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Macrophyte Species Diversity (macrophyte + species_diversity)

Distribution by Scientific Domains

Life Sciences	100%

Selected Abstracts

Macrophyte species diversity in formerly cultivated wetlands in Uganda

AFRICAN JOURNAL OF ECOLOGY, Issue 4 2008
Josephine Esaete
Abstract The diversity of major macrophytes was assessed in cultivated areas in Bukasa and Kinawataka wetlands in Central Uganda. One thousand and seventy-two plots of 1 × 1 m were established in 69 cultivated areas. Data were collected on species richness and abundance. Two-way analysis of covariance (ANCOVA) showed how cropping regimes affected macrophyte species richness and abundance. There were 127 plant species belonging to 37 families in cultivated areas. Of the 127 species, 42 were macrophytes and of the 37 families, fourteen contained macrophyte species. Plant species diversity was higher in the short-term cropping regime areas (11.3 species per 1 m2) than in the long-term cropping regime areas (9.3 species per 1 m2). However, macrophyte species richness was similar in the short-term (3.2 species per 1 m2) and the long-term (3.3 species per 1 m2) cropping regimes. The dominant families were Poaceae, Asteraceae and Cyperaceae with more than ten species each. The higher plant species diversity in cultivated areas than in uncultivated was because of nonmacrophyte species, thus cropping regime does not influence macrophyte species diversity. Increase in diversity of nonmacrophyte species in short-term cropping regime implies that the use of wetlands for agricultural crop growing may alter plant species composition and diversity during secondary succession. Résumé La diversité des principaux macrophytes a étéévaluée dans les régions cultivées des zones humides de Bukasa et de Kinawataka, au centre de l'Ouganda. On a établi 1072 plots d'1x1m, dans 69 zones cultivées. On a récolté des données sur la richesse et l'abondance des espèces. Une analyse de la covariance à deux voies (ANCOVA) a montré comment les régimes agricoles affectaient la richesse et l'abondance des espèces de macrophytes. Il y avait 127 espèces végétales appartenant à 37 familles dans les zones cultivées. De ces 127 espèces, 42 étaient des macrophytes, et des 37 familles, 14 comprenaient des espèces de macrophytes. La diversité des espèces végétales était plus élevée dans les surfaces subissant un régime cultural court (11,3 espèces/m2) que dans les surfaces soumises à un régime de culture plus long (9,3 espèces/m2). Cependant, la richesse en espèces de macrophytes était comparable pour le régime court (3,2 espèces/m2) et pour le plus long (3,3 espèces/m2). Les familles dominantes étaient les Poaceae, les Asteraceae et les Cyperaceae, qui comptaient chacune plus de 10 espèces. La diversité spécifique plus grande observée dans les aires cultivées était due aux espèces non macrophytes, et on peut donc dire que le régime de culture n'influence pas la diversité des espèces de macrophytes. L'augmentation de la diversité des espèces non macrophytes dans les cultures à régime court implique que l'utilisation des zones humides pour l'agriculture peut altérer par la suite la composition et la diversité des espèces végétales. [source]

Seasonal dynamics of macrophytes and phytoplankton in shallow lakes: a eutrophication-driven pathway from plants to plankton?

FRESHWATER BIOLOGY, Issue 3 2010
CARL D. SAYER
Summary 1. Seasonal relationships between macrophyte and phytoplankton populations may alter considerably as lakes undergo eutrophication. Understanding of these changes may be key to the interpretation of ecological processes operating over longer (decadal-centennial) timescales. 2. We explore the seasonal dynamics of macrophytes (measured twice in June and August) and phytoplankton (measured monthly May,September) populations in 39 shallow lakes (29 in the U.K. and 10 in Denmark) covering broad gradients for nutrients and plant abundance. 3. Three site groups were identified based on macrophyte seasonality; 16 lakes where macrophyte abundance was perennially low and the water generally turbid (,turbid lakes'); 7 where macrophyte abundance was high in June but low in August (,crashing' lakes); and 12 where macrophyte abundance was high in both June and August (,stable' lakes). The seasonal behaviour of the crashing and turbid lakes was extremely similar with a consistent increase in nutrient concentrations and chlorophyll- a over May,September. By contrast in the stable lakes, seasonal changes were dampened with chlorophyll- a consistently low (<10,15 ,g L,1) over the entire summer. The crashing lakes were dominated by one or a combination of Potamogeton pusillus, Potamogeton pectinatus and Zannichellia palustris, whereas Ceratophyllum demersum and Chara spp. were more abundant in the stable lakes. 4. A long-term loss of macrophyte species diversity has occurred in many shallow lakes affected by eutrophication. One common pathway is from a species-rich plant community with charophytes to a species-poor community dominated by P. pusillus, P. pectinatus and Z. palustris. Such compositional changes may often be accompanied by a substantial reduction in the seasonal duration of plant dominance and a greater tendency for incursions by phytoplankton. We hypothesise a slow-enacting (10,100 s years) feedback loop in nutrient-enriched shallow lakes whereby increases in algal abundance are associated with losses of macrophyte species and hence different plant seasonal strategies. In turn such changes may favour increased phytoplankton production thus placing further pressure on remaining macrophytes. This study blurs the distinction between so-called turbid phytoplankton-dominated and clear plant-dominated shallow lakes and suggests that plant loss from them may be a gradual process. [source]

Effects of stream restoration and management on plant communities in lowland streams

FRESHWATER BIOLOGY, Issue 1 2006
TINA CHARLOTTE MOUSTGAARD PEDERSEN
Summary 1. We evaluated restoration success on macrophyte species diversity and composition in lowland streams using communities in 30 naturally meandering stream reaches in the western part of Jutland, Denmark, as reference target communities. Fuzzy set clustering was used to examine the floristic and environmental similarity among reaches, whereas fuzzy set ordination was used to relate floristic patterns to environmental variables. 2. Two major groups of streams were identified based on their floristic composition. One group consisted of reference and restored reaches and the other of the majority of channelised reaches. We found that management exerted a strong influence on the macrophyte communities and that the identified groups were related to differences in management intensity. 3. Our results also indicate that bank morphology and bed level affected macrophyte communities in the streams, particularly the richness and abundance of terrestrial species. The analyses performed suggest that shallow and wide banks allow for a larger migration of species from the stream banks into the streams, thereby enhancing species diversity within the stream channel. 4. The results of this study suggest that macrophyte communities in channelised lowland streams can recover following restorative interventions given that stream management (i.e. weed cutting and dredging) is minimised and that stream banks are reprofiled to improve the lateral connectivity between the stream and its valley. [source]