Questioning the reliability of the point intercept method for assessing community functional structure in low-productive and highly diverse Mediterranean grasslands

Barkaoui Karim, Bernard-Verdier Maud, Navas Marie-Laure. 2013. Questioning the reliability of the point intercept method for assessing community functional structure in low-productive and highly diverse Mediterranean grasslands. Folia Geobotanica, 48 : 393-414.

Quartile : Q2, Sujet : PLANT SCIENCES

Résumé : Quantifying species relative abundances in plant communities remains a key issue for the assessment of community functional structure. This is particularly challenging when non-destructive estimates are required over time. We tested whether the point intercept method (PIM), originally developed for low-diverse communities, is relevant for assessing the aboveground biomass and functional structure of highly diverse, low-productive Mediterranean grasslands. We sampled 18 communities with the PIM along a gradient of soil depth and texture, twice over the growing season. After each sampling period, we harvested the aboveground biomass in order to measure species biomass and to assess species richness and community functional structure with plant height, leaf area and leaf dry matter content (LDMC). We investigated the relationship between point intercept measurements and aboveground biomass at three hierarchical levels (species, growth-form and community) to find generalizable calibration equations for estimating community biomass and tested for sensitivity of estimates to community structure. We then compared the community weighted mean (CWM) and variance (CWV) of LDMC, calculated with and without calibration. Differences in species growth strategy and phenology strongly impacted biomass estimates at both the species and the community level. These differences were, however, successfully accounted for by growth-form specific calibrations, which provided accurate estimates without any influence of community structure. Lack of calibration may have dramatic consequences on functional structure assessment by inducing errors in estimates of CWV up to 80 %, depending on growth-form proportions. This work contributes to a better understanding of the possible methodological biases induced during sampling with the PIM, when quantifying species relative abundances for functional structure assessment in complex communities.

Mots-clés Agrovoc : prairie, herbage, communauté végétale, biomasse aérienne, échantillonnage, biodiversité

Mots-clés géographiques Agrovoc : France, région méditerranéenne

Mots-clés libres : Aboveground biomass, Functional diversity, Mediterranean grasslands, Point-intercept method, Vegetation sampling

Classification Agris : F40 - Écologie végétale

Champ stratégique Cirad : Axe 6 (2005-2013) - Agriculture, environnement, nature et sociétés

Auteurs et affiliations

• Barkaoui Karim, CEFE (FRA) ORCID: 0000-0002-5787-3748 - auteur correspondant
• Bernard-Verdier Maud, CEFE (FRA)
• Navas Marie-Laure, Montpellier SupAgro (FRA)

Source : Cirad-Agritrop (https://agritrop.cirad.fr/597610/)

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