Carbon dioxide emission from tourism, as a focus of man-land relationship in tourism industry in the 21st century, is a vital index reflecting its effect on environment change. The article summarizes the contents of carbon dioxide emissions from tourism at different scales such as world, nation, region and unit. These results indicate that: (1) the accounting of the carbon dioxide emissions from tourism began from global and national scales at the end of the last century, then to regional and basic scales. (2) The Carbon dioxide emissions from tourism are mainly from high-developed countries and regions in terms of space, from the minority high-spending tourists in terms of behavior, from high-speed vehicles, high-grade accommodations and high-level tourism activities in terms of tourism element. The carbon dioxide emissions per capita of developing countries and regions are less than one tenth in developed countries and regions. As for the proportion of total emission, tourism transportation accounts for the largest, generally more than 65%, followed by accommodation, and the last is tourism activity. (3) Based on the systemic analysis of these coefficients of accounting carbon dioxide emissions in tourism, the paper indicates that there are progresses in the consistency of coefficients at global scale and diversity of coefficients at national, regional and unit scales, while the coefficients of developed countries and regions are higher than those of developing countries and regions. In addition, some recommendations including coefficients have given to China.
This paper reviews the development history of ecological risk assessment (EcoRA) and presents a perspective for EcoRA and management. EcoRA, which is aimed at appraising a wide range of undesirable impacts on ecosystems exposed to a possible eco-environmental hazard, has been highly recommended for environmental decision-making. The research progress are reviewed, including research area, content and method are reviewed. Based on this inspection, an integrated framework characterizing problem formulation, risk characterization and risk assessment is depicted to illumine future EcoRA. We conclude that larger-scale assessment studies are still lacking, and assessment theories and methods are being developed. In addition, regional EcoRA needs to make further efforts, especially in theoretical study, uncertainty analysis, integrated use of GIS software and comprehensive risk assessment at regional scale in the future work.
Mulch thickness is one of the important factors affecting soil moisture and temperature. Two field experiments were conducted at Gaolan, Gansu, China, to investigate the influence of gravel-sand mixture mulch thickness on soil temperature, evaporation, evapotranspiration, water use efficiency (WUE) and yield. There were 5 levels of gravel-sand mulch thickness in Experiment 1 (3, 5, 7, 9 and 11 cm; without crop) and 4 levels of gravel-sand mulch thickness plus 80% plastic film mulch in Experiment 2 (3, 5, 8 and 11 cm; cropped to watermelon). There was a close negative relationship between mulch thickness and soil evaporation, with exponential function. Mulch decreased soil evaporation up to a thickness of 7 cm. The soil temperature from 11:00 to 18:00 was slightly lower with mulching compared to no mulching and, as a result, mulch not only decreased the temperature difference between day and night, but also it had a lag. In addition, the peak soil temperature at 5 cm depth was reduced and the soil temperature at night was raised with increased mulch thickness. Mulch had no further effect on soil temperature when thickness is greater than 7 cm. With 80% plastic film mulch, a significant effect on watermelon yield and WUE was detected among the different treatments used in this study, with the highest yield and WUE obtained with the 8 cm mulch thickness treatment. Therefore, 7–8 cm of mulch thickness appears to be the most appropriate option for gravel-sand mulch to sustain high watermelon yield and WUE.
Perfluorooctane sulfonate (PFOS) is a ubiquitous environmental contaminant that has been found to pose various risks to fish health and the safety of aquatic ecosystem. Swimming performance is an integrated index of fitness in fish. However, little research has sought on the effects of PFOS on swimming performances of fish. Experiments were carried out to clarify the impacts of acute exposure to PFOS on behavior, swimming ability and metabolic rate in topmouth gudgeon ( ), to understand the underlying ecotoxicological effects of waterborne PFOS exposure on fish physiology and behavior. Fish were exposed to PFOS (0, 0.5, 2, 8 or 32 mg/L) for 96 h. Afterwards, the routine metabolic rate (RMR), spontaneous swimming behavior (SSB), fast-start swimming performance (FSP) and critical swimming speed ( ) of the topmouth gudgeon were examined. The results show reduced behavioral performance and increased physiological stress with increasing PFOS concentration. Both RMR, SSB and were significantly affected by PFOS exposure ( 0.05). The results indicate that the anaerobic swimming capacity was conserved, but the metabolic level, SSB and aerobic swimming performance in topmouth gudgeon were susceptible to PFOS contamination, and hence might be useful as considerable potential biomarkers of pollution.
Grassland ecosystems are important parts of terrestrial ecosystems and play an important role in the global carbon cycle. In recent years, the grasslands in Northern Tibet have experienced warming, and its precipitation has also increased. Alpine grassland irrigation measures could be a reasonable pathway to redistribute and make full use of the increased precipitation. In this study, we measured the soil respiration in alpine grassland in Northern Tibet under sprinkler head irrigation in the growing season to determine the relationships between soil temperature /water and ecosystem/soil respiration, soil moisture and Q , and soil temperature and Q . The results showed that after 2 years irrigation, alpine grassland aboveground biomass increased significantly, with 2010 higher than 2009. There was significant annual, seasonal and daily variation of soil respiration. Under irrigation, ecosystem respiration and soil respiration increased 75% and 64% respectively; soil water increase can promote the respiration of ecosystem and its components. In our results, the Q value was 2.23–2.81, over the global average. The irrigation can promote ecosystem respiration temperature sensitivity. There was a positive linear correlation between ecosystem respiration and grassland aboveground biomass. The aboveground biomass accounted for 32.8% of ecosystem respiration variation. Soil respiration accounted for more than 70% of ecosystem respiration, indicating that the contribution to carbon emissions of soil respiration is very high. In short, we can project that in grasslands biomass and ecosystem respiration will increase under future precipitation change, which will significantly affect the function of alpine grassland carbon storage.
Structure stability analysis is a vital prerequisite for the construction of eco-industrial chain. This study proposed four steps for applying an integrated structure stability index, which was derived to characterize both the diversity and equilibrium of eco-industrial chain, to structure stability analysis, and searching a final eco-industrial chain with the highest structure stability as follows: (1) analyzing links and link points of existing and planned industries through material and energy flow analysis; (2) identifying supplementary industries, which are integrated with pillar industries to enhance structure stability, through forward diffusion effect, backward diffusion effect and sideward diffusion effect analysis of pillar industries; (3) testing industrial structure stability by introducing an integrated structure stability index; (4) coupling of all definitized links and link points. These four steps were applied to a case study of Lianyungang Xuwei New Area, China. The results showed that: (1) there were 9 link points and 17 links of the planned five pillar industries in this area; (2) cement, building materials, chemical fertilizer, fine chemicals and marine chemicals with newly added 23 link points and 44 links should be considered as the supplementary industries; (3) the improvement in structure stability was confirmed by the integrated structure stability index increasing from 0.116 to 0.158 after adding supplementary industries; and (4) the final “steel–petrochemical-equipment manufacturing-logistics-IGCC polygeneration” eco-industrial chain was constructed by coupling 32 link points and 61 links. Therefore, by taking pillar industries as the kernel and by introducing an integrated structure stability index for the verification of stability improvement in industrial structure, these proposed four steps were proved to be an effective process and feasible method for enhancing the stability of eco-industrial system structure.
Because of the absence of natural records with high resolution, the study of environmental changes in arid and semi-arid desert regions, an important component of the global system, lags behind studies in other regions. In this paper, we summarize the literature on the evolution, forms, and profile features of nebkhas (coppice dunes), and discuss the environmental implications of their formation and development. Based on this review, we argue that future research should focus on the quantitative conversion of environmental proxies revealed by nebkha evolution into the corresponding environmental factors: quantitative definition of the stages of nebkha evolution, enhancing the precision of age-dating, strengthening of cross-disciplinary research, and the comparison of nebkha results with other natural records to provide stronger, more reliable conclusions.
Lipid biomarkers of microorganism and vegetation preserved in penguin droppings record historical changes in the West Antarctic climate and environment. -Alkanes, fatty acids and coprostanols have been determined in sediment core AD6 from penguin droppings in Ardley Island, West Antarctica, using GC or GC/MS/SIM. For -alkanes, the main carbon number was C with single-peak pattern, ΣC /ΣC value was from 0.27 to 0.61, the carbon preference index (CPI) was from 2.97 to 6.12 with significant odd–even predominance (OEP), and these indicate that the vegetation was dominated by mosses and lichens. For fatty acids, the main carbon numbers were C and C with double-peak pattern, ΣC /ΣC value was from 0.35 to 0.77, and the relative abundance ratio of even:odd carbon (CPI ) was from 2.88 to 6.40 with significant OEP. Bacteria invasion index (( C + C )/ C for fatty acids) showed high contribution of bacteria during 1977–1982, 1948–1953 and 1920–1925, indicating enhanced microbial activities. Meanwhile, CPI values decreased and extreme microbes contributed fatty acids with low carbon number to penguin dropping strata. Furthermore, the concentration of cholestanol and ratio of cholestanol/cholesterol in penguin dropping strata changed correspondingly, indicating that the microbial degradation played a major role in the increasing ratio of cholestanol/cholesterol during the sedimentation process. The down-core profiles of -alkanes, fatty acids and coprostanols in penguin dropping strata indicate that extreme microorganism and bacteria play important roles in the relatively simple Antarctic ecological system associated with climate conditions.
The litterbags with different mesh sizes (0.125, 1.000 and 3.000 mm) were placed on the forest floor in October 2010, and collected after each of the three stages in the freeze-thaw season (OF: the onset of freezing stage; DF: the deeply frozen stage; and TS: the thawing stage). Over the whole freeze-thaw period, 14.01% ± 1.26, 20.64% ± 1.61 and 30.89% ± 0.70 of N released from fir litter in the litterbags with 0.125, 1.000 and 3.000 mm, respectively. The contributions of meso- and macro-fauna to N releases were 21.45% ± 3.80 and 33.18% ± 5.39, respectively. Macro-fauna contributed more to N releases than meso-fauna regardless of decomposition stages in the freeze-thaw period. Compared with other stages in the freeze-thaw period, higher contributions of both macro- and meso-fauna were observed at DF stage, and the lower contributions at TS stage. The results suggested that soil fauna have a great contribution to N releases during litter decomposition in the freeze-thaw period, but the contribution was significantly affected by temperature dynamics and the body size of soil fauna.
Water blooms in eutrophic waters have been serious environmental problems in recent years. To explore effective measures to control this issue has been an interest of research. Our current study was designed to investigate the effects of submerged macrophyte All. exudates on the growth of four freshwater phytoplankton species, toxic , toxic and as well as natural phytoplankton assemblages of pond water. We also conducted a reciprocal response between and toxic using coexistence experiments. Our results showed that: (1) exudates significantly inhibited the growth of toxic , toxic and , with being the most sensitive, followed by toxic , and the least. exudates did not show inhibitory effect on ; (2) and toxic have reciprocal inhibitory effect, and the allelopathic interactions between the two different organisms are density dependent and affect their mutual growth; (3) exudates also can induce a decrease in chlorophyll a content and an inhibition in total dehydrogenase activity of the phytoplankton assemblages. Our present studies indicated the submerged macrophyte might be a potential useful tool to control phytoplankton blooms.
Shortage of food resources has significant effects on many physiological parameters of animals. The aim of the present study was to examine the relationship between the energetics countermeasures in response to food restriction and the levels of metabolism in . Survival rate, body mass, basal metabolic rate (BMR), nonshivering thermogenesis (NST), body fat mass, serum leptin levels and other physiological parameters were measured. Animals were divided into high-BMR (hBMR) and low-BMR (lBMR) group. The two groups were restricted to 70% of food intake for 4 weeks. The data showed that food intake increased by 24.5% in hBMR group than that in lBMR group before the experiment. Body mass, body fat mass, BMR and NST with hBMR or lBMR group significantly decreased after food restricting. Eighty percent of survived with hBMR group, but 60% of survived with lBMR group. Serum leptin levels were positively correlated with body mass, BMR and NST. The results suggested that could apply physiological adjustments to adapt the period of food shortage by reducing energy metabolism, providing the support for the “metabolism switch hypothesis”. with hBMR had decreased energy expenditure to maintain the normal physiological function. However, lBMR group could not decrease energy expenditure to meet the stress of available energy resource, which led to body mass decreased and mortality rate increased. Serum leptin levels may be involved in the regulation of energy balance and body mass in during the food restriction.
Soil acidification is defined as the process in which exchangeable cations are leaching and soil H concentration is raising thereby increases soil acidity. Changes in soil pH value and acid neutralizing capacity are mainly indicators of soil acidification. Soil acidification is considered to be a serious ecological and environmental issue, which not only reduces soil quality, but also decreases biodiversity of forest ecosystem and induces forest decline. With nitrogen (N) deposition rapidly increasing, its contribution to soil acidification becomes a major concern in the world. However, the impact of increased N deposition on soil acidification is not well addressed highlighting the need for further attention to the issue. In this paper, the studies on forest soil acidification induced by N deposition were reviewed. The factors related to soil acidification driven by N deposition were classified and discussed, which included soil acidic buffering capacity, N components in atmospheric N deposition, climate, plant species in forests, and N status in ecosystem. Iron (Fe) buffering phase and the consequent Fe toxicity occurring to the acidified soil caused by high N deposition were concerned. The scarcity of phosphorus (P) element induced by soil acidification was particularly emphasized. The research methods used to study soil acidification driven by N deposition were also evaluated. In the end we stressed the importance of the study on soil acidification especially in tropical and subtropical regions driven by N deposition and its mechanisms. This paper can serve for maintaining sustainable forest and agricultural ecosystems.
The effects of nitrogen, phosphorus, iron and silicon on growth of five species of marine benthic diatoms, namely and were studied by single factor experiments and the optimal concentration ratios of the four nutrient elements beneficial for diatoms growth were screened out separately using the L (3 ) orthogonal design. The results highlighted that nitrogen, phosphorus, iron and silicon all had highly significant effects on growth of five diatoms while the diatoms growth rates reached the highest averagely in the 2nd to the 6th culture day. In addition, the optimal concentrations (mg/L) of four nutrients suitable for diatoms growth were found higher than that in f/2 medium except that had the same concentration of nitrogen as that in f/2 medium which is optimal for growth. Moreover, the optimal growth concentrations of four elements for five diatoms varied in the range of 12.36–74.16 mg/L for nitrogen, 1.70–3.98 mg/L for phosphorus, 2.00–4.00 mg/L for iron, 23.01–69.03 mg/L for silicon, respectively. By means of the orthogonal test of four nutrients for five benthic diatoms, the optimal concentration ratios N:P:Fe:Si (mg/L) were obtained as follows: 74.16:2.27:3.33:23.01 for ; 37.08:3.98:4.00:11.50 for ; 49.44:3.98:3.33:34.51 for ; 12.36:1.70:4.00:11.50 for ; 74.16:2.27:4.00:69.03 for .
Ecologists have long ignored or underestimated the importance of plant–herbivore interactions owing to the diversities of herbivores, plant defensive strategies and ecological systems. In this review, we briefly discussed the categories of herbivores. Then we reviewed the major types of plant defenses against herbivores. Selective forces of herbivore pressures have led to the evolution of various defensive mechanisms in plants, which can be classified into (i) resistance traits that reduce the amount of damage received, including physical, chemical, and biotic traits; (ii) tolerance mechanisms that decrease the impact of herbivore damage, and (iii) escape strategies that reduce the probability of plants to be found by herbivores. These strategies have been studied at different levels from molecular genetics and genomics, to chemistry and physiology, to community and ecosystem ecology. We summarized the development of the methodology for studying plant defenses against herbivores. Particularly, 24 of those hypotheses and models, which are influential in the international community concerning the relationship between plants and herbivores, including the defensive mimicry hypothesis, the compensatory continuum hypothesis, the slow-growth-high-mortality hypothesis, etc, were introduced and grouped into four categories according to plant defense strategies in the present review. Finally, we also reviewed the research progress of plant–herbivore interactions in China, and discussed the perspectives of studies on plant–herbivore interactions.
Soil erosion may deteriorate soil microbial ecosystems, and assessing the impacts of soil erosion on soil micro-biological properties is important for eroded-soil restoration. Based on the simulated erosion plots with treatments of eight erosion depths (0, 10, 20, 30, 40, 50, 60 and 70 cm) and two sub-treatments of no fertilizer and chemical fertilizer situated in black soil region, northeast China, soil samples of the 0–20 cm layer in each plots were collected and several key soil biological parameters were determined. The results indicated that the values of all the variables of soil micro-biological properties had a linearly decreasing trend with increasing erosion depths. From erosion depth of 0–70 cm, the soil microbial biomass C (MBC), microbical biomass N (MBN), numbers of bacteria, mold, actinomyces, azotobacter, phosphorus bacteria, potassium bacteria, and catalase, urease, β-glucosidase, cellulase activities decreased by 93.4%, 93.1%, 87.7%, 78.2%, 82.9%, 72.7%, 79.7%, 79.6%, 91.3%, 89.8%,91.7% and 69.5%, respectively for fertilized plots, and 94.8%, 78.2%, 89.7%,59.0%, 92.3%, 72.7%, 79.7%, 78.4%, 90.0%, 87.9%, 92.6% and 75.0%, respectively, for unfertilized plots. There were significant correlations between soil organic matter (SOM), total N (TN) and soil micro-biological properties. Chemical fertilization increased available P (AP) ( < 0.001) and SOM ( < 0.05) significantly, but had no significant effect on MBC, MBN, microbial quantities and enzyme activities. The results showed that local conventional chemical fertilization did not enhance soil biological status and was not able to counterbalance the fertility loss incurred by soil erosion, and also suggest that protective measures to improve soil biological properties should be taken immediately.
In order to examine the response characteristics and possible reasons of and under salt stress at stage of seed germination, the seeds were treated with different concentrations of NaCl (0, 50, 100, 200 and 300 mmol⋅L ), 20 mmol⋅L LiCl or mannitol whose iso-osmotic concentrations corresponding to 200 mmol⋅L NaCl. The results showed that the germination rate of two species of saltbush was depressed with the increase of NaCl concentration, and showed greater salt tolerance compared with After removal of salt stress, the final germination ratio of was over 93%, while that of was only 56%. Evans blue staining revealed that 200 mmol⋅L NaCl did not damage membrane permeability of seed embryos, but significantly increased the membrane permeability of seed embryos and caused irreversible damage to them, especially radicles. The results on water uptake indicated that the inhibition of NaCl on seed germination was mainly due to osmotic stress instead of ionic toxicity, and exhibited higher salt tolerance due to its greater resistance to osmotic stress.
The increased use of nitrogen fertilizers in agriculture would cause migration of nitrogen to surface and groundwater; accordingly, would lead to water resources contamination. The objective of this study is to investigate the effect of potassium zeolite on nitrate and ammonium ions sorption and retention in a saturated sandy loam soil in a laboratory condition. The study was conducted as a completely randomized block design with four treatments of 0, 2, 4 and 8 g zeolite per kilogram soil and three replications. Ammonium nitrate fertilizer with concentration of 10 g l was added to soil columns and then leaching was performed. The results show that increasing potassium zeolite to soil causes reduction to the mobility of both nitrate and ammonium and enhancement of the retention of ions in soil. Ions leaching were simulated with convection–dispersion-equation (CDE) and mobile–immobile model (MIM) using HYDRUS-1D code. The results indicate that ammonium ion sorption by soil followed the Freundlich isotherm model. Absorption isotherms and dispersion ( ) coefficient were determined through the inverse modeling for both ions. Based on the results, optimized values of Freundlich isotherm were much less than the observed amounts. This shows that the HYDRUS-1D model underestimated the adsorption parameters to predict the ammonium ion mobility in soil macropores. Since soil has been disturbed, the prediction of CDE model was equal to MIM model approximately. Both models showed that as the amount of applied zeolite increases, the dispersion ( ) coefficient of nitrate and ammonium ions in the soil increases.
Dioecious plant species represent an major component of terrestrial ecosystems. Little is known about sex-specific responses to soil salinity. Rehd, which is a dioecious, deciduous tree, was employed as a test species in our study. In a semi-controlled environment, physiological responses to salinity were investigated in male and female cuttings, which were subjected to two salt regimes: 0 and 80 mM NaCl added to the Hoagland’s solution for one month growth. Relative to the control, the saline treatment significantly decreased net photosynthetic rate ( ), transpiration ( ), stomatal conductance ( ), carotenoids (Caro), chlorophyll a (Chl ), total chlorophyll (TC) and catalase (CAT) activity, but increased Na , Ca , K , malondialdehyde (MDA) content, superoxide dismutase (SOD) activity and carbon isotope composition ( C) in both sexes. Different sensitivity to saline conditions between males and females was detected. With higher soil salinity, females exhibited lower , Chl , TC, Chl / , Ca , Ca /Na , K /Na , SOD and CAT activities but higher Na and MDA content than males. However, there were no significant differences in these traits (except for SOD and CAT activities) detected in the control group. Our results indicated that males may be more tolerate to salinity than females, with females having lower gas exchanges, chlorophyll pigments, antioxidant enzyme activities, K /Na ratio and water use efficiency (WUE) than males.
Coarse woody debris (CWD) characteristics are expected to reflect forest stand features. Few studies evaluated logging-induced stand characteristics of secondary coniferous forests by quantifying the quality and quantity in CWD. After selective logging, the form of secondary forest of in the Qinling Mountains is inferior and the regeneration is poor. We measured the CWD characteristics of the forest which had an average CWD biomass amount of 12.56 t hm , and was predominated by abundant logs (65.68%), followed by snags (33.13%). The CWD biomass of . and was significantly higher than that of other species, which took up 85.51% of the total. Although there was no significant difference among different diameter sizes ( > 0.05), the CWD biomass of diameter 30–40 cm occupied 46.26% of the total (5.81 t hm ). Similarly, the CWD biomass of decay class I and II accounted for 39.89% (5.01 t hm ) and 33.04% (4.15 t hm ) of the total CWD biomass respectively, despite no significant difference among those 5 decay classes ( > 0.05). The results indicated that the combination of young forest developmental stage caused by past selective logging and natural and anthropogenic disturbances such as strong wind, tapping lacquer, firewood collection, and illegal tree felling played a crucial role in distribution characteristics of CWD in this secondary forest of . .
Drought is projected to become more prevalent in the future due to climate change, and its impact on the fate of terrestrial ecosystems has aroused great concern in the scientific community over the past decade. Mounting evidence suggests that drought may be the most important physical stress of terrestrial ecosystems: drought limits vegetation growth, increases wildfires, and induces tree mortality, among other impacts. Drought not only weakens the carbon sink function of terrestrial ecosystems but also may interfere directly or indirectly with biosphere–atmosphere interactions, further exacerbating climate change. This paper reviews the current evidence of the impacts of drought on terrestrial ecosystems, with particular emphasis on the ways in which drought alters the biological, biogeophysical and biogeochemical processes underlying the interaction between the biosphere and the atmosphere.