Exploring the Use of DSCOVR/EPIC Satellite Observations to Monitor Vegetation Phenology

Vegetation phenology plays a pivotal role in regulating several ecological processes and has profound impacts on global carbon exchange. Large-scale vegetation phenology monitoring mostly relies on Low-Earth-Orbit satellite observations with low temporal resolutions, leaving gaps in data that are important for monitoring seasonal vegetation phenology. High temporal resolution satellite observations have the potential to fill this gap by frequently collecting observations on a global scale, making it easier to study change over time. This study explored the potential of using the Earth Polychromatic Imaging Camera (EPIC) onboard the Deep Space Climate Observatory (DSCOVR) satellite, which captures images of the entire sunlit face of the Earth at a temporal resolution of once every 1–2 h, to observe vegetation phenology cycles in North America. We assessed the strengths and shortcomings of EPIC-based phenology information in comparison with the Moderate-resolution Imaging Spectroradiometer (MODIS), Enhanced Thematic Mapper (ETM+) onboard Landsat 7, and PhenoCam ground-based observations across six different plant functional types. Our results indicated that EPIC could capture and characterize seasonal changes of vegetation across different plant functional types and is particularly consistent in the estimated growing season length. Our results also provided new insights into the complementary features and benefits of the four datasets, which is valuable for improving our understanding of the complex response of vegetation to global climate variability and other disturbances and the impact of phenology changes on ecosystem productivity and global carbon exchange.

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Modeling of the Russell glacier's basal conditions at seasonal time scale using the satellite observations of surface ice speed

10.5194/egusphere-egu21-4672 ◽

2021 ◽

Author(s):

Anna Derkacheva ◽

Fabien Gillet-Chaulet ◽

Jeremie Mouginot

Keyword(s):

Time Series ◽

Temporal Resolution ◽

Flow Model ◽

In Situ Measurements ◽

Satellite Observations ◽

Surface Velocity ◽

Ice Flow ◽

Surface Ice ◽

The Impact

Greenland&#8217;s future response to climate change will be determined partly by various phenomena controlling ice flow. For the land-terminating sectors, the water lubricating the glacier's base is considered as a major control on the ice motion. For instance, the seasonal modulations of water input induced by summer melt can cause glacier speed-up up to +200-300% compared to the winter mean. Thus, a comprehensive understanding of variations in the basal conditions, which are at the origin of the glacier flow fluctuations, plays a key role for the climate projections.While the in-situ measurements stay a local and hard approach to investigate the basal conditions, ice flow modeling offers the possibility to invert for them over the large area based on observations of surface glacier speed and topography. During the last decade, the number of available satellite observations has increased significantly, allowing for far more frequent measurements of the glacier speed and precise reconstruction of the seasonal fluctuations. Here, we investigate the possibility of applying this satellite-derived time-series of surface ice velocity to reconstruct the annual behavior of the basal conditions with 2 weeks temporal resolution using an ice flow model.The area of this study is Russell glacier located on the southwest coast of Greenland. A time series of surface velocity dataset was created by merging measurements from Sentinel-1&2 and Landsat-8, covering an area up to 100 km inland with 150 m/pix spatial resolution and 2-weeks temporal resolution (Derkacheva et al. 2020). The 3D Full-Stokes ice flow model Elmer/Ice is used to invert for the effective basal friction coefficient for each time step.&#160; Usage of a friction law that has been derived for hard beds (Gagliardini et al., 2007) allows to constrain the variation of the basal effective pressure. Overall, the results from the model inversions give access to the evolution of the basal ice speed, friction, effective and water pressure, floatation fraction throughout a complete year. The results are compared with in-situ measurements in terms of absolute values and show a good agreement. The impact of the flow model setup, regularization, assumptions for the ice rheology, and the impact of noise in the speed data are also examined and compared with in-situ measurements.

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Seasonal and individual event-responsiveness are key determinants of carbon exchange across plant functional types

Oecologia ◽

10.1007/s00442-020-04718-5 ◽

2020 ◽

Vol 193 (4) ◽

pp. 811-825

Author(s):

Daniel E. Winkler ◽

Jayne Belnap ◽

Michael C. Duniway ◽

David Hoover ◽

Sasha C. Reed ◽

...

Keyword(s):

Plant Functional Types ◽

Carbon Exchange ◽

Individual Event ◽

Functional Types

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The Persisting Influence of Edge on Vegetation in Hemiboreal Alnus Glutinosa (L.) Gaertn. Swamp Forest Set-Asides Adjacent to Recently Disturbed Stands

Forests ◽

10.3390/f11101084 ◽

2020 ◽

Vol 11 (10) ◽

pp. 1084

Author(s):

Līga Liepa ◽

Zigmārs Rendenieks ◽

Āris Jansons ◽

Inga Straupe ◽

Edgars Dubrovskis ◽

...

Keyword(s):

Alnus Glutinosa ◽

Plant Functional Types ◽

Forest Stands ◽

Herbaceous Layer ◽

Clear Cut ◽

Functional Types ◽

Woodland Key Habitats ◽

The Impact ◽

Edge Influence ◽

Over Time

To increase set-aside areas and protect biodiversity values in managed hemiboreal forest landscapes, small forest parcels called Woodland Key Habitats have been designated in Baltic and Nordic countries. The aim of this study was to investigate the persisting influence of the edge on vegetation dynamics for young, medium-old and old edges in Alnus glutinosa (L.) Gaertn. Woodland Key Habitats. All of these edges are adjacent to recently disturbed (clear-cut) stands. We surveyed edge influence on vegetation in bryophyte, herbaceous, shrub and tree layers in 90 plots in 30 set-aside forest stands in Southern Latvia. We tested the differences in the number of species and projective coverage in all vegetation layers, but plant functional types were examined—separately in the herbaceous layer. We found that edge influence in protected forest stands of A. glutinosa swamp forests reflects strong changes in vegetation and plant functional types in the herbaceous layer mostly up to 20 years after clear-cut disturbance in adjacent stands. The greatest differences were between young edges (≤20 years) and old edges (≥41 years), but there were very few significant differences between medium-old (21–40 years) and old edges which signifies more rapid changes in the early stages of edge influence and gradual stabilization of vegetation later on. We found that in edges adjacent to recently disturbed stands (up to 20 years), significantly less rare and indicator epiphytic lichen species occur, but this occurrence increases over time and edge influence is no longer present beyond 20 years after disturbance. Changes in vegetation and species occurrence found in our study indicated the need to plan the allocation of set-aside patches in production forest landscapes to ensure connectivity over longer period of time. Careful planning of clear-cuts in neighboring areas over time can significantly reduce the impact of edge effect on these set-asides.

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Urbanization Impacts on Vegetation Phenology in China

Remote Sensing ◽

10.3390/rs10121905 ◽

2018 ◽

Vol 10 (12) ◽

pp. 1905 ◽

Cited By ~ 10

Author(s):

Qiang Ren ◽

Chunyang He ◽

Qingxu Huang ◽

Yuyu Zhou

Keyword(s):

Rural Areas ◽

Land Surface ◽

Urban Areas ◽

Growing Season ◽

Vegetation Phenology ◽

Rapid Urbanization ◽

Climate Zone ◽

Growing Season Length ◽

Impact Of Urbanization ◽

The Impact

Urbanization can affect the ecological processes, local climate and human health in urban areas by changing the vegetation phenology. In the past 20 years, China has experienced rapid urbanization. Thus, it is imperative to understand the impact of urbanization on vegetation phenology in China. In this study, we quantitatively analyzed the impact of urbanization on vegetation phenology at the national and climate zone scales using remotely sensed data. We found that the start of the growing season (SOS) was advanced by approximately 2.4 days (P < 0.01), and the end of the growing season (EOS) was delayed by approximately 0.7 days (P < 0.01) in the urban areas compared to the rural areas. As a result, the growing season length (GSL) was extended by approximately 3.1 days (P < 0.01). The difference in the SOS and GSL between the urban and rural areas increased from 2001 to 2014, with an annual rate of 0.2 days (R2 = 0.39, P < 0.05) and 0.2 days (R2 = 0.31, P < 0.05), respectively. We also found that the impact of urbanization on vegetation phenology varied among different vegetation types at the national and climate zone levels (P < 0.05). The SOS was negatively correlated with land surface temperature (LST), with a correlation coefficient of −0.24 (P < 0.01), and EOS and GSL were positively correlated with LST, with correlation coefficients of 0.56 and 0.44 (P < 0.01), respectively. The improved understanding of the impact of urbanization on vegetation phenology from this study will be of great help for policy-makers in terms of developing relevant strategies to mitigate the negative environmental effects of urbanization in China.

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Fire: plant functional types and patch mosaic burning in fire-prone ecosystems

Progress in Physical Geography Earth and Environment ◽

10.1177/0309133308096754 ◽

2008 ◽

Vol 32 (4) ◽

pp. 421-437 ◽

Cited By ~ 18

Author(s):

H.D. Allen

Keyword(s):

Landscape Heterogeneity ◽

Plant Functional Types ◽

Individual Species ◽

Above Ground Biomass ◽

Functional Types ◽

Patch Mosaic ◽

Disturbance Factor ◽

In Fire ◽

The Impact

Shared fire-survival and fire-persistence traits are found in taxonomically unrelated plant species that commonly grow in fire-prone ecosystems. Such traits include resprouting, after fire has killed the above-ground biomass, and postfire seed release after the death of individual plants. Classification of such traits has led to a change in focus from research on the impact of fire as a disturbance factor on individual species, towards research into plant functional types associated with fire. This has led to a better understanding of the timing and geographic evolution of such traits as either fire-adapted or as a selective response to other disturbance factors. The identification of fire-survival and fire-persistence traits in fire-prone ecosystems is the first focus of this paper. It is followed by a discussion of recent research which offers a critical reappraisal of patch mosaic burning as a means to increase landscape heterogeneity and biodiversity, including the role played by plant functional types in determining diversity. The fire-prone ecosystems of mediterranean-type shrublands and heathlands, savannas and grasslands, and boreal and other coniferous forests are the main geographic focus of the paper.

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Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

Symposium - International Astronomical Union ◽

10.1017/s0074180900178404 ◽

1962 ◽

Vol 14 ◽

pp. 415-418

Author(s):

K. P. Stanyukovich ◽

V. A. Bronshten

Keyword(s):

Explosive Charge ◽

The Moon ◽

Meteorite Impacts ◽

The Earth ◽

Lunar Craters ◽

The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

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