scholarly journals Assessing Land Degradation/Recovery in the African Sahel from Long-Term Earth Observation Based Primary Productivity and Precipitation Relationships

2013 ◽  
Vol 5 (2) ◽  
pp. 664-686 ◽  
Author(s):  
Rasmus Fensholt ◽  
Kjeld Rasmussen ◽  
Per Kaspersen ◽  
Silvia Huber ◽  
Stephanie Horion ◽  
...  
Keyword(s):  
Land Degradation ◽  
Primary Productivity ◽  
Earth Observation ◽  
African Sahel

Using net primary productivity and water use efficiency for assessing the degree of land degradation and rehabilitation in the Northeast Asia dryland region

2020 ◽  
Author(s):  
Sinkyu Kang ◽  
Wenping Kang
Keyword(s):  
Species Composition ◽  
Water Use Efficiency ◽  
Water Use ◽  
Land Degradation ◽  
Primary Productivity ◽  
Net Primary Productivity ◽  
Northeast Asia ◽  
Term Trend ◽  
Use Efficiency

<p>Changes in vegetation productivity and species composition have been used as conventional indicators of land degradation and rehabilitation assessments. The two biophysical parameters vary nonlinearly during land change process with various time lags, which provide, as a whole, a useful framework to diagnose degree of land degradation and rehabilitation. In this study, the net primary productivity (NPP) and water use efficiency (WUE), which are the proxies of vegetation productivity and ecophysiological properties related to species composition, were combined to develop an eco-physiological framework to assess the degree of land degradation in the Northeast-Asia dryland regions (NADR) from 1982 to 2012. Results from long-term trends analysis showed early, middle or late degradation stages occurred in northern grassland and central barren or sparsely vegetated regions, respectively, while the rehabilitation prevailed in eastern croplands and forest, southern, and western grassland. In contrast, short-term trend analysis illustrated the recent rehabilitation in mideastern Mongolia and Loess Plateau, which was unseen in long-term trend analysis. The spatial patterns and temporal changes of land degradation and rehabilitation could be explained partly by either or both natural and anthropogenic factors. Longterm drying and warming might induce land degradation in northern and central NADR, respectively, while the recovery projects and wetting conditions after 2000s promoted the land rehabilitation in Loess Plateau and mid-eastern Mongolia. Here, our NPP–WUE framework may contribute further conceptual development and rapid assessments on land degradation and rehabilitation in wide geographic regions.</p>

scholarly journals Non-Standard Discrete RothC Models for Soil Carbon Dynamics

Axioms ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 56
Author(s):  
Fasma Diele ◽  
Carmela Marangi ◽  
Angela Martiradonna
Keyword(s):  
Soil Carbon ◽  
Land Degradation ◽  
Biological Diversity ◽  
Negative Effects ◽  
Land Use Patterns ◽  
Use Patterns ◽  
Soil Carbon Content ◽  
Rothc Model ◽  
Key Indicators

Soil Organic Carbon (SOC) is one of the key indicators of land degradation. SOC positively affects soil functions with regard to habitats, biological diversity and soil fertility; therefore, a reduction in the SOC stock of soil results in degradation, and it may also have potential negative effects on soil-derived ecosystem services. Dynamical models, such as the Rothamsted Carbon (RothC) model, may predict the long-term behaviour of soil carbon content and may suggest optimal land use patterns suitable for the achievement of land degradation neutrality as measured in terms of the SOC indicator. In this paper, we compared continuous and discrete versions of the RothC model, especially to achieve long-term solutions. The original discrete formulation of the RothC model was then compared with a novel non-standard integrator that represents an alternative to the exponential Rosenbrock–Euler approach in the literature.

scholarly journals Multiple Evidence for Climate Patterns Influencing Ecosystem Productivity across Spatial Gradients in the Venice Lagoon

2021 ◽  
Vol 9 (4) ◽  
pp. 363
Author(s):  
Camilla Bertolini ◽  
Edouard Royer ◽  
Roberto Pastres
Keyword(s):  
Time Series ◽  
Primary Productivity ◽  
Clustering Analysis ◽  
Venice Lagoon ◽  
Spatial Effects ◽  
Spatial Gradients ◽  
Climate Forecasting ◽  
Oxygen Production Rate ◽  
Temporal And Spatial

Effects of climatic changes in transitional ecosystems are often not linear, with some areas likely experiencing faster or more intense responses, which something important to consider in the perspective of climate forecasting. In this study of the Venice lagoon, time series of the past decade were used, and primary productivity was estimated from hourly oxygen data using a published model. Temporal and spatial patterns of water temperature, salinity and productivity time series were identified by applying clustering analysis. Phytoplankton and nutrient data from long-term surveys were correlated to primary productivity model outputs. pmax, the maximum oxygen production rate in a given day, was found to positively correlate with plankton variables measured in surveys. Clustering analysis showed the occurrence of summer heatwaves in 2008, 2013, 2015 and 2018 and three warm prolonged summers (2012, 2017, 2019) coincided with lower summer pmax values. Spatial effects in terms of temperature were found with segregation between confined and open areas, although the patterns varied from year to year. Production and respiration differences showed that the lagoon, despite seasonality, was overall heterotrophic, with internal water bodies having greater values of heterotrophy. Warm, dry years with high salinity had lower degrees of summer autotrophy.

Long-term fertility experiments for irrigated rice in the West African Sahel: effect on soil characteristics

2004 ◽  
Vol 85 (1) ◽  
pp. 61-77 ◽  
Author(s):  
S.M. Haefele ◽  
M.C.S. Wopereis ◽  
A.-M. Schloebohm ◽  
H. Wiechmann
Keyword(s):  
Soil Characteristics ◽  
West African ◽  
The West ◽  
Irrigated Rice ◽  
West African Sahel ◽  
African Sahel

scholarly journals Differential arthropod responses to warming are altering the structure of Arctic communities

2018 ◽  
Vol 5 (4) ◽  
pp. 171503 ◽  
Author(s):  
Amanda M. Koltz ◽  
Niels M. Schmidt ◽  
Toke T. Høye
Keyword(s):  
Community Composition ◽  
Primary Productivity ◽  
Species Interactions ◽  
Ecosystem Processes ◽  
The Arctic ◽  
Individual Species ◽  
Freeze Thaw ◽  
Compositional Changes ◽  
Arctic Communities

The Arctic is experiencing some of the fastest rates of warming on the planet. Although many studies have documented responses to such warming by individual species, the idiosyncratic nature of these findings has prevented us from extrapolating them to community-level predictions. Here, we leverage the availability of a long-term dataset from Zackenberg, Greenland (593 700 specimens collected between 1996 and 2014), to investigate how climate parameters influence the abundance of different arthropod groups and overall community composition. We find that variation in mean seasonal temperatures, winter duration and winter freeze–thaw events is correlated with taxon-specific and habitat-dependent changes in arthropod abundances. In addition, we find that arthropod communities have exhibited compositional changes consistent with the expected effects of recent shifts towards warmer active seasons and fewer freeze–thaw events in NE Greenland. Changes in community composition are up to five times more extreme in drier than wet habitats, with herbivores and parasitoids generally increasing in abundance, while the opposite is true for surface detritivores. These results suggest that species interactions and food web dynamics are changing in the Arctic, with potential implications for key ecosystem processes such as decomposition, nutrient cycling and primary productivity.

Operational Delivery of Customized Earth Observation Data Using Web Coverage Service

2011 ◽  
pp. 385-400
Author(s):  
Wenli Yang
Keyword(s):  
Web Service ◽  
Earth Observation ◽  
Observation Data ◽  
Data Systems ◽  
On Demand ◽  
Promising Solution ◽  
Open Geospatial Consortium ◽  
Earth Observation Data ◽  
Operational Data

Global long term Earth Observation (EO) provides valuable information about the land, ocean, and atmosphere of the Earth. EO data are often archived in specialized data systems managed by the data collector’s system. For the data to be fully utilized, one of the most important aspects is to adopt technologies that will enable users to easily find and obtain needed data in a form that can be readily used with little or no manipulation. Many efforts have been made in this direction but few, if any, data providers can deliver on-demand and operational data to users in customized form. Geospatial Web Service has been considered a promising solution to this problem. This chapter discusses the potential for operational and scalable delivery of on-demand personalized EO data using the interoperable Web Coverage Service (WCS) developed by the Open Geospatial Consortium (OGC).

scholarly journals Estimation of the Particulate Organic Carbon to Chlorophyll-a Ratio Using MODIS-Aqua in the East/Japan Sea, South Korea

2020 ◽  
Vol 12 (5) ◽  
pp. 840 ◽  
Author(s):  
Dabin Lee ◽  
SeungHyun Son ◽  
HuiTae Joo ◽  
Kwanwoo Kim ◽  
Myung Joon Kim ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Particulate Organic Carbon ◽  
Chlorophyll A ◽  
Primary Productivity ◽  
Seasonal Variability ◽  
Japan Sea ◽  
Global Ocean ◽  
Phytoplankton Communities

In recent years, the change of marine environment due to climate change and declining primary productivity have been big concerns in the East/Japan Sea, Korea. However, the main causes for the recent changes are still not revealed clearly. The particulate organic carbon (POC) to chlorophyll-a (chl-a) ratio (POC:chl-a) could be a useful indicator for ecological and physiological conditions of phytoplankton communities and thus help us to understand the recent reduction of primary productivity in the East/Japan Sea. To derive the POC in the East/Japan Sea from a satellite dataset, the new regional POC algorithm was empirically derived with in-situ measured POC concentrations. A strong positive linear relationship (R2 = 0.6579) was observed between the estimated and in-situ measured POC concentrations. Our new POC algorithm proved a better performance in the East/Japan Sea compared to the previous one for the global ocean. Based on the new algorithm, long-term POC:chl-a ratios were obtained in the entire East/Japan Sea from 2003 to 2018. The POC:chl-a showed a strong seasonal variability in the East/Japan Sea. The spring and fall blooms of phytoplankton mainly driven by the growth of large diatoms seem to be a major factor for the seasonal variability in the POC:chl-a. Our new regional POC algorithm modified for the East/Japan Sea could potentially contribute to long-term monitoring for the climate-associated ecosystem changes in the East/Japan Sea. Although the new regional POC algorithm shows a good correspondence with in-situ observed POC concentrations, the algorithm should be further improved with continuous field surveys.

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