actions to prevent camping-related resource impacts.

Rainforest carnivore ecology in a managed forest reserve: Differential seasonal correlates between habitat components and relative abundance

Studies of relationships between seasons and Neotropical carnivore distributions tend to focus on water and prey availability without considering other habitat components such as escape, foraging, and resting cover. Our goal was to evaluate habitat characteristics that may be important for predicting the seasonal (dry or rainy) relative abundance of four commonly captured Neotropical carnivores (i.e., jaguar [Panthera onca], puma [Puma concolor], ocelot [Leopardus pardalis], and grey fox [Urocyon cinereoargenteus]) in Chiquibul Forest Reserve in Belize, Central America. We used trail camera data and random-effect Poisson models to investigate how prey ratios (number of prey detections/total detections), cover (e.g., logs and stumps used for hiding cover from predators), vegetation structure, and environmental site characteristics (e.g., site harvest-history, slope, aspect) were related to carnivore relative abundance. Both prey ratios and vegetation structure appeared in supported models more frequently than other environmental site characteristics and were negatively correlated with carnivore relative abundance. Supported models differed for each season for all species except jaguars for which mammalian prey ratios and prey cover at sites was always negatively correlated with jaguar relative abundance. Carnivores appeared to avoid sites where vegetation created ideal escape and hiding cover for prey even though prey may be less abundant. Our data suggest that vegetation structure and composition can create conditions conducive to carnivore foraging and that these characteristics can differ by season in the tropics.

Pesticide contamination and associated risk factors at public playgrounds near intensively managed apple and wine orchards

BackgroundPesticide levels are generally monitored within agricultural areas, but are commonly not assessed at public places. To assess possible contamination of non-target areas, 71 public playgrounds located next to intensively managed apple and wine orchards were selected in four valleys of South Tyrol (northern Italy). Further, the impact of environmental site characteristics on the number and concentration of pesticides was assessed. Grass samples from the selected playgrounds were collected and screened for 315 pesticide residues using standard gas chromatography and mass spectrometry.ResultsNearly half of the playgrounds (45%) were contaminated by at least one pesticide and a quarter (24%) by more than one. Eleven of the 12 different detected pesticides are classified as endocrine-active substances including the insecticide phosmet and the fungicide fluazinam showing the highest concentrations (0.069 and 0.26 mg kg−1, respectively). Additionally, one disinfectant and one preservation agent was found. Playgrounds in Venosta valley were most often contaminated (76% of all investigated playgrounds), highest concentrations were found in the Low Adige (2.02 mg kg−1). Pesticide concentrations were positively associated with areal proportion of apple orchards in the surroundings, the amount of rainfall and wind speed. In contrast, increasing global irradiance, opposite wind direction, increasing distance to agricultural sites and high wind speeds when pesticide application was not allowed were associated with decreasing pesticide contamination.ConclusionThis study is among the first investigating pesticide contamination of public playgrounds together with environmental factors in areas with pesticide-intensive agriculture at the beginning of the growing season. It is likely that playgrounds will be affected by more pesticides and higher concentrations over the course of the crop season. The result, that the majority of the detected pesticides are classified as endocrine active is worrisome as children are especially vulnerable. Hence, we recommend that pesticide risk assessments should better include protection measures for non-target areas.

Burn severity controls on postfire Araucaria‐Nothofagus regeneration in the Andean Cordillera

AbstractAimThe aim of the study was to investigate postfire regeneration patterns of Araucaria‐Nothofagus forests on the west slope of the Andes; to evaluate the relationship between remotely sensed burn severity and forest mortality; and to assess controls of burn severity on forest response at local spatio‐temporal scales.LocationAraucanía region in the western Andean Range of south‐central Chile where fire occurred during the 2001–2002 season.MethodsSampling of prefire stand structure and postfire vegetation response was performed along a burn severity gradient a decade after the fire. We evaluated the relationship between field‐measured tree mortality and satellite‐derived burn severity using a generalized linear model. We fit zero‐inflated mixture models to regeneration data of each genus to assess the importance of abiotic variables, stand characteristics, and biotic interactions.ResultsThe relative version of the delta Normalized Burn Ratio explained 85% of the variability in canopy mortality. Nearly 12,000 hectares burned; the majority at high severity (67%). Regeneration densities of both genera were lower at higher levels of burn severity and higher with greater total basal area (live, dead, and down trees). The relative effect size of burn severity on regeneration was nearly twice as large for Nothofagus, which suggests information legacies of Araucaria have cascading effects on postdisturbance material legacies.Main conclusionsAraucaria‐Nothofagus mortality from wildfire can be readily mapped using satellite‐derived burn severity. Although environmental site characteristics and biotic interactions mediate regeneration, basal area, and burn severity are the main mechanisms controlling regeneration. Forest refugia and postfire regeneration are vulnerable to recurrent fire. Therefore, we expect future fire (either increased severity or frequency), driven by landscape level changes, as a potential mechanism that can reduce local resilience of these forests as initial postfire material legacies (e.g., refugia and regeneration) are removed from the landscape. Our findings highlight an approach to quantify important attributes of forest disturbance and refugia, and identify areas for monitoring postdisturbance regeneration as the forests throughout south‐central Chile and Argentina face a multitude of potential change agents.

Post-Fire Native Seed Use in Western Colorado: A Look at Burned and Unburned Vegetation Communities

Wildfires on public lands in the United States are increasing in size and frequency over time. Government agency post-fire treatments often include seeding of native and nonnative plant species; however, the effectiveness of post-fire seeding has been questioned, and while the importance of using native species has been emphasized, more research on the effects of native seeding post-fire is needed. We sought to understand what characteristics of vegetation communities distinguished burned and unburned areas, and if environmental characteristics of sites would predictably alter community composition. We collected vegetation, ground cover, and environmental data during the summer of 2015 from public lands that burned in wildfires between 2005 and 2012 and were seeded with a native seed mix. We also collected data from unburned comparison areas that were not seeded. We found that biological soil crusts distinguished unburned areas while native forbs, nonnative forbs, and seeded native species distinguished burned areas. Surprisingly, Bromus tectorum (cheatgrass) was not important in distinguishing burned from unburned areas. Precipitation the year after fire influenced vegetation communities.

Quantifying Preferences for the Natural World Using Monetary and Nonmonetary Assessments of Value

Given that funds for biodiversity conservation are limited, there is a need to understand people’s preferences for its different components. To date, such preferences have largely been measured in monetary terms. However, how people value biodiversity may differ from economic theory, and there is little consensus over whether monetary metrics are always appropriate or the degree to which other methods offer alternative and complementary perspectives on value. We used a choice experiment to compare monetary amounts recreational visitors to urban green spaces were willing to pay for biodiversity enhancement (increases in species richness for birds, plants, and aquatic macroinvertebrates) with self-reported psychological gains in well-being derived from visiting the same sites. Willingness-to-pay (WTP) estimates were significant and positive, and respondents reported high gains in well-being across 3 axes derived from environmental psychology theories (reflection, attachment, continuity with past). The 2 metrics were broadly congruent. Participants with above-median self-reported well-being scores were willing to pay significantly higher amounts for enhancing species richness than those with below-median scores, regardless of taxon. The socio-economic and demographic background of participants played little role in determining either their well-being or the probability of choosing a paying option within the choice experiment. Site-level environmental characteristics were only somewhat related to WTP, but showed strong associations with self-reported well-being. Both approaches are likely to reflect a combination of the environmental properties of a site and unobserved individual preference heterogeneity for the natural world. Our results suggest that either metric will deliver mutually consistent results in an assessment of environmental preferences, although which approach is preferable depends on why one wishes to measure values for the natural world.

Community phylogenetic diversity and abiotic site characteristics influence abundance of the invasive plant Rhamnus cathartica L.

Aims Theory predicts that the success of introduced species is related to the diversity of native species through trait-based processes. Abiotic site characteristics may also affect a site’s susceptibility to invasion. We quantified resident plant species richness, phylogenetic diversity and several abiotic site characteristics for 24 oak forests in Minnesota, USA, to assess their impact on the abundance of a widespread, introduced terrestrial plant species, common buckthorn (Rhamnus cathartica L.). Specifically, we asked (1) whether resident species richness and phylogenetic diversity affected the abundance of R. cathartica and (2) what site characteristics explained the overall abundance of R. cathartica. Methods Our survey included 24 oak-dominated stands in Minnesota’s deciduous forests. In each stand, we identified all species in 16 plots. We also measured a series of environmental site characteristics, including canopy openness (a proxy for light availability), percent bare soil, soil pH, percent sand, an index of propagule availability, duff layer thickness (a proxy for earthworm activity), an index of insolation and slope. For all species present in at least one site, we estimated a community phylogeny. We combined all sitelevel characteristics, including phylogenetic diversity of the resident plant species, in a multiple regression model to examine site level drivers of community invasibility. Important Findings Results indicate that sites with higher overall plant phylogenetic diversity harbor less R. cathartica, even though native species richness was not significantly related to R. cathartica abundance. Regression analyses indicated that, in addition to resident species phylogenetic diversity, the most important predictors of R. cathartica abundance were canopy openness and the amount of bare soil, both positively related to the abundance of the invader. By combining the effects of abiotic site characteristics and resident species phylogenetic diversity in a model that predicted the abundance of R. cathartica, we were able to simultaneously account for a wide range of factors that might influence invasibility. Overall, our results suggest that management strategies aimed at reducing disturbances that lead to increased bare soil and light levels may be more successful if they also maximize phylogenetic diversity of the resident plant community.

Comparison of species and trait‐based approaches for describing sagebrush steppe response to range management

AbstractQuestionIs valuable information lost when plant trait group composition is used, rather than species composition, to describe plant community response to range management?LocationElkhead Watershed, Colorado, US.MethodsCurrent model‐building efforts use species composition to define changes in ecosystem state, but plant traits may offer a faster and more broadly applicable alternative. We (1) compare states defined by species composition to those defined by trait‐based groups of differing complexity and (2) determine how management and environmental site characteristics relate to species‐ and trait group‐defined states. We sampled 72 plots with different grazing and chemical shrub treatment histories on two soil types. We measured plant species composition in each plot and categorized species into trait groups using three classification schemes, which represented increasing numbers of traits and levels of classification complexity. The classifications employed easily measured traits that affect plant response to range management: life form, life history, resprouting ability, height, vegetative reproduction and N‐fixation. Using hierarchical cluster analysis, we identified states with similar species or trait group composition. We explored relationships between each set of potential states and management history and environmental factors using logistic regression.ResultsTrait‐based group composition and species composition identified many of the same potential states and responses to grazing and chemical shrub treatment. Relationships between species and trait group composition and management and environmental characteristics differed on the two soil types. Species composition was sensitive to more different management practices, on average, than trait group composition. Trait group composition revealed some relationships to management and environmental drivers that were not detected using species composition.ConclusionThis study confirms that species composition is a more sensitive indicator of sagebrush steppe response to range management, and some information is lost with a trait‐based approach. However, traits also add to depth of understanding by revealing additional community patterns related to different drivers. Using the most complex trait grouping scheme that is feasible in a particular study, and also looking for patterns based on simpler trait groups, will provide the most complete understanding of sagebrush steppe response to range management.

Urban Advantages and Disadvantages in Southeastern Europe: An Appreciation of Industrial Firms by Using Exploratory Factor Analysis

1. Introduction: Industrial Firms' Competitiveness and Local Assets Mainly, two traditional theories of strategic management, the Industrial Organization Theory and the Resource-Based View, try to explain the development and competitiveness of industrial firms. The first theory focuses on the forces of firms external environment that influenced their competitiveness (Porter, M.E., 1998), while the second one concerns firms internal environment--their own capacities and the sources that they have in order to become competitive (Barney, 2001; Wernerfelt, 1984). To the forces of external environment, are also referred the distinctive characteristics or urban assets where firms are located (Parkinson, et al., 2004; Begg, 1999; Deas, and Giordano, 2001). According to Maskell and Malmberg (1999), the competitiveness of industrial firms, depends on a particular combination of local characteristics that influence the distribution of economic activities, combining each time the capacity of each place on local and regional level. Through the analysis of the relationship between the territory (region, city) and the industrial firm, they try to find the answers on questions relating to how the forces of the spatial environment affect firms, through which ways and procedures these firms grow and how industrial systems (2), in which the firms belong to, affect the firms' development strategies. Porter, referring to the formation of the firms environment at micro level, he argued that it is understood through the correlation of four key areas of analysis: a) the quality of inputs / conditions of the local environment, b) the framework of the strategies and competition of the firm, c) the quality of demand conditions in the local environment and d) the presence of other related or supporting firms (Porter, 1998, 2000, 2003 / DTI 2003). As shown in figure 1 ('diamond model'), the factors that compose the above areas of analysis, represent both the firms as organizations and activities and environmental characteristics of sites / areas where the firms are located and which affect the productivity and the firms' development. Several other studies examine specific factors such as agglomeration economies and easy access to markets (national and European markets, access to customers and suppliers, existence of foreign firms and availability of supporting services) [CEC, 1993; Iammarino, and Pitelis, 2000; Haufler and Wooton, 1999; Nachum and Keeble, 2003; Redding and Venables, 2004; Iammarino and McCann, 2006)], regional and local policies (strong investments motives, local authorities attitude towards businesses, entrepreneurial climate, and low local taxes) [Fuller, et al., 2003; Cossentino, 1996; Bennett and Krebs, 1991; Devereux and Griffith, 2002; Young, 2005], labour factors (availability, quality and the specialization of the labour force) [Keune, 2001; Sforzi and Lorenzini, 2002 cited in Lazzeretti, et. al., 2008], cost of transportation and the costs of land use and labour (Harrington and Warf, 1995; Miller, 1977; Zhu, 2000), urban infrastructure (efficiency of road/highway network, railway connections, sea connections, air connections and telecommunications) [Vickerman, 1994, 1996; Gao, 2004]. Finally, a number of studies have define that role of the local authorities is very important since they can support the competitiveness of the existing firms and they can attract new ones, contributing to the creation of a dynamic business environment, (Leeming, 2002; Syrett, 1994). [FIGURE 1 OMITTED] Based on the above each firm is not just a formal structured entity, but contrary it is an important part of the wider local social, economic and cultural environment. This environment can provide competitive advantages, which might refer to the specific characteristics of the cities / areas (infrastructure, technology, expertise, etc.). These advantages will strengthen the competitiveness of the local firms and contribute to attracting and creating new ones (Keune, 2001; Cossentino, 1996). …

Multi-decadal Changes in Tundra Environments and Ecosystems: The International Polar Year-Back to the Future Project (IPY-BTF)

Polar and alpine environments are changing rapidly due to increases in temperature, which are amplified in the Arctic, as well as changes in many local factors. The impacts on ecosystems and their function have potential consequences for local residents and the global community. Tundra areas are vast and diverse, and the knowledge of geographical variation in environmental and ecosystem change is limited to relatively few locations, or to remote sensing approaches that are limited mostly to the past few decades. The International Polar Year, IPY, provided a context, stimulus and timely opportunities for re-visiting old research sites and data sets to collate data on past changes, to pass knowledge from old to new generations of researchers and to document environmental characteristics of sites to facilitate detection and attribution of future changes. Consequently, the project "Retrospective and Prospective Vegetation Change in the Polar Regions: Back to the Future," BTF, was proposed and endorsed as an IPY activity (project #512). With national funding support, teams of researchers re-visited former sites and data sets throughout the Arctic and some alpine regions. These efforts have amounted to a gamut of "BTF" studies that are collectively geographically expansive and disciplinary diverse. A selection of these studies are introduced and presented in the current issue together with a brief synthesis of their findings.

Morphological trends in main stem of Pinus radiata D. Don: Transition between vegetative and reproductive phase

Developmental patterns of structural units of the main tree axis of Pinus radiata were investigated in two plantations in Chile growing under different ecological conditions. Environmental characteristics of sites were recorded and structural features of sample trees were measured. Annual shoot length, number of growth units per annual shoot, growth unit length, and number of branches and cones per growth unit were statistically compared between sites and between vegetative and reproductive phases of trees. No clear pattern of stand development was apparent when variables were directly examined in terms of actual dimensions (cm) and time scale (years). In contrast, common patterns of development of structural parameters were indicated after dimensions and time were normalized so as to express them on a ontogenetic scale. The number of growth units per annual shoot and average length of annual shoot increased during the juvenile stage of development. Transition from juvenile to mature stages brought about a change in this trend, either stabilizing or reversing the pattern of development and size of these structural elements. The practical consequence of these changes on wood quality for industrial purposes is discussed.

Conservation of taxonomic and biological trait diversity of European stream macroinvertebrate communities: a case for a collective public database

The use of databases for the conservation of biodiversity is increasing. During the last decade, such a database has been created for European stream macroinvertebrates. Today, it includes 527 sites that are the least human-impacted representatives of many stream types across many European regions. It includes data on the abundance of 312 invertebrate genera, several environmental site characteristics, collection methods, bibliographic data sources, and 11 biological traits of the genera (e.g. size, life cycle, food and feeding habits, described in 61 categories). The database will be useful in addressing many topics that are potentially relevant to biodiversity conservation. To illustrate this potential, we provide examples of how the data could be exploited. First, we describe the frequency of some taxonomic and biological characteristics (e.g. richness and diversity of genera and traits) of the macroinvertebrate communities and assess how these characteristics are related (e.g. how trait richness increases with genus richness). Second, we describe the frequency of some characteristics of the genera and traits (e.g. occurrence frequency, abundance, dispersion index) and again assess how these characteristics are related (e.g. how occurrence increases with abundance). Finally, we suggest how the database could be developed into a collective, publicly accessible database that covers stream types and regions of Europe more comprehensively.

Revegetation Strategies After Saltcedar (Tamarix spp.) Control in Headwater, Transitional, and Depositional Watershed Areas1

Abstract The exotic saltcedar occupies headwater, transitional, and depositional watershed portions, and revegetation strategies can be quite different depending on these locations. Regardless of specific socioeconomic or biological needs (or both), sites must often be revegetated after control to avoid reinfestation or invasion by other exotic species. Where natural riparian hydrologic processes continue to function, natural regeneration can be used as an effective restoration mechanism. However, in altered river systems, harsh environmental site characteristics may occur that severely limit revegetation potential after control, particularly in depositional areas. Because of high costs associated with saltcedar control, revegetation, and follow-up management, specific treatment areas should be evaluated and prioritized based on revegetation potential. Specific consideration should be given to the establishment of sustainable plant communities for long-term exclusion of saltcedar and other exotics. Nomenc...

Spontaneous vegetation dynamics and restoration prospects for limestone quarries in Lebanon

Abstract. In terms of restoration planning, the analysis of natural regeneration processes represents a valuable starting point for the selection of suitable species to be used. This paper aims to identify colonizing key species among the pioneer vegetation of limestone quarries in Lebanon, to identify potential restoration strategies in terms of reconstitution of the pre‐mining vegetation cover. Characteristics of the major ground colonizers after disturbance were identified in a representative quarry in the thermo‐Mediterranean biozone. The floristic inventories resulted in a matrix of cover values of 107 species × 14 plots. Correspondence analyses were used to pinpoint similarities in the distribution of key species among the different environmental characteristics of sites. The main results reveal a heterogeneous floristic composition along the regeneration gradient, where annual R‐strategy taxa such as Inula viscosa and Ainsworthia cordata dominate on very perturbed and degraded sites. Less degraded areas within the quarry were rich in herbaceous perennial or shrub species such as Geranium dissectum, Stachys distans, Salvia triloba and Ptilostemon chamaepeuce. On relatively non‐degraded areas woody and shrub perennials such as Pinus brutia, Pistacia palaestina and Quercus calliprinos dominate, along with less stress tolerant taxa such as Arbutus andrachne and Cistus creticus. Species to be used in restoration projects should be chosen from among the local vegetation, according to frequency of occurrence during the whole succession process which will reflect their adaptability to local conditions and their relevance to restoration objectives.

Spontaneous vegetation dynamics and restoration prospects for limestone quarries in Lebanon

Abstract In terms of restoration planning, the analysis of natural regeneration processes represents a valuable starting point for the selection of suitable species to be used. This paper aims to identify colonizing key species among the pioneer vegetation of limestone quarries in Lebanon, to identify potential restoration strategies in terms of reconstitution of the pre-mining vegetation cover. Characteristics of the major ground colonizers after disturbance were identified in a representative quarry in the thermo-Mediterranean biozone. The floristic inventories resulted in a matrix of cover values of 107 species × 14 plots. Correspondence analyses were used to pinpoint similarities in the distribution of key species among the different environmental characteristics of sites. The main results reveal a heterogeneous floristic composition along the regeneration gradient, where annual R-strategy taxa such as Inula viscosa and Ainsworthia cordata dominate on very perturbed and degraded sites. Less degraded a...

Assessing Consumer Knowledge and Use of Landscape Plant Health Care and Integrated Pest Management Practices through a Computer-based Interactive Survey

Attendees at the 2001 Philadelphia Flower Show participated in an interactive-quiz-formatted survey on touch-screen computers to determine their knowledge and use of plant health care (PHC) and integrated pest management (IPM) practices. Participants answered 15 questions in three categories: 1) PHC practices (criteria for proper plant selection, correct planting practices, and reasons for mulching and pruning); 2) IPM practices (insect identification, plant and pest monitoring, and maintenance of records on pests found and treatments applied to their landscape plants); and 3) demographic and sociographic questions to aid in characterizing the survey population. Over half of the participants (58%) were interested in gardening and a majority (77%) were interested in protecting the environment. Most participants (66%) were between 36 and 60 years of age with a mean age of 47 years, 76% lived in and owned a single-family home, and greater than half (56%) had never purchased professional landscape services. Most recognized PHC criteria for proper site selection, although not all environmental site characteristics were recognized as being equally important. Nearly half (49%) identified the correct planting practice among the choices offered; while an equal number of participants chose among the several improper practices listed. Although reasons for mulching were properly identified by the respondents, excess mulching around trees was considered a proper planting practice by over 39% of the participants. When questioned about IPM practices, a majority reported that they identify pests prior to treating them (71%) and that they scouted their landscapes (82%). However, only 21% kept records of the pests that they had found and the treatments that they applied for those pests. Participants' responses were further examined using cluster analysis in order to characterize the participants and identify meaningful consumer knowledge segments for targeting future extension programming. Three distinct segments were identified: 1) horticulturally savvy (69% of the participants), 2) part-time gardener (25% of the participants), and 3) horticulturally challenged (6%). At least 47% of the horticulturally savvy and part-time gardeners correctly answered plant health care questions (44% of the total survey participants). These two segments included more individuals who were interested in gardening and protecting the environment and are potential targets for future PHC and IPM extension education programs. In contrast the horticulturally challenged recorded no interest in or opinion on gardening or protecting the environment. It is apparent that a majority of consumers are learning and employing PHC and IPM concepts. Proper site selection, planting practices, and mulching along with record keep- ing and pest identification proficiency remain key educational areas to be developed. Although not all gardeners are well versed in all subject matter, a basic knowledge of PHC and IPM is being demonstrated.

Macroinvertebrate drift in Amazon streams in relation to riparian forest cover and fish fauna

Macroinvertebrate drift was studied in 12 sites in 9 lowland streams (400m), three mid-altitude streams (2100 m) and three high-altitude streams (3800 m) in Ecuador. The purposes of our study was 1) to examine levels and periodicity of drift in relation to altitude, 2) to examine levels and periodicity of drift in relation to environmental site characteristics and 3) to examine the effect of deforestation and specific fish families on levels and diel periodicity of drift in the lowland streams. At all altitudes, day drift of terrestrial invertebrates was equal to or greater than that of aquatic invertebrates, while aquatic invertebrates always dominated drift at night. Mean day drift density of aquatic invertebrates was the same at the two high altitudes, while it was lower in the lowland streams. In contrast, night drift density was higher in lowland stream compared to the two highland stream groups. In all lowland streams drift of aquatic invertebrates was higher at night than at daytime (night: day drift ratio 2-45, mean: 10), while it was largely aperiodic in both groups of highland streams. In all lowland streams, drift was dominated by insects (mean 99.6 %). No significant correlations were found between drift density, drift % or periodicity and riparian forest cover, benthic macroinvertebrate densities or any other environmental site characteristic in the lowland streams. However, path analyses indicated that riparian forest had a significantly negative indirect effect on night and day drift densities, because an increase in riparian cover was associated with a decline in the abundance of fish and benthos. Species richness, density and biomass of fish were directly correlated with invertebrate drift. These parameters had no effect on total day or night drift densities or drift %, but were positively correlated with the night: day drift ratio. The night: day drift ratios were more closely correlated with the species richness of Loricariidae catfish than to any other fish family. Loricariidae are night active, benthic herbivorous-detritivorous scrapers of biofilm, and their presumed effect on drift periodicity is due to physical disturbance of benthic invertebrates during the night, and not necessarily to a behavioural response from benthic invertebrates. Drift of the dominant invertebrate families (Leptophlebiidae, Baetidae, Tricorythidae, Hydropsychidae and Chironomidae) varied among localities, but night: day drift ratios of all families were positively correlated with species richness of fish, although this pattern was only significant for Leptophlebiidae and Baetidae.

Nitrogen-fixing phylotypes of Chesapeake Bay and Neuse River estuary sediments.

Sediments often exhibit low rates of nitrogen fixation, despite the presence of elevated concentrations of inorganic nitrogen. The organisms that potentially fix nitrogen in sediments have not previously been identified. Amplification of nifH genes with degenerate primers was used to assess the diversity of diazotrophs in two distinct sediment systems, anoxic muds of Chesapeake Bay and shallow surficial sediments of the Neuse River. Phylogenetic analysis revealed that sequences obtained from mid-Chesapeake Bay, which receive high organic loading and are highly reducing, clustered closely with each other and with known anaerobic microorganisms, suggesting a low abundance of aerobic or facultative diazotrophs in these sediments. Sulfate reduction dominates in the surface, but methanogenesis becomes more important with depth. A thin (<1 cm) oxidized layer is present only in the spring. No archaeal nifH sequences were obtained from Chesapeake Bay. Sequences of nifH amplified from surficial sediments of the Neuse River were distant from Chesapeake Bay sequences and included nif phylotypes related to sequences previously reported from marine mats and the Spartina rhizosphere. Differences in environmental site characteristics appear to select for different types of sediment diazotrophs, which is reflected in the phylogenetic composition of amplified nifH sequences.

Characteristics and controlling factors of bank gullies in two semi-arid mediterranean environments

Bank gullies are gullies that are formed due to a height drop caused by a terrace or a river bank, which develop by headward retreat in erodible hillslopes. This study aims (i) to investigate the morphology of actively eroding bank gullies, i.e., geometrical characteristics resulting from past erosion and active erosion processes shaping the gully, and, (ii), to find relationships with environmental site characteristics, such as topographical parameters, material properties and climate. The ultimate goal is to identify the most important controlling factors of past and present bank gully erosion. Fifty-five active bank gullies formed in different lithologies by various erosion processes have been selected in the Guadalentin basin and the surroundings of Guadix (Southeast Spain). For each bank gully site, geometrical and topographical parameters of both the channel and the drainage basin were measured. Erosion features indicating activity at the gully head, such as tension cracks, plunge pools, undercutting, fluting, piping and rill or sheet erosion on sloping side walls were mapped, and samples were taken from distinct lithological layers that were considered to influence the type and intensity of erosion processes. A relationship could be shown between the presence of piping and fluting and a number of material characteristics, including particle size distribution, dispersion behaviour and electrical conductivity. On the other hand, lithology appeared not to be a differentiating factor on gully development in the long run, as expressed by the total eroded volume ( V). This parameter was most strongly related to the drainage basin area in which the entire bank gully had been formed ( A o), explaining 66% of the variance. The relationship is V=1.75* A o 0.59. No significant difference was found between regression lines through sub-datasets of different soil textural classes. Finally, multiple regression was used to include both topographical parameters and material characteristics in an explanatory and/or predictive equation for the total eroded bank gully volume. The results of the analyses using the entire dataset, including the sites in the Guadalentin as well as in the Guadix area, have been compared with the results for the separate study areas. Differences are not only related to topographical and lithological characteristics, but may also be the consequence of a different climate in the two areas.