Olivier Roupsard

Olivier Roupsard

orcid

Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
11 February 2022 in Global Change Biology
Verified
Journal Article
Open access
PDF file
JLJonas Lembrechts
Jonas Lembrechts
JHJohan van Den Hoogen
Johan van Den Hoogen
JAJuha Aalto
Juha Aalto
MAMichael B. Ashcroft
Michael B. Ashcroft
PFPieter De Frenne
Pieter De Frenne
JLJonathan Lenoir
Jonathan Lenoir
Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1‐km2resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1‐km2pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse‐grained air temperature estimates from ERA5‐Land (an atmospheric reanalysis by the European Centre for Medium‐Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome‐specific offsets emphasize that the projected impacts of climate and climate change on near‐surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil‐related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.

20 April 2020 in Global Change Biology
Verified
Journal Article
Closed access
PDF file
JLJonas Lembrechts
Jonas Lembrechts
JAJuha Aalto
Juha Aalto
MAMichael Ashcroft
Michael Ashcroft
PFPieter De Frenne
Pieter De Frenne
MKMartin Kopecký
Martin Kopecký
INIvan Nijs
Ivan Nijs

24 April 2017 in Geophysical Research Letters
Verified
Journal Article
Open access
PDF file
JKJohn H. Kim
John H. Kim
TFThierry Fourcaud
Thierry Fourcaud
CJChristophe Jourdan
Christophe Jourdan
JMJean‐Luc Maeght
Jean‐Luc Maeght
ZMZhun Mao
Zhun Mao
ASAlexia Stokes
Alexia Stokes
Although vegetation is increasingly used to mitigate landslide risks, how vegetation affects the temporal variability of slope stability is poorly understood, especially in earthquake‐prone regions. We combined 3‐year long soil moisture monitoring, measurements of soil physical properties and plant functional traits, and numerical modeling to compare slope stability under paired land uses with and without trees in tropical, subtropical, and temperate landslide‐ and earthquake‐prone regions. Trees improved stability for 5–12 months per year from drawdown of soil moisture and resulted in less interannual variability in the duration of high‐stability periods compared to slopes without trees. Our meta‐analysis of published data also showed that slopes with woody vegetation were more stable and less sensitive to climate and soil factors than slopes with herbaceous vegetation. However, estimates of earthquake magnitude necessary to destabilize slopes at our sites suggest that large additional stabilization from trees is necessary for meaningful protection against external triggers.

1 July 2020 in Agriculture, Ecosystems & Environment
Verified
Journal Article
Closed access
OROlivier Roupsard
Olivier Roupsard
AAAlain Audebert
Alain Audebert
ANAdama P. Ndour
Adama P. Ndour
CCCathy Clermont-Dauphin
Cathy Clermont-Dauphin
YAYelognissè Agbohessou
Yelognissè Agbohessou
LLLouise Leroux
Louise Leroux

25 October 2017 in Biogeosciences
Verified
Journal Article
Open access
PDF file
CSClifton R. Sabajo
Clifton R. Sabajo
GMGuerric Le Maire
Guerric Le Maire
TJTania June
Tania June
AMAna Meijide
Ana Meijide
OROlivier Roupsard
Olivier Roupsard
AKAlexander Knohl
Alexander Knohl
Indonesia is currently one of the regions with the highest transformation rate of land surface worldwide related to the expansion of oil palm plantations and other cash crops replacing forests on large scales. Land cover changes, which modify land surface properties, have a direct effect on the land surface temperature (LST), a key driver for many ecological functions. Despite the large historic land transformation in Indonesia toward oil palm and other cash crops and governmental plans for future expansion, this is the first study so far to quantify the impacts of land transformation on the LST in Indonesia. We analyze LST from the thermal band of a Landsat image and produce a high-resolution surface temperature map (30 m) for the lowlands of the Jambi province in Sumatra (Indonesia), a region which suffered large land transformation towards oil palm and other cash crops over the past decades. The comparison of LST, albedo, normalized differenced vegetation index (NDVI) and evapotranspiration (ET) between seven different land cover types (forest, urban areas, clear-cut land, young and mature oil palm plantations, acacia and rubber plantations) shows that forests have lower surface temperatures than the other land cover types, indicating a local warming effect after forest conversion. LST differences were up to 10.1 ± 2.6 °C (mean ± SD) between forest and clear-cut land. The differences in surface temperatures are explained by an evaporative cooling effect, which offsets the albedo warming effect. Our analysis of the LST trend of the past 16 years based on MODIS data shows that the average daytime surface temperature in the Jambi province increased by 1.05 °C, which followed the trend of observed land cover changes and exceeded the effects of climate warming. This study provides evidence that the expansion of oil palm plantations and other cash crops leads to changes in biophysical variables, warming the land surface and thus enhancing the increase of the air temperature because of climate change.

6 September 2016 in Remote Sensing
Verified
Journal Article
Open access
PDF file
MVManish Verma
Manish Verma
Joshua FisherJoshua Fisher
Joshua Fisher
KMKaniska Mallick
Kaniska Mallick
Youngryel RyuYoungryel Ryu
Youngryel Ryu
HKHideki Kobayashi
Hideki Kobayashi
ACAlessandro Cescatti Alessandro Cescatti
Alessandro Cescatti Alessandro Cescatti
Reliable and fine resolution estimates of surface net-radiation are required for estimating latent and sensible heat fluxes between the land surface and the atmosphere. However, currently, fine resolution estimates of net-radiation are not available and consequently it is challenging to develop multi-year estimates of evapotranspiration at scales that can capture land surface heterogeneity and are relevant for policy and decision-making. We developed and evaluated a global net-radiation product at 5 km and 8-day resolution by combining mutually consistent atmosphere and land data from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board Terra. Comparison with net-radiation measurements from 154 globally distributed sites (414 site-years) from the FLUXNET and Surface Radiation budget network (SURFRAD) showed that the net-radiation product agreed well with measurements across seasons and climate types in the extratropics (Wilmott’s index ranged from 0.74 for boreal to 0.63 for Mediterranean sites). Mean absolute deviation between the MODIS and measured net-radiation ranged from 38.0 ± 1.8 W∙m−2 in boreal to 72.0 ± 4.1 W∙m−2 in the tropical climates. The mean bias was small and constituted only 11%, 0.7%, 8.4%, 4.2%, 13.3%, and 5.4% of the mean absolute error in daytime net-radiation in boreal, Mediterranean, temperate-continental, temperate, semi-arid, and tropical climate, respectively. To assess the accuracy of the broader spatiotemporal patterns, we upscaled error-quantified MODIS net-radiation and compared it with the net-radiation estimates from the coarse spatial (1° × 1°) but high temporal resolution gridded net-radiation product from the Clouds and Earth’s Radiant Energy System (CERES). Our estimates agreed closely with the net-radiation estimates from the CERES. Difference between the two was less than 10 W·m−2 in 94% of the total land area. MODIS net-radiation product will be a valuable resource for the science community studying turbulent fluxes and energy budget at the Earth’s surface.