Presence Of Indicator Species Research Articles

Assessment of eutrophication and phytoplankton community impairment in the Buffalo River Area of Concern

A “weight of evidence” approach was used to assess trophic status and phytoplankton community characteristics as a step towards delisting beneficial use impairments in the Buffalo River Area of Concern (AOC). Using a combination of historical data and results of a sampling program conducted in 2006, trophic status was evaluated by considering threshold levels of total phosphorus and chlorophyll a, total phytoplankton abundance, reference-reach comparisons of total phosphorus and nitrate + nitrite, and an ecoregion (percentile) analysis. Microcystin toxin levels were used as an indicator of the presence of undesirable algae. Phytoplankton community characteristics were assessed through consideration of species richness, Shannon–Weaver Index of Diversity, presence of indicator species, centric:pennate diatom ratio, the Trophic Diatom Index (TDI), and the Pollution Tolerance Index (PTI). The weight of evidence suggests that the Buffalo River AOC does not have a eutrophication problem, but nutrient levels are sufficiently high to recommend further implementation of watershed Best Management Practices and continued water quality monitoring. Microcystin was present in all samples but at a level below the World Health Organization guidelines; based on this indicator we conclude that the AOC does not have a problem with undesirable algae. The phytoplankton community exhibits some anthropogenic impact as reflected by the TDI, PTI, and presence of certain indicator species, but these impacts do not indicate extreme stress. Based on the weight of evidence the Buffalo River Remedial Advisory Committee recently concluded that the AOC was not impaired in terms of eutrophication, presence of undesirable algae, and degradation of phytoplankton.

Landscape structure and management regime as indicators of calcareous grassland habitat condition and species diversity

This study investigates the importance of spatial landscape characteristics and habitat management on the condition of calcareous grassland in the North Down Natural Area, Kent UK. We used a digitised map of the study area containing shapefiles of all the habitats including 82 patches of calcareous grassland together with management information for each patch and data on the presence and abundance of a range of calcareous grassland indicator plant species. We defined habitat condition by presence of indicator species and used classification trees to generate models with rules for predicting habitat condition from the landscape spatial characteristics and management information. We also applied the same method to investigate the factors affecting presence or diversity of three ecological groups of positive indicator species and dominance of a negative indicator species. All the models except one showed good classification accuracy and high kappa statistic. Favourable habitat condition was predicted by presence of different types of grazing management, presence of woodland around patches of calcareous grassland and shape complexity. These results indicate that calcareous grassland in favourable condition is management-dependent but also located in less intensively managed landscapes. Unfavourable habitat condition was predicted by threat factors such as lack of management and high incidence of arable or improved grassland around patches of calcareous grassland, indicating nutrient enrichment and habitat degradation. Some of these factors also predicted high diversity of the different ecological species groups. The value of this method for predicting habitat condition and species diversity from baseline ecological data for conservation monitoring at the landscape level is emphasised.

An ecological look at saline wetlands

Due to the occurrence of considerable areas of wetlands in the world, the wise, sustainable use of these lands is one of major importance for ecologists and agriculturists. As the presence of indicator species and plant communities can be a measure of the compatibility between plants and edaphic conditions in these regions, the ecological niches of plant species in part of the southern coastal areas of the Caspian Sea have been studied to show the correlation of each species with its own habitat. The plant communities were separated with Ward's cluster analysis. The correlation of these communities and plant species with environmental factors was investigated with the CCA method, using PC-Ordination-4 software. The results showed that the soil EC, water table, soil pH, SAR and ESP were 14-157 dS/m, 0-240 cm, 6.5-8.5, 13.4-84.8 and 2-55%, respectively. This range of values, in addition to creating ecological niches for species with different ecological roles, was also effective in the formation of plant communities. The analysis of vegetation and soil data with the CCA method showed the relationships between soil factors and vegetation. In spite of the dominance of the species Halocnemum strobilaceum in all the plant communities, the correlation of this species with plant species such as Aeluropus littoralis, Salicornia europaea, Aeluropus lagopoides,Salsola aurantia and Puccinella distans in relation to changes in EC, water table, pH, SAR and ESP, is important from the point of view of sustaining the physical environment and ecological function. The simplification of these ecosystems (by drainage, agriculture, etc.) may disturb the natural equilibrium. As these ecosystems are susceptible and changes in their use are costly from the ecological and economic points of view, the wise use of ecosystems in their natural forms (rangelands and habitats) is recommended to prevent the spread of salinity and to protect habitats and biodiversity.

SPIDER ASSEMBLAGE STRUCTURE AND STABILITY IN A HETEROGENEOUS COASTAL DUNE SYSTEM (BELGIUM)

An analysis of the spider assemblage structure and the presence of indicator species in the Flemish coastal dunes are presented. The analysis is based on data from more than 170 year-round pitfall sampling campaigns from the 1970s onwards. We were able to find indicator species for all identified habitats. The assemblages are determined by variation in vegetation structure (succession), atmospheric and soil humidity and the occurrence of both natural of anthropogenic disturbance. In the fragmented habitats (grasslands and grey dunes), a clear relationship was found between the mean habitat size and the stability of the assemblage composition. In moss dominated dunes and short grasslands total species numbers do not increase with patch size. Due to microhabitat variation and the possibility of attaining viable population sizes the total number of typical species is, however, higher in larger patches. In small patches, edge effects are more important and the number of observed species is enlarged by the intrusion of species from nearby habitats.

INDICATORS OF PASTURE DEGRADATION OF TERSK-KUMA LOWLAND

The regularity of demonstration of the types of vegetation cover indicators of the Kochubei Biosphere Station, the characteristics of the development of indicator communities, and pasture digression processes in connection with unregulated cattle grazing have been studied. Changes in pasture communities are noted with varying degrees of loss of their floristic and phytocenotic potential and changes in the phytocenoses of digressive pastures. Under the conditions of external influence and as they increase, the ordinary components of the community are transformed into its dominant, that is, indicators. Identified plants - indicators, as well as communities - indicators, indicators of changes in the plant species composition of communities in the course of pasture digression. The presence of indicator species in communities is an important indicator for identifying the level of pasture load on vegetation and the most informative parameter for geobotanical monitoring of pasture vegetation. The geobotanical study showed the heterogeneity of pasture vegetation on the phytocenotic composition, which are in a state of severe disruption. The monitoring studies of pastures of the Kochubei Biosphere Station were conducted, where a complex of environmental factors has a significant impact on the change in the species composition and structure of pastures under various loads. The peculiarities of the development of pasture digression on the light chestnut soils of the study area are traced. Changes occurring in the vegetation cover of pastures under the influence of weak grazing are the disappearance of the large-grain cereals of the Stipa series with the predominance of fine-grained cereals like Festuca sulcáta. With intensive grazing with the disappearance of Festuca sulcáta and the emergence of shrubs Artemisia and others, more competitive species appear, this causes a change of plant communities. On the basis of floristic and cenotic analysis, it can be concluded that the types of indicators reducing their abundance under the influence of grazing are Stipa lessingiana, increasing their abundance under the influence of grazing are Artemisia, Ceratocarpus arenarius and other weeds.