Plant community changes within a mature pinyon-juniper woodland

Vegetal composition was determined during 1974 and 1984 using 60 permanent 50 m 2 plots within a mature pinyon-juniper community in northeastern Utah. Results indicated that not only was there little significant change in community composition, but with many species frequency and density remained nearly the same during the decade.     

Beetles from the environs of Lake Powell in southern Utah and northern Arizona

Sixty-eight species of beetles of 14 families were collected in pit traps in 12 major vegetative communities during environmental monitoring studies in the summers of 1971 to 1973 in southern Utah and northern Arizona. Seasonal and plant community differences and correlations in population and composition were noted for the 16 sites studied. Highest populations and the most species were found in a grass community, but occurred in different months in each of the three years. Lowest populations were found in a Coleogyne community, and fewest species in an Artemisia- grass community.     

Short-term effects of wildfire on montane stream ecosystems in the southern Rocky Mountains: one and two years post-burn

The frequency and intensity of wildfire in the western United States has increased over the last century, creating a heterogeneous mosaic of landscapes in various stages of recovery. The 2002 Hayman Fire was one of the largest wildfires in Colorado history and was unprecedented for its speed and intensity, with over 50%–70% of the burn area classified as moderate to high severity where much of the canopy crown was consumed. We evaluated the short-term impact of the Hayman Fire on ecological properties in montane stream ecosystems in the summers of 2003 and 2004, one and two years post-fire. Fire significantly altered surface temperature, dissolved oxygen concentration, and the chemical composition of stream water, including concentrations of nitrate, phosphate, and mineral salts. However, fire did not have significant impacts on stream conductivity, pH, or total concentrations of cations or anions during our study period. Streams in the burn area contained fewer benthic macroinvertebrate taxa compared to unburned streams during the year after fire and contained lower invertebrate densities and biomass compared to reference streams 2 years post-fire. Average C:N ratio of the benthic macroinvertebrate community was significantly and negatively related to stream nitrate concentration, possibly due to a shift in community composition or invertebrate nitrogen acquisition in fire-affected streams.     

A classification of aquatic plant communities within the Nothern Rocky Mountains

A synecological study of aquatic macrophyte plant communities was conducted across northern Idaho and western Montana during the summers of 1997, 1998, and 1999. A total of 111 natural and man-made water bodies were sampled based on a stratification of environmental variables thought to influence plant species distribution (i.e., elevation, landform, geology, and water body size). Plant species foliar cover data were used to develop a hierarchical, floristic-based community type classification with TWINSPAN and DECORANA software. Six planmergent (conspicuous portion of vegetative plant body on the water surface) and 24 submergent (vegetative plant body found primarily underwater) community types were identified. Multivariate analysis indicated that all community types displayed significant differences in plant species composition, and the Sorensons floristic similarity between communities averaged 10% for planmergent and 8% for submergent types. Canonical correspondence analysis was used to inspect relationships between abiotic factors and plant species abundance. Results of this analysis indicated some relationships between species distributions and abiotic factors; however, chance introduction of plant species to water bodies is a process considered to be equally important to the presence of the community types described.     

Habitat and community relationships of cliffrose ( Cowania mexicana var. stansburiana ) in central Utah

Cliffrose ( Cowania mexicana var. stansburiana [Torr.] Jepson) community measurements were taken in central Utah. Data revealed a high between-site similarity of 78.5%. Soil analysis for sites showed most macronutrients, and some micronutrients, relatively low. Cover of cliffrose was found to increase with increases in soil magnesium (p ≤ 0.01). Plants growing on the sites have adapted life cycles to exploit moisture and nutrients during seasons of maximum availability. Prevalent species in the community were cheatgrass ( Bromus tectorum ), cliffrose, madwort ( Alyssum alyssoides ), and bluebunch wheatgrass ( Agropyron spicatum ). Annual grasses were the most important life form to community composition; the second was shrubs. Ratios between soil nutrients and cliffrose tissue nutrients indicate active transport of some elements. Data indicated a steady decline in establishment of new cliffrose individuals on the sites since 1957. This lack of reproductive success is most likely due to a combination of factors but appears most influenced by the elevated levels of annual plants (mainly cheatgrass) on the sites. If the cliffrose communities in central Utah are to be maintained, special attention to their management must be considered and implemented.     

Arthropod and plant communities as indicators of land rehabilitation effectiveness in a semiarid shrubsteppe

We describe a case study evaluating the ecological impact of Bromus tectorum L. (cheatgrass) invasion following fire disturbance and the effectiveness of revegetation as a means of rehabilitation in a degraded semiarid shrubsteppe system. The effectiveness of rehabilitation efforts was assessed relative to arthropod richness, vegetation and arthropod community composition, and ground-cover characteristics in 3 habitats: undisturbed, burned and weed infested ( B. tectorum ), and burned then rehabilitated with native and nonnative vegetation. Arthropods were collected in each habitat using pitfall traps. Differences in arthropod richness were compared using rarefaction curves. Nonmetric multidimensional scaling and nonparametric multivariate statistical procedures, including analysis of similarity and similarity percentage routines, were used to compare arthropod and vegetation community composition and ground-cover characteristics between habitats. Arthropod communities in the rehabilitated habitat were distinct from those observed in the undisturbed and weed-infested habitats. Rehabilitation in this study resulted in a shift toward conditions observed in an undisturbed habitat and perhaps is an intermediate step to complete restoration. Arthropod richness, arthropod and vegetation community composition, and ground-cover characteristics were all useful indicators but returned slightly different results. Assessing multiple variables yielded the most complete understanding of the habitats studied.     

A quantitative survey of the aquatic invertebrate community in the “Monumento natural Salar de Surire” on the Chilean Altiplano

A quantitative survey of the aquatic invertebrate community at a salar on the Chilean Altiplano is described. To establish the taxonomic composition and abundance we monitored inter-annual changes in community structure for four consecutive years covering different conditions. The community was composed of 21 taxa, representing 16 families, and was mainly dominated by arthropods. We found a high number of endemic species compared to other freshwater systems despite the low abundances detected. There were statistically significant inter-annual differences in diversity. A canonical correlation indicated that species richness was mainly affected by temperature. We studied this unique system by taking advantage of the “natural laboratory” that it offers. We found a combination of eutrophic conditions with low species diversity at the consumer level. This system invites further research on the community dynamics and microevolutionary aspects of invertebrate populations.     

Effects of rangefire on soil algal crusts in semiarid shrub-steppe of the Lower Columbia Basin and their subsequent recovery

Effects of rangefire on soil algae in sagebrush steppe in the Lower Columbia Basin were studied. Dynamics of recovery of the soil algal community in the first two years following the fire were also documented. The study site was on the Arid Lands Ecology Reserve managed by Battelle Pacific Northwest Laboratory. Fire decreased the numbers of algae by more than an order of magnitude. Species composition in burned plots was similar to that in unburned plots, although some cyanophyte algae, particularly Nostoc commune , were decimated by the fire. Algal recovery took place in the winter months of the second year. Ninety taxa of algae were identified during the course of the study, over half of which were chlorophytes. Seasonal changes in the algal flora were also noted.     

Chemical and biological characteristics of desert rock pools in intermittent streams of Capitol Reef National Park, Utah

Chemical variability and biological communities of rock pools found in small desert drainage basins of Capitol Reef National Park were characterized over 8 mon in 1994. Neither flooding, drying, nor the presence or absence of surrounding vegetated wetlands had a great effect on chemical composition, which was very dilute and fluctuated somewhat in response to rain events. Neither flooding nor drying affected the composition of biological communities in the pools. Summer storms affected only a few drainages at a time, and only a few study pools of significant volume dried completely during the hot, dry summer. This suggests that only a portion of the Waterpocket Fold aquatic community is ever disturbed at a time, leaving undisturbed areas as a source of recovery. Pools bordered by vegetated wetlands always supported greater numbers of species throughout the year than those bordered only by bedrock, but the same taxa were found in both vegetated and bedrock pools. The rock pool fauna in Capitol Reef National Park appear to be resilient to climatic variability.     

Site characteristics and habitat requirements of the endangered dwarf bear-claw poppy ( Arctomecon humilis Coville, Papaveraceae)

Arctomecon humilis Cov. is a narrow endemic, confined to gypsiferous substrates derived from the Shnabkaib Member of the Moenkopi Formation in southwestern Utah. The characteristics of seven A. humilis sites were studied to define habitat requirements of the species. Both physical and biotic aspects of the habitat were analyzed; geology, soil chemistry, and physical properties, as well as vascular and nonvascular plant communities, were studied. Chemical and physical properties of these soils vary considerably from those supporting adjacent desert-shrub communities. The dominant vascular species on A. humilis sites are shadscale and Mormon tea. It was found that A. humilis occurred in portions of the habitat where shrubs were relatively less dense. A soil-surface, cryptogamic community contributed 84% or more of the total living cover on sites that supported A. humilis . Species composition of the cryptogamic community was highly similar among sites. Likewise, composition of the cryptogamic cover was similar when random samples were compared with samples centered on A. humilis plants. The Purgatory Flat site, which does not support the poppy, seems inseparable from A. humilis sites, in respect to soil characteristics and composition of the associated plant cover. There is reason to believe an A. humilis population could be established at the Purgatory Flat site.     

Bird community composition in relation to habitat and season in Betatakin Canyon, Navajo National Monument, Arizona

Bird species density, diversity, and species richness in relation to habitat and seasonal variations were studied in the Betatakin Canyon area of Navajo National Monument, Arizona. The two most prominent habitat types are a riparian forest deep in the canyon bottom and a mature pinyon-juniper woodland on the mesas and slopes above the canyon. One hundred thirty-five species of birds were encountered during the study and recorded by season and habitat. The avifauna assemblages demonstrate definite habitat selection into groups associated with the riparian and pinyon-juniper woodland communities. Diversity, density, and species richness were greatest in the riparian habitat during the spring and summer months. The differences in bird community composition were greater between seasons than between habitats. Pinyon pine and Gambel oak were highly selected as perch sites in the pinyon-juniper and riparian areas, respectively.     

Poisonous plants of Utah

Bird species density, diversity, and species richness in relation to habitat and seasonal variations were studied in the Betatakin Canyon area of Navajo National Monument, Arizona. The two most prominent habitat types are a riparian forest deep in the canyon bottom and a mature pinyon-juniper woodland on the mesas and slopes above the canyon. One hundred thirty-five species of birds were encountered during the study and recorded by season and habitat. The avifauna assemblages demonstrate definite habitat selection into groups associated with the riparian and pinyon-juniper woodland communities. Diversity, density, and species richness were greatest in the riparian habitat during the spring and summer months. The differences in bird community composition were greater between seasons than between habitats. Pinyon pine and Gambel oak were highly selected as perch sites in the pinyon-juniper and riparian areas, respectively.     

Understory seed rain in harvested pinyon-juniper woodlands

Seed rain was collected on six paired tree harvest and undisturbed plots in singleleaf pinyon ( Pinus monophylla )–Utah juniper ( Juniperus osteosperma ) stands. Approximately 14,600 seeds were collected during four years. Seed rain in undisturbed plots was similar to levels in mixed forest communities. Seed rain on harvest plots was similar to disturbed sites and grasslands. Seed rain levels reflect the current successional stage rather than the climax community type for the site. Seed rain increased in numbers and seed production per unit of plant cover following tree removal and especially on transition soil microsites. Only three to four of the plant species present on a site contributed greater than 10% of the total seed rain. Seed rain composition was similar on harvest and undisturbed plots (Jaccard Similarity Index Values = 47% to 67%) and explains in part the rapid reestablishment of predisturbance understory communities.     

Classification of the riparian vegetation along a 6-km reach of the Animas River, southwestern Colorado

Riparian ecosystems are important components of landscapes, particularly because of their role in biodiversity. A first step in using a ""coarse-filter"" approach to riparian biodiversity conservation is to determine the kinds of riparian ecosystems. These ecosystems vary substantially in plant species composition along a single river reach, as well as between rivers, and yet the river-reach scale has received little attention. We sampled the vascular plant composition of 67 contiguous patches of riparian vegetation along the reach of the Animas River, in southwestern Colorado's San Juan Mountains, that is relatively undisturbed by human land uses. Using cluster analysis and detrended correspondence analysis, we identified eight riparian community types along the reach. Using a new technique, we combined overstory size-class data and understory cover data to identify community types. The eight community types, which are in part the products of past floods, are spatially arranged along the reach in relation to variation in valley morphology, tributary location, and geomorphic landforms. These eight community types do not necessarily represent successional stages of a single potential vegetation type. This study at the river-reach scale suggests that sampling and analysis, as well as conservation, may need to be turned to the scale of patchiness produced by flood disturbances in the riverine landscape, since vegetation varies significantly at this scale.     

Temporal dynamics of invertebrate and aquatic plant communities at three intermittent ponds in livestock grazed Patagonian wetlands

Ponds are recognized worldwide as biodiversity hotspots; nevertheless in Patagonia studies are still needed that reveal the composition and status of their communities. This paper analyses the temporal patterns of aquatic invertebrates and assesses the environmental factors that best predict the variation in community structure at three small intermittent ponds, subjected to ranching practices (summer stocking) in the Patagonian steppe. Variables identified as important in structuring community assemblages were related to environmental conditions (rainfall and water temperature), chemical features (conductivity and pH) and biotic factors (macrophyte coverage). During the connected phase only a small number of invertebrate species were present, in contrast to the 11 taxa that were frequent and abundant during the isolated period (Eucyclops chilensis, Hyalella curvispina and Rhionaeschna sp. were dominant). In this sequence the submersed Myriophyllum quitense and Lilaeopsis macloviana played a crucial role offering habitat and food resources. The present study provides valuable information that can contribute to minimizing the environmental damage and the development of strategies for the conservation of Patagonian wetlands.     

Structure of insect community in the fungus Inonotus radiatus in riparian boreal forests

Basidiomes of polypore fungi host many insects. Yet systematic information about insect assemblages from most fungal species is lacking. We studied the insect community associated with the wood-decaying fungus Inonotus radiatus (Sowerby: Fr.) P. Karst. (Hymenochaetales). More specifically, we studied the effect of successional stage and weight of basidiomes, as well as shore exposition (north or south), on species richness and composition, as well as occurrence and abundance of the most abundant fungivores. Basidiomes were collected from riparian forests at five lakes in Sweden. Insects were reared out from the basidiomes in the laboratory. A total of 5645 adult insect individuals of 117 taxa were obtained. Among these, 2782 specimens of 36 taxa use Inonotus radiatus basidiomes as breeding habitat. Eight species of parasitic wasps were new to Sweden. The most abundant fungivore was Ennearthron cornutum (Ciidae), which is a generalist breeding in many polypore species. Based on our material and literature, the melandryid beetles Abdera affinis and A. flexuosa seem to be specialists on the order Hymenochaetales. Other frequent fungivores were Dorcatoma dresdensis (Ptinidae), and the lepidopterans Archinemapogon yildizae, Nemapogon cloacellus and N. picarellus (Tineidae). The parasitoid community associated with the tineid moths was similar to the community associated with the other polypore species in the order Polyporales. In contrast, the parasitoids associated with Dorcatoma (and/or Abdera) were different from the other Polyporales species, suggesting that the fungal host species is more important for these parasitoid species than the beetle host species itself. The most abundant and frequent parasitoids were the braconids Diospilus dispar and Colastes fritzeni, which both parasitise Dorcatoma. Species richness was significantly smaller in fresh than in more decayed basidiomes, but species composition did not differ. There was no difference in species composition or richness between north and south shorelines.     

Species composition, emergence, and habitat preferences of Trichoptera of the Sagehen Creek Basin, California, USA

An extensive study of larvae and adult Trichoptera of the Sagehen Creek basin. Sierra Nevada, California, USA, revealed 77 species representing 14 families and 41 genera. Twenty-six species were restricted to small water bodies (spring sources, seeps, spring streams, temporary ponds, and intermittent streams); 27 were restricted to Sagehen Creek, a second-order stream, and the mouths of two large spring streams. Similarity between species caught at black lights and those in emergence traps was 43%. There were two major peaks in adult emergence by species, midsummer and late summer-fall. A few species emerged during winter or throughout most of the year. The species composition of the community showed affinity with Oregon, the Great Basin, and the Rocky Mountains but very little similarity with the California Coast Range. Four of the most abundant species in the basin have very restricted distributions. Ecological separation of several groups of closely related species could be explained by major differences in larval habitats or by different emergence periods.     

On the parasitoid community of Aulacidea laurae (Hym., Cynipidae), with description of a new species of Adontomerus (Hym., Torymidae)

An account is given of parasitoids (Hym., Chalcidoidea) reared from Spanish galls of Aulacidea laurae (Hymenoptera, Cynipidae) which develop in achenes of Scorzonera laciniata (Asteraceae). The parasitoid community includes Adontomerus brevicaudatus (Hym., Torymidae) which is described as new. Final instar larva of the new species is also described. The generic placement of A. brevicaudatus and the composition of the parasitoid community are discussed.     

Forest-floor treatments in Arizona ponderosa pine restoration ecosystems: no short-term effects on plant communities

Leaf litter accumulation during fire exclusion and increases in tree density in postsettlement southwestern Pinus ponderosa forests may limit the establishment of understory vegetation. We performed an experiment in P. ponderosa forests of northern Arizona to ascertain plant community responses to forest-floor scarification and Oi removal on thirty-six 100-m 2 plots overlaid on an existing ecological restoration experiment that involved tree thinning and prescribed burning. Constrasting with findings from many other forest types, forest-floor treatments had no effect on community diversity or composition during the 2-year experiment. S?rensen similarities were as high as 97% between posttreatment years within treatments; and successional vectors also provided little indication that treatments may appreciably affect longer-term successional trajectories. Lack of response to these fairly drastic treatments is surprising given these forests' exceptionally heavy Oi horizons and large proportions of conifer litter. Apparently shading, belowground competition for water or nutrients, or other tree-associated factors more strongly limit understory communities than does leaf litter. Based on sparse A-horizon seed banks averaging <300 seeds ? m –2 and limited aboveground vegetation, we hypothesize that seed shortages, particularly for native perennials, also partly precluded a treatment response. Because extensive unvegetated areas at these restoration sites may be colonized by exotics, conservative management strategies could include testing the seeding or outplanting of desirable native species as an option for filling unoccupied microsites. Reporting of "no treatment effect" experiments such as this one is important to avoid biasing meta-analyses, as is future research to clarify combinations of factors limiting understory communities. Increased understanding of these limiting factors may lead to identification of other treatments that promote recovery of native species during ecological restoration in this region.