Know more

About cookies

What is a "cookie"?

A "cookie" is a piece of information, usually small and identified by a name, which may be sent to your browser by a website you are visiting. Your web browser will store it for a period of time, and send it back to the web server each time you log on again.

Different types of cookies are placed on the sites:

  • Cookies strictly necessary for the proper functioning of the site
  • Cookies deposited by third party sites to improve the interactivity of the site, to collect statistics

Learn more about cookies and how they work

The different types of cookies used on this site

Cookies strictly necessary for the site to function

These cookies allow the main services of the site to function optimally. You can technically block them using your browser settings but your experience on the site may be degraded.

Furthermore, you have the possibility of opposing the use of audience measurement tracers strictly necessary for the functioning and current administration of the website in the cookie management window accessible via the link located in the footer of the site.

Technical cookies

Name of the cookie

Purpose

Shelf life

CAS and PHP session cookies

Login credentials, session security

Session

Tarteaucitron

Saving your cookie consent choices

12 months

Audience measurement cookies (AT Internet)

Name of the cookie

Purpose

Shelf life

atid

Trace the visitor's route in order to establish visit statistics.

13 months

atuserid

Store the anonymous ID of the visitor who starts the first time he visits the site

13 months

atidvisitor

Identify the numbers (unique identifiers of a site) seen by the visitor and store the visitor's identifiers.

13 months

About the AT Internet audience measurement tool :

AT Internet's audience measurement tool Analytics is deployed on this site in order to obtain information on visitors' navigation and to improve its use.

The French data protection authority (CNIL) has granted an exemption to AT Internet's Web Analytics cookie. This tool is thus exempt from the collection of the Internet user's consent with regard to the deposit of analytics cookies. However, you can refuse the deposit of these cookies via the cookie management panel.

Good to know:

  • The data collected are not cross-checked with other processing operations
  • The deposited cookie is only used to produce anonymous statistics
  • The cookie does not allow the user's navigation on other sites to be tracked.

Third party cookies to improve the interactivity of the site

This site relies on certain services provided by third parties which allow :

  • to offer interactive content;
  • improve usability and facilitate the sharing of content on social networks;
  • view videos and animated presentations directly on our website;
  • protect form entries from robots;
  • monitor the performance of the site.

These third parties will collect and use your browsing data for their own purposes.

How to accept or reject cookies

When you start browsing an eZpublish site, the appearance of the "cookies" banner allows you to accept or refuse all the cookies we use. This banner will be displayed as long as you have not made a choice, even if you are browsing on another page of the site.

You can change your choices at any time by clicking on the "Cookie Management" link.

You can manage these cookies in your browser. Here are the procedures to follow: Firefox; Chrome; Explorer; Safari; Opera

For more information about the cookies we use, you can contact INRAE's Data Protection Officer by email at cil-dpo@inrae.fr or by post at :

INRAE

24, chemin de Borde Rouge -Auzeville - CS52627 31326 Castanet Tolosan cedex - France

Last update: May 2021

Menu Logo TULIP Nouveau bandeau tutelles EN

Home

A relationship between population or ecosystem stability and study area

A relationship between population or ecosystem stability and study area
© Amanda Slater
The temporal stability of a population or ecosystem was known to increase with spatial scale, but this relationship had never been made explicit. Researchers from SETE (CNRS and Paul Sabatier University) and their international collaborators describe for the first time the Invariability-Area Relationship (IAR) in a Nature Communications article. They establish a theoretical relationship and measure it with plant production and bird communities data.

The more an ecosystem varies through time, the greater the likelihood of low values of ecosystem services or abundances. Now, low abundance can be dramatic for threatened species and low levels of ecosystem services can have adverse consequences for human well-being. When abundance fluctuate through time, the risks associated with low abundance years (extinction, shortages) are generally not offset by the benefits of high abundance years. Temporal stability is therefore a variable of great interest for the management and conservation of biodiversity and ecosystems.

The spatial scale is an essential parameter of any measure of temporal stability, and these two measurements are expected to be positively related. However, the relationship between temporal stability (invariability) and the spatial scale (area considered) had never before been made explicit and applied to the ecology of communities and ecosystems.

Relation Invariabilité – Aire pour la production primaire terrestre (IAR)

The Invariability –Area Relationship for terrestrial primary production, from plot to the globe scale, presents three phases characterized by a steep slope at small and large scales. Field data (left) are from two 50-hectars tropical forests (scale of 10-4 to 0.5 km²). Remote sensing data (right) are from MODIS (Moderate-Resolution Imaging Spectroradiometer), from a scale of 1 km² to the globe.

The article in Nature Communications establishes a Theoretical Invariability Area Relationship (IAR) and shows that its shape depends on spatial synchrony, that measures simultaneity of fluctuations. Close populations fluctuate together more than remote populations so that synchrony decreases with distance. If this decay accelerates with distance, as in an exponential relationship, the IAR presents three phases, characterized by stronger increases in invariability at small and large scales. Such triphasic IARs are observed for terrestrial primary production of the plot scale on a global scale.

When synchrony between populations decreases slowly with the geographical distance separating them, the IAR is almost linear on a log-log scale. These near-linear IARs are observed for the biomass of North American birds at both species and community levels. This quasi-linearity could come from the relatively small range of spatial scales considered.

The IAR echoes the well-known relationship between species numbers and sampled area in the Species-Area Relationship (SAR), which also has a three-phase shape from plot to globe scale. IAR offers opportunities similar to SAR, which is widely used in conservation biology to predict the consequences of habitat loss for biodiversity. For example, IAR can be used to predict the effects of habitat loss on vulnerable populations or on ecosystem services, which SAR does not consider. The authors show that IAR could also help detecting the approach of "catastrophic" transitions during ecosystem degradation. The future will tell us if this new relationship will deliver as much as the SAR has.

See also

Référence

Wang S., Loreau M., Arnoldi J-F., Fang J., Rahman K.A., Tao S., de Mazancourt C. An invariability-area relationship sheds new light on the spatial scaling of ecological stability. Nature Communications (2017)

DOI: 10.1038/ncomms15211

Contact

Claire de Mazancourt, Centre de Théorie et Modélisation de la Biodiversité, Station d’Ecologie Théorique et Expérimentale (SETE), CNRS/Université Paul Sabatier

Tel : 05 61 04 05 80

Mail : claire.demazancourt@sete.cnrs.fr