Water productivity evaluation for grain crops in irrigated regions of China

Improving crop water productivity is necessary for ensuring food and ecological security. To quantify the water utilization in grain production from multiple perspectives, gross inflow water productivity (WP_g), generalized water productivity (WP_u), evapotranspiration water productivity (WP_ET) and irrigation water productivity (WP_I) were screened in this study. Then, we calculated and analyzed the temporal and spatial variation of the water productivity indices (WPs) in the irrigated land of 31 provinces of China based on the data collected from 459 irrigation districts. The results show that the national values of the four indices were 0.694, 0.860, 1.314, and 1.361 kg/m³, and almost all of the provincial WPs increased from 1998 to 2010. The Moran's I analysis shows all of the WP indices were significantly clustered, both globally and locally, in the study years. WPs of the provinces in and around Huang-Huai-Hai Plain are high, while provinces in the northeast, south of the Yangtze River and the northwest of China showed lower water use efficiency. There is a large difference among the four indices in the scientific connotation and numerical performance, and the degree of the spatial difference was WP_I > WP_ET > WP_u > WP_g. It is necessary to promote WP in the irrigated land of China, and the provinces in the northeast should be chosen as the key regions to develop water-saving agriculture because of the high production of grain and the low value of WP. Policy decision-making based on the spatial pattern of WP and their relationships among indices for specified regions are also discussed in this paper.     

Emergy Net Primary Production (ENPP) as basis for calculation of Ecological Footprint

Society needs urgently good tools to understand the biosphere dynamics, become aware of Earth's biophysical limits and make appraisals of environmental performance of human dominated systems. In this context, the Ecological Footprint (EF) was suggested as one of the most important tools. But, according to calculations based on Emergy Analysis, the indicators of EF could underestimate the problem of human carrying support. EF does not consider the work of untouched nature in productivity and ecosystems services. In order to improve the EF results, the present study suggests: (a) to include the ecosystems not considered in conventional EF i.e. tundra, deserts and areas covered by ice; (b) to consider the value of Net Primary Production (NPP) in Emergy units (seJ m^?2 year^?1) as the base for the calculation of Equivalent Factors (EQF); (c) to account for the consumption of fossil energy used in collection, treatment and distribution of water for domestic use, for this the carbon emissions data (in tonC m^?3 of water) were used. Introducing these changes to the conventional EF calculation and considering the Peruvian economy (in 2004) as the study case, the Biocapacity obtained was 14.31 gha capita^?1 and the footprint was 6.68 gha capita^?1. These values mean that Peru can support 2.14 times its population if the current life style is maintained, as opposed to the 4.0 times ratio obtained with a conventional EF calculation.     

Expanding ecological appropriation approach: Solar space method and a case study in Yangzhou city,East China

In this paper, the authors made an attempt to measure appropriation of ecosystems more reasonably and effectively based on examining the advantages and disadvantages of emergy analysis and ecological footprint. By combining emergy analysis with ecological footprint (EF) in terms of spatial equivalent of energy productivity, a new method of solar space (SS) and its calculating framework was proposed, and some necessary parameters for this method of analysis were calculated. A case study was followed under this calculating framework for Yangzhou city, Jiangsu province, Eastern China, using the data of the year 2000. The main results are as follows: (1) The ecological space in Yangzhou city includes earth surface space and solar space, and their demands were bigger than their supply. In the year of 2000, the earth surface space had an absolute deficit of 2.3063E?02 Ga-ha per capita (global hectares), and the solar space had an absolute deficit of 1.4944E?04 Sa-ha per capita (solar hectares). (2) There was a relative ecological deficit of 3.68% in earth surface space, and that of 154.86% in solar space. (3) Only freshwater areas and built-up areas were in a state of surplus, and there was a relative ecological surplus of 82.66% for freshwater areas, being greater than that for built-up areas. (4) The ranking of absolute ecological deficit in a descending order was as follows: solar space > arable land > pasture > forest > marine area > garden land, while the relative ecological deficit was the following: solar space > pasture land > forest land > arable land > garden land, except marine areas.A qualitative comparison of methodology was made between solar space method and ecological footprint according to their capability to describe the temporal-spatial characteristics of ecosystems appropriation. Moreover, a quantitative comparison was also conducted to show their differences in applicability to the assessment of ecosystems appropriation. It was shown that the calculating results from solar space method were bigger than that from ecological footprint because the former supplemented additional items of appropriation omitted by the later and included some new items of indirect appropriation that were excluded by the later. It is found that the new measure of solar space operates well as an indicator of the city's appropriation to ecosystems.     

Island urbanization and its ecological consequences: A case study in the Zhoushan Island,East China

Islands, which provide multiple ecosystem services, are subject to increasing urbanization pressure due to the ongoing marine development, especially in developing countries. Insights into the island urbanization mechanism and its ecological consequences are essential to sustainable development. In the present paper, the satellite images, nighttime lights, and topographic data were integrated to characterize the spatially explicit urbanization process and mechanism during 1995–2011 in the Zhoushan Island, East China. Furthermore, the corresponding spatially explicit changes in ecosystem services, including net primary productivity (NPP), carbon sequestration and oxygen production (CSOP), nutrient cycling, crop production, and habitat quality, were quantified based on the Carnegie–Ames–Stanford Approach (CASA) and Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) models. The results showed that the Zhoushan Island had experienced a rapid urbanization over the years, with significant urban encroachment on the farmland and tidal flat. Moreover, the urban land expansion was positively correlated with that of the nighttime lights and negatively correlated with the elevation, slope, and the distance to shoreline. These indicated that the urban expansion was resulted from the enhancement of socioeconomic activities, and concentrated in the near-shore areas with low altitude and gentle slope. The urban encroachment on other land use types resulted in a decrease of 3.4 Gg C a⁻¹ NPP, 8.7 Gg a⁻¹ CSOP, 13.2 Gg a⁻¹ nutrient cycling, and 12.3 t a⁻¹ crop production, respectively. In addition, the habitat quality in 11% area of this island degraded substantially. Therefore, to achieve sustainable development of islands, it is urgent to implement more stringent policies, such as island spatial regulation, environmental impact assessment, intensive land use, and urban greening, etc.     

The effect of land type diversity and spatial heterogeneity on farmland birds in Norway

The decline in farmland birds observed throughout Europe during recent decades has attracted much attention. Agricultural intensification or land abandonment are commonly forwarded as key drivers. Several countries have established agri-environmental schemes (AES) to counter these negative trends among farmland birds. This paper reports a study of the relationship between land use and bird species in the agricultural landscape of Norway. The main objective was to investigate the effect of spatial heterogeneity and diversity of land use on total richness and abundance of farmland birds at a national level.Monitoring the distribution and abundance of birds is part of the Norwegian monitoring programme for agricultural landscapes. The monitoring programme is based on mapping of 1 × 1 km squares distributed across the entire agricultural landscape. Within these squares permanent observation points are established for bird monitoring. Detailed interpretation of aerial photographs provides the land classification. We tested the relationship between landscape metrics at different levels of land type detail and species richness and abundance of farmland and non-farmland birds.There was a positive relationship between species richness and abundance of farmland birds and agricultural area. For non-farmland birds the relationship was negative. Spatial heterogeneity of land use was a significant positive factor for both farmland and non-farmland species. High land type diversity was positive for farmland bird richness, but negative for abundance. Non-farmland bird richness was not affected by land type diversity, but abundance had a negative response.The results presented in this paper highlight the importance of a spatial heterogeneous landscape. However, we also found that land type diversity could negatively affect the abundance of both farmland and non-farmland birds. Our findings suggest a need for different management approaches depending on whether the aim is increased species richness or abundance. Achieving both aims with the same means might be difficult. We thus suggest a need for land use analyses before proper management strategies can be implemented.     

Non-phytin phosphorus requirements of commercial broilers and White Leghorn layers

Experiments were conducted to determine the optimum requirements of non-phytin phosphorus (NPP) in commercial broilers and White Leghorn layers. Five levels of NPP (2.5, 3.0, 3.5, 4.0 and 4.5 g kg⁻¹ diet) were tested to assess the NPP requirement of commercial broilers (3–30 days of age) fed maize–soya diets containing 10 g Ca kg⁻¹. Each level of NPP was fed to quadruplicate groups of ten chicks each. Inclusion of graded levels of NPP significantly (P < 0.01) influenced body weight gain, feed intake, tibia ash content, phosphorus content in serum, tibia ash and phosphorus retention. The predicted NPP requirements for body weight gain, P content in serum and tibia ash were 4.4, 4.48 and 4.1 g kg⁻¹ diet, respectively. The NPP requirement for tibia ash was the highest (7.4 g kg⁻¹ diet). Similarly, four levels of NPP (2.0, 2.5, 3.0 and 3.5 g kg⁻¹ diet) were tested with maize–soya diets containing 35 g Ca kg⁻¹ for White Leghorn layers (266–350 days of age). Each diet was tested on four groups of 12 hens in each. Egg production was not influenced by the variation in dietary NPP levels. The predicted NPP requirements for better egg weight and shell thickness were 2.6 and 2.4 g kg⁻¹ diet, respectively, while for the serum inorganic P level the value was 3.42 g kg⁻¹ diet. Therefore, it can be concluded that commercial broilers need about 4.4 g NPP kg⁻¹ diet for better performance, whereas, White Leghorn layers need not more than 2.0 g NPP kg⁻¹ diet for better egg production. However, layers require 2.6 g NPP kg⁻¹ diet to produce eggs with better egg size and shell quality.     

Ecological footprint (EF): An expanded role in calculating resource productivity (RP) using China and the G20 member countries as examples

As resources become scarcer measuring resource productivity (RP) is more important. Quantifying the value of natural resources is challenging but the ecological footprint (EF) concept provides one method of uniformly describing a variety of natural resources. Current assessments of RP mainly revolve around output efficiency of resources, namely the ratio of GDP to natural resource usage.This paper develops a new method of calculating the RP by using the EF as an indicator of the natural resource input and gross domestic product (GDP) as the output in the equation of RP = GDP/EF. A regression analysis is carried out using GDP per capita and RP of China from 1997 to 2011, and a comparative analysis with the members of the G20 countries according to their RP and per capita GDP in 2008. The results indicate that RP correlates with the per capita GDP, showing that RP is a valid indicator which can be used to measure a country’s level of economic development.     

Soil organic carbon fractions are affected by different land uses in an agro-pastoral transitional zone in Northeastern China

Soil organic carbon (SOC) consists of various C fractions with different stabilities and chemical compositions that are differently affected by changes in land use. A better understanding of the responses of different C fractions to land uses is vital for maintaining soil quality and mitigating global warming. Using data from a short-term land use experiment in northeastern China, this paper investigated the effect of five land uses, corn cropland (Corn), alfalfa grassland (Alfalfa), artificial grassland of Lyemus chinensis (AG), Lyemus chinensis grassland for mowing (AG + Mow) and restored grassland (RG), on the dynamics of total SOC and four SOC fractions with increasing degrees of oxidizability at 0 to 50 cm depths. The results show that land use had a significant effect (P < 0.05) on the total SOC and SOC fractions of very labile C (F1), labile C (F2) and less labile C (F3), while the difference in recalcitrant C (F4) was less pronounced. SOC in the study area was characterized by a predominantly very labile C fraction, and the percentages of F1 to total SOC were more than 40% for all land uses. Compared with Corn, the treatments AG + Mow, AG and RG decreased the percentage of F1 to SOC (by 4.49%, 6.53% and 3.55%, respectively) and increased the percentages of F2 (by 3.32%, 2.77% and 6.60%, respectively) and F3 (by 4.47%, 3.46% and 0.3%, respectively) to SOC. These findings suggest that land-use type is a major factor that influences soil C fractions and that labile C fractions contribute a large part of the total SOC. In addition, grassland colonization of croplands improves soil C sequestration in northeastern China.     

Changes of soil organic carbon,nitrogen and phosphorus concentrations under different land uses in marshes of Sanjiang Plain

Wetlands provide a large pool of organic matter and nutrients, and are important for maintaining material cycle balances in terrestrial ecosystems, and also help retard climate change. Land use changes in wetlands have greatly disturbed the natural evolution of wetland ecosystems. Wetland drainage and reclamation alters the physical, chemical and biological conditions of the wetland, thus significantly disturbing the material cycles, leading to significant changes in the biogeochemical processes of carbon, nitrogen and phosphorus in the wetland. The wetlands in the Sanjiang Plain are the largest area of fresh wetlands in China. However, the area has experienced major land uses changes since the 1950s; areas of the wetland have been drained and converted to arable land. Some studies have been conducted into the effects of land use change on material cycles in the Sanjiang Plain wetlands but few reports have discussed the C/N and C/P ratios and pH values as indicators of wetland degradation due to land use changes. We selected eight land uses: humus marsh (HM), marshy meadow (MM), drained humus marsh (DHM), drained marshy meadow (DMM), tillage land (TL), abandoned land (AL), natural secondary forest (NSF) and artificial forest (AF), in the Honghe area of the Sanjiang Plain. We studied changes in the total organic carbon (TOC), total nitrogen (TN), total phosphorus (TP), C/N and C/P ratios and pH values in topsoil (0–20 cm) of these eight different land uses. The possible mechanisms underlying the changes, and the significance of the C/N and C/P ratios as indicators of soil quality were also discussed. In the natural wetland, the TOC, TN and TP concentrations in the soil were high, with values of 203.5 g/kg, 20.2 g/kg and 1.44 g/kg, respectively, in HM; and 59.2 g/kg, 5.28 g/kg and 0.83 g/kg, respectively, in MM. Drainage of the HM has led to decreases in the TOC, TN and TP concentrations of about 50%. Significant decreases were also observed in TOC, TN and TP for NSF and AF compared to HM. Drained MM led to decreases in the TOC and TN of about 45%, but had little effect on TP. Marshy meadow that had been drained for more than 10 years experienced an exponential decline in TOC, TN and TP, with decreases of more than 60% for TOC and TN, and 20% for TP. However, after being abandoned for a short time (5 years), the TOC, TN and TP concentrations in soil experienced little change because poor water conditions combined with low productivity led to a large loss of soil organic matter. Land use change in the marsh areas has led to a decrease in C/N and C/P ratios of the soil, which are positively related to TOC and TN with different land uses (P < 0.05). Marsh reclamation has led to decreasing C/N and C/P ratios in soil and increasing pH values, which are negatively related to TOC, TN and TP (P < 0.05). Changes in carbon, nitrogen and phosphorus in soil with different land uses were mainly regulated by water-heat conditions and microbial activity, while the C/N and C/P ratios were mainly regulated by substrate availability. Our results suggest that C/N and C/P ratios and the pH value could be used as indicators to evaluate the quality and nutrient status of wetland soil under different land uses.     

Regulating effects of climate,net primary productivity,and nitrogen on carbon sequestration rates in temperate wetlands,Northeast China

Temperate wetlands in the Northern Hemisphere have high long-term carbon sequestration rates, and play critical roles in mitigating regional and global atmospheric CO₂ increases at the century timescale. We measured soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) from 11 typical freshwater wetlands (Heilongjiang Province) and one saline wetland (Jilin Province) in Northeast China, and estimated carbon sequestration rates using ²¹⁰Pb and ¹³⁷Cs dating technology. Effects of climate, net primary productivity, and nutrient availability on carbon sequestration rates (R_carbon) were also evaluated. Chronological results showed that surface soil within the 0–40 cm depth formed during the past 70–205 years. Soil accretion rates ranged from 2.20 to 5.83 mm yr⁻¹, with an average of 3.84 ± 1.25 mm yr⁻¹ (mean ± SD). R_carbon ranged from 61.60 to 318.5 gC m⁻² yr⁻¹ and was significantly different among wetland types. Average R_carbon was 202.7 gC m⁻² yr⁻¹ in the freshwater wetlands and 61.6 gC m⁻² yr⁻¹ in the saline marsh. About 1.04 × 10⁸ tons of carbon was estimated to be captured by temperate wetland soils annually in Heilongjiang Province (in the scope of 45.381–51.085°N, 125.132–132.324°E). Correlation analysis showed little impact of net primary productivity (NPP) and soil nutrient contents on R_carbon, whereas climate, specifically the combined dynamics of temperature and precipitation, was the predominant factor affecting R_carbon. The negative relationship observed between R_carbon and annual mean temperature (T) indicates that warming in Northeast China could reduce R_carbon. Significant positive relationships were observed between annual precipitation (P), the hydrothermal coefficient (defined as P/AT, where AT was accumulative temperature ≥10 °C), and R_carbon, indicating that a cold, humid climate would enhance R_carbon. Current climate change in Northeast China, characterized by warming and drought, may form positive feedbacks with R_carbon in temperate wetlands and accelerate carbon loss from wetland soils.     

2000-2015年安徽省植被净初级生产力时空分布特征及其驱动因素

安徽省是我国的农业大省,其生态系统的动态变化直接关系粮食安全。植被NPP的变化可以有效反映生态系统的变化。基于MOD17A3 NPP数据、气象数据和土地利用类型数据,采用偏差分析法、变异系数、趋势分析法和相关分析法对安徽省2000-2015年植被NPP的时空格局、变化趋势及驱动因子进行研究。结果表明：（1）2000-2015年安徽省植被NPP平均值为476.6gC/m²;波动范围为396.6-531.8gC/m²;植被NPP具有较强的空间分异性,整体上呈现南高北低趋势;（2）不同土地覆盖类型的年均NPP差异明显,其中林地最高,为535.5gC/m²,而且不同地类的NPP年际变化幅度不同,主要表现在林地和草地的变化幅度相对较大;（3）植被NPP受气候、环境变化以及人类活动等多种因素共同影响,其中受气候因素中降雨影响较大,但是随着人类活动日益频繁,城市化逐渐成为NPP变化的主要驱动力。     

Carbon footprints of rice production in five typical rice districts in China

Five provinces located in the five main rice-growing regions in China were selected as study areas, which were Jiangsu, Heilongjiang, Sichuan, Guangdong and Hunan province respectively in the middle and lower reaches of the Yangtze River, northern, southwest, southern and central rice districts. Carbon footprints of rice production in these five provinces were calculated through the life cycle assessment method using governmental statistical data, industrial standards and relevant technical data separately. Material and energy consumptions were estimated, key stages of energy consumptions and carbon emissions were identified as well. Moreover, improving measurements had been suggested correspondingly. The results indicated that: the energy consumptions of rice production in these five provinces ranked as following (high to low): Guangdong, Heilongjiang, Hunan, Sichuan and Jiangsu. The carbon footprints of rice production were 2504.20 kg carbon dioxide equation per ton rice (kgCO₂-eq./t) (Guangdong province), 2326.47 kgCO₂-eq./t (Hunan province), 1889.97 kgCO₂-eq./t (Heilongjiang province), 1538.90 kgCO₂-eq./t (Sichuan province) and 1344.92 kgCO₂-eq./t (Jiangsu province) respectively. Reducing the quantities of urea and using the intermittent irrigation method could decrease energy consumption as well as carbon footprint.     

Importance of a traditional irrigation system in amphibian conservation in the Cinque Terre National Park (NW Italy)

In Mediterranean agricultural landscapes the impact of irrigation on biodiversity, and in particular on wildlife, remains controversial. This study investigated the role of traditional irrigation in the conservation of amphibians in the smallest and most densely populated national park in Italy, the Cinque Terre National Park (CTNP). The coastline in this area is so steep that dry stone walls were built to create arable land surfaces, irrigated by water stored in small open tanks. An almost complete census of these tanks and a survey of amphibian populations in natural and artificial habitats were undertaken from 2009 to 2012. A total of 58 water tanks were censused, 12 of them being empty, damaged or abandoned. All the tanks containing water were built in concrete and had small volume capacities (mean = 3.6, range 0.3–12.4 m³) but, overall, hosted all the seven aquatic amphibian species still present in the Park's natural freshwater habitats. Amphibians bred in 66% of the tanks still used for irrigation; large tanks were occupied more often than small tanks and hosted a different, more species-rich amphibian community. These results have management implications and confirm that, in the CTNP, extensive agriculture and biodiversity are compatible, and that maintaining traditional irrigation systems will benefit amphibian populations, especially in the case of drier climate scenarios.     

Mapping soil organic matter in low-relief areas based on land surface diurnal temperature difference and a vegetation index

Accurate estimates of the spatial variability of soil organic matter (SOM) are necessary to properly evaluate soil fertility and soil carbon sequestration potential. In plains and gently undulating terrains, soil spatial variability is not closely related to relief, and thus digital soil mapping (DSM) methods based on soil–landscape relationships often fail in these areas. Therefore, different predictors are needed for DSM in the plains. Time-series remotely sensed data, including thermal imagery and vegetation indices provide possibilities for mapping SOM in such areas. Two low-relief agricultural areas (Peixian County, 28 km × 28 km and Jiangyan County, 38 km × 50 km) in northwest and middle Jiangsu Province, east China, were chosen as case study areas. Land surface diurnal temperature difference (DTD) extracted from moderate resolution imaging spectroradiometer (MODIS) land surface temperature (LST), and soil-adjusted vegetation index (SAVI) at the peak of growing season calculated from Landsat ETM+ image were used as predictors. Regression kriging (RK) with a mixed linear model fitted by residual maximum likelihood (REML) and residuals interpolated by simple kriging (SK) were used to model and map SOM spatial distribution; ordinary kriging (OK) was used as a baseline comparison. The root mean squared error, mean error and mean absolute error calculated from leave-one-out cross-validation were used to assess prediction accuracy. Results showed that the proposed covariates provided added value to the observations. SAVI aggregated to MODIS resolution was able to identify local highs and lows not apparent from the DTD imagery alone. Despite the apparent similarity of the two areas, the spatial structure of residuals from the linear mixed models were quite different; ranges on the order of 3 km in Jiangyan but 16 km in Peixian, and accuracy of best models differed by a factor of two (3.3 g/kg and 6.3 g/kg SOM, respectively). This suggests that time-series remotely sensed data can provide useful auxiliary variable for mapping SOM in low-relief agricultural areas, with three important cautions: (1) image dates must be carefully chosen; (2) vegetation indices should supplement diurnal temperature differences, (3) model structure must be calibrated for each area.     

Comparison of volumetric and stress-weighted water footprint of grain products in China

The water footprint (WF) concept links physical and virtual forms of water, which can be used for research on the impact on water resources imposed by human consumption or production activities. Debates remain on the calculation methods due to WF being applied for different research purposes, and the large amounts of data required for the calculation being hard to obtain. This paper calculated and compared two WFs called volumetric WF (the volumes of blue and green water are combined with the same weight) and stress-weighted WF (the volumes of blue and green water are combined with different weights) based on water use data to research crop water productivity of grain crops and its impact on water resources in each region of China. Results for volumetric WF and stress-weighted WF of grain products of each region in China differed greatly. In 2010, the average volumetric WF was 1.25 m³/kg with the blue component 0.53 m³/kg, and the average stress-weighted WF was 0.51 m³/kg. In addition, there were significant differences of both kinds of WFs among regions in China. The results showed that volumetric WF could be used as a comprehensive indicator for evaluating crop water productivity, specified in space and time by source (green and blue WFs). Stress-weighted WF could offer a meaningful way of making quantitative comparisons between products, production systems and services in terms of their potential to contribute to water scarcity. The spatial distribution of these two WFs can help decision making to develop water-saving measures, relieve water stress and restore ecosystems for each region in China.     

The impact of arbuscular mycorrhizal fungi in mitigating salt-induced adverse effects in sweet basil (Ocimum basilicum L.)

Salinity is one of the serious abiotic stresses adversely affecting the majority of arable lands worldwide, limiting the crop productivity of most of the economically important crops. Sweet basil (Osmium basilicum) plants were grown in a non-saline soil (EC = 0.64 dS m⁻¹), in low saline soil (EC = 5 dS m⁻¹), and in a high saline soil (EC = 10 dS m⁻¹). There were differences between arbuscular mycorrhizal (Glomus deserticola) colonized plants (+AMF) and non-colonized plants (−AMF). Mycorrhiza mitigated the reduction of K, P and Ca uptake due to salinity. The balance between K/Na and between Ca/Na was improved in +AMF plants. Growth enhancement by mycorrhiza was independent from plant phosphorus content under high salinity levels. Different growth parameters, salt stress tolerance and accumulation of proline content were investigated, these results showed that the use of mycorrhizal inoculum (AMF) was able to enhance the productivity of sweet basil plants under salinity conditions. Mycorrhizal inoculation significantly increased chlorophyll content and water use efficiency under salinity stress. The sweet basil plants appeared to have high dependency on AMF which improved plant growth, photosynthetic efficiency, gas exchange and water use efficiency under salinity stress. In this study, there was evidence that colonization with AMF can alleviate the detrimental salinity stress influence on the growth and productivity of sweet basil plants.     

Mark-recapture of the endangered franciscana dolphin (Pontoporia blainvillei) killed in gillnet fisheries to estimate past bycatch from time series of stranded carcasses in southern Brazil

Incidental fishery mortality estimates of franciscana based on stranding data are biased downwards, as only a fraction of the total bycatch ends up ashore. We estimated the probability of a franciscana incidentally killed by the coastal gillnet fisheries in southern Brazil to wash ashore and used this as a correction factor to back-calculate fishing related mortality from a dataset of carcasses collected between 1979 and 1998. From November 2005 to January 2009, 145 franciscanas incidentally killed in nets were tagged and returned to the sea. Only 11 of the tagged animals were found during beach surveys. Generalized Linear Models were used to model the probability of a tagged franciscana reaching the shore as a function of the covariates wave period, wind direction and intensity, distance from coast and the target species of the fishery. The target species had a significant effect on the stranding probability. The stranding probability of a tagged franciscana was higher in the fishery targeting white croaker (Micropogonias furnieri) (median = 0.105; 95% CI = 0.05–0.18) rather than weakfish (Cynoscion guatucupa) (0.013; 0.0003–0.069). As the stranding probability estimate for weakfish was imprecise (wide credible interval) we decided to hind cast the number of franciscanas incidentally killed for white croaker season only. The corrected estimate of franciscana mortality was approximately 10 times higher than previous estimates based solely on stranding data. Finally, this novel mark-recapture approach provides a useful correction factor to reduce the bias in incidental mortality estimates derived from stranding data.     

The effects of different urban land use patterns on soil microbial biomass nitrogen and enzyme activities in urban area of Beijing, China

Soil microbes are affected by various abiotic and biotic factors in urban ecosystem due to land use change. The effects of different land use patterns on soil microbial properties and soil quality are, however, largely unknown. This study compared soil nutrient status, microbial biomass nitrogen and enzyme activities under five different land use patterns—nature forest, park, farmland, street green, and roadside tree sites at various soil depths in Beijing, China. The results showed that soil properties were significantly affected by urban land use patterns and soil depths in the urban environment. Compared to forest sites, soil nutrients were markedly decreased in other land use patterns, except the highest soil organic matter content in roadside tree sites in 0–10 cm soil layer. Soil microbial biomass nitrogen showed the order as follows: nature forest > park > farmland > street green > roadside tree in 0–10 cm soil layer, and it decreased along with the soil depth gradient. Furthermore, urease activity was highest in nature forest and lowest in street green and roadside tree soils in each depth, while the activity of protease ranged between 0.84 and 3.94 mg g^?1 with the peak appeared in roadside tree at 30–40 cm soil layers. Nitrate reductase activity was also extremely higher in street green than other land use patterns. Correlation analyses suggested that change of soil microbial biomass and enzyme activity in different land use patterns were mainly controlled by nutrient availability and soil fertility in urban soils.     

Above-ground biomass estimation based on NPP time-series − A novel approach for biomass estimation in semi-arid Kazakhstan

Biomass is a sensitive indicator of environmental change and ecological functioning. Quantification of biomass is essential to identify and monitor those areas threatened by degradation and desertification. This is especially important in arid and semi-arid environments. However, robust techniques to monitor carbon stocks over large areas and through time are still missing. The major objective of the presented study is to develop a novel approach for biomass estimation in semi-arid environments using remote-sensing based Net Primary Productivity (NPP) data.The developed methodical concept aims at derivation of above-ground grass and shrub biomass for natural environments. It is based on NPP time-series and plants’ relative growth rates. Fractional cover data provide information about grass and shrub coverage. The developed approach has been applied to three study areas in Kazakhstan, in which field data were collected for validation.Biomass maps were derived that show the spatial distribution of grass and shrub biomass. Validation revealed a moderate correlation (R = 0.68) with field data for grass biomass. For shrub biomass, a high correlation (R = 0.83) is retrieved when fractional cover information from field observations is used.The presented novel approach for biomass estimation is based on remote sensing derived NPP time-series and is thus potentially transferable in space and time. This is a great advantage compared to commonly applied empirical relationships. The presented concept can be adapted to be applied to other vegetation communities. Providing the necessary data about fractional vegetation cover is available, the method will allow for repeated and large-area biomass estimation for natural semi-arid environments as needed for observing changes in biomass and support sustainable land management.