Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

This review aims to determine how environ- mental characteristics of aquatic habitats rule species occurrence, life-history traits and community dynamics among aquatic plants, and if these particular adaptations and responses fit in with general predictions relating to abiotic factors and plant communities. The way key abiotic factors in aquatic habitats affect (1) plant life (recruitment, growth, and reproduction) and dispersal, and (2) the dynamics of plant communities is discussed. Many factors related to plant nutrition are rather similar in both aquatic and terrestrial habitats (e.g. light, temperature, substrate nutrient content, CO2 availability) or differ markedly in intensity (e.g. light), variations (e.g. temperature) or in their effective importance for plant growth (e.g. nutrient content in substrate and water). Water movements (water- table fluctuations or flow velocity) have particularly drastic consequences on plants because of the density of water leading to strong mechanical strains on plant tissues, and because dewatering leads to catastrophic habitat modifi- cations for aquatic plants devoid of cuticle and support tissues. Several abiotic factors that affect aquatic plants, such as substrate anoxia, inorganic carbon availability or temperature, may be modified by global change. This in turn may amplify competitive processes, and lead ulti- mately to the dominance of phytoplankton and floating species. Conserving the diversity of aquatic plants will rely on their ability to adapt to new ecological conditions or escape through migration.

Response of aquatic plants to abiotic factors: a review

Aquatic plants are important components of many freshwater ecosystems. In this review we examine natural and anthropogenic influences on the distribution and abundance of aquatic plants, and develo...

Environmental influences on aquatic plants in freshwater ecosystems

Aquatic macrophytes are aquatic photosynthetic organisms, large enough to see with the naked eye, that actively grow permanently or periodically submerged below, floating on, or growing up through the water surface. Aquatic macrophytes are represented in seven plant divisions: Cyanobacteria, Chlorophyta, Rhodophyta, Xanthophyta, Bryophyta, Pteridophyta and Spermatophyta. Species composition and distribution of aquatic macrophytes in the more primitive divisions are less well known than for the vascular macrophytes (Pteridophyta and Spermatophyta), which are represented by 33 orders and 88 families with about 2,614 species in c. 412 genera. These c. 2,614 aquatic species of Pteridophyta and Spermatophyta evolved from land plants and represent only a small fraction (∼1%) of the total number of vascular plants. Our analysis of the numbers and distribution of vascular macrophytes showed that whilst many species have broad ranges, species diversity is highest in the Neotropics, intermediate in the Oriental, Nearctic and Afrotropics, lower in the Palearctic and Australasia, lower again in the Pacific Oceanic Islands, and lowest in the Antarctic region. About 39% of the c. 412 genera containing aquatic vascular macrophytes are endemic to a single biogeographic region, with 61–64% of all aquatic vascular plant species found in the Afrotropics and Neotropics being endemic to those regions. Aquatic macrophytes play an important role in the structure and function of aquatic ecosystems and certain macrophyte species (e.g., rice) are cultivated for human consumption, yet several of the worst invasive weeds in the world are aquatic plants. Many of the threats to fresh waters (e.g., climate change, eutrophication) will result in reduced macrophyte diversity and will, in turn, threaten the faunal diversity of aquatic ecosystems and favour the establishment of exotic species, at the expense of native species.

http://fada.biodiversity.be/mce_docs/pdf/FADA_Chambers.pdf

Global diversity of aquatic macrophytes in freshwater

Herbaceous vegetation under temperate climatic conditions generally shows nitrogen- or phosphorus-limited plant growth, which creates conditions for a high botanical diversity. Is nitrogen (N) or phosphorus (P) the most important limiting factor, or are both generally in short supply? What are the consequences of Increased N and P inputs that result from anthropogenic disturbances? A new indicator of N or P limitation, that is, the vegetation N:P ratio, allows us to address these questions for a range of mires, dune slacks and moist grasslands.

Nitrogen-or phosphorus-limited growth in herbaceous, wet vegetation : relations with atmospheric input and management regimes

Relationships between aquatic plants and environmental factors along a steep himalayan altitudinal gradient

Physical and chemical factors were studied in 34 lentic waterbodies distributed along a steep altitudinal gradient ranging from tropical (77 m) to high alpine (up to 4,980 m) environments in Nepal. Bicarbonate and calcium were dominant among anions and cations, respectively, reflecting a strong influence of carbonate weathering and watershed area, rather than altitudinal climate. The relative patterns of dominant ions were similar among lakes in all altitudinal regions, although total concentrations increased with decreasing altitude. Total suspended solids were relatively high in the study lakes, as is also typical of rivers in the Ganges watershed. Suspended solids had a greater influence on water transparency than did algal biomass in the study lakes. In general, high-altitude waterbodies were oligotrophic, while those at low altitude were eutrophic. The productivity of high-altitude study lakes appeared to be limited by both available phosphorus and nitrogen, while lowland ones were nitrogen-limited. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Physical and Chemical Limnology of 34 Lentic Waterbodies along a Tropical-to-Alpine Altitudinal Gradient in Nepal

Increasing the amount of organic-carbon stored in the biomass of terrestrial ecosystems is an effective way to reduce the net anthropogenic emissions of greenhouse gases to the atmosphere. This can be done by conserving existing ecological reservoirs of fixed organic-carbon, maintaining or enhancing the rate of sequestration, and restoring stocks that have been depleted by past land-use practices. Most trading systems for greenhouse-gas offsets recognize the validity of projects that gain ecological offsets, and permit them to sell carbon credits in an emerging marketplace for these novel commodities. Although ecological carbon-offset projects have been criticized from a variety of perspectives, most of the supposed problems can be satisfactorily mitigated. In addition to offsetting emissions of greenhouse gases, ecological proj- ects that accumulate carbon credits may have a strong cross-linkage to the conservation of natural values, which in itself is an important action for society to undertake. This is, however, less of a consideration for projects that are based on anthropogenic ecosystems, such as no-till agricultural systems and plantation forests, which provide relatively few benefits to native biodiversity and might even detract from that objective if developed on newly converted natural habitat. More- over, the existing rules for carbon-offset systems exclude some kinds of ecological projects from the trading markets, even though they would result in avoided emissions or enhanced sequestration of organic-carbon. As the emerging marketplace for carbon offsets grows, it will be important to understand the co-benefits and side effects of offset projects on non-car- bon values, including native biodiversity. Resume´ : L'augmentation des quantites de carbone organique accumulees dans la biomasse des ecosystemes terrestres constitue un moyen efficace pour reduire les emissions anthropogenes nettes de gaz a effets de serre dans l'atmosphere. On peut atteindre cet objectif en conservant les reservoirs ecologiques de carbone organique existants, en maintenant ou en augmentant le taux de sequestration, et en restaurant les reserves qui ont eteepuisees par les utilisations passees des ter- ritoires. La plupart des systemes de compensation des gaz aeffet de serre reconnaissent la validitedes projets conduisant ades compensations ecologiques et leur permettent de vendre des credits de carbone dans un marcheemergent visant ces nouveaux biens marchands. Bien que les projets ecologiques de compensation du carbone aient etecritiques selon differ- entes perspectives, on peut mitiger de facon satisfaisante, la plupart des supposes problemes. En plus de compenser les emissions de gaz aeffets de serre, les projets ecologiques qui accumulent des credits de carbone peuvent presenter des liens etroits avec la conservation de valeurs naturelles, qui en soi constituent une action importante que doit entreprendre la societe´. Cependant, cette consideration s'applique moins aux projets bases sur des activites anthropogeniques comme les systemes de culture sans labour et les plantations forestieres, qui rapportent relativement peu de benefices a la biodiversite´ indigene et peuvent meme s'eloigner de l'objectif, si on les applique ades habitats naturels recemment convertis. De plus, les regles existantes pour les systemes de compensation du carbone excluent certains types de projets ecologiques du mar- cheboursier, meme s'ils permettraient d'eviter des emissions ou augmenter la sequestration de carbone organique. Ame- sure que les marchesemergents des compensations en carbone s'accroissent, il deviendra important de comprendre les cobenefices et les effets secondaires des projets de compensation de valeurs autres que le carbone, incluant la biodiversite´ indigene. (Traduit par la Redaction)

/pdf/carbon-credits-and-the-conservation-of-natural-areas-5cs6y6zkod.pdf

Paresh Lacoul

Papers

Environmental influences on aquatic plants in freshwater ecosystems

Relationships between aquatic plants and environmental factors along a steep himalayan altitudinal gradient

Physical and Chemical Limnology of 34 Lentic Waterbodies along a Tropical-to-Alpine Altitudinal Gradient in Nepal

Carbon credits and the conservation of natural areas