scholarly journals Spatio-Temporal Variations of Carbon Use Efficiency in Natural Terrestrial Ecosystems and the Relationship with Climatic Factors in the Songnen Plain, China

2019 ◽  
Vol 11 (21) ◽  
pp. 2513 ◽  
Author(s):  
Bo Li ◽  
Fang Huang ◽  
Lijie Qin ◽  
Hang Qi ◽  
Ning Sun
Keyword(s):  
Primary Productivity ◽  
Land Surface ◽  
Climatic Factors ◽  
Transitional Region ◽  
Songnen Plain ◽  
Natural Ecosystems ◽  
Land Surface Phenology ◽  
Carbon Use Efficiency ◽  
Use Efficiency ◽  
The Impact

The Songnen Plain (SNP) is an important grain production base, and is designated as an ecological red-line as a protected area in China. Natural ecosystems such as the ecological protection barrier play an important role in maintaining the productivity and sustainability of farmland. Carbon use efficiency (CUE), defined as the ratio of net primary productivity (NPP) to gross primary productivity (GPP), represents the ecosystem capacity of transferring carbon from the atmosphere to terrestrial biomass. The understanding of the CUE of natural ecosystems in protected farmland areas is vital to predicting the impact of global change and human disturbances on carbon budgets and evaluating ecosystem functions. To date, the changes in CUE at different time scales and their relationships with climatic factors have yet to be fully understood. CUE and the response to land surface phenology are also deserving attention. In this study, variations in ecosystem CUE in the SNP during 2001–2015 were investigated using Moderate-Resolution Imaging Spectroradiometer (MODIS) GPP and NPP data products estimated using the Carnegie-Ames-Stanford approach (CASA) model. The relationships between CUE and phenological and climate factors were explored. The results showed that ecosystem CUE fluctuated over time in the SNP. The lowest and highest CUE values mainly occurred in May and October, respectively. At seasonal scale, average CUE followed a descending order of Autumn > Summer > Spring. The CUE of mixed forest was greater than that of other ecosystems at both monthly and seasonal scales. Land surface phenology plays an important role in the regulation of CUE. The earlier start (SOS), the later end (EOS) and longer length (LOS) of the growing season would contribute increasing of CUE. Precipitation and temperature affected CUE positively in most areas of the SNP. These findings help explain the CUE of natural ecosystems in the protected farmland areas and improve our understanding of ecosystem carbon allocation dynamics in temperate semi-humid to semi-arid transitional region under climate and phenological fluctuations.

scholarly journals The Spatiotemporal Changes and the Impacts of Climate Factors on Grassland in the Northern Songnen Plain (China)

2021 ◽  
Vol 13 (12) ◽  
pp. 6568
Author(s):  
Liping Wang ◽  
Shufeng Zheng ◽  
Xiang Wang
Keyword(s):  
Climatic Factors ◽  
Climate Factors ◽  
Cultivated Land ◽  
Songnen Plain ◽  
Spatiotemporal Evolution ◽  
High Coverage ◽  
Unused Land ◽  
Spatiotemporal Changes ◽  
The Impact ◽  
Evolution Trend

Grassland is an important ecosystem; the spatiotemporal evolution trend of grassland and its impacts on climatic factors play an irreplaceable role in maintaining regional sustainable development and ecological balance. In this paper, based on the remote sensing images of 1990, 2000, 2010, 2020, and 3S technology, we use the methods of dynamic rate and transfer matrix to analyze the spatiotemporal evolution trend of the northern Songnen Plain (China). The method of grey correlation is used to analyze the impact of climate factors on it. The results showed that the grassland changed dramatically and unevenly across the three periods of 1990–2000, 2000–2010, and 2010–2020, with the biggest change in the last period. The internal conversion of grassland mainly occurred between H-grassland (high coverage grassland) and M-grassland (medium coverage grassland), while the transformation rarely occurred in L-grassland (low coverage grassland) due to its small area. There has been a transfer-in from cultivated land, woodland, and unused land to H-grassland and M-grassland. The grassland transfer-out was mainly from H-grassland and M-grassland to cultivated land and unused land. What’s more, the transformation mainly occurred in Daqing City, Suihua City, Qiqihar city, as well as occurring in the west of Harbin and the southwest of Heihe city. Climate change has exacerbated the reduction of grassland areas. In summary, the spatiotemporal change rates of grassland area in the north of Songnen Plain initially showed a mild decrease and were then followed by a rapid decrease. Climate factors were of great significance to the spatiotemporal changes of grassland, and precipitation had a greater impact on the reduction of grassland. The results can provide meaningful information for grassland change, grassland protection, and management in the northern Songnen Plain.

scholarly journals Competing roles of rising CO<sub>2</sub> and climate change in the contemporary European carbon balance

2007 ◽  
Vol 4 (4) ◽  
pp. 2385-2405 ◽  
Author(s):  
R. Harrison ◽  
C. Jones
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Carbon Balance ◽  
Atmospheric Co2 ◽  
Natural Ecosystems ◽  
Climate Effect ◽  
Carbon Cycle Model ◽  
Land Use And Management ◽  
The Impact ◽  
And Storage

Abstract. Natural ecosystems respond to, and may affect climate change through uptake and storage of atmospheric CO2. Here we use the land-surface and carbon cycle model JULES to simulate the contemporary European carbon balance and its sensitivity to rising CO2 and changes in climate. We find that the impact of climate change is to decrease the ability of Europe to store carbon by about 175 TgC yr−1. In contrast, the effect of rising atmospheric CO2 has been to stimulate increased uptake and storage. The CO2 effect is currently dominant leading to a net increase of around 150 TgC yr−1. Our simulations do not at present include other important factors such as land use and management, the effects of forest age classes and nitrogen deposition. There seems to be an emerging consensus that changes in climate will weaken the European land-surface's ability to take up and store carbon. It is likely that this effect is happening at the present and will continue even more strongly in the future as climate continues to change. Although CO2 enhanced growth currently exceeds the climate effect, this may not continue indefinitely. Understanding this balance and its implications for mitigation policies is becoming increasingly important.

scholarly journals Trends and land surface phenological responses to climate variability in the Argentina Pampas

2020 ◽  
Vol 46 (2) ◽  
pp. 581-602
Author(s):  
B. Lara ◽  
M. Gandini ◽  
P. Gantes ◽  
S.D. Matteucci
Keyword(s):  
Climate Variability ◽  
Land Surface ◽  
Vegetation Index ◽  
Future Climate Change ◽  
Linear Estimator ◽  
Positive Trend ◽  
Land Surface Phenology ◽  
First Case ◽  
Annual Productivity ◽  
The Impact

Understanding the interaction between land surface and atmosphere processes is fundamental for predicting the effects of future climate change on ecosystem functioning and carbon dynamics. The objectives of this work were to analyze the trends in land surface phenology (LSP) metrics from remote sensing data, and to reveal their relationship with precipitation and ENSO phenomenon in the Argentina Pampas. Using a time series of MODIS Normalized Difference Vegetation Index (NDVI) data from 2000 to 2014, the start of the growing season (SOS), the annual integral of NDVI (i-NDVI, linear estimator of annual productivity), the timing of the annual maximum NDVI (t-MAX) and the annual relative range of NDVI (RREL, estimator of seasonality) were obtained for the Argentina Pampas. Then, spatial and temporal relationships with the Multivariate ENSO Index (MEI) and precipitation were analyzed. Results showed a negative trend in annual productivity over a 53.6% of the study area associated to natural and semi-natural grassland under cattle grazing, whereas a 40.3% of Argentina Pampas showed a significant positive trend in seasonality of carbon gains. The study also reveals that climate variability has a significant impact on land surface phenology in Argentina Pampas, although the impact is heterogeneous. SOS and t-MAX showed a significant negative correlation with the precipitation indicating an earlier occurrence. 23.6% and 28.4% of the study area showed a positive correlation of the annual productivity with MEI and precipitation, respectively, associated to rangelands (in the first case) and to both rangeland and croplands, in the second case. Climate variability did not explain the seasonal variability of phenology. The relationships found between LSP metrics and climate variability could be important for implementation of strategies for natural resource management.

scholarly journals Global cropland monthly Gross Primary Production in the year 2000

2014 ◽  
Vol 11 (2) ◽  
pp. 3465-3488
Author(s):  
T. Chen ◽  
G. R. van der Werf ◽  
N. Gobron ◽  
E. J. Moors ◽  
A. J. Dolman
Keyword(s):  
Primary Production ◽  
Survey Data ◽  
Land Surface ◽  
Gross Primary Production ◽  
Co2 Exchange ◽  
Light Use Efficiency ◽  
Natural Ecosystems ◽  
Use Efficiency ◽  
Crop Types ◽  
Year 2000

Abstract. Croplands cover about 12% of the ice-free terrestrial land surface. Compared with natural ecosystems, croplands have distinct characteristics due to anthropogenic influences. Their global gross primary production (GPP) is not well constrained and estimates vary between 8.2 and 14.2 Pg C yr−1. We quantified global cropland GPP using a light use efficiency (LUE) model, employing satellite observations and survey data of crop types and distribution. A novel step in our analysis was to assign a maximum light use efficiency estimate (&amp;varepsilon;&amp;ast;GPP) to each of the 26 different crop types, instead of taking a uniform value as done in the past. These &amp;varepsilon;&amp;ast;GPP values were calculated based on flux tower CO2 exchange measurements and a literature survey of field studies, and ranged from 1.20 g CMJ−1 to 2.96 g CMJ−1. Global cropland GPP was estimated to be 11.05 Pg C yr−1 in the year 2000. Maize contributed most to this (1.55 Pg C yr−1), and the continent of Asia contributed most with 38.9% of global cropland GPP. In the continental United States, annual cropland GPP (1.28 Pg C yr−1) was close to values reported previously (1.24 Pg C yr−1) constrained by harvest records, but our estimates of &amp;varepsilon;&amp;ast;GPP values were much higher. Our results are sensitive to satellite information and survey data on crop type and extent, but provide a consistent and data-driven approach to generate a look-up table of &amp;varepsilon;&amp;ast;GPP for the 26 crop types for potential use in other vegetation models.

scholarly journals The Effect of Snow Depth on Spring Wildfires on the Hulunbuir from 2001–2018 Based on MODIS

2019 ◽  
Vol 11 (3) ◽  
pp. 321 ◽  
Author(s):  
Hong Ying ◽  
Yu Shan ◽  
Hongyan Zhang ◽  
Tao Yuan ◽  
Wu Rihan ◽  
...  
Keyword(s):  
Land Surface ◽  
Snow Depth ◽  
Hurst Exponent ◽  
Linear Regression Analysis ◽  
Sustainable Use ◽  
Estimation Method ◽  
Burned Area ◽  
Natural Ecosystems ◽  
Wildfire Occurrence ◽  
The Impact

Wildfires are one of the important disturbance factors in natural ecosystems and occur frequently around the world. Detailed research on the impact of wildfires is crucial not only for the development of livestock husbandry but also for the sustainable use of natural resources. In this study, based on the Moderate Resolution Imaging Spectroradiometer (MODIS) burned area product MC464A1 and site snow depth measurements, the kernel density estimation method (KDE), unary linear regression analysis, Sen + Mann-Kendall trend analysis, correlation analysis, and R/S analysis were used to evaluate the relationship between snow and spring wildfires (SWFs) in Hulunbuir. Our results indicated that SWFs decreased during the period of 2001–2018, were mainly distributed in the eastern portion of the study area, and that the highest SWF density was 7 events/km2. In contrast, the maximum snow depth increased during the period of 2001–2018 and the snow depth was deeper in the middle but shallower in the east and west. The SWFs and snow depth have significant negative correlations over space and time. The snow depth mainly affects the occurrence of SWFs indirectly by affecting the land surface temperature (LST) and Land Surface Water Index (LSWI) in spring. The snow depth was positively correlated with the LSWI in most of Hulunbuir and strongly negatively correlated with the LST, and this correlation was stronger in the eastern and western regions of Hulunbuir. The results of the Hurst exponent indicated that in the future, the snow depth trend will be opposite that of the current state, meaning that the trend of decreasing snow depth will increase dramatically in most of the study area, and SWFs may become more prominent. According to the validation results, the Hurst exponent is a reliable method for predicting the snow depth tendency. This research can be based on the snow conditions of the previous year to identify areas where fires are most likely to occur, enabling an improved and more targeted preparation for spring fire prevention. Additionally, the present study expands the theory and methods of wildfire occurrence research and promotes research on disasters and disaster chains.

scholarly journals The Variations of Satellite-Based Ecosystem Water Use and Carbon Use Efficiency and Their Linkages with Climate and Human Drivers in the Songnen Plain, China

2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Bo Li ◽  
Fang Huang ◽  
Shuai Chang ◽  
Ning Sun
Keyword(s):  
Water Use ◽  
Human Impacts ◽  
Sunshine Duration ◽  
Carbon Assimilation ◽  
Terrestrial Ecosystem ◽  
Impact Factors ◽  
Climate Factors ◽  
Songnen Plain ◽  
Carbon Use Efficiency ◽  
Use Efficiency

Ecosystem water use efficiency (WUE) and carbon use efficiency (CUE), as two of the most important ecological indicators of an ecosystem, represent the carbon assimilation rate of unit water consumption and the capacity of transferring carbon from the atmosphere to potential carbon sinks. Revealing WUE and CUE changes and their impact factors is vital for regional carbon-water interactions and carbon budget assessment. Climate affects carbon and water processes differently. Compared to WUE, the variations in CUE in response to climate factors and human activity remain inadequately understood. In this study, ecosystem-level WUE and CUE variations in the Songnen Plain (SNP), Northeast China, during 2001–2015, were investigated using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data. The relationships between WUE, CUE, main climate factors, and human impacts were explored. The results showed that ecosystem WUE and CUE have fluctuated over time, with regional average values of 1.319 gC·kg−1H2O and 0.516, respectively. Deciduous broad-leaved forests had the highest average WUE but the lowest CUE. The multiyear average CUE of grassland ranked in first place, while the lowest WUE indicated that a lesser capacity of net productivity was generated by the use of limited water supply. WUE and CUE showed a downward trend in most areas of the SNP, indicating that the carbon sequestration capacity of the terrestrial ecosystem became weaker in the past 15 years. Annual precipitation and relative humidity had positive influences on WUE and CUE in more than 60% of the study area. The total annual sunshine duration and annual average temperature negatively affected WUE and CUE in most areas. Human activities had a positive effect on ecosystem WUE changes in the SNP but might inhibit CUE variations. Our findings aid in understanding the biological regulation mechanisms of carbon-water cycle coupling and provide a scientific basis for formulating sustainable regional development strategies and guiding water and land resources management.

The impact of climatic and non-climatic factors on land surface temperature in southwestern Romania

2016 ◽  
Vol 130 (3-4) ◽  
pp. 775-790 ◽  
Author(s):  
Cristina Florina Roşca ◽  
Gabriela Victoria Harpa ◽  
Adina-Eliza Croitoru ◽  
Ioana Herbel ◽  
Alexandru Mircea Imbroane ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Land Surface Temperature ◽  
Land Surface ◽  
Climatic Factors ◽  
The Impact

Technology Lecture. Land restoration: now and in the future

1984 ◽  
Vol 223 (1230) ◽  
pp. 1-23 ◽  
Keyword(s):  
Land Surface ◽  
Ecological Knowledge ◽  
Land Restoration ◽  
Natural Ecosystems ◽  
Degraded Land ◽  
Ecological Processes ◽  
Proper Understanding ◽  
Productive Land ◽  
The Right ◽  
The Impact

Derelict and degraded land destroys amenity, causes pollution and is a waste of productive land surface. Despite the worldwide activity to restore it there is an enormous backlog, which in England has increased since 1974. In the past much of this restoration was empirically based and not always successful. But natural ecosystems develop unaided on raw starting materials by natural ecological processes. A proper understanding of these has led to more reliable and inexpensive restoration techniques. At the same time we have come to realize that, because, at the start, the slate has been wiped clean, many different end points are possible. Derelict land is a challenge and opportunity for creative manipulation of our landscape. Yet what is achieved in practice is often pedestrian, unscientific and uneconomic. Often the simple treatments that would minimize the impact of industrial activity, and would set the restoration off early and in the right direction, are not carried out. Yet there are plenty of good examples of what can be done. It appears that once more we may be victims of the British failure in technology and imagination transfer. For this the fault seems to lie broadly, not only with planners, industrialists and government, for not always making sure something is done, but also with scientists, for not applying their ecological knowledge sufficiently to problems of hard practice.

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