Cultivated Sites Research Articles

Urbanization-induced site condition changes of peri-urban cultivated land in the black soil region of northeast China

The site condition of cultivated land greatly influences the utilization and management of cultivated land resources and is an element that is disturbed tremendously by urbanization. Since the rejuvenation of the northeast old industrial base strategy in 2003, urbanization in northeast China has progressed rapidly. The excessive urban sprawl has profoundly changed land use structure in the peri-urban area of the black soil region, and the subsequent site condition changes will impede the full utilization of cultivated land resources. This study used the suburb of Changchun Kuancheng District as an empirical case, and employed a patch-scale site assessment system to analyze dynamic changes in cultivated land site conditions at a typical rural-urban interface of the black soil region from 2004 to 2014. Cultivated land loss and land use changes were prominent in the study area and the land conversion rate was shown to be accelerating. Most of the occupied cultivated land was converted to urban areas such as industrial land or urban settlements. However, a part of the occupied cultivated land was left unutilized, which indicates how the urban sprawl is jeopardizing benefits of both urban development and cultivated land protection. Besides direct occupation of cultivated land resources, urbanization has led to a loss of cultivated land with good site conditions and a deterioration of the site conditions of unconverted cultivated land in the peri-urban area. Urbanization has fragmented peri-urban cultivated land, increased farming distance and brought more frequent anthropogenic disturbances. On the other hand, it has also improved transportation conditions and the local ecological environment. As site condition is believed to be closely related to both cultivated land loss and cultivation abandonment, the deterioration will aggravate the loss of cultivated land resources in a disguised form.

The impact of cultivation on CO2 and CH4 fluxes over organic soils in Sweden

Cultivated organic soils are large contributors to global greenhouse gas emissions. We measured carbon dioxide (CO2) and methane (CH4) fluxes from two organic soil plots in central Sweden between 2012 and 2016 using the eddy covariance technique. One site was cultivated whilst the other was set aside with no cultivation occurring. The aim was to establish the impact that cultivation had on the carbon balance. Over the five year period the set aside field acted as a net carbon source whilst the cultivated site was seen to be a small carbon sink. The set aside was further seen to act as a small methane sink over a 36 month period, which reduced the CO2 source by ca. 10% in terms of CO2 equivalents. Considering exported biomass, both sites were carbon sources in terms of Net Biome Production (NBP).

Agricultural history drives structure and tree species composition of second growth forest over 100 years in southeastern Ohio, USA

AbstractQuestionMost modern forest in eastern North America has recolonized after abandonment from agriculture. Cultivation and pasturing, historically the dominant forms of agriculture, differ in their environmental legacies and potentially influence stand development following abandonment. We ask how the legacy of agriculture plays out in development of second‐growth stands, and whether tree community composition and structure differ between sites with contrasting land‐use histories.LocationSoutheast Ohio, USA.MethodsThirty‐five second‐growth stands were sorted into a replicated chronosequence of formerly cultivated and pastured sites spanning 80 yr. Stand age and land‐use history were determined from historical aerial photographs and from site characteristics including microtopography and soil profiles. In addition, a control group was selected consisting of long‐established forest stands showing no signs of agricultural disturbance. At each site stand composition and structure were described using the point‐centred quarter method.ResultsStand density declined and basal area increased through the chronosequence but neither pastured nor cultivated sites reached levels observed in the control group. Density decreased most dramatically between the 41–60‐ and 61–80‐yr age classes, consistent with competitive stand thinning. Tree community composition changed through time, reflecting a shift away from light‐demanding successional species and toward long‐lived, shade‐tolerant species characteristic of long‐established forests. Composition and structure did not differ significantly between cultivated and pastured sites, but individual species did show significant differences, with the greatest contrast evident shortly after abandonment.ConclusionsStand development following agriculture appears to be a process of convergence in species composition and density. Because most deciduous forest in eastern North America is <80‐yr‐old, these results suggest that most forest is still accruing biomass and has yet to reach a stable density and composition.

Restoration and sequestration of carbon and nitrogen in the degraded northern coastal area in Nile Delta, Egypt for climate change mitigation

Most of coastal area in Nile Delta, Egypt, is salt-affected soils and have low carbon (C) and nitrogen (N) inputs as a result of declining vegetation growth and low net primary production. Therefore, this study amid to compare between C and N pools in degraded (uncultivated and salt-affected soil) and restored (cultivated and reclaimed 20 years ago) locations in North Nile Delta. and to examine the impact of cultivation on sequestering C and N pools in this area as one of the most important methods for mitigating climate change impacts. C and N pools increased significantly in surface soil from 2.99 and 0.43 Mgh−1 in uncultivated sites to 19.26 and 1.66 Mgh−1 in cultivated ones as salinity was reduced and net primary production was increased due to leaching and reclamation. Particulate (associated with sand) and nonparticulate (associated with clay +silt) soil organic C or N was significantly higher cultivated sites. In addition, nonparticulate organic C or N was lower than particulate part indicating and supporting the strong relationship between organic matter and clay. The sequestration rate (in approximately 1 m profile) was 1.69 and 0.14 Mgh−1 yr.−1 C and N pools respectively. Although the cultivation is leading to loss of organic matter in some areas; C and N in this coastal area are partially restored and stored. Therefore, restoration and appropriate management practices will lead to mitigate the negative impacts of climate change in this area.

Imbricated Spaces

This article explores how the socio-spatial relationship between cities and nature is changing under the cultural conditions of the twenty-first century. I argue that contemporary urban parks such as New York’s High Line, along with less cultivated sites of city-nature intersections such as vacant lots, represent variations of an emergent type of social space, which I term imbricated spaces. Imbricated spaces present “city” and “nature” as active agents in their creation through the decay of the built environment and the growth of the natural environment. The transformation of city-nature imbrications into culturally valued spaces, whether through architectural intervention, artistic representation, or phenomenological experience, reflects that such spaces not only have wide resonance but that their growing presence on the urban landscape is correlated with a broader recognition of how nonhuman agency—in particular, climate change and industrial decay—is shaping the social spaces of contemporary cities.

Dynamics of water vapor and energy exchanges above two contrasting Sudanian climate ecosystems in Northern Benin (West Africa)

AbstractNatural ecosystems in sub‐Saharan Africa are experiencing intense changes that will probably modify land surface feedbacks and consequently the regional climate. In this study, we have analyzed water vapor (QLE) and sensible heat (QH) fluxes over a woodland (Bellefoungou, BE) and a cultivated area (Nalohou, NA) in the Sudanian climate of Northern Benin, using 2 years (from July 2008 to June 2010) of eddy covariance measurements. The evaporative fraction (EF) response to environmental and surface variables was investigated at seasonal scale. Soil moisture was found to be the main environmental factor controlling energy partitioning. During the wet seasons, EF was rather stable with an average of 0.75 ± 0.07 over the woodland and 0.70 ± 0.025 over the cultivated area. This means that 70–75% of the available energy was changed into actual evapotranspiration during the investigated wet seasons depending on the vegetation type. The cumulative annual actual evapotranspiration (AET) varied between 730 ± 50 mm yr−1 at the NA site and 1040 ± 70 mm yr−1 at the BE site. With similar weather conditions at the two sites, the BE site showed 30% higher AET values than the NA site. The sensible heat flux QH at the cultivated site was always higher than that of the woodland site, but observed differences were much less than those of QLE. In a land surface conversion context, these differences are expected to impact both atmospheric dynamics and the hydrological cycle.

Agricultural land-use change in a Mexican oligotrophic desert depletes ecosystem stability

BackgroundGlobal demand for food has led to increased land-use change, particularly in dry land ecosystems, which has caused several environmental problems due to the soil degradation. In the Cuatro Cienegas Basin (CCB), alfalfa production irrigated by flooding impacts strongly on the soil.MethodsIn order to analyze the effect of such agricultural land-use change on soil nutrient dynamics and soil bacterial community composition, this work examined an agricultural gradient within the CCB which was comprised of a native desert grassland, a plot currently cultivated with alfalfa and a former agricultural field that had been abandoned for over 30 years. For each site, we analyzed C, N and P dynamic fractions, the activity of the enzyme phosphatase and the bacterial composition obtained using 16S rRNA clone libraries.ResultsThe results showed that the cultivated site presented a greater availability of water and dissolved organic carbon, these conditions promoted mineralization processes mediated by heterotrophic microorganisms, while the abandoned land was limited by water and dissolved organic nitrogen. The low amount of dissolved organic matter promoted nitrification, which is mediated by autotrophic microorganisms. The microbial N immobilization process and specific phosphatase activity were both favored in the native grassland. As expected, differences in bacterial taxonomical composition were observed among sites. The abandoned site exhibited similar compositions than native grassland, while the cultivated site differed.DiscussionThe results suggest that the transformation of native grassland into agricultural land induces drastic changes in soil nutrient dynamics as well as in the bacterial community. However, with the absence of agricultural practices, some of the soil characteristics analyzed slowly recovers their natural state.

Physical properties of peat soils under different land use options

AbstractPristine peat soils are characterized by large porosity, low density and large water and organic matter contents. Drainage and management practices change peat properties by oxidation, compaction and mineral matter additions. This study examined differences in physical properties (hydraulic conductivity, water retention curve, bulk density, porosity, von Post degree of decomposition) in soil profiles of two peatland forests, a cultivated peatland, a peat extraction area and two pristine mires originally within the same peatland area. Soil hydraulic conductivity of the drained sites (median hydraulic conductivities: 3.3 × 10−5 m/s, 2.9 × 10−8 m/s and 8.5 × 10−8 m/s for the forests, the cultivated site and the peat extraction area, respectively) was predicted better by land use option than by soil physical parameters. Detailed physical measurements were accompanied by monitoring of the water levels between drains. The model ‘DRAINMOD’ was used to assess the hydrology and the rapid fluctuations seen in groundwater depths. Hydraulic conductivity values needed to match the simulation of observed depth to groundwater data were an order of magnitude greater than those determined in field measurements, suggesting that macropore flow was an important pathway at the study sites. The rapid response of depth to groundwater during rainfall events indicated a small effective porosity and this was supported by the small measured values of drainable porosity. This study highlighted the potential role of land use and macropore flow in controlling water table fluctuation and related processes in peat soils.

Ecological restoration of a copper polluted vineyard: Long-term impact of farmland abandonment on soil bio-chemical properties and microbial communities

This study aimed at investigating the degree of interference of high soil copper (Cu) contamination when an old vineyard is converted into a protected area. This study was performed within an intensive agricultural system; it was organized into a two-factorial nested design to analyze the impact of management (conventional vs re-naturalized orchard) and position within each orchard (tree-rows and strips). Chemical and biochemical properties along with bacterial and fungal communities, evaluated with PCR-DGGE starting from total soil DNA, were analyzed. Total Cu was localized in tree rows in the old vineyard at 1000 mg kg−1 of soil, whereas it did not exceed 80 mg kg−1 soil in the other treatments. Total organic carbon and all biochemical properties significantly improved in re-naturalized compared to conventionally cultivated site, while no significant differences were observed between tree row and strip. Moreover, a higher extractable carbon-extractable nitrogen (Cext-to-Next) ratio in the re-naturalized (19.3) site than in the conventionally managed site (10.2) indicated a shift of soil system from C-limited to N-limited, confirming a successful ecological restoration. Deep improvement of soil biochemical properties exceeded the negative impact of Cu contamination. A shift of bacterial community composition as well as increased bacterial diversity in Cu contaminated treatment indicated a bacterial response to Cu stress; to the contrary, soil fungi were less susceptible than bacteria, though an overall reduction of fungal DNA was detected. Findings suggest that ecological restoration of highly polluted agricultural soils leads to overcoming the reduction of soil functionalities linked to Cu contamination and opens interesting perspectives for mitigating Cu stress in agricultural soils with strategies based on conservative agriculture.

Cultivation and domestication of highbush blueberry (Vaccinium corymbosum) alters abundance, diversity and virulence of entomopathogenic nematodes

We investigated the interactive effect of plant domestication and perennial cultivation on abundance, diversity and virulence of entomopathogenic nematodes (EPN) associated with highbush blueberry (Vaccinium corymbosum). The rhizospheric soil of V. corymbosum plants was sampled in coupled wild and cultivated sites within the Pinelands National Reserve, New Jersey, USA from 2011 to 2013 at three points during each year. To isolate and assess abundance of EPN communities, soil samples were baited with wax moth larvae (Galleria mellonella). A subsample of EPNs isolated from the soil was identified using molecular barcoding. The virulence of three native isolates against oriental beetle, Anomala orientalis, larvae was assessed at multiple densities of nematodes per host. A cursory assessment of EPN diversity was based on variation in molecular barcodes because many sequences could not be identified in the genomic database GenBank. The variation among barcodes suggested that diversity was higher in rhizospheric soil associated with wild plants than that of cultivated fields. Steinernema glaseri was the only EPN species able to be identified using molecular methods and was the only species isolated from the six cultivated fields with EPN presence. An interaction of environment, sampling point, and year explained significant differences in EPN abundance in 2011 and 2012 when soil samples were assessed by plant. However, in 2013, soil was assessed by field rather than plant and our results show EPN abundance was higher in cultivated than in wild sites. Soil nutrients and characteristics were also assessed in 2013. A PCA analysis of soil characteristics linked higher plant nutrients to soil from cultivated fields and higher soil moisture, organic matter, boron and lower pH to wild plant-associated soil. In this study, cultivation of domesticated V. corymbosum increases the abundance of the more virulent EPN species against the presumed host, A. orientalis but appears to eliminate genetic variability from the EPN community.

不同干扰下阿拉善荒漠啮齿动物优势种对气候变化的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 不同干扰下阿拉善荒漠啮齿动物优势种对气候变化的响应 DOI: 10.5846/stxb201408061564 作者: 作者单位: 内蒙古农业大学生态环境学院,内蒙古农业大学生态环境学院,内蒙古自治区林业监测规划院,内蒙古农业大学生态环境学院,中国农业科学研究院草原研究所,内蒙古医科大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(30160019, 30560028, 30760044, 31160096);公益性行业(农业)科研专项经费项目(201203041);中央级公益性科研院所基本科研业务费专项资金(中国农业科学院草原研究所)资助项目(1610332015012) Responses of dominant rodentspecies to climate change in different disturbed habitats in the Alashan desert Author: Affiliation: College of Ecology and Environmental Science, Inner Mongolia Agricultural University,,College of Ecology and Environmental Science, Inner Mongolia Agricultural University,,,College of Ecology and Environmental Science, Inner Mongolia Agricultural University,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:气候变化已对物种分布范围和丰富度产生了极大的影响。荒漠生态系统对气候变化的反应可能更加敏感。作为荒漠生态系统的重要组成者,了解荒漠啮齿动物特别是优势鼠种将对气候变化如何响应,对于荒漠地区生物多样性的维持将具有重要意义。2002-2010年,采用标志重捕法对阿拉善荒漠4种不同生境下啮齿动物优势种群进行了研究,分别利用Spearman相关分析以及典范对应分析(Canonical Correspondence analysis,CCA)对啮齿动物优势种群动态与年平均温度和年降水量的相关性进行了分析。结果表明,不同啮齿动物优势种对温度和降雨的响应不同,尤其以子午沙鼠表现最为显著。跳鼠对温度的适宜性要高于仓鼠科的子午沙鼠和黑线仓鼠,而仓鼠科啮齿动物对降雨的适宜性高于跳鼠。较小尺度上的人为干扰更可能从改变食性和生境的途径上加剧或缓冲降雨对荒漠啮齿动物优势种的影响,而不是改变温度对啮齿动物的作用。 Abstract:The Northern Hemisphere of the earth has been experiencing remarkable climate warming in last century. Climate change has a profound influence on the distribution, range, and richness of species. Temperature and precipitation are two indicators of climate in most of studies. Because hydrothermic factor has a significant effect on desert ecosystem, it is particularly sensitive to climate fluctuations. Rodents are especially important components of the desert ecosystem, and are dominant species that play a key role in these systems. In addition, desert rodents have played an important role in the development of ecological theory and in the understanding of adaptations to xeric environments. Therefore, understanding the response of dominant rodent species to climate change is significant to biodiversity conversion. Desert ecosystems in China, compared with similar ecosystems in other continents, suffer more disturbances from human activities. Alxa desert is a typical desert ecosystem in China. Annual mean temperatures of Alxa desert have risen 9.05 degrees, and precipitation has increased 23.46mm in last decade. Against this Background, the response of desert rodents, especially dominant rodent species, to climate change, and how this response influences by human disturbances are keeping unknown. A study was conducted from 2002 to 2010 at prohibited-grazing, rotational-grazing, over-grazing, and cultivated sites to investigate the response of dominant rodent species to climate change in Alashan, Inner Mongolia, China. Rodent species were identified among and monitored with a live-trapping method. We trapped nine species including Dipus sagitta, Stylodipus andrewsi, Allactaga sibirica, Phodopus roborovskii, Cricetulus barabensis, Allocricetulus eversmanni, Meriones meridianus, Meriones unguiculatus and Spermophilus alaschanicus. M. meridianus was the dominant rodent species in prohibited-grazing and cultivated sites. However, A. sibirica and D. sagitta was the dominant rodent species in over-grazing and rotational grazing sites, respectively. The relationships of annual mean temperature and precipitation with rodent abundance were analyzed with Spearman correlation analysis and canonical correspondence analysis. The results showed that the response to temperature and precipitation was variable across rodent species. M. meridianus abundance was significantly correlated with annual precipitation in the previous year and annual mean temperature. The abundance optimum of A. sibirica and D. sagitta with respect to temperature was higher than that of M. meridianus and C. barabensis, but this pattern was reversed with respect to precipitation. Effect of temperature on desert rodent should be worked through influencing biology and ecological characteristics of animal, while precipitation affects the rodents through changing food resource and habitat. Precipitation has a pulse effect on M. meridianus abundance. These results suggested that human disturbance, occurring at a smaller spatial scale, should intensify or buffer the influence of precipitation rather than temperature on the dominant rodent species through altering food resource availability and habitat quality. These disturbances complex the response of rodent species to climate change, and have a further effect to community structure of desert rodent. 参考文献 相似文献 引证文献

Response of evapotranspiration and CO2 fluxes to discrete precipitation pulses over degraded grassland and cultivated corn surfaces in a semiarid area of Northeastern China

The effects of precipitation pulses on evapotranspiration (ET) and CO2 fluxes were evaluated over different land surfaces in a semiarid area using eddy covariance technique. ET responded to rain events throughout the growing season, but the degree of responses varied among seasons. In spring and fall, ET slightly responded to precipitation pulses, because the precipitation amount in the rainfall event was small and very discrete. As the rainy season started in early summer, responses of ET to precipitation pulses significantly increased. In late summer, the intensity of responses in ET was weakened because the soils retain moisture by the high-frequency rainfall events and the antecedent soil moisture. Regarding CO2 exchange, in early summer, the net CO2 uptake slightly increased at the cultivated corn site after rain pulses, while the degraded grassland site experienced comparatively greater responses. In late summer, the cultivated corn site exhibited more negative CO2 flux after rain than the grassland site, and the responses of net CO2 uptake to rain pulses were much stronger than those in early summer. The soil moisture content and vegetation cover are the key factors in determining the responses of ET and CO2 fluxes to precipitation pulses in these two semiarid ecosystems.

Spatial variation related to hydrologic patterns and vegetation in greenhouse gas fluxes from the Mississippi Delta agricultural region

Analysis of microbial gas emissions collected with field chambers were combined with soil genetic and chemical analyses to determine hotspots of greenhouse gas emissions from vegetated cropland, drainage ditch, riparian zone, and wetland habitats in the Tunica and Sunflower Counties of the north Mississippi Delta agricultural region. Methane (CH4) emissions were highest in sites with highest soil moisture (wetlands) and low water flow rates, whereas carbon dioxide (CO2) emission peaked in sites with intermediate soil moisture (riparian zone). Nitrous oxide (N2O) emissions were highest in the cropland and riparian zones, although soil genetic and chemical data suggest a difference in N2O sources between these two sites. Denitrification gene (nosZ) abundances indicate denitrification-derived N2O products in intermittently-flooded sites, while soil [NO3−+NO2−] concentrations suggest nitrification-derived N2O products in dry cultivated sites. Vegetation reduced gas emissions in riparian zone habitat, but had no effect in wetland habitat. Substantial and consistent differences in gas emission rates between two neighboring wetlands corresponded to differences in flow regime. Wetland hydrologic flow regime is the factor regulating the distinct gas emission differences observed between two neighboring wetlands. This study demonstrates the importance of hydrologic factors and location-specific vegetation on gas emission hotspots in this intensively-managed agricultural landscape.

SDS-PAGE Characterisation of Crude Seed and Leaf Proteins in <i>Corchorus</i> Species

Crude protein separation was carried out for Corchorus incisifolious, Corchorus aestuans, Corchorus tridens and Corchorus olitorious using Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Plants were collected both from wild and cultivated sites and samples included leaves and seeds for the electrophoretic study. Distinct polymorphism in electrophoretic banding patterns of seed and leaf proteins following SDS- PAGE was observed in the four Corchorus species studied. Forty- two polypeptide bands were observed in the seed and a total of eleven polypeptide bands were observed in the leaves of the Corchorus species studied. The electrophoretic study revealed protein bands with various intensities ranging from high, to low and faint. The results showed that there was variation in both the seed and leaf proteins of the Corchorus species studied. A dendrogram constructed based on the Single Linkage Cluster Analysis (SLCA) clustering method revealed three major clusters for seeds. Cluster I consisted of C. incisifolious and C. aestuans, cluster II consisted of C. tridens, while cluster III consisted of C. olitorious. The leaf protein extracts were grouped into two clusters, cluster one containing C. incisifolious and C. aestuans, while the other contained C. tridens and C. olitorious.

SDS-PAGE Characterisation of Crude Seed and Leaf Proteins in <i>Corchorus</i> Species

Crude protein separation was carried out for Corchorus incisifolious, Corchorus aestuans, Corchorus tridens and Corchorus olitorious using Sodium Dodecyl Sulphate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). Plants were collected both from wild and cultivated sites and samples included leaves and seeds for the electrophoretic study. Distinct polymorphism in electrophoretic banding patterns of seed and leaf proteins following SDS- PAGE was observed in the four Corchorus species studied. Forty- two polypeptide bands were observed in the seed and a total of eleven polypeptide bands were observed in the leaves of the Corchorus species studied. The electrophoretic study revealed protein bands with various intensities ranging from high, to low and faint. The results showed that there was variation in both the seed and leaf proteins of the Corchorus species studied. A dendrogram constructed based on the Single Linkage Cluster Analysis (SLCA) clustering method revealed three major clusters for seeds. Cluster I consisted of C. incisifolious and C. aestuans, cluster II consisted of C. tridens, while cluster III consisted of C. olitorious. The leaf protein extracts were grouped into two clusters, cluster one containing C. incisifolious and C. aestuans, while the other contained C. tridens and C. olitorious.

Assessing the impact of cultivation and plant domestication of highbush blueberry (Vaccinium corymbosum) on soil properties and associated plant-parasitic nematode communities

We investigated the interactive effects of plant domestication and perennial cultivation on diversity and richness of plant-parasitic nematode (PPN) communities associated with highbush blueberry (Vaccinium corymbosum). Rhizospheric soil of V. corymbosum plants was sampled in coupled wild and cultivated sites within the Pinelands National Reserve. Although PPN diversity was higher in cultivated plant soil samples, richness was higher in wild plant soil samples. The most important soil properties, iron and calcium, were associated with cultivated soil and were the best predictors of genera abundance patterns. Nematodes in the genus Criconemoides were 187× more abundant in wild sites than cultivated and thus, were significant indicators of wild sites. In this study cultivation of V. corymbosum appears to benefit the PPN community but alters the community composition considerably.

Ecological, morphological, and histological studies on Blaps polycresta (Coleoptera: Tenebrionidae) as biomonitors of cadmium soil pollution.

Soil pollution in Egypt became far more serious than before due to either the heavy usage of different toxic pesticides or aerosol deposition of industrial pollutants. The present mentioned ground beetle, Blaps polycresta Tschinkel 1975 (Coleoptera: Tenebrionidae), showed ecological, morphological, and histological alterations in adult insects as biomonitors. Two cultivated sites (reference and polluted) were chosen for sampling the insects. The results indicated a significant increase in soil cadmium concentration of the polluted site leading to sex-specific difference in cadmium accumulation in gonads and alimentary canal of insects that being higher in males than females. The cadmium pollution leads significantly to a decrease in population density, a reduction in body weight, an increase in mortality rate, and an increase in sex ratio of the insects. The results also revealed a striking decrease in body length of the polluted insects with a marked increase in the percentage of deformed gonads and alimentary canal of both sexes. Some histopathological alterations were also recorded in testis, ovary, and midgut of the polluted insects. Our results confirmed that beetles are a good bioindicator for soil pollution, and the different studied parameters could be easily employed as sensitive monitors for cadmium soil pollution.

Plutonium as a tracer for soil erosion assessment in northeast China

Soil erosion is one of the most serious environmental and agricultural problems faced by human society. Assessing intensity is an important issue for controlling soil erosion and improving eco-environmental quality. The suitability of the application of plutonium (Pu) as a tracer for soil erosion assessment in northeast China was investigated by comparing with that of 137Cs. Here we build on preliminary work, in which we investigated the potential of Pu as a soil erosion tracer by sampling additional reference sites and potential erosive sites, along the Liaodong Bay region in northeast China, for Pu isotopes and 137Cs. 240Pu/239Pu atomic ratios in all samples were approximately 0.18, which indicated that the dominant source of Pu was the global fallout. Pu showed very similar distribution patterns to those of 137Cs at both uncultivated and cultivated sites. 239+240Pu concentrations in all uncultivated soil cores followed an exponential decline with soil depth, whereas at cultivated sites, Pu was homogenously distributed in plow horizons. Factors such as planted crop types, as well as methods and frequencies of irrigation and tillage were suggested to influence the distribution of radionuclides in cultivated land. The baseline inventories of 239+240Pu and 137Cs were 88.4 and 1688Bqm−2 respectively. Soil erosion rates estimated by 239+240Pu tracing method were consistent with those obtained by the 137Cs method, confirming that Pu is an effective tracer with a similar tracing behavior to that of 137Cs for soil erosion assessment.

Characterization of Heavy Metal Fractions in Agricultural Soils by Sequential Extraction Procedure: The Relationship Between Soil Properties and Heavy Metal Fractions

The present research was conducted to determine heavy metals in agricultural soils from Çanakkale, Turkey, using a sequential extraction procedure (acid soluble, reducible, oxidizable, and residual) as proposed by the Community Bureau of Reference (BCR) of the European Commission. Soil samples were taken from 12 different cultivated sites and analyzed for Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn concentrations. The results revealed an order of Mn > Cd > Pb > Co > Ni > Cu > Zn > Cr for the heavy metals based on the sum of the first three fractions (acid soluble + reducible + oxidizable). The relationships between soil properties and each metal fraction were identified through Pearsons's correlation analysis. Hierarchical cluster analysis was performed to determine the behaviors and similarities of metals in each fraction. While Mn, Pb, and Zn exhibited subjective behaviors in the acid-soluble fraction, Cd, Co, Cu, Cr, and Ni exhibited similar behaviors with each other.

English

Wetlands provide enormous socioeconomic and environmental values. However, wetlands are threatened by conversion for agricultural land in southwestern Ethiopia. The study aims to assess the impact of wetland cultivation on plant species richness, composition and soil fertility. Plant species richness and composition was investigated for 30 plots in each site of adjacent uncultivated and cultivated wetlands sites and total of 60 sampling plots were used. Soil samples were collected from 18 sample plots (9 in each site) selected using simple random method from plots used for plant survey. The results showed that cultivated sites have significantly higher (P<0.05) species richness, diversity and evenness indices than uncultivated wetlands. Though, this seems positive biological integrity in cultivated site, some ecologically and socioeconomically valuable wetland plant species were lost. Similarity of species (index 30.51%) between two sites was low. Moisture content, clay, organic carbon, total nitrogen, available phosphorous, cation exchange capacity (CEC), exchangeable K+ and Na+ were significantly (P<0.05) lower while silt, pH and electric conductivity (EC) were significantly (P<0.05) higher for cultivated site respect to uncultivated site. However, bulk density, sand, exchangeable Mg2+ and Ca2+ were not significantly (P>0.05) affected. Hence, planning wise use strategy for sustainable management of wetlands is essential.   Key words: Wetland cultivation, species composition, soil physico-chemical properties, South-Bench District.&nbsp