scholarly journals Reviews and syntheses: Australian vegetation phenology: new insights from satellite remote sensing and digital repeat photography

2016 ◽  
Vol 13 (17) ◽  
pp. 5085-5102 ◽  
Author(s):  
Caitlin E. Moore ◽  
Tim Brown ◽  
Trevor F. Keenan ◽  
Remko A. Duursma ◽  
Albert I. J. M. van Dijk ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Tropical Rainforests ◽  
Vegetation Phenology ◽  
Repeat Photography ◽  
Tropical Savannas ◽  
Diverse Range ◽  
Canopy Development ◽  
Continental Scale ◽  
Digital Repeat Photography

Abstract. Phenology is the study of periodic biological occurrences and can provide important insights into the influence of climatic variability and change on ecosystems. Understanding Australia's vegetation phenology is a challenge due to its diverse range of ecosystems, from savannas and tropical rainforests to temperate eucalypt woodlands, semi-arid scrublands, and alpine grasslands. These ecosystems exhibit marked differences in seasonal patterns of canopy development and plant life-cycle events, much of which deviates from the predictable seasonal phenological pulse of temperate deciduous and boreal biomes. Many Australian ecosystems are subject to irregular events (i.e. drought, flooding, cyclones, and fire) that can alter ecosystem composition, structure, and functioning just as much as seasonal change. We show how satellite remote sensing and ground-based digital repeat photography (i.e. phenocams) can be used to improve understanding of phenology in Australian ecosystems. First, we examine temporal variation in phenology on the continental scale using the enhanced vegetation index (EVI), calculated from MODerate resolution Imaging Spectroradiometer (MODIS) data. Spatial gradients are revealed, ranging from regions with pronounced seasonality in canopy development (i.e. tropical savannas) to regions where seasonal variation is minimal (i.e. tropical rainforests) or high but irregular (i.e. arid ecosystems). Next, we use time series colour information extracted from phenocam imagery to illustrate a range of phenological signals in four contrasting Australian ecosystems. These include greening and senescing events in tropical savannas and temperate eucalypt understorey, as well as strong seasonal dynamics of individual trees in a seemingly static evergreen rainforest. We also demonstrate how phenology links with ecosystem gross primary productivity (from eddy covariance) and discuss why these processes are linked in some ecosystems but not others. We conclude that phenocams have the potential to greatly improve the current understanding of Australian ecosystems. To facilitate the sharing of this information, we have formed the Australian Phenocam Network (http://phenocam.org.au/).

scholarly journals Australian vegetation phenology: new insights from satellite remote sensing and digital repeat photography

2016 ◽  
Author(s):  
Caitlin E. Moore ◽  
Tim Brown ◽  
Trevor F. Keenan ◽  
Remko A. Duursma ◽  
Albert I. J. M. van Dijk ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Tropical Rainforests ◽  
Vegetation Phenology ◽  
Repeat Photography ◽  
Tropical Savannas ◽  
Diverse Range ◽  
Canopy Development ◽  
Continental Scale ◽  
Digital Repeat Photography

Abstract. Phenology is the study of periodic biological occurrences and can provide important insights into the influence of climatic variability and change on ecosystems. Understanding Australia’s vegetation phenology is a challenge due to its diverse range of ecosystems, from savannas and tropical rainforests to temperate eucalypt woodlands, semi-arid scrublands and alpine grasslands. These ecosystems exhibit marked differences in seasonal patterns of canopy development and plant life-cycle events, much of which deviates from the predictable seasonal phenological pulse of temperate deciduous and boreal biomes. Many Australian ecosystems are subject to irregular events (i.e., drought, flooding, cyclones and fire) that can alter ecosystem composition, structure and functioning just as much as seasonal change. We show how satellite remote sensing and ground-based digital repeat photography (i.e. phenocams) can be used to improve understanding of phenology in Australian ecosystems. First, we examine temporal variation in phenology at the continental scale using the Enhanced Vegetation Index (EVI), calculated from MODerate resolution Imaging Spectroradiomter (MODIS) data. Spatial gradients are revealed, ranging from regions with pronounced seasonality in canopy development (i.e., tropical savannas) to regions where seasonal variation is minimal (i.e., tropical rainforests) or high but irregular (i.e., arid ecosystems). Next, we use time series colour information extracted from phenocam imagery to illustrate a range of phenological signals in four contrasting Australian ecosystems. These include greening and senescing events in tropical savannas and temperate eucalypt understory, as well as strong seasonal dynamics of individual trees in a seemingly static evergreen rainforest. We also demonstrate how phenology links with ecosystem gross primary productivity (from eddy covariance) and discuss why these processes are linked in some ecosystems but not others. We conclude that phenocams have the potential to greatly improve current understanding of Australian ecosystems. To facilitate sharing of this information, we have formed the Australian Phenocam Network (http://phenocam.org.au/).

Satellite remote sensing and natural disturbances

2019 ◽  
pp. 37-50
Author(s):  
Nathalie Pettorelli
Keyword(s):  
Remote Sensing ◽  
Satellite Remote Sensing ◽  
Accurate Information ◽  
Ecological Knowledge ◽  
Natural Disturbances ◽  
Ecosystem Impacts ◽  
Spatial And Temporal Scales ◽  
Continental Scale ◽  
Management Actions ◽  
Wild Fire

This chapter provides an overview of how satellite remote sensing can help map the occurrence, and risk of occurrence, of several environmental disturbances; assess the extent of the associated damages; and monitor the recovery of the areas impacted by these disturbances. It particularly focuses on floods, wild fires, droughts, frost, extreme winter warming events, infestations and blooms, and bleaching events, as these are all well-known natural disturbances likely to change in frequency of occurrence and intensity over the coming decades. Through the use of examples, this chapter demonstrates how the utility of satellite remote sensing resides in the ability it provides to separate and characterise (i.e. through form, intensity, and trajectory) disturbances and responses at various spatial and temporal scales, thereby facilitating ecological knowledge expansion and the identification of relevant management actions. In particular, this contribution shows how satellites offer multiple opportunities to gain accurate information on the location, spatial extent, and duration of disturbances at the continental scale, which is needed to evaluate the ecosystem impacts of land cover changes due to, for example, wild fire, insect epidemics, and flooding, thereby reducing uncertainties in our ability to model global carbon budgets.

Vegetation phenology can be captured with digital repeat photography and linked to variability of root nutrition inHedysarum alpinum

2012 ◽  
Vol 16 (2) ◽  
pp. 317-324 ◽  
Author(s):  
W. Nijland ◽  
N.C. Coops ◽  
S.C.P. Coogan ◽  
C.W. Bater ◽  
M.A. Wulder ◽  
...  
Keyword(s):  
Vegetation Phenology ◽  
Repeat Photography ◽  
Digital Repeat Photography

Monitoring fire-affected areas using temporal profiles of spectral signal from time series MODIS satellite images

2020 ◽  
Author(s):  
Konstantina Tsipoka ◽  
Nikos Koutsias
Keyword(s):  
Remote Sensing ◽  
Time Series ◽  
Satellite Remote Sensing ◽  
Satellite Images ◽  
Vegetation Recovery ◽  
Burned Area ◽  
Vegetation Phenology ◽  
Spectral Signal ◽  
Temporal Profiles ◽  
Modis Satellite Images

<p>Vegetation phenology is an important element of vegetation characteristics that can be useful in vegetation monitoring especially when satellite remote sensing observations are used. In that sense temporal profiles extracted from spectral signal of time series MODIS satellite images can be used to characterize vegetation phenology and thus to be helpful for monitoring vegetation recovery in fire-affected areas. The aim of this study is to explore the phenology patterns and the vegetation recovery pattern of various wildfires occurred in Greece during the period 2000-2020. Satellite remote sensing data from MODIS satellites in the period from 2000 to 2020 were acquired and processed to extract the temporal profiles of the spectral signal for selected areas inside and outside the fire-affected areas. This dataset and time period analyzed together with the time that these fires occurred gave the opportunity to create temporal profiles for some years before and some years after the fire. Different metrics linked to key phenological events have been created and used to assess vegetation recovery in the fire-affected areas. Apart of the use of the original spectral data we estimated and used vegetation indices commonly found in vegetation studies as well as in burned area mapping studies. In this study we explore the strength and the use of these time series satellite data to characterize vegetation phenology as an aid to assess the fire-affected areas and to monitor their vegetation recovery.</p>

scholarly journals Digital photography for assessing vegetation phenology in two contrasting northern ecosystems

2016 ◽  
Author(s):  
Maiju Linkosalmi ◽  
Mika Aurela ◽  
Juha-Pekka Tuovinen ◽  
Mikko Peltoniemi ◽  
Cemal M. Tanis ◽  
...  
Keyword(s):  
Digital Images ◽  
Time Windows ◽  
Coniferous Forest ◽  
Minor Effect ◽  
Forest Site ◽  
Vegetation Phenology ◽  
Repeat Photography ◽  
A Minor ◽  
Ecosystem Flux ◽  
Digital Repeat Photography

Abstract. Digital repeat photography has become a widely used tool for assessing the annual course of vegetation phenology of different ecosystems. A greenness measure derived from digital images potentially provides an inexpensive and powerful means to analyze the annual cycle of ecosystem phenology. By using the Green Chromatic Coordinate (GCC), we examined the feasibility of digital repeat photography for assessing the vegetation phenology in two contrasting high-latitude ecosystems. While the seasonal changes in GCC are more obvious for the ecosystem that is dominated by annual plants (open wetland), clear seasonal patterns were also observed for the evergreen ecosystem (coniferous forest). Limited solar radiation restricts the use of images during the night and in wintertime, for which time windows were determined based on images of a grey reference plate. The variability in cloudiness had only a minor effect on GCC, and GCC did not depend on the sun angle and direction either. The GCC of wetland developed in tandem with the daily photosynthetic capacity estimated from the atmosphere-ecosystem flux measurements. At the forest site, the seasonal GCC cycle correlated well with the flux data in 2015 but there were some temporary deviations in 2014. The year-to-year differences were most likely generated by meteorological conditions, especially the differences in temperature. In addition to depicting the seasonal course of ecosystem functioning, GCC was shown to respond to physiological changes on a daily time scale. It seems that our northern sites, with a short and pronounced growing season, suit especially well for the monitoring of phenological variations with digital images.

scholarly journals Using Digital Photography to Track Understory Phenology in Mediterranean Cork Oak Woodlands

2021 ◽  
Vol 13 (4) ◽  
pp. 776
Author(s):  
Catarina Jorge ◽  
João M. N. Silva ◽  
Joana Boavida-Portugal ◽  
Cristina Soares ◽  
Sofia Cerasoli
Keyword(s):  
Climatic Factors ◽  
Cork Oak ◽  
Understory Vegetation ◽  
Coefficient Of Determination ◽  
Maximum Temperature ◽  
Vegetation Phenology ◽  
Repeat Photography ◽  
Shrub Species ◽  
Oak Woodlands ◽  
Digital Repeat Photography

Monitoring vegetation is extremely relevant in the context of climate change, and digital repeat photography is a method that has gained momentum due to a low cost–benefit ratio. This work aims to demonstrate the possibility of using digital cameras instead of field spectroradiometers (FS) to track understory vegetation phenology in Mediterranean cork oak woodlands. A commercial camera was used to take monthly photographs that were processed with the Phenopix package to extract green chromatic coordinates (GCC). GCC showed good agreement with the normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) obtained with FS data. The herbaceous layer displayed a very good fit between GCC and NDVI (coefficient of determination, represented by r2 = 0.89). On the contrary, the GCC of shrubs (Cistus salviifolius and Ulex airensis) showed a better fit with NDWI (r2 = 0.78 and 0.55, respectively) than with NDVI (r2 = 0.60 and 0.30). Models show that grouping shrub species together improves the predictive results obtained with ulex but not with cistus. Concerning the relationship with climatic factors, all vegetation types showed a response to rainfall and temperature. Grasses and cistus showed similar responses to meteorological drivers, particularly mean maximum temperature (r = −0.66 and −0.63, respectively). The use of digital repeat photography to track vegetation phenology was found to be very suitable for understory vegetation with the exception of one shrub species. Thus, this method proves to have the potential to monitor a wide spectrum of understory vegetation at a much lower cost than FS.

scholarly journals Digital photography for assessing the link between vegetation phenology and CO<sub>2</sub> exchange in two contrasting northern ecosystems

2016 ◽  
Vol 5 (2) ◽  
pp. 417-426 ◽  
Author(s):  
Maiju Linkosalmi ◽  
Mika Aurela ◽  
Juha-Pekka Tuovinen ◽  
Mikko Peltoniemi ◽  
Cemal M. Tanis ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Gross Primary Production ◽  
Coniferous Forest ◽  
Co2 Flux ◽  
Minor Effect ◽  
Forest Site ◽  
Vegetation Phenology ◽  
Repeat Photography ◽  
A Minor ◽  
Digital Repeat Photography

Abstract. Digital repeat photography has become a widely used tool for assessing the annual course of vegetation phenology of different ecosystems. By using the green chromatic coordinate (GCC) as a greenness measure, we examined the feasibility of digital repeat photography for assessing the vegetation phenology in two contrasting high-latitude ecosystems. Ecosystem–atmosphere CO2 fluxes and various meteorological variables were continuously measured at both sites. While the seasonal changes in GCC were more obvious for the ecosystem that is dominated by annual plants (open wetland), clear seasonal patterns were also observed for the evergreen ecosystem (coniferous forest). Daily and seasonal time periods with sufficient solar radiation were determined based on images of a grey reference plate. The variability in cloudiness had only a minor effect on GCC, and GCC did not depend on the sun angle and direction either. The daily GCC of wetland correlated well with the daily photosynthetic capacity estimated from the CO2 flux measurements. At the forest site, the correlation was high in 2015 but there were discernible deviations during the course of the summer of 2014. The year-to-year differences were most likely generated by meteorological conditions, with higher temperatures coinciding with higher GCCs. In addition to depicting the seasonal course of ecosystem functioning, GCC was shown to respond to environmental changes on a timescale of days. Overall, monitoring of phenological variations with digital images provides a powerful tool for linking gross primary production and phenology.

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