Northeast Institute of Geography and Agroecology, Chinese Academy Of Sciences
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Comparison of object-based and pixel-based Random Forest algorithm for wetland vegetation mapping using high spatial resolution GF-1 and SAR data
No full textVegetation is an integral component of wetland ecosystems. Mapping distribution, quality and quantity of wetland vegetation is important for wetland protection, management and restoration. This study evaluated the performance of object-based and pixel-based Random Forest (RF) algorithms for mapping wetland vegetation using a new Chinese high spatial resolution Gaofen-1 (GF-1) satellite image, L-band PALSAR and C-band Radarsat-2 data. This research utilized the wavelet-principal component analysis (PCA) image fusion technique to integrate multispectral GF-1 and synthetic aperture radar (SAR) images. Comparison of six classification scenarios indicates that the use of additional multi-source datasets achieved higher classification accuracy. The specific conclusions of this study include the followings:(1) the classification of GF-1, Radarsat-2 and PALSAR images found statistically significant difference between pixel-based and object-based methods; (2) object-based and pixel-based RF classifications both achieved greater 80% overall accuracy for both GF-1 and GF-1 fused with SAR images; (3) object-based classifications improved overall accuracy between 3%-10% in all scenarios when compared to pixel-based classifications; (4) object-based classifications produced by the integration of GF-1, Radarsat-2 and PALSAR images outperformed any of the lone datasets, and achieved 89.64% overall accuracy. (C) 2016 Elsevier Ltd. All rights reserved
Bacterial communities incorporating plant-derived carbon in the soybean rhizosphere in Mollisols that differ in soil organic carbon content
No full textA primary factor regulating the composition of the microbial community in the rhizosphere is carbon (C) efflux from root systems, which fundamentally influences microbial functions in the rhizosphere, such as biodegradation, plant growth, and rhizosphere signalling. However, information regarding the incorporation of plant-C by the bacterial community in the rhizosphere is limited, particularly in soybean. Soybean plants were grown in rhizo-boxes containing low-or high-organic C (C-org) Mollisols and labelled with (CO2)-C-13 at the flowering stage. After soil DNA was extracted from the rhizosphere, C-13-DNA was separated from C-12-DNA using the stable isotope probing method, followed by pyrosequencing analysis. Between soils, significant differences in the abundance of genera incorporating C-13 in the rhizosphere were observed, with Aquincola, Dechloromonas, Massilia, Amycolatopsis, Delftia, Magnetospirillum, Psychrobacter, Ochrobactrum, Pseudoxanthomonas and Niastella showing greater relative abundances in low-C-org soil (p < 0.05) compared to high-C-org soil. However, the opposite trend was observed for Enhydrobacter, Flavisolibacter, Propionibacterium and Staphylococcus. Correspondingly, the number of operational taxonomic units in each genus varied between soils. Soil type greatly affected the flow of plant-C into rhizospheric bacterial community. The plant-C metabolizing bacteria may contribute to the transformation of rhizodeposits in the soil and soil C sequestration
Long-term biochar application influences soil microbial community and its potential roles in semiarid farmland
No full textBiochar addition to soil can change soil physicochemical properties, resulting in a shift of the soil microbial community. However, it is uncertain how long-term biochar application affects the soil microbial community and diversity in drylands. To determine the underlying mechanism, a 3.5-year spring maize (Zea mays L.) field experiment with biochar applications was conducted to elucidate the effect of biochar on soil microbial abundance and community composition as well as its potential applications in drylands of the Loess Plateau in Northwest China. Soil samples from a 0-20 cm depth for four biochar treatments, including 0 (CO, as the control), 10 (C10), 30 (C30) and 50 (C50) t ha(-1), were examined using phospholipid fatty acid (PLFA) analysis. It was found that the proportion of arbuscular mycorrhizal fungi (AMF) and the ratio of AMF/saprotrophic fungi (SF) correlated with the biochar levels, for example, the C30 treatment significantly decreased the absolute SF but increased the ratio of AMF/SF. Especially, both the AMF/SF and Fungi/Bacteria ratios were significantly increased in the C50 treatment, suggesting that high amounts of biochar could increase fungal rather than bacterial diversity. In addition, soil organic C (SOC) (P < 0.01), KMnO4-oxidizable C (KMnO4-C) (P < 0.01), and the C management index (CMI) (P < 0.01) were confirmed to play significant roles in shaping the soil microbial community composition. SOC and total N were significantly increased by biochar application, and total P was increased in the C30 treatment. However, compared with the CO treatment, the C50 treatment significantly decreased KMnO4-C and the CMI, suggesting the proper level of biochar addition to soil should be considered for the improvement of soil organic materials. Accordingly, biochar application at 30 t ha(-1), which was connected with a decreased absolute SF and an increased AMF/SF ratio, could be a choice for improving soil quality and nutrient availability in semiarid farmland
Identification of ZOUPI Orthologs in Soybean Potentially Involved in Endosperm Breakdown and Embryogenic Development
No full textSoybean (Glycine max Merr.) is the world's most widely grown legume and provides an important source of protein and oil. Improvement of seed quality requires deep insights into the genetic regulation of seed development. The endosperm serves as a temporary source of nutrients that are transported from maternal to filial tissues, and it also generates signals for proper embryo formation. Endosperm cell death is associated with the processes of nutrient transfer and embryo expansion. The bHLH domain transcription factor AtZHOUPI (AtZOU) plays a key role in both the lysis of the transient endosperm and the formation of embryo cuticle in Arabidopsis thaliana. There are two copies of soybean GmZOU (GmZOU-1 and GmZOU-2), which fall into the same phylogenetic clade as AtZOU. These two copies share the same transcription orientation and are the result of tandem duplication. The expression of GmZOUs is limited to the endosperm, where it peaks during the heart embryo stage. When the exogenous GmZOU-1 and GmZOU-2 were expressed in the zou-4 mutant of Arabidopsis, only GmZOU-1 partially complemented the zou mutant phenotype, as indicated by endosperm breakdown and embryo cuticle formation in the transgenic lines. This research confirmed that the GmZOU-1 is a ZOU ortholog that may be responsible for endosperm breakdown and embryo cuticle formation in soybean
The spatiotemporal variation analysis of virtual water for agriculture and livestock husbandry: A study for Jilin Province in China
No full textWith the rapid development of economic, water crisis is becoming more and more serious and would be an important obstacle to the sustainable development of society. Virtual water theory and its applications in agriculture can provide important strategies for realizing the reasonable utilization and sustainable development of water resources. Using the Penman-Monteith model and Theil index combining the CROPWAT software, this work takes Jilin Province as study area quantifying the virtual water content of agriculture and livestock husbandry and giving a comprehensive evaluation of their spatiotemporal structure evolution. This study aims to help make clear the water consumption of agriculture and livestock husbandry, and offer advice on rational water utilization and agricultural structure adjustment. The results show that the total virtual water (TVW) proportion of agriculture presents a gradual growth trend While that of livestock husbandry reduces during the study period. In space, central Jilin shows the highest virtual water content of agriculture as Well as livestock husbandry, the TVW in central Jilin is about 35.8 billion m(3). The TVW of maize is highest among six studied crops, and the cattle shows the highest TVW in the four kinds of animals. The distribution of TVW calculated by us and the distribution of actual water resources have remarkable difference, which leads to the increase of water consumption and cost of agricultural production. Finally, we discuss the driving force of the spatiotemporal variation of the TVW for agriculture and livestock husbandry, and also give some advises for the planting structural adjustment. This work is helpful for the sustainable development of agricultural and livestock husbandry and realizing efficient utilization of water resources. (C) 2017 Elsevier B.V. All rights reserved
Microbial association with the dynamics of particulate organic carbon in response to the amendment of elevated CO2-derived wheat residue into a Mollisol
No full textAs the chemical quality of crop residue is likely to be affected by elevated CO2 (eCO(2)), residue amendments may influence soil organic carbon (SOC) sequestration. However, inMollisols, the dynamics of the SOC fractions in response to amendment with wheat residue produced under eCO(2) and the corresponding microbial community composition remain unknown. Such investigation is essential to residuemanagement, which affects the soil quality and productivity of future farming systems. To narrowthis knowledge gap, C-13-labeled shoot and root residue derived fromambient CO2 (aCO(2)) or eCO(2) were amended intoMollisols and incubated for 200 days. The soil was sampled during the incubation period to determine the residue-C retained in the three SOC fractions, i. e., coarse intra-aggregate particulate organic C (coarse iPOC), fine iPOC and mineral-associated organic C (MOC). The soil bacterial community was assessed using a MiSeq sequencing instrument. The results showed that the increase in SOC concentrations attributable to the application of the wheat residue primarily occurred in the coarse iPOC fraction. Comparedwith the aCO(2)-derived shoot residue, the amendment of eCO(2)-derived shoot residue resulted in greater SOC concentrations, whereas no significant differences (P > 0.05) were observed between the aCO(2)-and eCO(2)-derived roots. Principal coordinates analysis (PCoA) showed that the residue amendment significantly (P <= 0.05) altered the bacterial community composition comparedwith the non-residue amendment. Additionally, the bacterial community in the aCO(2)-derived shoot treatment differed from those in the other residue treatments until day 200 of the incubation period. The eCO(2)-derived shoot treatment significantly increased (P <= 0.05) the relative abundances of the genera Acidobacteriaceae_(Subgroup_1)_ uncultured, Bryobacter, Candidatus_Solibacter, Gemmatimonas and Nitrosomonadaceae_uncultured, whereas the opposite trend was observed in Nonomuraea, Actinomadura, Streptomyces and Arthrobacter (P <= 0.05). These results imply that the response of the microbial community to the eCO(2)-derived shoot treatment is associated with its contribution to the POC fractions. (C) 2017 Elsevier B.V. All rights reserved
Thin ferrihydrite sediment capping sequestrates phosphorus experiencing redox conditions in a shallow temperate lacustrine wetland
No full textSynthesized ferrihydrite (Fh) with the dosages of 0.3, 0.6 and 0.9 cm thickness (labeled as Fh, 2Fh and 3Fh respectively, equivalent to 248-774 g/m(2)) were deployed to serve as the reactive capping layer covering the Ornamental Lake sediments, the Royal Botanic Garden of Melbourne. The sediments were exposed to an alternating regime of oxic/anoxic conditions using laboratory reactors for 45 days. Dynamics of disSolved oxygen (DO), pH, filterable reactive phosphorus (FRP), filterable ammonium (NHS'), nitrate and nitrite (NOx), total dissolved nitrogen (TDN) and dissolved iron (Fe) of overlying water were examined. After incubation, O-2 and H2S profiles across the water-sediment interface were observed with microelectrodes. The element distributions in the upper sediments were tested as well. Results showed that DO and pH kept relatively stable during oxic period, while decreased significantly during anoxic period. Fh cappings decreased both DO and pH, and inhibited the release of FRP. No significant increments of FRP in overlying waters were observedduring anoxic period. Fh cappings prompted the releases of NH4+ and TDN, while inhibited that of NO(x center dot)NH(4)(+)increased while NOx decreased during anoxic period. Fe(II) and TFe increased only in 3Fh, especially during anoxic conditions. Fh cappings increased O-2 and H2S concentrations across the water-sediment interfaces. TP and TN in the sediments decreased after capping, while TFe increased significantly. We concluded that 0.6 cm thickness of (496 g/m(2)) Fh capping could sequestrate P, even experiencing redox conditions. (C) 2017 Elsevier Ltd. All rights reserved
Local PM10 and PM2.5 emission inventories from agricultural tillage and harvest in northeastern China
No full textMineral particles or particulate matters (PMs) emitted during agricultural activities are major recurring sources of atmospheric aerosol loading. However, precise PM inventory from agricultural tillage and harvest in agricultural regions is challenged by infrequent local emission factor (EF) measurements. To understand PM emissions from these practices in northeastern China, we measured EFs of PM10 and PM2.5 from three field operations (i.e., tilling, planting and harvesting) in major crop production (i.e., corn and soybean), using portable real-time PM analyzers and weather station data. County-level PM10 and PM2.5 emissions from agricultural tillage and harvest were estimated, based on local EFs, crop areas and crop calendars. The EFs averaged (107 +/- 27), (17 +/- 5) and 26 mg/m(2) for field tilling, planting and harvesting under relatively dry conditions (i.e., soil moisture <15%), respectively. The EFs of PM from field tillage and planting operations were negatively affected by topsoil moisture. The magnitude of PM10 and PM2.5 emissions from these three activities were estimated to be 35.1 and 9.8 kilotons/yr in northeastern China, respectively, of which Heilongjiang Province accounted for approximately 45%. Spatiotemporal distribution showed that most PM10 emission occurred in April, May and October and were concentrated in the central regions of the northeastern plain, which is dominated by dryland crops. Further work is needed to estimate the contribution of agricultural dust emissions to regional air quality in northeastern China. (C) 2016 The Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V