Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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Effects of climate warming on phenological characteristics of urban forest in Shenyang City, China
No full textChange in plant phenology is one of the most sensitive ecological responses to climate warming. Little information is known about the effects of climate warming on phenology of urban tree species in the northern forest of China. In this study, we investigated the phenological characteristics of the main tree species in the urban forest of Shengyang City in China and the correlation between phenology and atmospheric temperature from the discontinuous data during past 42 years over three time periods (from 1962 to 1965, 1977 to 1978, and 2000 to 2005). The results showed that the annual average temperature in Shenyang City showed an increasing trend and increased by 0.96A degrees C from 1962 to 2005 due to climate warming. The germination phenology of the urban trees was negatively correlated with the temperature in winter and early spring. The leafing phenology was mainly influenced by the temperature in spring before leafing. Influenced by climate warming, the germination, leafing, and flowering phenologies of this urban forest in 2005 were 14, 13, and 10 days earlier than those in 1962, respectively. We inferred that further warming in winter might prolong the growing season of urban trees in the northern forest of China
Effects of forest type and urbanization on species composition and diversity of urban forest in Changchun, Northeast China
No full textUrban forest is considered as the most important component of urban green infrastructure and can make vital contributions to urban biodiversity. Understanding the species composition and diversity of urban forest is important for urban biodiversity enrichment. In this study, we evaluated the urban forest woody plant diversity and spatial pattern in Changchun, northeast China. The differentiations in species composition and diversity among types of urban forests and gradients of urbanization were then explored. Principal Component Analysis (PCA) was performed to characterize the species distribution. Similarity Percentage (SIMPER) analysis was adopted to determine the species differentiation and the main contributed species among different urban forest types and different urbanization gradients. The results showed that urban forest species in Changchun were abundant with 88 species that belonged to 50 genera and 24 families. The three major species were Salix matsudana, Populus davidiana, and Pinus sylvestris var. mongolica. Native species were preferred in urban forest of Changchun. Significant differentiations in species composition were observed among different types of urban forests. Attached forest (AF) had the highest species richness and biodiversity, whereas production and management forest (PF) had the lowest ones. SIMPER results showed the highest species dissimilarity between AF and PF and lowest species dissimilarity between AF and landscape and relaxation forest (LF). For different urbanization gradients, species richness and diversity in the third ring were the highest and in the first ring were the lowest. SIMPER results showed the lowest species dissimilarity between the third ring and the fourth ring and highest species dissimilarity between the first ring and the fourth ring. Based on the 10/20/30 "rule of thumb", the diversity must be urgently increased at the species, genus, and family levels for EF and PF. For different urbanization gradients, diversity should be increased at the species level in the first ring and the fifth ring, and should be increased at the family level in the second ring and the fifth ring
Electrokinetic remediation of heavy metals contaminated kaolin by a CNT-covered polyethylene terephthalate yarn cathode
No full textIn the current study, carbon nanotube (CNT) covered polyethylene terephthalate yarns (PET-CNT) electrode has been investigated as a novel cathode material for the electrokinetic (EK) remediation of multi-metals (Cd, Cu, Ni, Pb, Zn) contaminated kaolin. The results of scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) showed that CNT was successfully covered on the surface of PET. The results obtained from EK process showed that PET-CNT as a cathode obviously elevated electric current and electro-osmotic flow (EOF), significantly decreased kaolin pH, and enhanced heavy metals removal efficiencies. The removal efficiencies of Cd, Cu, Ni, Pb, and Zn in PET-CNT treatment were 89.7%, 63.6%, 90.7%, 19.2%, and 88.7%, respectively. In comparison with the Pt/Ti and graphite treatments, the removal efficiencies of Cd, Ni, and Zn were improved at least about 30%, Cu and Pb were improved at least 16.6% and 6.9%, respectively. Our results demonstrated the PET-CNT was a good alternative cathode material for enhancing efficiency of EK remediation. (C) 2016 Elsevier Ltd. All rights reserved
Estimates of recent Hg pollution in Northeast China using peat profiles from Great Hinggan Mountains
No full textOmbrotrophic peatlands are regarded as one of the faithful archives of atmospheric mercury (Hg) deposition, and a large number of studies on Hg accumulation in peatlands have been reported in Europe and North America. Comparatively little information is available about peat chronological records of atmospheric Hg flux in China. We investigated the concentration and historical accumulation rate of Hg (Hg AR) through geochemical analysis of three 210 Pb-dated peat cores from Great Hinggan Mountain, Northeast China. Statistical analysis indicated no significant correlations between peat humification proxies and Hg concentration. The average Hg concentration (13.3 +/- 1.5 mu g kg(-1)) and Hg AR (7.2 +/- 0.9 mu g m(-2) year(-1)) in the pre-1830 peat layers were designated as the pre-industrial, background values. The temporal variations of Hg AR show an obvious peak in 1980 +/- 10, which correspond to periods of specific social activities where heightened Hg pollution was likely. The major peaking period follows a global trend and the decreasing pattern of Hg AR in the last two decades might be likely due to the increasingly intense global environmental regulation on Hg emission
Evaluating the Effectiveness of Conservation on Mangroves: A Remote Sensing-Based Comparison for Two Adjacent Protected Areas in Shenzhen and Hong Kong, China
No full textMangroves are ecologically important ecosystems and globally protected. The purpose of this study was to evaluate the effectiveness of mangrove conservation efforts in two adjacent protected areas in China that were under the management policies of the Ramsar Convention (Mai Po Marshes Nature Reserve (MPMNR), Hong Kong) and China's National Nature Reserve System (Futian Mangrove National Nature Reserve (FMNNR), Shenzhen). To achieve this goal, eleven Landsat images were chosen and classified, areal extent and landscape metrics were then calculated. The results showed that: from 1973-2015, the areal extent of mangroves in both reserves increased, but the net change for the MPMNR (281.43 hm(2)) was much higher than those of the FMNNR (101.97 hm(2)). In general, the area-weighted centroid of the mangroves in FMNNR moved seaward by approximately 120 m, whereas in the MPMNR, the centroid moved seaward even farther (410 m). Although both reserves saw increased integrality and connectivity of the mangrove patches, the patches in the MPMNR always had higher integrality than those in the FMNNR. We concluded that the mangroves in the MPMNR were more effectively protected than those in the FMNNR. This study may provide assistance to the formulation of generally accepted criteria for remote sensing-based evaluation of conservation effectiveness, and may facilitate the development of appropriate mangrove forest conservation and management strategies in other counties
Mesoplophoroidea (Acari, Oribatida) of China
No full textThe oribatid mite superfamily Mesoplophoroidea (Acari, Oribatida) is reviewed. Seven species in four genera of Mesoplophoroidea from China, including a new species, Mesoplophora (Mesoplophora) heterotricha sp. nov. from Hainan Province, are identified. Tritonymph of Apoplophora pantotrema (Berlese, 1913) is described based on material from China. A comprehensive, fully referenced checklist of all known species and keys to all known species worldwide are provided to facilitate the further study on this group
Methane emissions from created and restored freshwater and brackish marshes in southwest Florida, USA
No full textIt is important to estimate greenhouse gas emissions from newly created and restored wetlands so that we learn how to design them to minimize these emissions. Spatial and temporal patterns of methane emissions were measured in three wetland marsh complexes in southwest Florida: a created freshwater marsh on a university campus, a restored brackish/salt marsh on the fringe of a mangrove (Rhizophora mangle) coastal swamp; and a natural freshwater marsh adjacent to a cypress (Taxodium distichum) strand. Non steady -state rigid chambers were used twice a day (morning and afternoon) on a monthly schedule for 13 months. The mean +/- standard error (median) of methane emissions from permanently and intermittently flooded areas were 124 +/- 47 (0) and 0.8 +/- 0.7 (0) g-CH4-C m(-2) y(-1) in the created freshwater marsh, and 58 +/- 14 (9.4) and 0.1 +/- 0.3 (0) g-CH4-C m(-2) y(-1) in the restored brackish marsh. Methane missions were 0.8 +/- 0.5 (0) g-CH4-C M-2 y(-1) in the intermittently flooded natural freshwater marsh that served as our control. In general, average methane emissions were higher from permanently than intermittently flooding areas (P 0.05). CH4 emissions exhibited strong quadratic and linear relationships with water depth when all sites were compared (P< 0.05), but no significant relationships with soil temperature or salinity. These results give useful information on ways to minimize methane emissions when creating and restoring wetlands. But these results should be only one of the considerations for wetland design as other ecosystem services should also be considered. (C) 2016 Elsevier B.V. All rights reserved
Optimizing the freezing rate for ovine semen cryopreservation: Phospholipid profiles and functions of the plasma membrane and quality and fertilization of spermatozoa
No full textThe objective of this study was to investigate the effects of freezing rate on plasma membrane (PM) phospholipids and the function and fertilization of ram spermatozoa during freezing. Semen was obtained from 10 Merino rams using an artificial vagina, diluted with glucose-egg yolk buffer, and frozen in a programmable freezer at rates of -1, -20, -40, -60, and -80 degrees C/min. After thawing, we examined PM phospholipid content and distribution, fluidity, permeability, potential, spermatozoa quality, and in vivo and in vitro fertilization rates. The results showed that phospholipid, phosphatidylserine (PS), phosphatidylethanolamine (PE), and phosphatidylglycerol (PG) contents of the PM decreased significantly (P 0.05), whereas cleavage rate (69.67 +/- 5.11%) at -40 degrees C/min increased significantly (P < 0.05). Therefore, the optimal freezing rate to cryopreserve ram spermatozoa based on cryoinjury of phospholipids, membrane functions, and fertilization rate was -40 degrees C/min. (C) 2016 Published by Elsevier B.V
Preparation and Application of a Xanthate-Modified Thiourea Chitosan Sponge for the Removal of Pb(II) from Aqueous Solutions
No full textAs chitosan has low uptake for Pb(II) and high solubility in monoprotic acids, a simple procedure using nontoxic chitosan as a precursor at room temperature was developed to prepare a xanthate-modified thiourea chitosan sponge (XTCS) by lyophilization for enhancing Pb(II) removal in water. The sponge structure of XTCS improved both stability and separation performance. Adsorption results showed that pH markedly affected the adsorption performance of XTCS. The adsorption process attained equilibrium in 45 min with a maximum adsorption capacity of 188.04 mg g(-1) at room temperature. The pseudo second -order kinetic equation and Langmuir isotherm model were suitable to describe the adsorption behavior of XTCS. The physicochemical characteristics of XTCS were investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that Pb(II) removal mechanism of XTCS was mainly dependent on complexations of sulfur and nitrogen atoms and ion exchange
Responses of ammonia-oxidizing bacterial communities to land-use and seasonal changes in Mollisols of Northeast China
No full textIn this study, AOB community was investigated over a 2-year period in cultivated Mollisols (0-20 cm) with three fertilizer treatments [no fertilizer (NoF), chemical fertilizer (CF) and chemical fertilizer plus manure (CFM)] and in an adjacent plot under natural restoration (NR). The crop rotation of maize, soybean and wheat was repeated every three years. The NR plot was abandoned agricultural land that was naturally revegetated with grasses. The AOB communities were characterized by clone sequencing of amoA gene targets, which encode ammonia monooxygenase subunit A. Phylogenetic analyses showed that the AOB communities in the Mollisols of Northeast China were related to defined groups, including clusters 1, 2, 3a, 3b, 9, and 10 in Nitrosospira and cluster 7 in Nitrosomonas. Nitrosospira cluster 3 was the most frequently recovered AOB in all treatments, and cluster 3a.2 and 3a.2-related sequences were common in cultivated soils. However, 12-27% of sequences were not related to any known AOB species, indicating a high diversity of AOB communities in Mollisols. There was a distinct AOB community in the NR plot and the cultivated plots, consistent with the hypothesis that land-use alters AOB community, and this appeared to be related to the soil pH. Cultivated soils with added N fertilizer had a greater frequency of clones in the Nitrosospira cluster 10 sequence type, but suppressed clones in the Nitrosospira cluster 3a.1 sequence type, whereas Nitrosomonas sequences were only recovered from the CFM treatment. The AOB clone frequency differed between the growing and non-growing seasons, possibly because the AOB communities were favoured by warm, moist soil conditions or the active plant rhizosphere during the growing season. The ecological implications of land-use change and seasonality on the contribution of these diverse AOB communities to primary production in Mollisols merits further attention. (C) 2016 Elsevier Masson SAS. All rights reserved