A game theoretical model of deforestation in human-environment relationships

We studied a two-person game regarding deforestation in human-environment relationships. Each landowner manages a single land parcel where the state of land-use is forested, agricultural, or abandoned. The landowner has two strategies available: forest conservation and deforestation. The choice of deforestation provides a high return to the landowner, but it degrades the forest ecosystem services produced on a neighboring land parcel managed by a different landowner. Given spatial interactions between the two landowners, each landowner decides which strategy to choose by comparing the expected discounted utility of each strategy. Expected discounted utility is determined by taking into account the current and future utilities to be received, according to the state transition on the two land parcels. The state transition is described by a Markov chain that incorporates a landowner's choice about whether to deforest and the dynamics of agricultural abandonment and forest regeneration. By considering a stationary distribution of the Markov chain for land-use transitions, we derive explicit conditions for Nash equilibrium. We found that a slow regeneration of forests favors mutual cooperation (forest conservation). As the forest regenerates faster, mutual cooperation transforms to double Nash equilibria (mutual cooperation and mutual defection), and finally mutual defection (deforestation) leads to a unique Nash equilibrium. Two different types of social dilemma emerge in our deforestation game. The stag-hunt dilemma is most likely to occur under an unsustainable resource supply, where forest regenerates extremely slowly but agricultural abandonment happens quite rapidly. In contrast, the prisoner's dilemma is likely under a persistent or circulating supply of resources, where forest regenerates rapidly and agricultural abandonment occurs slowly or rapidly. These results show how humans and the environment mutually shape the dilemma structure in forest management, implying that solutions to dilemmas depend on environmental properties.     

乙烯对苹果果实细胞壁降解效应初探

以陕西主栽苹果品种'秦冠'为试材,研究了不同浓度乙烯利以及加热处理下苹果果实中与细胞壁代谢相关酶的活性变化及其与细胞壁组分降解的关系.结果表明:乙烯对各细胞壁酶活性的促进效应因乙烯利施用浓度不同而异.乙烯利浓度由10 mg/L增至1 000 mg/L时,果胶甲酯酶(PME)、多聚半乳糖醛酸酶(PG)和纤维素酶(CS)的活性先逐渐增强,而后又被抑制;木聚糖(Xyl)没有受到明显影响.加热处理可增进乙烯利的作用,如在60℃时,PME、PG、CS、Xyl活性分别是对照的1.5、2.7、1.1和1.5倍.PG活性的显著增加同时引起了果实可溶性糖含量的显著升高,但其他酶活性变化与可溶性糖含量无直接相关.     

水分胁迫对银水牛果生长及光合气体交换参数的影响

实验以盆栽3年生银水牛果幼苗为材料,设置正常供水(W1)和轻度(W2)、中度(W3)、重度(W4)土壤水分胁迫共4个处理进行人工模拟实验,以探讨银水牛果的抗旱特征.结果显示,(1)随着水分胁迫的加剧,W2～W4银水牛果植株生长量较W1分别显著降低58.85%、72.06%、87.31%,地径生长量较W1分别显著降低38.46%、61.92%、84.62%;(2)随着水分胁迫的加剧,Pn日变化曲线由"单峰型"转为"双峰型",且Pn、Gs、Tr逐渐降低,Ls值升高;(3)W3处理下Ci值最小,Ls值最大,而水分利用效率WUE最高;(4)随着水分胁迫的加剧,Gs与Pn的相关性迅速下降,W2～W4的相关系数较W1分别下降5.06%、8.47%、24.38%;W4处理下Ci与Pn呈负相关.研究表明,银水牛果在土壤含水量为7.2%～14.35%干旱条件下水分利用效率最高,证明银水牛果具有较强的抗旱性.     

Reverse Problem Formulation for Integrating Process Discharges with Watersheds and Drainage Systems

This work introduces a new approach to integrating the discharges of industrial processes with macroscopic watershed systems. The key concept is that environmental quality models (such as material flow analysis) can be inverted and included in an optimization formulation that seeks to determine the maximum allowable target for the process discharges while meeting the overall environmental requirements of the watershed. Because of its holistic nature, this approach simultaneously considers the effects of the inputs and outputs to the watershed (e.g., agricultural, residential, wastewater treatment plants, industrial, and so on) and the various physical, chemical, and biological phenomena occurring within the watershed. An optimization formulation is developed to systematically represent the reverse problem formulation. To illustrate the effectiveness of this approach, a case study is solved to manage phosphorus in Bahr El‐Baqar drainage system leading to Lake Manzala in Egypt. The key environmental and economic aspects are addressed and used to screen plant location and discharges.     

The Dematerialization Potential of the Australian Economy

In this article we test the long‐term dematerialization potential for Australia in terms of materials, energy, and water use as well as CO₂ emissions by introducing concrete targets for major sectors. Major improvements in the construction and housing, transport and mobility, and food and nutrition sectors in the Australian economy, if coupled with significant reductions in the resource export sectors, would substantially improve the current material, energy, and emission intensive pattern of Australia's production and consumption system. Using the Australian Stocks and Flows Framework we model all system interactions to understand the contributions of large‐scale changes in technology, infrastructure, and lifestyle to decoupling the economy from the environment. The modeling shows a considerable reduction in natural resource use, while energy and water use decrease to a much lesser extent because a reduction in natural resource consumption creates a trade‐off in energy use. It also shows that trade and economic growth may continue, but at a reduced rate compared with a business‐as‐usual scenario. The findings of our modeling are discussed in light of the large body of literature on dematerialization, eco‐efficiency, and rebound effects that may occur when efficiency is increased. We argue that Australia cannot rely on incremental efficiency gains but has to undergo a sustainability transition to achieve a low carbon future to keep in line with the international effort to avoid climate change and resource use conflicts. We touch upon the institutional changes that would be required to guide a sustainability transition in the Australian economy, such as an emission trading scheme.     

On the importance of body size in the colonisation of ephemeral resource patches by vagile consumers

A study on the colonisation of leaf detritus patches by vagile macroinvertebrates in a brackish lagoon is presented in the framework of a conceptual model where a body size-related constraint on patch use behaviour is explicitly considered. Abundance patterns of dominant macroinvertebrate taxa were characterised by short-term, non-random fluctuations, showing significant site-dependent variations. Yet, a site-independent covariation was observed between patterns’ fractal dimension and the average body mass of each taxon, indicating that, while the temporal scales characterising the colonisation patterns may be highly species-specific, cross-species generalisations are possible based on body size. The generality of these results was supported by literature data on temporal patterns of carcass colonisation by bathyal fish. The importance of size-related mechanisms in regulating the aggregation of vagile consumers on resource patches and, ultimately, their coexistence at both an inter- and intra-specific level, is discussed.     

Design of a biofilter packed with crab shell and operation of the biofilter fed with leaf mold solution as a nutrient

After measuring toluene adsorption (15.7 mg-toluene/g-material), water holding capacity (18.5%), organic content (53.8%), specific surface area (18.1 m²/g-material), and microbial attachment, crab shells were chosen as the main packing material for a biofilter design. The crab shells, cheap and abundant in the Gangneung area, also have relatively rigid structure, low density, and ability to neutralize acids generated during mineralization of toluene. Since towel scraps have water holding capacity as high as 301.2%, 10% of the total packing was supplemented with them to compensate for low water holding capacity of the crab shells. The biofilter fed with defined chemical medium under 0.8∼1.3 mg/L of inlet toluene concentration and 18 seconds of residence time showed satisfactory removal efficiency of over 97% and 72.8 g/h·m³ of removal capacity. For the purpose of deceasing operation costs, leaf mold solution was tried as an alternative nutrient instead of a defined chemical medium. The removal efficiency and removal capacity were 85% and 56.3 g/h·m³, respectively, using the same inlet toluene concentration and residence time. This research shows the possibility of recycling crab shell waste as packing material for biofilter. In addition, leaf mold was able to serve as an alternative nutrient, which remarkably decreased the operating cost of the biofilter.     

Regional water resource implications of bioethanol production in the Southeastern United States

The Energy Independence and Security Act (EISA) of 2007 mandates US production of 136 billion L of biofuel by 2022. This target implies an appropriation of regional primary production for dedicated feedstocks at scales that may dramatically affect water supply, exacerbate existing water quality challenges, and force undesirable environmental resource trade offs. Using a comparative life cycle approach, we assess energy balances and water resource implications for four dedicated ethanol feedstocks – corn, sugarcane, sweet sorghum, and southern pine – in two southeastern states, Florida and Georgia, which are a presumed epicenter for future biofuel production. Net energy benefit ratios for ethanol and coproducts range were 1.26 for corn, 1.94 for sweet sorghum, 2.51 for sugarcane, and 2.97 for southern pine. Corn also has high nitrogen (N) and water demand (11.2 kg GJ_net^?1 and 188 m³ GJ_net^?1, respectively) compared with other feedstocks, making it a poor choice for regional ethanol production. Southern pine, in contrast, has relatively low N demand (0.4 kg GJ_net^?1) and negligible irrigation needs. However, it has comparatively low gross productivity, which results in large land area per unit ethanol production (208 m² GJ_net^?1), and, by association, substantial indirect and incremental water use (51 m³ GJ_net^?1). Ultimately, all four feedstocks require substantial land (10.1, 3.1, 2.5, and 6.1 million ha for corn, sugarcane, sweet sorghum, and pine, respectively), annual N fertilization (3230, 574, 396, 109 million kg N) and annual total water (54 400, 20 840, 8840, and 14 970 million m³) resources when scaled up to meet EISA renewable fuel standards production goals. This production would, in turn, offset only 17.5% of regional gasoline consumption on a gross basis, and substantially less when evaluated on a net basis. Utilization of existing waste biomass sources may ameliorate these effects, but does not obviate the need for dedicated primary feedstock production. Careful scrutiny of environmental trade‐offs is necessary before embracing aggressive ethanol production mandates.     

Past century changes in Araucaria angustifolia (Bertol.) Kuntze water use efficiency and growth in forest and grassland ecosystems of southern Brazil: implications for forest expansion

Araucaria angustifolia (Bertol.) Kuntze is an indigenous conifer tree restricted to the southern region of South America that plays a key role in the dynamics of regional ecosystems where forest expansion over grasslands has been observed. Here, we evaluate the changes in intrinsic water use efficiency (iWUE) and basal area increment (BAI) of this species in response to atmospheric CO₂, temperature and precipitation over the last century. Our investigation is based on tree-rings taken from trees located in forest and grassland sites in southern Brazil. Differences in carbon isotopic composition ( δ ¹³C), ¹³CO₂ discrimination (Δ¹³C) and intracellular carbon concentration ( C _i ) are also reported. Our results indicate an age effect on Δ¹³C in forest trees during the first decades of growth. This age effect is not linked to an initial BAI suppression, suggesting the previous existence of nonforested vegetation in the forest sites. After maturity all trees show similar temporal trends in carbon isotope-derived variables and increasing iWUE, however, absolute values are significantly different between forest and grassland sites. The iWUE is higher in forest trees, indicating greater water competition or nutritional availability, relative to grassland, or both. BAI is also higher in forest trees, but it is not linked with iWUE or atmospheric CO₂. Nevertheless, in both forest and grassland sites A. angustifolia has had growth limitations corresponding to low precipitation and high temperatures observed in the 1940s.     

Pan-European regional-scale modelling of water and N efficiencies of rapeseed cultivation for biodiesel production

The energy produced from the investment in biofuel crops needs to account for the environmental impacts on soil, water, climate change and ecosystem services. A regionalized approach is needed to evaluate the environmental costs of large-scale biofuel production. We present a regional pan-European simulation of rapeseed ( Brassica napus ) cultivation. Rapeseed is the European Union's dominant biofuel crop with a share of about 80% of the feedstock. To improve the assessment of the environmental impact of this biodiesel production, we performed a pan-European simulation of rapeseed cultivation at a 10 × 10 km scale with Environmental Policy Integrated Climate (EPIC). The model runs with a daily time step and model input consists of spatialized meteorological measurements, and topographic, soil, land use, and farm management practices data and information. Default EPIC model parameters were calibrated based on literature. Modelled rapeseed yields were satisfactory compared with yields at regional level reported for 151 regions obtained for the period from 1995 to 2003 for 27 European Union member countries, along with consistent modelled and reported yield responses to precipitation, radiation and vapour pressure deficit at regional level. The model is currently set up so that plant nutrient stress is not occurring. Total fertilizer consumption at country level was compared with IFA/FAO data. This approach allows us to evaluate environmental pressures and efficiencies arising from and associated with rapeseed cultivation to further complete the environmental balance of biofuel production and consumption.