Liana Anderson | University of Oxford (original) (raw)

Papers by Liana Anderson

Revista GeoNorte, Mar 11, 2024

Global Change Biology, Nov 17, 2020

Remote Sensing, May 4, 2012

Nature Ecology and Evolution, Nov 17, 2022

Global Ecology and Biogeography, Aug 9, 2022

AimThe aim was to evaluate fire activity for the entire Amazon and Amazon regions within each cou... more AimThe aim was to evaluate fire activity for the entire Amazon and Amazon regions within each country/department from 2003 to 2020, assessing the potential contributions of drought and deforestation and contrasting 2020 with the previous years.LocationAmazoniasensu lato.Time periodAnnually from 2003 to 2020.Major taxa studiedTerrestrial plants.MethodsWe collected time series of MODIS active fire detections and burned area and assessed the yearly burned area of several land‐use/land‐cover types. We also divided the Amazon territory into 10 km × 10 km grid cells to identify annual anomalies in active fire occurrence, rainfall, maximum cumulative water deficit (MCWD) and deforestation. Rainfall and MCWD anomalies for a given cell each year consisted of annual values at least one standard deviation below average for that cell from 2003 to 2020, whereas fire and deforestation anomalies had annual values at least one standard deviation above the average for that cell.ResultsBrazil and Bolivia have contributed, on average, >70% and about 15%, respectively, of annual active fire detections in the Amazon, in addition to more than half and about one‐third of annual burned areas in the region. On average, 32% of annual burned areas in the Amazon have consisted of agricultural lands, 29% of natural grasslands and 16% of old‐growth forests. The annual extent of areas with fire anomalies was significantly associated with the annual extent of areas with deforestation anomalies, but not significantly associated with the annual extent of areas experiencing water deficit anomalies. In 2020, the total burned area in the Amazon was the greatest since 2010, and the ratio of burned area per active fire was the second greatest of the time series, despite a much lower extent of areas with anomalously high water deficit in comparison to the 2015–2016 megadrought.Main conclusionsOur findings suggest that the majority of anomalously high fire occurrences in the Amazon since 2003 did not occur in anomalous drought conditions. The intensification of agricultural fires and deforestation aggravated the burning of Amazonian ecosystems in 2020.

Climate resilience and sustainability, Jul 31, 2021

Cadernos De Saude Publica, Dec 31, 2022

Amazon deforestation data are used as a gauge, at the national and international levels, to indic... more Amazon deforestation data are used as a gauge, at the national and international levels, to indicate the current situation of the political management of the control of and combat against this process, which is usually widely disseminated in the media. Due to the weakening of environmental policies in recent years, there was a forecast that deforestation for the year 2020 1 would be the highest of the decade, above that of 2019, which exceeded 10,800km 2 1 , the highest rate since 2008. Although 2020 had a slightly lower rate than 2019, deforestation in 2021 and 2022 exceeded 12,000km 2 2 , which again featured prominently in global media. Recently, the Yanomami crisis revealed another growing threat to Amazonian life: the push of mining activities in the region. Estimates point to increased mining rates mainly after 2010, and 2020 data showed that the total mining area exceeded the industrial mining area 3. The negative impacts-beyond social and cultural ruptures caused to indigenous peoplesinclude increased disease rates, environmental contamination, and food insecurity 4. The advance of deforestation reveals a small part of the socio-environmental problem related to the Amazonian forests. A recent study 5 quantified that fire, forest fragmentation and logging between 2001 and 2018 have already impacted more than 5.5% of the forests in the entire Amazon basin, and this extension corresponds to 112% of the total area deforested in that period. If we add to this list of forest degradation vectors the occurrence of extreme droughts, the area increases to 38% of the remaining Amazonian forests. It is widely known that fire is the main instrument for disposing of biomass after clear-cutting the forest, and that it causes a series of negative socioeconomic and environmental impacts. For example, on the global scale, greenhouse gas emissions from slash-and-burn practices and wildfires directly affect the rainfall and temperature regime and, on the regional scale, directly generate air pollution, thus affecting air quality 6,7. Locally, the negative impacts of fires include the degradation of soils and forests, the imposition of restrictions and losses on those who depend on them, affecting their properties, public infrastructure or even services 8. However, it is much less known that areas with forest fragmentation 9 , logging 10 , and forest areas that have already been affected by fire are more susceptible to new fires 11. Moreover, extreme droughts, which have intensified and become more recurrent due to climate change 12 , amplify the extent and magnitude of fires 7. This means that even if deforestation rates are controlled, there are still all the other forcings that lead to the occurrence of fires present in human practices and Amazonian landscapes 13 , and these have increased over this century 14 .

Remote Sensing, Dec 8, 2017

Amazonia is the world largest tropical forest, playing a key role in the global carbon cycle. Thu... more Amazonia is the world largest tropical forest, playing a key role in the global carbon cycle. Thus, understanding climate controls of photosynthetic activity in this region is critical. The establishment of the relationship between photosynthetic activity and climate has been controversial when based on conventional remote sensing-derived indices. Here, we use nine years of solar-induced chlorophyll fluorescence (ChlF) data from the Global Ozone Monitoring Experiment (GOME-2) sensor, as a direct proxy for photosynthesis, to assess the seasonal response of photosynthetic activity to solar radiation and precipitation in Amazonia. Our results suggest that 76% of photosynthesis seasonality in Amazonia is explained by seasonal variations of solar radiation. However, 13% of these forests are limited by precipitation. The combination of both radiation and precipitation drives photosynthesis in the remaining 11% of the area. Photosynthesis tends to rise only after radiation increases in 61% of the forests. Furthermore, photosynthesis peaks in the wet season in about 58% of the Amazon forest. We found that a threshold of ≈1943 mm per year can be defined as a limit for precipitation phenological dependence. With the potential increase in the frequency and intensity of extreme droughts, forests that have the photosynthetic process currently associated with radiation seasonality may shift towards a more water-limited system.

Revista Brasileira de Cartografia, Jun 30, 2018

Environmental Research Letters, Dec 1, 2021

Fire is one of the main anthropogenic drivers that threatens the Amazon. Despite the clear link b... more Fire is one of the main anthropogenic drivers that threatens the Amazon. Despite the clear link between rainfall and fire, the spatial and temporal relationship between these variables is still poorly understood in the Amazon. Here, we stratified the Amazon basin according to the dry season onset/end and investigated its relationship with the spatio-temporal variation of fire. We used monthly time series of active fires from 2003 to 2019 to characterize the fire dynamics throughout the year and to identify the fire peak months. More than 50% (32 246) of the annual mean active fires occurred in the peak month. In 52% of the cells, the peaks occurred between August–September and in 48% between October–March, showing well-defined seasonal patterns related to spatio-temporal variation of the dry season. Fire peaks occurred in the last two months of the dry season in 67% of the cells and in 20% in the first month of the rainy season. The shorter the dry season, the more concentrated was the occurrence of active fires in the peak month, with a predominance above 70% in cells with a dry season between one and three months. We defined a Critical Fire Period by identifying the consecutive months that concentrated at least 80% of active fires in the year. This period included two to three months between January and March in the northwest, and in the far north it lasted up to seven months, ending in March–April. In the south, it varied between two and three months, starting in August. In the northeast, it was three to four months, between August and December. By quantifying the role of the dry season in driving fire seasonality across the Amazon basin, we provide recommendations to monitor fire dynamics that can support decision makers in management policies and measures to avoid environmentally or socially harmful fires.

Global CHIRPS MCWD Dataset The MCWD (Maximum Cumulative Water Defici... more Global CHIRPS MCWD Dataset The MCWD (Maximum Cumulative Water Deficit) is a measure of drought severity, which corresponds to the maximum value of the monthly accumulated water deficit reached for each pixel within the year. The MCWD is a useful indicator of meteorologically induced water stress without taking into account local soil conditions and plant adaptations, which are poorly understood in Amazonia. The full method of MCWD is described in Aragão et al. (2007; https://doi.org/10.1029/2006GL028946). Detail about CHIRPS (Rainfall Estimates from Rain Gauge and Satellite Observations) can be found in Funk et al. (2015; https://doi.org/10.1038/sdata.2015.66). Coverage: Spanning 50°S-50°N (and all longitudes/land areas) Period: 1981 to 2020 Spatial resolution: 0.05-degree Temporal resolution: Annual Coordinate reference system: Geographic Coordinate System (Datum WGS84) File format: The zip file containing 40 files (one per year) in compressed TIFF format. Code: https://zenodo.org/record/5034650 Dataset usage: It is free to use, but if you use this dataset in your work, please make sure to cite the repository and our paper properly. We also welcome users to invite us for collaboration. For the use of this dataset, please cite: Silva Junior, C.H.L. et al. Global CHIRPS MCWD (Maximum Cumulative Water Deficit) Dataset. Zenodo (2021). DOI: 10.5281/zenodo.4903340. https://doi.org/10.5281/zenodo.4903340 Silva Junior, C.H.L. et al. Fire Responses to the 2010 and 2015/2016 Amazonian Droughts. Front. Earth Sci. (2019). DOI: 10.3389/feart.2019.00097. https://doi.org/10.3389/feart.2019.00097 Funk, C. et al. The climate hazards infrared precipitation with stations—a new environmental record for monitoring extremes. Scientific Data (2015). DOI: 10.1038/sdata.2015.66. https://doi.org/10.1038/sdata.2015.66