scholarly journals Remotely monitoring ecosystem respiration from various grasslands along a large-scale east–west transect across northern China

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Xuguang Tang ◽  
Yanlian Zhou ◽  
Hengpeng Li ◽  
Li Yao ◽  
Zhi Ding ◽  
...  
Keyword(s):  
Large Scale ◽  
Ecosystem Respiration ◽  
Northern China ◽  
East West

Late-summer carbon fluxes from Canadian forests and peatlands along an east–west continental transect

2006 ◽  
Vol 36 (3) ◽  
pp. 783-800 ◽  
Author(s):  
Carole Coursolle ◽  
Hank A Margolis ◽  
Alan G Barr ◽  
T Andrew Black ◽  
Brian D Amiro ◽  
...  
Keyword(s):  
Large Scale ◽  
Ecosystem Respiration ◽  
Late Summer ◽  
Ecosystem Productivity ◽  
Diurnal Courses ◽  
Continental Scale ◽  
Young Forest ◽  
C Cycle ◽  
Use Efficiency ◽  
East West

Net ecosystem productivity (NEP) during August 2003 was measured by using eddy covariance above 17 forest and 3 peatland sites along an east–west continental-scale transect in Canada. Measured sites included recently disturbed stands, young forest stands, intermediate-aged conifer stands, mature deciduous stands, mature conifer stands, fens, and an open shrub bog. Diurnal courses of NEP showed strong coherence within the different ecosystem categories. Recently disturbed sites showed the weakest diurnal cycle; and intermediate-aged conifers, the strongest. The western treed fen had a more pronounced diurnal pattern than the eastern shrub bog or the Saskatchewan patterned fen. All but three sites were clearly afternoon C sinks. Ecosystem respiration was highest for the young fire sites. The intermediate-aged conifer sites had the highest maximum NEP (NEPmax) and gross ecosystem productivity (GEPmax), attaining rates that would be consistent with the presence of a strong terrestrial C sink in regions where these types of forest are common. These results support the idea that large-scale C cycle modeling activities would benefit from information on the age-class distribution and disturbance types within larger grid cells. Light use efficiency followed a pattern similar to that of NEPmax and GEPmax. Four of the five recently disturbed sites and all three of the peatland sites had low water use efficiencies.

scholarly journals Farm Size, Risk Aversion and Overuse of Fertilizer: The Heterogeneity of Large-Scale and Small-Scale Wheat Farmers in Northern China

Land ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 111
Author(s):  
Haixia Wu ◽  
Hantao Hao ◽  
Hongzhen Lei ◽  
Yan Ge ◽  
Hengtong Shi ◽  
...  
Keyword(s):  
Risk Aversion ◽  
Large Scale ◽  
Northern China ◽  
Fertilizer Application ◽  
Chemical Fertilizer ◽  
Farm Size ◽  
Small Scale ◽  
Fertilizer Use ◽  
Deviation Degree ◽  
Small Scale Farmers

The excessive use of fertilizer has resulted in serious environmental degradation and a high health cost in China. Understanding the reasons for the overuse of fertilizer is critical to the sustainable development of Chinese agriculture, and large-scale operation is considered as one of the measures to deal with the excessive fertilizer use. Under the premise of fully considering the resource endowment and heterogeneity of large-scale farmers and small-scale farmers in production and management, different production decision-making frameworks were constructed. Based on the 300 large-scale farmers and 480 small-scale farmers in eight provinces of northern China wheat region, we analyzed the optimal fertilizer use amount and its deviation as well as the influencing factors of small-scale and large-scale farmers, then further clarified whether the development of scale management could solve the problem of excessive fertilizer use. The empirical results show that: (1) both small-scale farmers and large-scale farmers deviated from the optimal fertilizer application amount, where the deviation degree of optimal fertilizer application of small-scale farmers is significantly higher than that of large-scale farmers, with a deviation degree of 35.43% and 23.69% for small and large scale farmers, respectively; (2) not all wheat growers in North China had the problem of excessive use of chemical fertilizer, as the optimal level of chemical fertilizer application in Heilongjiang and Inner Mongolia are 346.5 kgha−1 and 335.25 kgha−1, while the actual fertilizer use amount was 337.2 kgha−1 and 324.6 kgha−1, respectively; and (3) the higher the risk aversion level, farmers tended to apply more fertilizer to ensure grain output. Therefore, increasing farm size should be integrated into actions such as improving technological innovation and providing better information transfer to achieve the goal of zero-increase in Chinese fertilizer use.

Large-scale hybrid accidental urban wetland for polluted river purification in northern China: Evidence and implications for urban river management

2021 ◽  
Vol 22 ◽  
pp. 101542 ◽  
Author(s):  
Mathieu Nsenga Kumwimba ◽  
Xinzhu Li ◽  
Wei wang ◽  
L.H.D.K.U. De Silva ◽  
Linlin Bao ◽  
...  
Keyword(s):  
Large Scale ◽  
Northern China ◽  
River Management ◽  
Urban River ◽  
Polluted River ◽  
Urban Wetland

Carbon Footprint Assessment of a Large-Scale Pig Production System in Northern China: A Case Study

2018 ◽  
Vol 61 (3) ◽  
pp. 1121-1131 ◽  
Author(s):  
Yuanqing Zhou ◽  
Hongmin Dong ◽  
Hongwei Xin ◽  
Zhiping Zhu ◽  
Wenqiang Huang ◽  
...  
Keyword(s):  
Large Scale ◽  
Ghg Emissions ◽  
Northern China ◽  
Manure Management ◽  
Traditional Practice ◽  
Enteric Fermentation ◽  
Pig Production ◽  
Transport Distance ◽  
Feed Production ◽  
Crop Planting

Abstract. China raises 50% of global live pigs. However, few studies on the carbon footprint (CF) of large-scale pig production based on China’s actual production conditions have been carried out. In this study, life cycle assessment (LCA) and actual production data of a typical large-scale pig farm in northern China were used to assess the greenhouse gas (GHG) emissions or CF associated with the whole process of pig production, including feed production (crop planting, feed processing, and transportation), enteric fermentation, manure management, and energy consumption. The results showed a CF of 3.39 kg CO2-eq per kg of live market pig and relative contributions of 55%, 28%, 13%, and 4% to the total CF by feed production, manure management, farm energy consumption, and enteric fermentation, respectively. Crop planting accounted for 66% of the feed production CF, while feed processing and transportation accounted for the remaining 34%. Long-distance transport of semi-raw feed materials caused by planting-feeding separation and over-fertilization in feed crop planting were two main reasons for the largest contribution of GHG emissions from feed production to the total CF. The CF from nitrogen fertilizer application accounted for 33% to 44% of crop planting and contributed to 16% of the total CF. The CF from the transport of feed ingredients accounted for 17% of the total CF. If the amount of nitrogen fertilizer used for producing the main feed ingredients is reduced from 209 kg hm-2 (for corn) and 216 kg hm-2 (for wheat) to 140 kg hm-2 (corn) and 180 kg hm-2 (wheat), the total CF would be reduced by 7%. If the transport distance for feed materials decreased from 325 to 493 km to 30 km, along with reducing the number of empty vehicles for transport, the total CF would be reduced by 18%. The combined CF mitigation potential for over-fertilization and transport distance is 26%. In addition, the use of pit storage, anaerobic digestion, and lagoon for manure management can reduce GHG emissions from manure management by 76% as compared to the traditional practice of pit storage and lagoon. This case study reveals the impact of planting-feeding separation and over-fertilization on the CF of the pig supply chain in China. The manure management practice of pit storage, anaerobic digestion, and lagoon is much more conductive to reducing the CF as compared to the traditional practice of pit storage and lagoon. Keywords: Greenhouse gas, Life cycle assessment, Mitigation, Pig.

scholarly journals Upside-down fluxes Down Under: CO<sub>2</sub> net sink in winter and net source in summer in a temperate evergreen broadleaf forest

2018 ◽  
Vol 15 (12) ◽  
pp. 3703-3716 ◽  
Author(s):  
Alexandre A. Renchon ◽  
Anne Griebel ◽  
Daniel Metzen ◽  
Christopher A. Williams ◽  
Belinda Medlyn ◽  
...  
Keyword(s):  
Large Scale ◽  
Vegetation Index ◽  
Ecosystem Respiration ◽  
Vapour Pressure Deficit ◽  
Summer Rainfall ◽  
Mean Annual Precipitation ◽  
Surface Conductance ◽  
Mean Annual Temperature ◽  
Eddy Covariance Method ◽  
Area Index

Abstract. Predicting the seasonal dynamics of ecosystem carbon fluxes is challenging in broadleaved evergreen forests because of their moderate climates and subtle changes in canopy phenology. We assessed the climatic and biotic drivers of the seasonality of net ecosystem–atmosphere CO2 exchange (NEE) of a eucalyptus-dominated forest near Sydney, Australia, using the eddy covariance method. The climate is characterised by a mean annual precipitation of 800 mm and a mean annual temperature of 18 ∘C, hot summers and mild winters, with highly variable precipitation. In the 4-year study, the ecosystem was a sink each year (−225 g C m−2 yr−1 on average, with a standard deviation of 108 g C m−2 yr−1); inter-annual variations were not related to meteorological conditions. Daily net C uptake was always detected during the cooler, drier winter months (June through August), while net C loss occurred during the warmer, wetter summer months (December through February). Gross primary productivity (GPP) seasonality was low, despite longer days with higher light intensity in summer, because vapour pressure deficit (D) and air temperature (Ta) restricted surface conductance during summer while winter temperatures were still high enough to support photosynthesis. Maximum GPP during ideal environmental conditions was significantly correlated with remotely sensed enhanced vegetation index (EVI; r2 = 0.46) and with canopy leaf area index (LAI; r2 = 0.29), which increased rapidly after mid-summer rainfall events. Ecosystem respiration (ER) was highest during summer in wet soils and lowest during winter months. ER had larger seasonal amplitude compared to GPP, and therefore drove the seasonal variation of NEE. Because summer carbon uptake may become increasingly limited by atmospheric demand and high temperature, and because ecosystem respiration could be enhanced by rising temperatures, our results suggest the potential for large-scale seasonal shifts in NEE in sclerophyll vegetation under climate change.

Satellite-based large-scale vegetation dynamics in ecological restoration programmes of Northern China

2018 ◽  
Vol 40 (5-6) ◽  
pp. 2296-2312 ◽  
Author(s):  
Zhitao Wu ◽  
Lu Yu ◽  
Xiaoyu Zhang ◽  
Ziqiang Du ◽  
Hong Zhang
Keyword(s):  
Ecological Restoration ◽  
Vegetation Dynamics ◽  
Large Scale ◽  
Northern China

scholarly journals Changes in Air Pollution Following the COVID-19 Epidemic in Northern China: The Role of Meteorology

2021 ◽  
Vol 9 ◽  
Author(s):  
Tian Xian ◽  
Zhanqing Li ◽  
Jing Wei
Keyword(s):  
Air Pollution ◽  
Large Scale ◽  
Human Life ◽  
Northern China ◽  
Control Measures ◽  
Economic Activities ◽  
Low Wind Speed ◽  
Seasonal Signals ◽  
Haze Formation ◽  
Holiday Effects

COVID-19 has a tremendous impact on both human life and the environment due to the unprecedented large-scale shutdown of economic activities at the beginning of 2020. While it was widely expected to see a dramatic reduction in air pollution, reality appears to be much more complex due to the joint influences of emissions and meteorology in dictating air pollution. By analyzing ample meteorological and environmental observational data, this study attempts to evaluate the contribution of an economic lockdown or at a well-below normal level across China to air pollution during the COVID-19 pandemic in the Beijing-Tianjin-Hebei region. Besides the unprecedented emission reductions that helped to improve air quality, multiple other factors came into play, such as high humidity and low wind speed that are favorable for haze formation. After separating long-term trends, seasonal signals, holiday effects, and meteorological contributions concerning climatology, we estimated that the relative contributions of human activities to changes in particulate matter with a diameter of less than 2.5 μm and nitrogen dioxide during the epidemic were −17.13 μg/m3 and −0.03 μg/m3, respectively, with negative quantities denoting reductions to air pollution. Furthermore, comparing the changes in PM2.5 and NO2 concentrations after lockdown revealed that for short-term control measures, meteorological factors mainly affected pollutant particles.

scholarly journals Quantifying Horizontal and Vertical Movements in Ho Chi Minh City by Sentinel-1 Radar Interferometry

2020 ◽  
Author(s):  
Dinh Ho Tong Minh ◽  
Yen-Nhi NGO ◽  
Thu Trang Lê ◽  
Trung Chon Le ◽  
Hong Son Bui ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
European Space Agency ◽  
Ground Subsidence ◽  
Ho Chi Minh City ◽  
Vertical Movements ◽  
Space Agency ◽  
Permanent Scatterers ◽  
The City ◽  
East West

Ho Chi Minh City (HCMC), the most populous city and the economic center of Viet Nam, has faced ground subsidence in recent decades. This work aims at providing an unprecedented spatial extent coverage of the subsidence in HCMC in both horizontal and vertical components using Interferometric Synthetic Aperture Radar (InSAR) time series. For this purpose, an advanced InSAR technique PSDS (Permanent Scatterers and Distributed Scatterers) was applied to two big European Space Agency (ESA) Sentinel-1 datasets composed of 96 ascending and 202 descending images, acquired from 2014 to 2020 over HCMC area. A time series of 33 Cosmos SkyMED images was also used for comparison purpose. The combination of ascending and descending satellite passes allows the decomposition of the light of sight velocities into horizontal East-west and vertical components. By taking into account the presence of the horizontal East-west movement, our finding indicates that the precision of the decomposed vertical velocity can be improved up to 3 mm/year for Sentinel-1 data. The obtained results revealed that subsidence is most severe in areas along the Sai Gon river in the northwest-southeast axis and the southwest of the city with the maximum value up to 80 mm/year, consistent with findings in the literature. The magnitude of horizontal East-West velocities is relatively small and a large-scale westward motion can be observed in the northwest of the city at a rate of 2-5 mm/year. Together, these results reinforced the remarkable suitability of ESA's Sentinel-1 SAR for subsidence applications even for non-Europe countries such as Vietnam and Southeast Asia.

scholarly journals A Multi-Site Evaluation of Winter Hardiness in Indigenous Alfalfa Cultivars in Northern China

Atmosphere ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1538
Author(s):  
Lijun Xu ◽  
Qian Liu ◽  
Yingying Nie ◽  
Feng Li ◽  
Guixia Yang ◽  
...  
Keyword(s):  
Large Scale ◽  
Production Systems ◽  
Comprehensive Evaluation ◽  
Perennial Grass ◽  
Cropping System ◽  
Northern China ◽  
Winter Hardiness ◽  
Grass Species ◽  
Average Score ◽  
Field Evidence

Integration of perennial grass species into the current food production systems, especially in the agropastoral regions worldwide, may produce multiple benefits including, among others, a more stable productivity and a smaller eco-environmental footprint. However, one of the fundamental challenges facing the large-scale adoption of such grass species is their ability to withstand the vagaries of winter in these regions. Here, we present a comprehensive evaluation of the winter hardiness of 50 indigenous Chinese cultivars of alfalfa, a high-quality leguminous perennial grass, in comparison with six introduced U.S. cultivars in a multi-site field experiment in northern China. Our results reveal that indigenous cultivars have stronger winter hardiness than introduced cultivars. Cultivars native in the north performed better than southern cultivars, suggesting that suitability evaluation is an unavoidable step proceeding any regional implementations. Our results also show that the metric we used to assess alfalfa’s winter hardiness, the average score index (ASI), produced more consistent results than another more-widely used metric of winter survival rate (WSR). These findings offer a systematic field evidence that supports regional cropping system adjustment and production system betterment to ensure food security under climate change in the region and beyond.

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