Assemblages of drosophilids (Diptera, Drosophilidae) in mangrove forests: community ecology and species diversity

Brazilian fauna of drosophilids has been researched in various ecosystems, but those in mangrove forests remain overlooked in Brazil and elsewhere. The present study attempts to characterise the assemblages of drosophilids of this environment, based on 28 collections taken in three mangrove areas in Santa Catarina Island, southern Brazil. The three mangroves surveyed were different in their surroundings, which varied from highly urbanised areas to conservation areas with natural vegetation. Overall, 69 species were collected, and no remarkable difference was detected in species composition and abundances or in the richness, evenness and heterogeneity between sites. The species abundance distribution observed fitted to a theoretical lognormal distribution in the three mangroves. The species richness scored and the performance of the species richness estimators showed an unexpectedly high diversity, considering the very low floristic diversity and the harsh conditions of the environment. Regarding species composition and abundances, the drosophilid mangrove assemblages were shown to be more similar to those found in open environments, with a marked dominance of exotic species. Finally, considering the apparent lack of feeding and breeding sites, we suggest that mangrove forests are acting as sink habitats for the drosophilids populations.

The Alps Vegetation Database - a geo-referenced community-level archive of all terrestrial plants occurring in the Alps.

Mountain ranges are biodiversity hotspots worldwide and provide refuge to many organisms under contemporary climate change. Gathering field information on mountain biodiversity over time is of primary importance to understand the response of biotic communities to climate changes. For plants, several long-term observation sites and networks of mountain biodiversity are emerging worldwide to gather field data and monitor altitudinal range shifts and community composition changes under contemporary climate change. Most of these monitoring sites, however, focus on alpine ecosystems and mountain summits, such as the global observation research initiative in alpine environments (GLORIA). Here we describe the Alps Vegetation Database, a comprehensive community level archive (GIVD ID EU-00-014) which aims at compiling all available geo-referenced vegetation plots from lowland forests to alpine grasslands across the greatest mountain range in Europe: the Alps. This research initiative was funded between 2008 and 2011 by the Danish Council for Independent Research and was part of a larger project to compare cross-scale plant community structure between the Alps and the Scandes. The Alps Vegetation Database currently harbours 35,731 geo-referenced vegetation plots and 5,023 valid taxa across Mediterranean, temperate and alpine environments. The data are mainly used by the main contributors of the Alps Vegetation Database in an ecoinformatics approach to test hypotheses related to plant macroecology and biogeography, but external proposals for joint collaborations are welcome.

Permanent.Plot.ch - a database for Swiss permanent vegetation plots

The aim of the Permanent.Plot.ch project is the conservation of historical data about permanent plots in Switzerland and the monitoring of vegetation in a context of environmental changes (mainly climate and land use). Permanent plots are currently being recognized as valuable tools to monitor long-term effects of environmental changes on vegetation. Often used in short studies (3 to 5 years), they are generally abandoned at the end of projects. However, their full potential might only be revealed after 10 or more years, once the location is lost. For instance, some of the oldest permanent plots in Switzerland (first half of the 20th century) were nearly lost, although they are now very valuable data. The Permanent.Plot.ch national database (GIVD ID EU-CH-001), by storing historical and recent data, will allow to ensuring future access to data from permanent vegetation plots. As the database contains some private data, it is not directly available on internet but an overview of the data can be downloaded from internet (http://www.unil.ch/ppch) and precise data are available on request.

Improving plant functional groups for dynamic models of biodiversity: at the crossroads between functional and community ecology

The pace of on-going climate change calls for reliable plant biodiversity scenarios. Traditional dynamic vegetation models use plant functional types that are summarized to such an extent that they become meaningless for biodiversity scenarios. Hybrid dynamic vegetation models of intermediate complexity (hybrid-DVMs) have recently been developed to address this issue. These models, at the crossroads between phenomenological and process-based models, are able to involve an intermediate number of well-chosen plant functional groups (PFGs). The challenge is to build meaningful PFGs that are representative of plant biodiversity, and consistent with the parameters and processes of hybrid-DVMs. Here, we propose and test a framework based on few selected traits to define a limited number of PFGs, which are both representative of the diversity (functional and taxonomic) of the flora in the Ecrins National Park, and adapted to hybrid-DVMs. This new classification scheme, together with recent advances in vegetation modeling, constitutes a step forward for mechanistic biodiversity modeling.

Effects of riparian vegetation removal on nutrient retention in a Mediterranean stream

We examined the effects of riparian vegetation removal on algal dynamics and stream nutrient retention efficiency by comparing NH4-N and PO4-P uptake lengths from a logged and an unlogged reach in Riera Major, a forested Mediterranean stream in northeastern Spain. From June to September 1995, we executed 6 short-term additions of N (as NH4Cl) and P (as Na2HPO4) in a 200-m section to measure nutrient uptake lengths. The study site included 2 clearly differentiated reaches in terms of canopy cover by riparian trees: the first 100 m were completely logged (i.e., the logged reach) and the remaining 100 m were left intact (i.e., the shaded reach). Trees were removed from the banks of the logged reach in the winter previous to our sampling. In the shaded reach, riparian vegetation was dominated by alders (Alnus glutinosa). The study was conducted during summer and fall months when differences in light availability between the 2 reaches were greatest because of forest canopy conditions. Algal biomass and % of stream surface covered by algae were higher in the logged than in the shaded reach, indicating that logging had a stimulatory effect on algae in the stream. Overall, nutrient retention efficiency was higher (i.e., shorter uptake lengths) in the logged than in the shaded reach, especially for PO4-P. Despite a greater increase in PO4-P retention efficiency relative to that of NH4-N following logging, retention efficiency for NH4-N was higher than for PO4-P in both study reaches. The PO4-P mass-transfer coefficient was correlated with primary production in both study reaches, indicating that algal activity plays an important role in controlling PO4-P dynamics in this stream. In contrast, the NH4-N mass-transfer coefficient showed a positive relation-ship only with % of algal coverage in the logged reach, and was not correlated with any algal-related parameter in the shaded reach. The lack of correlation with algal production suggests that mechanisms other than algal activity (i.e., microbial heterotrophic processes or abiotic mechanisms) may also influence NH4-N retention in this stream. Overall, this study shows that logging disturbances in small shaded streams may alter in-stream ecological features that lead to changes in stream nutrient retention efficiency. Moreover, it emphasizes that alteration of the tight linkage between the stream channel and the adjacent riparian zone may directly and indirectly impact biogeochemical processes with implications for stream ecosystem functioning.

Syntaxonomic conspectus of the vegetation of Catalonia and Andorra. I: Hygrophilous herbaceous communities.

The first part of a general survey of the vegetation of Catalonia andAndorra, this paper reports all the phytocoenological associations and subassociations recorded in this area. For each community, we provide the correct name and usual synonyms, its typification (where appropriate), all the references including relevés, and the most outstanding features of its structure, species composition, ecology, distribution and diversity. Moreover, associations and subassociations are ordered appropriately in a syntaxonomic scheme. Syntaxonomic ranks are considered in a fairly broad, conservative sense. This classification established 101 associations, which correspond to the classes Lemnetea, Zosteretea, Potametea, Littorelletea, Montio-Cardaminetea, Phragmiti-Magnocaricetea, Scheuchzerio-Caricetea, Isoeto-Nanojuncetea and Molinio-Arrhenatheretea.

Plant diversity across five vegetation belts in the Pyrenees (Catalonia, Spain)

In this paper we analyze the size and habitat partitioning of the vascular floras of five areas of the NE Iberian Peninsula, representing five distinct vegetation belts and three floristic regions: Mediterranean (basal belt), medio-European (submontane and montane belts) and Boreo-Alpine (subalpine and alpine belts). Each area covered over 1000 ha, and was fairly uniform in terms of potential vegetation, bedrock and bioclimate. They excluded large villages and field areas, the landscape being mainly natural or moderately anthropized.

Population ecology of Paepalanthus polyanthus (Bong.) Kunth: demography and life history of a sand dune monocarpic plant

Aspects of population dynamics and life history of Paepalanthus polyanthus (Bong.) Kunth, a sand dune monocarpic plant, were evaluated. A five year study was carried out on three permanent plots (5 m x 5 m) in a sand dune slack at Joaquina beach, Santa Catarina State, Brazil. From December 1986 to June 1989, the population decreased due to the death of the post reproductive plants and a low emergence of seedlings. In June 1989, a great recruitment occurred, but no plants survived. The population re-established itself by 1990-1991. The emergence and high survival of seedlings depended on periods of high pluviosity. Nevertheless, the summer flooding and episodes of drought represented key factors in mortality. The birth and mortality rates varied among the areas. It is suggested that these differences are related with depth of the ground water and with vegetation cover at each site. Paepalanthus polyanthus can reproduce in the second year of life, but few plants do this. The chances of survival and reproduction increase with the size of the basal leaf rosette. Although the production of seeds increases with size, the risk of unexpected flooding, for instance, suggest that a great delay in reproduction might not be the most favorable strategy.

Vegetation changes in a river oasis on the southern rim of the Taklamakan Desert in China between 1956 and 2000

The indigenous vegetation surrounding the river oases on the southern rim of the Taklamakan Desert has drastically diminished due to overexploitation as a source of fodder, timber and fuel for the human population. The change in the spatial extent of landscape forms and vegetation types around the Qira oasis was analyzed by comparing SPOT satellite images from 1998 with aerial photographs from 1956. The analysis was supplemented by field surveys in 1999 and 2000. The study is part of a joint Chinese-European project with the aim of assessing the current state of the foreland vegetation, of gathering information on the regeneration potential and of suggesting procedures for a sustainable management. With 33 mm of annual precipitation, plants can only grow if they have access to groundwater, lakes or rivers. Most of the available water comes into the desert via rivers in the form of seasonal flooding events resulting from snow melt in the Kun Lun Mountains. This water is captured in canal systems and used for irrigation of arable fields. Among the eight herbaceous and woody vegetation types and the type of open sand without any plant life that were mapped in 2000 in the oasis foreland, only the latter, the oasis border between cultivated land and open Populus euphratica forests and Tamarix ramosissima-Phragmites australis riverbed vegetation could be clearly identified on the photographs from 1956. The comparison of the images revealed that the oasis increased in area between 1956 and 2000. Shifting sand was successfully combated near to the oasis borders but increased in extent at the outward border of the foreland vegetation. In contrast to expectations, the area covered with Populus trees was smaller in 1956 than today due to some new forests in the north of the oasis that have grown up since 1977. Subfossil wood and leaf remnants of Populus euphratica that were found in many places in the foreland must have originated from forests destroyed before 1956. In the last 50 years, the main Qira River has shifted its bed significantly northward and developed a new furcation with a large new bed in 1986. The natural river dynamics are not only an important factor in forming the oasis’ landscape but also in providing the only possible regeneration sites for all occurring plant species. The conclusion of the study is that the oasis landscape has changed considerably in the last 50 years due to natural floodings and to vegetation degradation by human overexploitation. The trend towards decreasing width of the indigenous vegetation belt resulting from the advancing desert and the expansion of arable land is particularly alarming because a decrease in its protective function against shifting sand can be expected in the future.

Influence of vegetation on the nocturnal foraging behaviors and vertebrate prey capture by endangered Burrowing Owls

Restrictions in technology have limited past habitat selection studies for many species to the home-range level, as a finer-scale understanding was often not possible. Consequently, these studies may not identify the true mechanism driving habitat selection patterns, which may influence how such results are applied in conservation. We used GPS dataloggers with digital video recorders to identify foraging modes and locations in which endangered Burrowing Owls (Athene cunicularia) captured prey. We measured the coarse and fine-scale characteristics of vegetation at locations in which owls searched for, versus where they caught, vertebrate prey. Most prey items were caught using hover-hunting. Burrowing Owls searched for, and caught, vertebrate prey in all cover types, but were more likely to kill prey in areas with sparse and less dense vegetative cover. Management strategies designed to increase Burrowing Owl foraging success in the Canadian prairies should try to ensure a mosaic of vegetation heights across cover types.

Variables associated with nest survival of Golden-winged Warblers (Vermivora chrysoptera) among vegetation communities commonly used for nesting

Among shrubland- and young forest-nesting bird species in North America, Golden-winged Warblers (Vermivora chrysoptera) are one of the most rapidly declining partly because of limited nesting habitat. Creation and management of high quality vegetation communities used for nesting are needed to reduce declines. Thus, we examined whether common characteristics could be managed across much of the Golden-winged Warbler’s breeding range to increase daily survival rate (DSR) of nests. We monitored 388 nests on 62 sites throughout Minnesota, Wisconsin, New York, North Carolina, Pennsylvania, Tennessee, and West Virginia. We evaluated competing DSR models in spatial-temporal (dominant vegetation type, population segment, state, and year), intraseasonal (nest stage and time-within-season), and vegetation model suites. The best-supported DSR models among the three model suites suggested potential associations between daily survival rate of nests and state, time-within-season, percent grass and Rubus cover within 1 m of the nest, and distance to later successional forest edge. Overall, grass cover (negative association with DSR above 50%) and Rubus cover (DSR lowest at about 30%) within 1 m of the nest and distance to later successional forest edge (negative association with DSR) may represent common management targets across our states for increasing Golden-winged Warbler DSR, particularly in the Appalachian Mountains population segment. Context-specific adjustments to management strategies, such as in wetlands or areas of overlap with Blue-winged Warblers (Vermivora cyanoptera), may be necessary to increase DSR for Golden-winged Warblers.

Effects of Gunnison Sage-Grouse habitat treatment efforts on associated avifauna and vegetation structure

Conservation efforts over the last 20 years for the Gunnison Sage-Grouse (Centrocercus minimus) have involved extensive habitat manipulations done predominantly to improve brood rearing habitat for the grouse. However, the effects of Gunnison Sage-Grouse habitat treatments on sympatric avifauna and responses of vegetation to manipulations are rarely measured, and if they are, it is immediately following treatment implementation. This study examined the concept of umbrella species management by retrospectively comparing density and occupancy of eight sagebrush associated songbird species and six measures of vegetation in treated and control sites. Our results suggested that songbird densities and occupancy changed for birds at the extreme ends of their association with sagebrush and varied with fine-scale habitat structure. We found Brewer’s Sparrows (Spizella breweri) decreased in density on treated sites and Vesper Sparrows (Pooecetes gramineus) increased. Occupancy estimation revealed that Brewer’s Sparrows and Green-tailed Towhees (Pipilo chlorurus) occupied significantly fewer treated points whereas Vesper Sparrows occupied significantly more. Vegetation comparisons between treated and control areas found shrub cover to be 26% lower in treated sites. Lower shrub cover in treated areas may explain the differences in occupancy and densities of the species sampled based on known habitat needs. The fine-scale analysis showed a negative relationship to forb height and cover for the Sage Sparrow (Amphispiza belli) indicating, from vegetation measures showing grass and forb cover during a good precipitation year covered significantly more area in the treatment than the control sites, that Sage Sparrows may also not respond favorably to Gunnison Sage-Grouse habitat treatments. While the concept of an umbrella species is appealing, evidence from this study suggests that conservation efforts aimed at the Gunnison Sage-Grouse may not be particularly effective for conserving other sagebrush obligate species of concern. This is probably due to Gunnison Sage-Grouse habitat management being focused on the improvement of brood rearing habitat which reduces sagebrush cover and promotes development of understory forbs and grasses.

Land degradation and vegetation distribution in Chott El Beida wetland, Algeria

The aim of this study is to explore the environmental factors that determine plant Community distribution in northeast Algeria. This paper provides a quantitative analysis of the vegetation-environment relationships for a study site in the Cholt El Beida wetland, a RAMSAR site in Setif, Algeria. Sixty vegetation plots were sampled and analysed using TWINSPAN and Detrended Correspondence Analysis (DCA) in order to identify the principal vegetation communities and determine the environmental gradients associated with these. 127 species belonging to 41 families and 114 genera were recorded. Six of the recorded species were endemic representing 4.7% of the total species. The richest families were Compositae, Gramineae, Cruciferae and Chenopodiaceae. Therophytes and hemicryptophytes were the most frequent life forms. the Mediterranean floristic element is dominant and is represented by 39 species. The samples were classified into four main community types. The principal DCA axes represent gradients of soil salinity, moisture and anthropogenic pressure. The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities and a greater understanding of controlling environmental factors. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in often critically endangered Mediterranean wetland areas. (C) 2008 Elsevier Ltd. All rights reserved.

A GIS-based empirical model for vegetation prediction in Lefka Ori, Crete

The aim of the study was to establish and verify a predictive vegetation model for plant community distribution in the alti-Mediterranean zone of the Lefka Ori massif, western Crete. Based on previous work three variables were identified as significant determinants of plant community distribution, namely altitude, slope angle and geomorphic landform. The response of four community types against these variables was tested using classification trees analysis in order to model community type occurrence. V-fold cross-validation plots were used to determine the length of the best fitting tree. The final 9node tree selected, classified correctly 92.5% of the samples. The results were used to provide decision rules for the construction of a spatial model for each community type. The model was implemented within a Geographical Information System (GIS) to predict the distribution of each community type in the study site. The evaluation of the model in the field using an error matrix gave an overall accuracy of 71%. The user's accuracy was higher for the Crepis-Cirsium (100%) and Telephium-Herniaria community type (66.7%) and relatively lower for the Peucedanum-Alyssum and Dianthus-Lomelosia community types (63.2% and 62.5%, respectively). Misclassification and field validation points to the need for improved geomorphological mapping and suggests the presence of transitional communities between existing community types.

Environmental factors and vegetation composition, Lefka Ori Massif, Crete, S. Aegean

Aim The aim of this study was to explore the environmental factors that determine the spatial distribution of oro-mediterranean and alti-mediterranean plant communities in Crete. Location The paper provides a quantitative analysis of vegetation-environment relationships for two study areas within the Lefka Ori massif Crete, a proposed Natura 2000 site. Methods Eleven environmental variables were recorded: altitude, slope, aspect, percentage of bare rock, percentage of unvegetated ground, soil depth, pH, organic matter content and percentages of sand, silt and clay content. Classification of the vegetation was based on twinspan, while detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were used to identify environmental gradients linked to community distribution. Results One hundred and twenty-five species were recorded from 120 plots located within the two study areas. Forty-seven of the recorded species are endemic, belonging to 35 families. Hemicryptophytes and chamaephytes were the most frequent, suggesting a typical oro-mediterranean life form spectrum. The samples were classified into five main community types and one transitional. The main gradients, identified by CCA, were altitude and surface cover type in the North-west site, while in the Central site the gradients were soil formation-development and surface cover type. Main conclusions The use of classification in combination with ordination techniques resulted in a good discrimination between plant communities and a greater understanding of controlling environmental factors. The methodology adopted can be employed for improving baseline information on plant community ecology and distribution in Mediterranean mountain zones.