The use of understory species as indicators of landform ecosystem type in heavily disturbed forest: an evaluation in the Haut-Saint-Laurent,Quebec

An ecological study of the Municipalité Régionale de Comté (MRC) du Haut-Saint-Laurent area, a highly disturbed landscape located south-west of Montréal (Québec), was carried out. The aim of this study was to establish links between indicator species of ecosystems and geomorphological features in a heavily disturbed background. Analysis to obtain the ecological groups are based on the links of herbaceous plants and shrubs. This approach is defined as a sociological one where grouping is based only on the species' affinity. In order to obtain ecological groups, similarity measures using the chi-square coefficient were calculated on the relative cover values of the 150 retained species from 452 plots. An intermediate linkage cluster analysis was then performed on the similarity matrix thus created. By this procedure, 56 ecological groups were obtained. These groups were then characterized according to abiotic variables, especially the geomorphological data, by the use of binary discriminant analysis. Results indicate that 39 of these 56 groups were significantly associated specifically with one of 10 morphogenic features, while 13 of these 56 groups were associated with 2 or 3 features. The ecological groups which were associated with one specific geomorphological process showed a strong link to one texture and one specific drainage class. On the other hand, the groups which were associated with several features were linked with one drainage class, usually imperfect, and a certain topographic situation. However, ecological groups showing a strong association to more than one feature can be of cartographic use, provided soil texture is analysed to determine the origin of the deposit. Finally, the type of deposit becomes non determinant on vegetation where drainage and topographic variables indicate poorly or very poorly drained sites. Non-significant groups should be used as indicators of drainage and topographical conditions but not as indicators of geomorphological deposits. The ecological groups not associated with morphogenic features demonstrated mostly a heliophilic character. Thus, the ubiquitous character of ecological groups is not exclusive to species taking advantage of disturbances.     

Recovery Deficiency Following Tree Mortality in Mangroves of Two Caribbean Islands: Field Survey and Statistical Classification

Mangrove species are well adapted to the harsh ecological conditions of their environment throughout the tropics. However, in the islands of Guadeloupe and Martinique (Lesser Antilles), deficient forest recovery was evidenced in 43 mangrove sites (>1000 m²) affected by apparently natural tree mortality. Such sites were recorded from four chronological sets of aerial photographs between 1950 and 1995, and field-investigated in terms of environment and vegetation characteristics. Given the speculative relationship between the slow-regenerating vegetation and its present environment within non-steady state, disturbed sites, statistical analyses arbitrarily matching physicochemical and biological data were primarily avoided. On one hand, principal component analysis (PCA), combined with an agglomerative hierarchical classification, was performed on environmental, rank-ordered data; on the other hand, multidimensional scaling (MDS) was implemented on vegetation data. Discriminant analyses (DA) further characterized the environment/vegetation interrelationships for each site type. Ultimately, three main types of mortality sites have been distinguished among the study areas. One type clustered the sites showing the lowest salinity values and the highest surge vulnerability whose dominant mangrove species is Rhizophora. Another type presented highly saline sites having clayey soils with pure, stunted, Avicennia stands. The last type consisted of peculiar forest gaps on deep, compact, peat soils. During the rainy season, these sites turned into shallow ponds scattered with living, young Rhizophora and large, standing, dead Avicennia. The authors suggest that this classification may serve as a comprehensive framework to test subsequent hypotheses (hurricanes, droughts…) on the origins of natural massive tree mortality and the causes of recovery deficiency in mangroves of the Caribbean.     

Ecohydrological Source‐Sink Interrelationships between Vegetation Patches and Soil Hydrological Properties along a Disturbance Gradient Reveal a Restoration Threshold

Vegetation, soil, and hydrology in drylands often collectively exhibit strong ecohydrological interrelationships in which vegetation both influences and is influenced by runoff, particularly on sites with more gradual slopes. These two‐way relationships have important implications for ecological restoration of disturbed sites, such as those being reclaimed following mining, yet studies from both ecological and hydrological perspectives specifically evaluating how the strength of ecohydrological interrelationships varies for a range of natural and restored conditions are still missing. We assessed two‐way relationships between vegetation and soil hydrological properties by evaluating patterns of both plant community structure and soil hydrological characteristics related to runoff for natural sites and restored sites following mining. At the plot scale, we identified eight ecohydrological units based on interrelationships between vegetation communities and hydrological properties associated with runoff along a progression from source to sink patch types. Similarly, at the hillslope scale, which included patches of different types, we found a correspondence between the proportions of source and sink patches and both vegetation community and hydrological properties. The relative strength of ecohydrological interrelationships in hillslope mosaics decreased with decreasing disturbance except for rilled hillslopes, likely because parts of the hillslope become isolated from the others. Our results highlight, in general, how ecohydrological interrelationships are related with degree of disturbance, and in particular, how rilling alters ecohydrological interrelationships, thereby precluding effective restoration.     

Vegetation analysis of the Mediterranean region of Nile Delta

Thirty-four vegetation clusters identified in the present study, after the application of TWINSPAN and DCA multivariate techniques, were assigned into 8 vegetation types, each of definite vegetation and habitat characters. The suggested vegetation types are well segregated along the DCA axis one which reflects soil moisture, salinity (as indicated by EC values), fertility (as indicated by the organic matter and nitrogen contents) and species diversity gradients. In general, soil moisture and soil fertility increase and species diversity decreases with the following sequence of vegetation types:Echinops spinosissimus-Ononis serrata on inland sand dunes,Pancratium maritimum on coastal sand dunes,Halocnemum strobilaceum-Salsola kali in saline sand deposits,Atriplex halimus-Chenopodium murale along the terraces and slopes of drains,Arthrocnemum glaucum-Tamarix nilotica in salt marshes,Chenopodium murale along the slopes of drains,Phragmites australis along the littoral zones of drains, andLemna gibba-Potamogeton crispus in the water zone. This sequence reflects also a gradient of human interference, starting with the vegetation of the less disturbed habitats (sand dunes and saline sand deposits) and ending with the fully man-made habitats (drain zones).     

Classification and ordination of communities of soil arthropods in an urban park of Osaka City

To assess the effect of management of a park on soil arthropods, communities of Oribatida and Collembola were analyzed at 11 sites of different vegetation in Tsurumi Park, an urban park of Osaka City. The type of canopy layer and soil density strongly affected the community parameters, such as species diversity. Ordination revealed that soil density, contents of organic matter, and shrub layer were important for variety in the oribatid community; the shrub layer was important for the collembolan community. Species richness of both arthropod groups was highest in a mixed forest and lowest on bare land, while the abundance of Collembola was highest on a lawn site. Areas of a common vegetation type had a similar oribatid community;Trichogalumma nipponica dominated in deciduous forests,Eohypochthonius crassisetiger in mixed forests and one of coniferous forests. On the other hand, collembolan communities did not correspond with the vegetation.Sminthurinus sp. was collected from every site, and the most abundant species wasCryptopygus thermophilus that exhibited an outbreak on lawn sites. A significant correlation existed between species diversities but not between abundances of Oribatida and Collembola.     

Use of ecological groups in analysis and classification of plant communities in a section of western Quebec

A plant community analysis and classification were done for an integrated ecological study, in the lake Abitibi region, Quebec. Two levels of vegetation analysis were used: the ecological group level and the community level. Species were first grouped according to their sociological affinities. The ecological significance of those groupings was studied by principal component analysis, with the inclusion of abiotic variables, and by the study of ecological profiles. Secondly, the concurrent use of ecological groups permitted the definition and characterization of noda. The relationships between the noda, in the space defined by the ecological groups, were analyzed by principal coordinate analysis on which is superimposed the shortest spanning tree. Those combined analyses permitted the identification of 35 community types which vary mainly according to surficial deposits (organic or mineral), drainage, relative richness of soils in bases, flooding, presence of bedrock outcrops. fire perturbations and microclimate. Those variations are discussed according to the exlusive or non-exclusive character of the ecological groups.     

Degeneration of species-rich Calthion palustris hay meadows; some considerations on the community concept

Abstract. An overview of the vegetation history of Calthion palustris meadows is presented with special emphasis on the natural habitats of the character species. The response of meadow species under the influence of drainage was calculated using species-environment response curve techniques. The changes were monitored in permanent plots situated on sites with various intensities of drainage. The similarity with an undisturbed local reference type of the hay meadow community was calculated for all plots and years. On this basis a half-life time of the Calthion palustris stands could be assessed. The half-life time was small in the plots which are most affected by drainage. The response to drainage of character species of the Calthion palustris was very different. This imposes problems for some definitions of the community concept.     

稀土尾矿土壤细菌群落结构对植被修复的响应

选用赣州-安远稀土弃废尾矿及其不同植被修复的堆浸田为研究对象,调查废弃尾矿及6种不同植被修复方案下土壤理化性质的变化,并利用变性凝胶梯度电泳(DGGE)技术,分析土壤微生物群落结构对植被修复的响应。结果表明:与未修复尾矿土壤相比,经不同植被修复后的土壤理化性质均得到明显改良,其中土壤含水量、有机质含量均比未修复尾矿土壤增加2—3倍。微生物群落结构分析表明,植被修复后土壤微生物群落与废弃尾矿土壤微生物群落亲缘度仅为0.21,表明植被修复后,土壤微生物群落结构发生了明显变化,且微生物多样性、均匀度、丰富度与未修复尾矿土壤相比均有了明显的提高。而在不同植被修复方案中,以湿地松和山胡椒为优势群落的两种植被修复方案对土壤改良效果最为明显,这两种修复方案不仅能显著改善土壤的固水性、有机质含量,并且对微生物群落的改善作用也最为显著。典范对应分析表明,废弃尾矿土壤微生物群落结构受土壤p H影响最为显著,而植被修复后土壤微生物群落的环境影响因子则转变为含水量、有机质、有机碳及总磷含量。进一步揭示了微生物在植被修复过程中所起到的重要作用,并为矿山生态重建过程中的土壤改良工作提供了丰富的理论依据。     

Re-establishing a saltmarsh vegetation structure in a changing climate

Summary A major management decision in an ecological restoration or rehabilitation project is whether supplementary planting or natural vegetation regeneration is the better alternative or if a combination can be applied. Management decisions are further complicated when the project involves saltmarsh as tidal cycles, the effects of salinity and sea level rise add to the complexity of decisions. The ecological values of the saltmarsh community in Australia were only recognized relatively recently but the endangered ecological community listing in 1994 (under the New South Wales Threatened Species Conservation Act 1995) highlighted the need to protect, rehabilitate and restore saltmarsh. This project measured vegetation change after soil profile reconstruction in saltmarsh surrounding Sponsors Lagoon, Fingal Peninsula in north coastal New South Wales, Australia. Restored sites (planted and non‐planted) were compared with nearby disturbed (control) and reference sites. The dominant species in the community to be restored were Saltwater Couch (Sporobolus virginicus), Suaeda (Suaeda australis), Sarcocornia (Sarcocornia quinqueflora ssp. quinqueflora and Sea Rush (Juncus kraussii ssp. australiensis). Changes in percentage cover of the species in the first three years after soil reconstruction work showed that the dominant Saltwater Couch established only from vegetative growth arising from remnant vegetation but there was strong seedling regeneration of several other species. It was concluded that planting is important for species that are less vagile, in larger, denuded parts of this site where their resilience is lower and natural regeneration potential is limited. An understanding of the biology of the individual species is therefore likely to be essential in saltmarsh restoration projects. A combination of techniques, incorporating planting of slower establishing species and encouragement of seed‐germinated colonizers is useful for initial site stabilization and progressive ecological recovery at this site. The inclusion of migration zones in the planning phase will allow for the long‐term viability of this restoration project.     

Terrestrial Arthropods as Indicators of Ecological Restoration Success in Coastal Sage Scrub (California, U.S.A.)

Abstract Ecological restoration enjoys widespread use as a technique to mitigate for environmental damage. Success of a restoration project often is evaluated on the basis of plant cover only. Recovery of a native arthropod fauna is also important to achieve conservation goals. I sampled arthropod communities by pitfall trapping in undisturbed, disturbed, and restored coastal sage scrub habitats in southern California. I evaluated arthropod community composition, diversity, and abundance using summary statistics, cluster analysis, and detrended correspondence analysis (DCA) and investigated influence of vegetation on arthropod communities with multiple regression analysis. Arthropod diversity at undisturbed and disturbed sites was greater than at sites that were 5 and 15 years following restoration ( p < 0.05). Number of arthropod species was not significantly different among undisturbed, disturbed, and restored sites, and two restoration sites had significantly more individuals than other sites. Vegetation at disturbed and undisturbed sites differed significantly; older restorations did not differ significantly from undisturbed sites in diversity, percent cover, or structural complexity. In multiple regression models, arthropod species richness and diversity was negatively related to vegetation height but positively related to structural complexity at intermediate heights. Exotic arthropod species were negatively associated with overall arthropod diversity, with abundance of the earwig Forficula auricularia best predicting diversity at comparison (not restored) sites (r² = 0.29), and abundance of the spider Dysdera crocata and the ant Linepithema humile predicting diversity at all sites combined (r² = 0.48). Native scavengers were less abundant at restored sites than all other sites and, with a notable exception, native predators were less abundant as well. DCA of all species separated restored sites from all other sites on the first axis, which was highly correlated with arthropod diversity and exotic arthropod species abundance. Lower taxonomic levels showed similar but weaker patterns, with example families not discriminating between site histories. Vegetation characteristics did not differ significantly between the newly restored site and disturbed sites, or between mature restoration sites and undisturbed sites. In contrast, arthropod communities at all restored sites were, as a group, significantly different from both disturbed and undisturbed sites. As found in other studies of other restoration sites, arthropod communities are less diverse and have altered guild structure. If restoration is to be successful as compensatory mitigation, restoration success standards must be expanded to include arthropods.     

Plant communities on anthropogenically disturbed sites on the Chukotka Peninsula,Russia

Abstract. The vegetation of anthropogenically disturbed sites on the Chukotka Peninsula was investigated in 1986 and 1990. 102 sites had been bulldozed free of vegetation and soil between 2 and 20 yr ago and revegetated. Anthropogenic vegetation differs considerably from natural tundra. The total plant cover decreases, lichens are absent, moss composition changes, and graminoids predominate. A floristic classification was developed in order to describe the diversity of anthropogenic communities formed on these sites. Four associations were distinguished, all belonging to the alliance Poion glaucomalacanthae. An additional alliance characterized by Alopecurus alpinus is suggested for colder sites, but it has not yet been described. There is a correspondence of associations to substrate types. The association Phippsietum algidae was found only on loam substrate. The Artemisietum glomeratae and Saxifragetum punctatae are connected with rubble or gravel. The graminoid association Arctagrostietum arundinaceae is generally widespread in disturbed habitats and occurs on a variety of substrate types.     

Response of stream macroinvertebrate assemblages to erosion control structures in a wastewater dominated urban stream in the southwestern U.S.

Effects of stream erosion control structures on aquatic macroinvertebrates were studied (2000–2009) in a wastewater dominated drainage (Wash) in Las Vegas, Nevada. Mainstem sites with and without structures, wastewater treatment plant outfalls, a reference site above treatment plant inputs, and tributary sites were sampled. Ordination suggested hydrology and channel characteristics (current velocity, stream depth, and width), and water quality (conductivity) were primary factors in organizing macroinvertebrate communities, with some variables altered at structures. Treatment plant inputs changed hydrology (increased flows), water chemistry (conductivity decreased below treatment plants), and temperature. Assemblages differed between site types, with midges and damselflies important at tributary sites and Fallceon mayflies and Smicridea caddisflies common at erosion control structures. Locally unique communities developed at structures which also may have facilitated exotic species invasions. Analyses showed that taxa richness increased over time at these sites and differed significantly from richness at sites without structures. Structures appeared important in retaining organic matter and, among mainstem sites, coarse particulate organic matter was highest, but variable, at structures and at wetlands above the structures. Erosion control structures, coupled with warm effluent, high baseflows, and altered water quality resulted in development of a macroinvertebrate community that did not trend towards reference or tributary sites. In this case, ecological communities at structures used for river restoration were not on a continuum between disturbed and reference sites. Goal setting of community responses at these structures would have required insight beyond the simple use of reference site attributes.     

Disturbance regime changes the trait distribution,phylogenetic structure and community assembly of tropical rain forests

A rapidly increasing effort to merge functional community ecology and phylogenetic biology has increased our understanding of community assembly. However, studies using both phylogenetic‐ and trait‐based methods have been mainly conducted in old‐growth forests, with fewer studies in human‐disturbed communities, which play an increasingly important role in providing ecosystem services as primary forests are degraded. We used data from 18 1‐ha plots in tropical old‐growth forests and secondary forests with different disturbance histories (logging and shifting cultivation) and vegetation types (tropical lowland and montane forests) on Hainan Island, southern China. The distributions of 11 functional traits were compared among these six forest types. We used a null model approach to assess the effects of disturbance regimes on variation in response and effect traits and community phylogenetic structure across different stem sizes (saplings, treelets, and adult trees) and spatial scales (10–50 m). We found significant differences in the distribution of functional traits in highly disturbed lowland sites versus other forest types. Many individuals in highly disturbed lowland sites were deciduous, spiny, with non‐fleshy fruits and seeds dispersed passively or by wind, and low SLA. The response traits of coexisting species were clustered in all sites except for highly disturbed lowland sites where evenness was evident. There were different distributions of effect traits for saplings and treelets among different forest types but adult trees showed stronger clustering of trait values with increasing spatial scale among all forest types. Phylogenetic clustering predominated across all size classes and spatial scales in the highly disturbed lowland sites, and evenness in other forest types. High disturbance can lead to abiotic filtering, generating a community dominated by closely related species with disturbance‐adapted traits, where biotic interactions play a relatively minor role. In lightly disturbed and old growth forests, multiple processes simultaneously drive the community assembly, but biotic processes dominate at the fine scale.     

Feral horse impacts on threatened plants and animals in sub‐alpine and montane environments in Victoria,Australia

Feral herbivores are a major driver of biodiversity loss globally and can alter the structure, composition and functioning of ecosystems. The direct impacts of feral herbivores on plant communities are well studied, but the direct and indirect effect they have on wildlife is not well understood. In Victoria (south‐eastern Australia), a large feral Horse (Equus caballus) population coincides with highly sensitive and nationally endangered Alpine Sphagnum Bogs and Associated Fens communities, and several threatened animal species. We assessed the impact of feral horses on this ecological community and the Alpine Water Skink (Eulamprus kosciuskoi) and the Broad‐toothed Rat (Mastacomys fuscus) at 20 sites with varying levels of horse disturbance. We used scat counts to determine an index of feral horse abundance and quantified impacts associated with their presence in the landscape. Active searches were used for Alpine Water Skink and scat and runway surveys for Broad‐toothed Rat. We also measured the vegetation structure and the abundance of different vegetation types (life forms). Our results suggest that feral horses are associated with vegetation types and characteristics that negatively influence the presence or abundance of Alpine Water Skink and Broad‐toothed Rat. Sites with high horse activity had more low‐growing forbs, and the abundance of Alpine Water Skink was negatively related to this vegetation type. Grasses, sedges, rushes and shrubs were also less dense and lower in height in high horse activity sites, and Broad‐toothed Rat was less likely to be present in areas with these habitat attributes. We recommend that feral horses are controlled to protect these threatened vertebrate species and their Sphagnum bog habitat.     

Identification and siting of native vegetation types on disturbed land: demonstration of statistical methods

Question: How does one best choose native vegetation types and site them in reclamation of disturbed sites ranging from cropland and strip mines? Application: World‐wide, demonstrated in SE Montana. Methods: We assumed that pre‐disturbance native communities are the best targets for revegetation, and that the environmental facet each occupies naturally provides its optimal habitat. Given this assumption, we used pre‐strip‐mine data (800 points from a 88 km² site) to demonstrate statistical methods for identifying native communities, describing them, and determining their environments. Results and conclusions: Classification and pruning analysis provided an objective method for choosing the number of target community types to be used in reclamation. The composition of eight target types, identified with these analyses, was described with a relevé table to provide a species list, target cover levels and support the choice of species to be seeded. As a basis for siting communities, we modeled community presence as a function of topography, slope/aspect, and substrate. Logistic GLMs identified the optimal environment for each community. Classification and Regression Tree (CART) analysis identified the most probable community in each environmental facet. Topography and slope were generally the best predictors in these models. Because our analyses relate native vegetation to undisturbed environments, our results may apply best to sites with minimal substrate disturbance (i.e. better to abandoned cropland than to strip‐mined sites).     

Do exotic pine plantations favour the spread of invasive herbivorous mammals in Patagonia?

Changes in land use patterns and vegetation can trigger ecological change in occupancy and community composition. Among the potential ecological consequences of land use change is altered susceptibility to occupancy by invasive species. We investigated the responses of three introduced mammals (red deer, Cervus elaphus; wild boar, Sus scrofa; and European hare, Lepus europaeus) to replacement of native vegetation by exotic pine plantations in the Patagonian forest‐steppe ecotone using camera‐trap surveys (8633 trap‐days). We used logistic regression models to relate species presence with habitat variables at stand and landscape scales. Red deer and wild boar used pine plantations significantly more frequently than native vegetation. In contrast, occurrence of European hares did not differ between pine plantations and native vegetation, although hares were recorded more frequently in firebreaks than in plantations or native vegetation. Presence of red deer and wild boar was positively associated with cover of pine plantations at the landscape scale, and negatively associated with mid‐storey cover and diversity at the stand scale. European hares preferred sites with low arboreal and mid‐storey cover. Our results suggest that pine plantations promote increased abundances of invasive species whose original distributions are associated with woodlands (red deer and wild boar), and could act as source or pathways for invasive species to new areas.     

Grasshopper biodiversity and bioindicators in Australian tropical savannas: Responses to disturbance in Kakadu National Park

Grasshoppers are a dominant group of herbivorous insects throughout the world, and their high diversity, functional importance, sensitivity to disturbance and ease of sampling makes them potentially useful bioindicators for land management. In Australia, however, the dynamics of grasshopper assemblages are extremely poorly understood. Here we describe the responses of grasshopper (Acridoidea, Eumastacoidea and Tettigonioidea) assemblages in the Kakadu region of the Northern Territory, Australia to disturbance associated with mining. Three questions were addressed in this study: (i) do local grasshopper assemblages show consistent responses to disturbance?; (ii) can particular species or functional groups be identified that are reliable indicators of ecological disturbance?; and (iii) to what extent do the responses of grasshopper assemblages merely reflect those of vegetation? Grasshoppers were sampled at 26 sites located in and around the Ranger uranium mine, representing three habitat types with respect to degree of disturbance: (i) ‘natural’ (10 sites representing a range of ‘undisturbed’ savanna habitats); (ii) ‘disturbed’ (10 sites representing a range of disturbances, but with soil intact); and (iii) ‘waste rock’ (six sites undergoing rehabilitation on a constructed landform). A total of 56 grasshopper species in 46 genera was recorded during the study, with site species richness ranging from five to 20. There were no significant differences between habitat types in site species diversity, but multivariate analysis demonstrated a strong correspondence between grasshopper species composition and degree of habitat disturbance. Using Indicator Species Analysis, six species and one functional group were identified as significant indicators of habitat type in relation to disturbance. Grasshopper responses were correlated with that of vegetation, but grasshopper assemblages showed apparently meaningful differentiation among disturbed sites that was not evident on the basis of floristic data. Our results demonstrate that grasshopper assemblages respond to disturbances associated with human land use and that these responses do not simply reflect those of plants. Grasshoppers are therefore potentially useful bioindicators of ecological disturbance in Australia, but further work is required on the extent to which their responses reflect general ecological change.     

Use of vegetation classification and plant indicators to assess grazing abandonment in Estonian coastal wetlands

Question: What are the effects of grazing abandonment on the vegetation composition of Estonian coastal wetlands? Location: Vormsi Island and Silma Nature Reserve in western Estonia, Europe. Methods: Local knowledge and field reconnaissance were used to identify current and historical management levels of wetland sites within the west Estonian study area. Nine study sites, with varying management histories, were selected comprising an area of 287 ha. A total of 198 quadrats were taken from 43 distinct vegetation patches in five of the sites. TWINSPAN analysis was used to identify community type, and a phytosociological key was constructed for character taxa. This vegetation classification was then applied within a GIS‐based context to classify all the study sites, using a ground survey technique and 1:2000 scale air photos. Results: We identified 11 different brackish coastal wetland community types. Indicator species were defined with community characteristics for the seven main vegetation types readily recognisable in the field. Coastal wet grasslands were most extensive in grazed sites, or sites that had been more intensively grazed, while abandoned sites were largely composed of Phragmites australis stands, tall grassland, and scrub. Site variations based on vegetation composition were significantly correlated with past grazing intensity. Plant community types showed significant edaphic differences, with particularly low soil moisture and high conductivity and pH for open pioneer patches compared to other vegetation types. Conclusion: Abandonment of traditionally grazed coastal grasslands threatens their characteristic biodiversity. This study found that grazing abandonment reduced the extent of coastal wetland grasslands of particular conservation value. Nevertheless, plant species of conservation interest were found across the sequence of community types described. The study shows that grazing is an important factor influencing coastal wetland plant communities but suggests that vegetation distribution is affected by environmental variables, such as topography.     

Arbuscular mycorrhizal fungi in a semiarid copper mining area in Brazil

The occurrence of arbuscular mycorrhizal fungi (AMF) in a copper mining area was investigated. Soil samples were collected from six sites at the Mineração Caraiba, Bahia State, northeastern Brazil, comprising: (1) a site that receives the waste product; (2) a site that receives low grade deposits; (3) the interface between the caatinga and site 1; (4) the surroundings of the industrial area; (5) the site for extracting topsoil for land filling; (6) the preserved caatinga. Thirty-two plant species were identified around the collection locations. Trap cultures were maintained in the greenhouse for 3 months, using bahia grass ( Paspalum notatum Flügge) as the host plant. Spores were extracted from soil and 21 AMF species (15 Glomus and one of each of Acaulospora, Archaeospora, Entrophospora, Gigaspora , Paraglomus and Scutellospora) were identified. In site 1, plants or AMF were not found during the dry season. Site 6, with native vegetation, had the highest number of plants and AMF species. The disturbed sites showed less plant diversification, with the community of AMF being quantitative and qualitatively affected by disturbance.     

Development of vegetation based soil quality indices for mineralized terrane in arid and semi-arid regions

Soil quality indices (SQIs) are often management driven and attempt to describe key relationships between above- and below-ground parameters. In terrestrial systems, indices that were initially developed and modified for agroecosystems have been applied to non-agricultural systems in increasing number. We develop an SQI in arid and semi-arid ecosystems of the Western US impacted by different types of geologic mineralization using the relationship between vegetation community parameters and soil abiotic and biotic properties. We analyze these relations in soils associated with three different mineralization types: podiform chromite, Cu/Mo porphyry, and acid-sulfate gold vein systems at four different sites in California and Nevada. Soil samples were collected from undisturbed soils in both mineralized and nearby unmineralized substrates as well as from waste rock and tailings. Aboveground net primary productivity (ANPP), canopy cover and shrub density were measured for the vegetative communities. Minimum data sets were developed based on correlations between the soil and vegetation parameters, refined using principal components analysis, scored using non-linear functions, and combined into an overall SQI. The indices are comprised of one or two microbial parameters and three to six abiotic parameters, the latter consisting of nutrients and metals. Given the preliminary development of this approach, the parameters and combinations to arrive at an SQI for a given site cannot at this time be correlated or compared with that of another site. This SQI approach provides a means of quantifying disturbed ecosystem recovery resulting from mining, and could be applied to other disturbances in a way that readily distills the information for potential use by land managers. However, severely disturbed areas with little to no aboveground biomass, such as unreclaimed tailings, have likely crossed an ecological threshold that precludes the use of this type of monitoring tool.