Response of ecological storage and conservation to land use transformation: A case study of a mining town in China

Rapid land use transformation shaped by agriculture, industrialization and population urbanization has a great influence on ecological environment. Based on theory of ecosystem service functions, this study aims at revealing the response of ecological storage and conservation to each unit area of land use transformation. Taking Cishan Town, a mining town in China, as a case study, this paper estimates the “past-present-future” ecological storage impacted by the process, result and possibility of land use transformation. The local land use and industrial distribution show that the active areas of land use transformation are also the areas of concentration of human (industrial) activities. Ecological storage shows the different responses to land use ways. And then this study combines the ecological storage indices with the indices of ecosystem pattern and land condition into the“5A” framework (active state, active degree, active possibility, active balance and active condition) for grading ecological conservation, and then assigns all regions of Cishan Town into different grades through membership functions for complex mapping of ecological conservation. The research results show that the ecological conservation in Cishan goes toward two extreme grades (best grade and worst grade). Uneven and unbalanced land use transformation is the main cause of that. Hence, rational and timely reflection of impact of land use transformation on ecological storage and conservation can assist land use planners and local government in adjusting land use ways and balancing regional ecology and economy.     

Application of eco-exergy for assessment of ecosystem health and development of structurally dynamic models

Eco-exergy has been widely used in the assessment of ecosystem health, parameter estimations, calibrations, validations and prognoses. It offers insights into the understanding of ecosystem dynamics and disturbance-driven changes. Particularly, structurally dynamic models (SDMs), which are developed using eco-exergy as the goal function, have been applied in explaining and exploring ecosystem properties and changes in community structure driven by biotic and abiotic factors. In this paper, we review the application of eco-exergy for the assessment of ecosystem health and development of structurally dynamic models (SDMs). The limitations and possible future applications of the approach are also addressed.     

Modeling ecosystem responses to prescribed fires in a phosphorus-enriched Everglades wetland: I. Phosphorus dynamics and cattail recovery

We have developed and applied a process-based model, the Wetland Ecosystem Model (WEM), to evaluate the effects of a prescribed fire on the phosphorus (P) dynamics and cattail (Typha domingensis) growth in a P-enriched area in the Florida Everglades. The WEM couples major ecosystem processes including carbon (C), nitrogen (N) and P biogeochemical cycles, plant growth, hydrology, and fire disturbance. The model is used to assess the effects of a prescribed fire on P dynamics and cattail growth through dynamic interaction among four modules: fire, water chemistry, soil, and vegetation. The simulation results are in agreement with observed data including cattail above- and belowground biomass and dead mass, P concentration in surface-water, pore-water, and soil, and soil and water temperature. Cattail aboveground biomass reached the unburned level one year after burn; belowground biomass recovered to unburned level one and half years after the fire, however, dead mass did not completely reach unburned level two years after fires. The fire increased water and soil temperatures in the short term, while indirectly increasing the sensitivity of water and soil temperature post-fire response to air temperature by altering the energy exchange between air and water through a canopy gap created by fire. The fire also altered the P dynamics in surface-water and pore-water. A post-fire P pulse that lasted for less than one month was observed in surface-water. A similar P pulse, but in a small magnitude and a longer duration, was also observed in the pore-water total phosphorus (TP), and then came back to normal level after approximately three months. No significant changes in soil TP was observed during the study period. Meanwhile, no significant changes in water nutrients were observed downstream of the study plot. This finding indicated that the P-enriched wetlands in Everglades act as a buffer in regulating the P concentration in surface-water. Our study showed that the distance of fire effects on a 300 m × 300 m plot was less than 300 m downstream. Sensitivity analysis identified that the air temperature and hydrological conditions are two important driving factors which may alter the cattail community dynamics in response to prescribed fires. Similar to the filed studies, this study provided evidences that fire played an important role in managing plant growth and P dynamics in the Florida Everglades.     

Modification of an ecosystem model for filling medium-sized gaps in tower-based estimates of net ecosystem productivity

Gap filling of flux data is necessary to assist with periodic interruptions in the measurement data stream. The gap-filling model (GFM), first described in Xing et al. [Xing, Z., Bourque, C.P.-A., Meng, F.-R., Zha, T.-S., Cox, R.M., Swift, E., 2007. A simple net ecosystem productivity model for gap filling of tower-based fluxes: an extension of Landsberg's equation with modifications to the light interception term. Ecol. Model. 206, 250–262], was modified to account for the day-to-day control of net ecosystem productivity (NEP) by incorporating air and soil temperature as new controlling variables in the calculation of NEP. To account for the multiple-phase influences of air and soil temperature on plant growth we model ecosystem respiration as a function of soil and canopy respiration. The paper presents model development in an incremental fashion in order to quantify the contribution of individual model enhancements to the prediction of NEP during periods when air and soil temperature variations are important.     

AQUATOX: Modeling environmental fate and ecological effects in aquatic ecosystems

AQUATOX combines aquatic ecosystem, chemical fate, and ecotoxicological constructs to obtain a truly integrative fate and effects model. It is a general, mechanistic ecological risk assessment model intended to be used to evaluate past, present, and future direct and indirect effects from various stressors including nutrients, organic wastes, sediments, toxic organic chemicals, flow, and temperature in aquatic ecosystems. The model has a very flexible structure and provides multiple analytical tools useful for evaluating ecological effects, including uncertainty analysis, nominal range sensitivity analysis, comparison of perturbed and control simulations, and graphing and tabulation of predicted concentrations, rates, and photosynthetic limitations. It can represent a full aquatic food web, including multiple genera and guilds of periphyton, phytoplankton, submersed aquatic vegetation, invertebrates, and fish and associated organic toxicants. It can model up to 20 organic chemicals simultaneously. (It does not model metals.) Modeled processes for organic toxicants include chemodynamics of neutral and ionized organic chemicals, bioaccumulation as a function of sorption and bioenergetics, biotransformation to daughter products, and sublethal and lethal toxicity. It has an extensive library of default biotic, chemical, and toxicological parameters and incorporates the ICE regression equations for estimating toxicity in numerous organisms. The model has been implemented for streams, small rivers, ponds, lakes, reservoirs, and estuaries. It is an integral part of the BASINS system with linkage to the watershed models HSPF and SWAT.     

Effects of Bridge Shading on Estuarine Marsh Benthic Invertebrate Community Structure and Function

The effect of bridge shading on estuarine marsh food webs was assessed by comparing benthic invertebrate communities beneath seven highway bridges with marshes outside of bridge-affected areas (reference marshes). We used light attenuation and height–width ratio (HW ratio), which takes into account the two main bridge characteristics that determine the degree of shading, to quantify the impact of shading on invertebrate communities. Low bridges, with HW ratio <0.7 and light attenuation greater than 85–90%, had benthic invertebrate densities and diversity that were significantly lower than reference marshes. Density of benthic invertebrates at low bridges was 25–52% (29,685–72,920 organisms/m²) of densities measured in adjacent reference marshes (119,329–173,351 organisms/m²). Likewise, there were fewer taxa under low bridges (5.8/11.35 cm² core) as compared to the reference marshes (9.0/11.35 cm² core). Density of numerically dominant taxa (e.g., oligochaetes and nematodes) as well as surface- and subsurface deposit feeders also were reduced under low bridges. Decreased invertebrate density, diversity, dominant taxa, and alterations of trophic feeding groups beneath low bridges was correlated with diminished above- and below-ground macrophyte biomass that presumably resulted in fewer food resources and available refuges from predators. With a greater knowledge of bridge shading effects, bridge construction and design may be improved to reduce the impacts on estuarine benthic invertebrate communities and overall ecosystem structure and function.     

Fuzzy Modeling of Interactions Among Environmental Stressors in the Ecosystem of Lake Koronia,Greece

The development of a model for assessing the impact and interactions of stressors in the ecosystem of Lake Koronia, based on fuzzy inference, is presented in this paper. The proposed fuzzy inference model assesses the synergistic interactions among several significant stressors on fish production. These stressors include industrial pollution, pesticide and nutrient usage due to agricultural activities, and water level decrease due to irrigation works. Apart from the experts knowledge, expressed in a set of fuzzy rules, a number of parameters such as pH, conductivity, biochemical and chemical oxygen demand, and nitrate concentration were used as stressor indicators. The proposed model is capable of simulating the effect of a large variety of environmental conditions, and it can be used as a dynamic tool for ecosystem risk assessment since it produces both qualitative and quantitative results, allowing for comparisons of predictions with on-going observational research and ecosystem monitoring. Its operation was successfully verified for a number of different conditions, ranging from low stressor impact to high stressor impact (where, in fact, the fish production was diminished). Moreover, the proposed fuzzy inference model can be used as a tool for the investigation of the behavior of the aquatic ecosystem under a large number of hypothetical environmental risk scenarios.     

Developing a spatial framework of common ecological regions for the conterminous United States

In 1996, nine federal agencies with mandates to inventory and manage the nation's land, water, and biological resources signed a memorandum of understanding entitled “Developing a Spatial Framework of Ecological Units of The United States.” This spatial framework is the basis for interagency coordination and collaboration in the development of ecosystem management strategies. One of the objectives in this memorandum is the development of a map of common ecological regions for the conterminous United States. The regions defined in the spatial framework will be areas within which biotic, abiotic, terrestrial, and aquatic capacities and potentials are similar. The agencies agreed to begin by exploring areas of agreement and disagreement in three federal natural-resource spatial frameworks—Major Land Resource Areas of the US Department of Agriculture (USDA) Natural Resources Conservation Service, National Hierarchy of Ecological Units of the USDA Forest Service, and Level III Ecoregions of the US Environmental Protection Agency. The explicit intention is that the framework will foster an ecological understanding of the landscape, rather than an understanding based on a single resource, single discipline, or single agency perspective. This paper describes the origin, capabilities, and limitations of three major federal agency frameworks and suggests why a common ecological framework is desirable. The scientific and programmatic benefits of common ecological regions are described, and a proposed process for development of the common framework is presented.     

Analytical conceptual plan to reforest central Himalaya for sustainable development

The Central Himalayan region is suffering from severe ecological problems as a consequence of deforestation and that threatens the subsistence population of the region. We analyze this problem and propose a plan for ecologically sustainable development for the region based on an analysis of the interrelationships of various ecosystems, particularly cropland and forest ecosystems, around which most human activities are concentrated. Each energy unit of agronomic yield leads to expenditure of about 12 energy units of forest/grazing land energy. Because with rapidly declining forest area, this form of agriculture is no longer sustainable and cannot be converted into a fossil fuel-based agriculture, we propose that agriculture in the mountain region has to be largely replaced with farm forests to revitalize the environment and to generate the basic needs of the subsistence economy of the hill population whose food grain needs can be met from the plains. We conclude by describing the advantages that are likely to accrue to the people for their long-term future. In terms of both energy and money, the value of resources collected from the forest to support agriculture in the present systems far exceeds the value of food grain that would be required to enable the proposed farm forest-based systems to function. At regional level, the proposed system would generate more energy than the existing systems, not only because the productivity of forest is about tenfold greater than that of cropland, but also because the proposed plan promotes recovery of various ecosystems.