Dynamics of community structure and bio-thermodynamic health of soil organisms following subtropical forest succession.

Soil organisms play essential roles in maintaining multiple ecosystem processes, but our understanding of the dynamics of these communities during forest succession remains limited. In this study, the dynamics of soil organism communities were measured along a 3-step succession sequence of subtropical forests (i.e., a conifer forest, CF; a mixed conifer and broad-leaved forest, MF; and a monsoon evergreen broad-leaved forest, BF). The eco-exergy evaluation method was used as a complement to the classic community structure index system to reveal the holistic dynamics of the bio-thermodynamic health of soil organism communities in a forest succession series. Association between the self-organization of soil organisms, soil properties, and plant factors were explored through redundancy analyses (RDA). The results indicated that the biomass of soil microbes progressively increased in the dry season, from 0.75 g m-2 in CF to 1.75 g m-2 in BF. Microbial eco-exergy showed a similar pattern, while the community structure and the specific eco-exergy remained constant. Different trends for the seasons were observed for the soil fauna community, where the community biomass increased from 0.72 g m-2 to over 1.97 g m-2 in the dry season, but decreased from 3.94 g m-2 to 2.36 g m-2 in the wet season. Faunal eco-exergies followed a similar pattern. Consequently, the average annual biomass of the soil faunal community remained constant (2.17-2.39 g m-2) along the forest succession sequence, while the significant seasonal differences in both faunal biomass and eco-exergy observed at the early successional stage (CF) were insignificant in the middle and late forest successional stages (MF and BF). Both the dynamics of soil microbes and soil fauna were tightly correlated with tree biomass and with soil physicochemical properties, especially soil pH, moisture, total nitrogen, nitrate nitrogen, and organic matter content.

Canopy and understory nitrogen additions did not significantly change the community structure of soil fauna under a mature subtropical forest.

Increasing nitrogen (N) deposition has seriously harmed the structure and function of ecosystems throughout the world and this problem has been increasing. How N deposition affects soil faunal communities is poorly understood, compared to plant and microbial communities. Canopy and understory N additions of 25 and 50 kg ha-1 year-1 were employed to determine whether the effects of N addition on the soil fauna differ between N released to the canopy or to the understory. Specifically, we examined how the soil fauna survives when N additions produce desynchronized and complex impacts on the soil, microbes and litter quantity under mature subtropical forest ecosystems. Our results showed that no significant differences were observed between the soil faunal communities receiving canopy and understory N additions. This is consistent with our observation that the concentrations of ammonia nitrogen and nitrate nitrogen in the soil did not significantly differ under the two different methods of applying N. There were no observed effects on the litter quantity, soil microbial Phospholipid Fatty Acids or soil physical-chemical properties; therefore, it is not surprising that N treatments for 4 years did not significantly alter the community structure of soil fauna under the mature subtropical forest sites. However, the shifts in seasonal differences in the microbial communities under the N treatments had a positive effect on soil microbial development compared to control, which might also produce a time-delay influence on the relative development of the soil fauna under mature subtropical forest in the future. Further dynamic monitoring is needed to illustrate the possible effects and mechanisms by which increasing N deposition may alter soil faunal development in the future.

Emergy evaluation for decision-making in complex multifunctional farming systems.

In a montado farm, commonly found in the South Portugal, human activities benefit from important fluxes of renewable resources. In this study, traditional economic and emergy evaluations are compared to determine their potential contributions to understanding this complex system and applied to a case study of a farm. This allows us to determine how each method values local natural resources and purchased factors of production and services in an empirical context. Results show that the montado farm has a renewable component evaluated at 27% of the total social costs of the system and that the work of natural resources is undervalued in economic budget accounting. Economic evaluation's relative value of purchased factors and services is three and half times higher than their emergy share. We propose that complementing economic budget accounting with emergy accounting provides a benchmark to evaluate the environmental contribution to agricultural and farming systems. In this way, factors external to markets can be evaluated for farming systems, bringing to economic analysis a full evaluation of resources, including the bio-geophysical system's contributions to wealth, enlarging total economic value of resources with a donor perspective enabling a better informed and comprehensive accounting to attain sustainable economic decisions and public policies.

A Sustainability Analysis of Two Rapeseed Farming Ecosystems in Khorramabad, Iran Based on Emergy and Economic Analyses.

In the past two decades, rapeseed farming has garnered attention, because it offers the possibility of attaining self-sufficiency in the production of edible oil, which is a strategic product for Iran. Therefore, the overarching goal of this research was to provide sound strategies to further the development of rapeseed farming and to increase the sustainability and productivity of rapeseed production systems. Progress toward this goal was made by assessing subsistence and commercial rapeseed production systems in Khorramabad, Iran during the 2017-2018 crop year using both emergy and economic indices. The calculated values of the ESI*, %R, ELR, and ELR* indices showed the higher ecological sustainability of the subsistence farming system compared to the commercial system of rapeseed production. According to these indices, the main reason for the lower sustainability of the commercial rapeseed production system was the large amount of soil organic matter that was lost per unit input of nonrenewable resources used. A large emergy exchange ratio in favor of the buyer, the increased environmental sustainability when the market impact is considered, the lower emergy consumption per unit of output, and the higher productivity of the production factors all reflect the relative advantage of the commercial system based on the indices of EERY, EISD, UEV, and total factor productivity (TFP), respectively. Hence, our findings revealed that in the commercial rapeseed production system, the ecologic sustainability of the system can be improved drastically by employing scientific solutions for the comprehensive management of the production ecosystems, especially through the amelioration of soil organic matter and prevention of its loss. Besides improving the farmers' technical knowledge, the integration of small lots into the production system is recommended for improving the economic sustainability of the subsistence production system.

Comparison of the sustainability of bean production systems based on emergy and economic analyses.

To address increasing demand, bean producers have intensified agricultural activities by increasing application of industrial inputs. Such intensification can impose environmental risks to vulnerable ecosystems. Emergy and economic analyses were utilized in this study to investigate and compare the environmental performance of five management patterns specified by differing degrees of intensification, i.e., ecologic, integrated, low-, medium-, and high-input production systems at Bean Research Station in Khorram Dasht, Iran. The total emergy supporting these systems was estimated to be 6.52E + 15, 1.22E + 16, 6.62E + 15, 1.10E + 16, and 1.54E + 16 sej ha-1 for the ecologic, integrated, low-, medium-, and high-input systems, respectively. The purchased emergy inputs accounted for the largest portion of the total emergy inputs to these systems and ranged between 60.84 and 75.80%. The renewable fractions, transformities, emergy yield ratios, environmental loading ratios, emergy sustainability indices, and the economic output to input ratios demonstrate that the ecologic and low-input systems performed well compared to the three more industrial systems when considering their environmental sustainability. However, the more industrial systems had comparatively higher economic output. Generally, the results illustrate that sustainable bean production will depend on the transition from fossil fuel-intensive systems to more natural resource-intensive ones. To achieve more sustainable systems, applying conservation tillage and replacing chemical fertilizer with organic fertilizer are advocated for use in bean production systems. Joint use of emergy and economic evaluation provided different but complementary standpoints for comparison of the five bean production systems examined, and can assist in solving the problems that may occur in decision-making.

Emergy-based indicators for evaluating ecosystem health: A case study of three benthic ecosystem networks influenced by coastal upwelling in northern Chile (SE Pacific coast).

It has been hypothesized that ecosystem health describes the state in which all processes operating within an ecosystem are functioning at a level of optimum efficiency to maximize system empower. In this study, systems analysis of networks and information flows is used within this definition of ecosystem health to assess the condition of the benthic ecosystems in three coastal bays in northern Chile. These highly productive ecosystems are characterized by the inflow of cold, nutrient-rich waters of low oxygen concentration derived from coastal upwelling of deep waters and the interruption of upwelling flow during El Niño events when warmer waters with higher oxygen and lower nutrient concentrations enter these coastal systems. Also, these ecosystems support important artisanal benthic fisheries and are affected by industrial activities in the coastal zone. Energy Systems Theory (EST) and Emergy Analysis (EA) were applied to quantify the health of these benthic ecosystems and evaluate differences in their structure, organization and functional capacities, which are related to their emergy signatures. The marked dominance of these benthic ecosystems by nitrate from upwelling resulted in unbalanced emergy signatures, suggesting less development and system diversity compared to other coastal ecosystems with more balanced emergy signatures. Macro-descriptors and network properties, such as emergy-based ascendency and the quality-adjusted Shannon diversity index were highest for Mejillones Bay, followed by Antofagasta and then Tongoy Bay. The Average Mutual Information (AMI) index adjusted for energy quality and the emergy-based A/C (ascendency to capacity) ratio, were higher for Tongoy Bay, suggesting functional differences in health among the three ecosystems. Thus, the emergy-based macro descriptors and other indicators used in our analysis indicate that the benthic networks examined have different structural and functional characteristics that lead to different characterizations of their states of health. As a result of this complexity, management policies should be implemented within a systemic context for analysis that considers all the factors determining the relative health of each ecosystem.

An R Package for Open, Reproducible Analysis of Urban Water Systems, With Application to Chicago.

Urban water systems consist of natural and engineered flows of water interacting in complex ways. System complexity can be understood via mass conservative models that account for the interrelationships among all major flows and storages. We have developed a generic urban water system model in the R package CityWaterBalance. CityWaterBalance provides a reproducible workflow for studying urban water systems by facilitating automated retrievals of open data and post-processing with open source R functions. It allows the user to 1) rapidly assemble a quantitative, comprehensive assessment of flows thorough an urban area, and 2) easily change the spatial and temporal boundaries of analysis. We use CityWaterBalance to evaluate the water system in the Chicago metropolitan area on a monthly basis for water years 2001-2010. Results are used to consider 1) impacts of management decisions aimed at reducing stormwater and combined sewer overflows and 2) the significance of future changes in precipitation.

Bamboo vs. crops: an integrated emergy and economic evaluation of using bamboo to replace crops in south Sichuan Province, China.

Based on long-term monitoring conducted in Chang-ning county, a pilot site of the 'Grain for Green Program' (GFGP), an integrated emergy and economic method was applied to evaluate the dynamic ecological-economic performance of 3 kinds of bamboo systems planted on sloping farmland. The results confirmed the positive effects of all 3 kinds of bamboo systems on water conservation and soil erosion control. The benefits gained progressively increased during the first 8 years after conversion, going from 4639 to 16127 EMyuan/ha/yr on average. All three bamboo plantations were much more sustainable than common agricultural crops planted on sloping land (CP) on both the short and long-term scales with their Emergy Sustainability Index (ESI) and Emergy Index for Sustainable Development (EISD), respectively, being 14.07-325.71 and 80.35-265.80 times that of CP. However, all 3 bamboo plantations had a Net Economic Benefit (NEB) less than that of CP during the first 8 years after conversion. Even with the government-mandated ecological compensation applied, the annual NEBECs of the Bambusa rigida (BR) and Phyllostachys pubescense (PP) plantations were, respectively, 3922.03 and 7422.77 yuan/ha/yr lower than the NEB of CP. Emergy-based evaluation of ecosystem services provides an objective reference for applying ecological compensation in strategy-making, but it cannot wholly solve the economic viability problem faced by all bamboo plantations. Inter-planting annual herbs or edible fungus, such as Dictyophora echinovolvata, within bamboo forests, especially in young bamboo plantations, might be a direction for optimizing bamboo cultivation that would improve its economic viability.

Integrated emergy and economic evaluation of lotus-root production systems on reclaimed wetlands surrounding the Pearl River Estuary, China.

Lotus (Newnbo nucifera, Gaertn) is the most important aquatic vegetable in China, with a cultivation history of over 3000 years. The emergy, energy, material, and money flows of three lotus root cultivation modes in Wanqingsha, Nansha District, Guangzhou, China were examined using Energy Systems Language models and emergy evaluation to better understand their ecological and economic characteristics on multiple spatial and temporal scales. The natural resource foundations, economic characteristics and sustainability of these modes were evaluated and compared. The results showed that although all three modes were highly dependent on purchased emergy inputs, their potential impacts as measured by the local (ELRL) and global (ELRW) environmental loading ratios were less than 1.2 and 0.7, respectively. The lotus-fish mode was the most sustainable with its emergy index of sustainable development (EISD) 2.09 and 2.13 times that of the pure lotus and lotus-shrimp modes, respectively. All three lotus-root production modes had superior economic viability, since their Output/Input ratio ranged from 2.56 to 4.95. The results indicated that agricultural systems may have different environmental impacts and sustainability characteristics at different spatial and temporal scales, and that these impacts and characteristics can be simultaneously explored using integrated emergy and economic evaluations.

Dynamics of ecosystem services provided by subtropical forests in Southeast China during succession as measured by donor and receiver value.

The trends in the provision of ecosystem services during restoration and succession of subtropical forests and plantations were quantified, in terms of both receiver and donor values, based on a case study of a 3-step secondary succession series that included a 400-year-old subtropical forest and a 23-year history of growth on 3 subtropical forest plantations in Southeastern China. The 'People's Republic of China Forestry Standard: Forest Ecosystem Service Valuation Norms' was revised and applied to quantify the receiver values of ecosystem services, which were then compared with emergy-based, donor values of the services. The results revealed that the efficiencies of subtropical forests and plantations in providing ecosystem services were 2 orders of magnitude higher than similar services provided by the current China economic system, and these efficiencies kept increasing over the course of succession. As a result, we conclude that afforestation is an efficient way to accelerate both the ability and efficiency of subtropical forests to provide ecosystem services. The ability of different ecosystems to provide services depends on the concentration of available natural resources in the system at a large scale, but also on the ability of the ecosystems to capture natural resources in the same or similar environments.

Eco-exergy and emergy based self-organization of three forest plantations in lower subtropical China.

The bio-thermodynamic structures of a mixed native species plantation, a conifer plantation and an Acacia mangium plantation in Southern China were quantified over a period of 15 years based on eco-exergy methods. The efficiencies of structural development and maintenance were quantified through an integrated application of eco-exergy and emergy methods. The results showed that the storage of eco-exergy increased over 3 times in all three plantations, as predicted by the maximum eco-exergy principle. This trend was primarily seen due to the accumulation of biomass, instead of an increase in the specific eco-exergy (eco-exergy per unit biomass), although species richness did increase. The eco-exergy to emergy and eco-exergy to empower ratios of the three plantations generally increased during the study period, but the rate of increase slowed down after 20 years. The dominant trees are the largest contributors to the eco-exergy stored in the plantations, and thus, the introduction of suitable indigenous tree species should be considered after the existing trees pass through their period of most rapid growth or around 20 years after planting. The combined application of C-values and suggested weighting factors in the eco-exergy calculation can imply opposite results, but may also supply useful information for forest management.

Relationships between watershed emergy flow and coastal New England salt marsh structure, function, and condition.

This study evaluated the link between watershed activities and salt marsh structure, function, and condition using spatial emergy flow density (areal empower density) in the watershed and field data from 10 tidal salt marshes in Narragansett Bay, RI, USA. The field-collected data were obtained during several years of vegetation, invertebrate, soil, and water quality sampling. The use of emergy as an accounting mechanism allowed disparate factors (e.g., the amount of building construction and the consumption of electricity) to be combined into a single landscape index while retaining a uniform quantitative definition of the intensity of landscape development. It expanded upon typical land use percentage studies by weighting each category for the intensity of development. At the RI salt marsh sites, an impact index (watershed emergy flow normalized for marsh area) showed significant correlations with mudflat infauna species richness, mussel density, plant species richness, the extent and density of dominant plant species, and denitrification potential within the high salt marsh. Over the 4-year period examined, a loading index (watershed emergy flow normalized for watershed area) showed significant correlations with nitrite and nitrate concentrations, as well as with the nitrogen to phosphorus ratios in stream discharge into the marshes. Both the emergy impact and loading indices were significantly correlated with a salt marsh condition index derived from intensive field-based assessments. Comparison of the emergy indices to calculated nitrogen loading estimates for each watershed also produced significant positive correlations. These results suggest that watershed emergy flow is a robust index of human disturbance and a potential tool for rapid assessment of coastal wetland condition.

Diagnosis of potential stressors adversely affecting benthic communities in New Bedford Harbor, MA (USA).

Diagnosing the causes of impaired ecosystems in the marine environment is critical for effective management action. When ecological impairment is based on toxicological or biological criteria (i.e., degraded benthic community composition or toxicity test results), managers are faced with the additional problem of diagnosing the cause of impairment before plans can be initiated to reduce the pollutant loading. We evaluated a number of diagnostic tools to determine their ability to identify pollutants in New Bedford Harbor (NBH), Massachusetts (USA), using a modified version of the US Environmental Protection Agency's (USEPA) stressor identification (SI) guidance. In this study, we linked chemical sources and toxic chemicals in the sediment with spatial concentration studies; we also linked toxic chemicals in the sediment with toxicity test results using toxicity identification and evaluation (TIE) studies. We used geographical information systems (GIS) maps to determine sources and to aid in determining spatially integrated inorganic nitrogen (SIIN). The SIIN values of reference and test estuaries were quantified and compared. Using this approach, we determined that toxic chemicals continue to be active stressors in NBH and that a moderate nutrient stress exists, but we were unable to link the nutrient stressor with a source. Also excess sedimentation was evaluated, but it does not appear to be an active stressor in this harbor. The research included an evaluation of the effectiveness of tools under development that may be used to evaluate stressors in water bodies. We found that the following tools were useful in diagnosing active stressors: toxicity tests, toxicity identification and evaluation (TIE) methods, comparison of grain size-normalized total organic carbon (TOC) ratios with reference sites, and comparison of SIIN with reference sites. This approach allowed us to successfully evaluate stressors in NBH retrospectively; however, a limitation in using retrospective data sets is that the approach may underestimate current or newly emerging stressors.

An energy systems view of sustainability: emergy evaluation of the San Luis Basin, Colorado.

Energy Systems Theory (EST) provides a framework for understanding and interpreting sustainability. EST implies that "what is sustainable" for a system at any given level of organization is determined by the cycles of change originating in the next larger system and within the system of concern. The pulsing paradigm explains the ubiquitous cycles of change that apparently govern ecosystems, rather than succession to a steady state that is then sustainable. Therefore, to make robust decisions among environmental policies and alternatives, decision-makers need to know where their system resides in the cycles of change that govern it. This theory was examined by performing an emergy evaluation of the sustainability of a regional system, the San Luis Basin (SLB), CO. By 1980, the SLB contained a climax stage agricultural system with well-developed crop and livestock production along with food and animal waste processing. The SLB is also a hinterland in that it exports raw materials and primary products (exploitation stage) to more developed areas. Emergy indices calculated for the SLB from 1995 to 2005 revealed changes in the relative sustainability of the system over this time. The sustainability of the region as indicated by the renewable emergy used as a percent of total use declined 4%, whereas, the renewable carrying capacity declined 6% over this time. The Emergy Sustainability Index (ESI) showed the largest decline (27%) in the sustainability of the region. The total emergy used by the SLB, a measure of system well-being, was fairly stable (CV = 0.05). In 1997, using renewable emergy alone, the SLB could support 50.7% of its population at the current standard of living, while under similar conditions the U.S. could support only 4.8% of its population. In contrast to other indices of sustainability, a new index, the Emergy Sustainable Use Index (ESUI), which considers the benefits gained by the larger system compared to the potential for local environmental damage, increased 34% over the period.

Can sediment total organic carbon and grain size be used to diagnose organic enrichment in estuaries?

Eutrophication (i.e., nutrient enrichment, organic enrichment, and oxygen depletion) is one of the most common sources of impairment in Clean Water Act 303(d)-listed waters in the United States. Although eutrophication can eventually cause adverse effects to the benthos, it may be difficult to diagnose. Sediment organic carbon (OC) content has been used as an indicator of enrichment in sediments, but the amount of surface area available for carbon adsorption must be considered. We investigated the utility of the relationship between OC and sediment grain size as an indicator of eutrophication. Data from the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program was used to test this relationship. However, anthropogenic contaminants are also capable of causing adverse effects to the benthos and often co-occur with elevated levels of OC. Contaminant analysis and toxicity tests were not consistently related to enrichment status as defined by relationship between total OC and grain size. Although variability in response occurred, reflecting the variance in the water column factors (dissolved oxygen, chlorophyll a, and nutrients) and limited sample sizes, the data supported the hypothesis that sites designated as enriched were eutrophied. Dissolved oxygen levels were reduced at enriched sites, whereas chlorophyll a and nutrients were higher at enriched sites. This suggests that the relationship of OC to grain size can be used as a screening tool to diagnose eutrophication.

Integrated emergy, energy and economic evaluation of rice and vegetable production systems in alluvial paddy fields: implications for agricultural policy in China.

China is the largest rice producing and consuming country in the world, but rice production has given way to the production of vegetables during the past twenty years. The government has been trying to stop this land-use conversion and increase the area in rice-vegetable rotation. Important questions that must be answered to determine what strategy is best for society are, "What is the reason behind this conversion?"; "Which system is more productive and which is more sustainable?"; and "How can economic policy be used to adjust the pattern of farmland use to attain sustainable development?" To answer these questions, a combined evaluation of these agricultural production systems was done using emergy, energy and economic methods. An economic analysis clearly showed that the reason for this conversion was simply that the economic output/input ratio and the benefit density of the vegetable production system were greater than that of rice. However, both energy and emergy evaluations showed that long-term rice was the best choice for sustainable development, followed by rotation systems. The current price of rice is lower than the em-value of rice produced from the long-term rice system, but higher than that of rice produced from the rotation system. Scenario analysis showed that if the government increases the price of rice to the em-value of rice produced from the long-term rice system, US$0.4/kg, and takes the value of soil organic matter into account, the economic output/input ratios of both the rice and rotation systems will be higher than that of the vegetable system. The three methods, energy, emergy and economics, are different but complementary, each revealing a different aspect of the same system. Their combined use shows not only the reasons behind a system's current state or condition, but also the way to adjust these systems to move toward more sustainable states.

Ecological and economic dynamics of the Shunde agricultural system under China's small city development strategy.

The agricultural and industrial development of small cities is the primary environmental management strategy employed to make full use of extra labor in the rural areas of China. The ecological and economic consequences of this development strategy will affect over 100 million people and change the organization of the Chinese landscape. In this study, we examined the agricultural development of Shunde, a small city in Guangdong Province, over the period 1978 until 2000. Our analysis of the ecological and economic dynamics of the agricultural system revealed the dominant role of labor in the intensification of agricultural production, even though the use of fuels, fertilizers and machines also increased during this time. The Shunde agricultural system was examined from both biophysical or donor-based and human utility or receiver-based perspectives, using emergy and economic methods, respectively. After 22 years of urbanization, the Shunde agricultural system was still able to fill 96% of the local demand for agricultural products using only 6% of its total yield compared to using 14% of the total yield in 1978. Aquaculture developed quickly during the study period as grain production decreased. In 2000, the production of fish, pork, and vegetables accounted for 92% of the total emergy output of the system; however, the emergy buying power of the money received in exchange was lower than the emergy contained in the products exported. The excess emergy exported is the basis for a high quality diet delivered to city dwellers at a relatively low price. In the 1980s, the productivity of both land and labor increased; but after 1992 the productivity of labor decreased, causing the efficiency of the whole agricultural system to decrease. We recommend that processing plants be established for the main agricultural products of Shunde to decrease the emergy loss in trading and to increase employment. The effect of including monetized ecosystem services in the balance between the emergy delivered to the markets in agricultural products and the emergy buying power of the money received was to decrease the emergy gained by the Shunde agricultural system.