. Assembly rules provide one possible unifying framework for community ecology. Given a species pool, and measured traits for each species, the objective is to specify which traits (and therefore which subset of species) will occur in a particular environment. Because the problem primarily involves traits and environments, answers should be generalizable to systems with very different taxonomic composition. In this context, the environment functions like a filter (or sieve) removing all species lacking specified combinations of traits. In this way, assembly rules are a community level analogue of natural selection. Response rules follow a similar process except that they transform a vector of species abundances to a new vector using the same information. Examples already exist from a range of habitats, scales, and kinds of organisms.

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Assembly and response rules: two goals for predictive community ecology

Much as Rachel Carson's \"Silent Spring\" was a call to action against the pesticides that were devastating bird populations, Charles S. Elton's classic \"The Ecology of Invasions by Animals and Plants\" sounded an early warning about an environmental catastrophe that has become all too familiar today-the invasion of nonnative species. From kudzu to zebra mussels to Asian long-horned beetles, nonnative species are colonizing new habitats around the world at an alarming rate thanks to accidental and intentional human intervention. One of the leading causes of extinctions of native animals and plants, invasive species also wreak severe economic havoc, causing $79 billion worth of damage in the United States alone. Elton explains the devastating effects that invasive species can have on local ecosystems in clear, concise language and with numerous examples. The first book on invasion biology, and still the most cited, Elton's masterpiece provides an accessible, engaging introduction to one of the most important environmental crises of our time. Charles S. Elton was one of the founders of ecology, who also established and led Oxford University's Bureau of Animal Population. His work has influenced generations of ecologists and zoologists, and his publications remain central to the literature in modern biology. \"History has caught up with Charles Elton's foresight, and \"The Ecology of Invasions\" can now be seen as one of the central scientific books of our century.\"-David Quammen, from the Foreword to \"Killer Algae: The True Tale of a Biological Invasion\

The Ecology of Invasions by Animals and Plants

Effects of submersed macrophytes on ecosystem processes

Urbanization is a massive, unplanned experiment that already affects large acreages and is spreading in many areas of the United States (Alig and Healy 1987). Urban areas are conservatively defined as those with human populations denser than 620 individuals/km2 (United States Bureau of Census 1980, Bourne and Simmons 1982). In 1989, 74% of the United States population (203 million people) resided in urban areas and that number is expected to increase to >80% by the year 2025 (Fox 1987, Haub and Kent 1989). The increase in urban population throughout the country has resulted in the conversion of cropland, pastures, and forests into urban and suburban environments

Ecosystem Structure and Function along Urban‐Rural Gradients: An Unexploited Opportunity for Ecology

Wetlands and streams buffer the interactions among uplands and adjacent aquatic systems. Phosphorus (P) is often the key nutrient found to be limiting in both estuarine and freshwater ecosystems. As such, the ability of wetlands and streams to retain P is key to determining downstream water quality. This article reviews the processes and factors regulating P retention in streams and wetlands and evaluates selected methodologies used to estimate P retention in these systems. Phosphorus retention mechanisms reviewed include uptake and release by vegetation, periphyton and microorganisms; sorption and exchange reactions with soils and sediments; chemical precipitation in the water column; and sedimentation and entrainment. These mechanisms exemplify the combined biological, physical, and chemical nature of P retention in wetlands and streams. Methodologies used to estimate P retention include empirical input-output analysis and mass balances, and process kinetics applied at various scales, including micro- a...

/pdf/phosphorus-retention-in-streams-and-wetlands-a-review-1tz9yqefze.pdf

Phosphorus Retention in Streams and Wetlands: A Review

The Eurasian watermilfoil (Myriophyllum spicatum L.) has partially replaced wild celery (Vallisneria americana Michx.) as a community dominant in the littoral zones of lakes of Madison, Wisconsin. The two species have very different growth forms, with that of M. spicatum corresponding more closely to the optimal growth form simulated by the macrophyte production model WEED. The objective of this research was to investigate the mechanisms by which Vallisneria could compensate for its nonoptimal growth form and coexist with Myriophyllum.A quantification of midsummer growth form for the two species at a rooting depth of 80-90 cm showed that M. spicatum had 68% of its shoot biomass within 30 cm of the surface, whereas V. americana had 62% of its leaf biomass within 30 cm of the bottom. Vallisneria had a light extinction coefficient ranging from 0.013 to 0.019 m2·g-1, much higher than the value (ca. 0.006 m2·g-1) for M. spicatum. This indicates less effective penetration of light to lower leaves of V. americana. Half-saturation constants describing the light-dependence of carbon uptake in "shade" and "sun" tissues ranged from 60-197 microeinsteins·m-2·s-1 for V. americana, and 164-365 μeinsteins·m-2·s-1 for M. spicatum. The optimum temperature for photosynthesis was 33.6°C for M. spicatum and 32.6°C for V. americana, but Myriophyllum was nearly twice as effective at carbon uptake at 10°C. Integration of all of the above features with WEED showed that, for midsummer conditions, V. americana more than compensated for apparently disadvantageous morphological features by its greater physiological adaptability to low light regimes. Coupled with the temperature-dependence of photosynthesis, it appears that V. americana is favored by midsummer conditions, whereas M. spicatum is at an advantage at other times.

Coexistence and the comparative light relations of the submersed macrophytes Myriophyllum spicatum L. and Vallisneria americana Michx.

The uptake of phosphorus, the biomass, and the standing P stock were measured over the course of a year in roots and shoots of the Eurasian watermilfoil, Myriophyllum spicatum, from Lake Wingra, Wisconsin. The resulting data were used to estimate the relative contributions of root and shoot uptake to the phosphorus economy of the plant and to examine the role of the plant in moving phosphorus between sediment and water. The total yearly uptake of P by a square meter of Myriophyllum was 3.0 g P m-*. Root uptake accounted for 2.2 g, shoot uptake only 0.8 g. The rate of P release from healthy shoots was insignificant, but about 2.8 g P m-* yr-l was lost due to shoot turnover. Since most of the P uptake is by the roots and much of the plant P is transferred to and lost by the shoots, Myriophyllum is a potentially important vector in the movement ofP from the sediments to the water. The net transfer of P from the sediments to shoots of Myriophyllum in Lake Wingra is about 2.0 g P m-* yr-l. Release of this P during decay makes Myriophyllum an important source of P for pelagic phytoplankton and can explain much of the previously reported P export from the littoral zone of Lake Wingra.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1986.31.6.1312

Phosphorus transfer from sediments by Myriophyllum spicatum1

Temperature, phosphorus, and nitrogen were investigated as possible factors influencing decay of Myriophyllum spicatum shoots. In laboratory experiments, nitrogen enrichment significantly increased decay rates while phosphorus enrichment did not. Similar increases in decay rate per unit of added nitrogen occurred whether nitrogen was provided as nitrate or was present as additional tissue nitrogen. Exponential decay coefficients depended on temperature with a Q10 of about 3. Predictions of decay rates during litter bag experiments were based on laboratory responses of decay rate to temperature and initial nitrogen concentration of the shoots. Observed decay rates correlated closely with predictions, demonstrating the usefulness of temperature and shoot nitrogen content in explaining variations in decay rates in Lake Wingra. However, predictions underestimated decay rates. Possible explanations for the discrepancies include slow establishment of the detrital microflora, lower nitrogen availability, and absence of animals in the laboratory incubations.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.1979.24.3.0520

Effects of nutrients and temperature on decomposition of Myriophyllum spicatum L. in a hard‐water eutrophic lake1

The littoral regions of most aquatic ecosystems represent some of the most productive communities of the world (Wetzel 1964) and, as such, warrant intensive investigation. Lake Wingra (Madison, Wisconsin, U.S.A.) contains an extensive littoral zone. Lake Wingra was selected as an intensive study site within the Eastern Deciduous Forest Biome, US-IBP, and is the focus of an interdisciplinary ecosystems analysis study involving more than twenty-two subprojects. The lake is approximately 139-6 ha, with a littoral zone encompassing 31% (43 ha) of the total area. The lake is highly alkaline (80-200 mg CaCO3 equivalent per litre), with high (7-10-3) pH values prevailing within the littoral during midsummer. Most of the phosphorus enters the lake via a storm sewer system from an urban watershed, and dissolved phosphorus concentrations in the littoral range from 5 to 33 jug 1-1 during summer (Kluesener 1972). Phytoplankton production in the pelagial is very high with the annual mean rate of carbon fixation near 2 g C m-2 day (Koonce 1972). The littoral of Lake Wingra is dominated by the submergent macrophyte Myriophyllum spicatum L. (Eurasian water milfoil). The macrophyte vegetation of the lake affords an extensive substratum for colonization by periphytic epiphyton. Apparent net primary production of the community is high and, in addition, a considerable level of extracellular secretion ('excretion') of photosynthate occurs. This excretant, generally about 5% of total net photosynthesis of macrophytes in Lake Wingra, is available for channelling through other trophic levels within the ecosystem. Another important aspect of the macrophyte component of the littoral of Lake Wingra is the dense structure which the macrophytes provide as a habitat for bluegill sunfish (Lepomis macrochiris Raf.). The habitat has the appearance of a dense forest and may serve as a factor in the high numbers and small individual size of fish in the bluegill population of the lake. The macrophytes contribute considerably to the annual detritus pool. Since submergent macrophytes remove nutrients from both the water and sediments (Bristow & Whitcombe 1971), the plants are expected to have a significant role in the nitrogen and phosphorus cycling in the lake.

Michael S. Adams

Papers

Coexistence and the comparative light relations of the submersed macrophytes Myriophyllum spicatum L. and Vallisneria americana Michx.

Phosphorus transfer from sediments by Myriophyllum spicatum1

Effects of nutrients and temperature on decomposition of Myriophyllum spicatum L. in a hard‐water eutrophic lake1

Seasonal Production of the Myriophyllum Component of the Littoral of Lake Wingra, Wisconsin

The macrophyte tissue nutrient pool of a hardwater eutrophic lake: Implications for macrophyte harvesting