Effects of sampling time, species richness and observer on the exhaustiveness of plant censuses

Archaux, Frédéric; Gosselin, Frédéric; Bergès, Laurent; Chevalier, Richard

doi:10.1111/j.1654-1103.2006.tb02449.x

Cited by 93 publications

(80 citation statements)

References 13 publications

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“…In 2006, we standardized both sampling time (to 30 min with two operators) and sampling area (to 400 m 2 ) in order to correct for lack of exhaustiveness in plant inventories (Archaux et al 2006). In addition, we visually estimated the global cover percentage for each vegetation layer.…”

Section: Sampling Designmentioning

confidence: 99%

Decreasing deer browsing pressure influenced understory vegetation dynamics over 30 years

Boulanger

Baltzinger²,

Saı̈d

et al. 2014

Annals of Forest Science

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Abstract& Key message Thanks to the concomitant recordings of vegetation and deer browsing sampled first in 1976, then resurveyed in 2006, we show that forest plant communities shifted in response to deer population dynamics, stand management and eutrophication. & Context and aims High deer populations alter forest understory dynamics worldwide. However, no study ever attempted to rank the importance of deer herbivory relatively to other environmental drivers. In the Arc-en-Barrois National Forest (France), we investigated whether (i) deer browsing is a critical driver of vegetation composition and dynamics, (ii) the vegetation communities recover after a decrease in deer populations. & Methods In 2006, we resurveyed 321 plots from a network of 1027 plots where vegetation composition and browsing pressure was first assessed in 1976. We used coinertia analysis to identify the gradients in vegetation composition in 1976, when abiotic variables were also recorded. We assessed shifts in plant community composition using mean Ellenberg indicator values, analysed plot scores shifts along the axes of the coinertia analysis and correlated these shifts with changes in browsing pressure. & Results Two major gradients determined vegetation composition in 1976: edaphic variables (nitrogen availability and soil moisture) and browsing pressure. Over the next 30 years, we noticed a strong increase in nitrophilous plant species frequency and community composition shifted towards lightly browsed characteristics, accompanying a decrease in browsing pressure. Shifts in community composition were significantly correlated with the intensity of changes in browsing pressure, showing that deer population dynamics were a determinant driver of changes in plant assemblages. We observed an incomplete recovery of the communities 25 years after the reduction of deer densities, suggesting a delayed response to deer population reduction. Long-term monitoring of forest biodiversity should therefore include browsing pressure assessment to control for potential effects of wild ungulates.

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Section: Sampling Designmentioning

confidence: 99%

Decreasing deer browsing pressure influenced understory vegetation dynamics over 30 years

Boulanger

Baltzinger²,

Saı̈d

et al. 2014

Annals of Forest Science

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“…MIVs were used to separately assess climate, light and nutrient richness conditions. Ellenberg et al (1992) and Gégout et al (2005) A total of 63 teams with different levels of expertise in plant identification were involved in floristic data gathering, and as a result, random variation could be substantial due to observer effects, overlooking plants, and species misidentification (Archaux et al 2006). However, the MIV system is considered a robust bioindicator tool that is only weakly influenced by plant survey exhaustiveness and plot size (Ewald 2003;Archaux et al 2007).…”

Section: Mean Plant Indicator Values (Miv)mentioning

confidence: 99%

Unexpected long-range edge-to-forest interior environmental gradients

Bergès¹,

Pellissier

Avon³

et al. 2013

Landscape Ecol

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We examined the relationships between distance-to-edge and environmental factors inferred from mean plant indicator values across large distance-to-edge and patch size gradients.Floristic composition, landscape metrics and site variables (climate, soil and forest management) were collected on 19989 plots in 1801 forest patches in Northern France using the French National Forest Inventory. Statistical models were applied to mean plant indicator values (MIV) from Ellenberg and Ecoplant databases for soil pH, soil nitrogen (N), soil humidity (F), light (L) and air temperature (Ta) using distance-to-edge and forest patch size as predictors. The five mean indicator values significantly varied with distance-to-edge and MIV.pH, N and Ta decreased over distances in excess of 500 m. Consistent very long edgeto-interior gradients were also detected for site variables. The distance-to-edge effect remained significant after controlling for site differences, especially for MIV.pH and N.Significant edge-to-core gradients of MIV were detected over much larger ranges than previously recognised. Neither the presence of an ecological boundary between forest and the surrounding matrix, nor microclimate, soil or forest management heterogeneity within forest patches can fully explain this long edge-to-interior gradient observed in MIV. Two hypotheses are discussed for MIV.pH and N: (1) soil eutrophication, due to atmospheric N deposition, which could occur deeper into forest cores than previously acknowledged; (2) land-use legacies, as the periphery of ancient forests is more often occupied by recent forests where former agricultural practices have irreversibly modified topsoil properties. Land use history data would help identify the drivers underlying these long-range edge gradients.

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“…We checked the robustness of the CA axes towards potential inaccuracies of floristic censuses due to time or spatial strategies or the observer (Archaux et al, 2006;2007) and towards analysis options. This verification was performed with a Multiple Factorial Analysis (MFA) (Escofier and Pages, 1994) testing the stability of CA axes and plot coordinates: on one hand, by increasing the number of plots where a plant must be present to be taken into account from 3 to 30, and on the other hand, comparing presence/absence and BraunBlanquet coefficients in the analysis.…”

Section: Robustness Of the Model Designmentioning

confidence: 99%

“…The flora census was performed with a "variable-time strategy with minimum time limit" (Archaux et al, 2006), e.g. for a minimum of 1/2 h with a stop if no new species was found within 5 min.…”

Section: Variablesmentioning

confidence: 99%

A new bioclimatic model calibrated with vegetation for Mediterranean forest areas

et al. 2008

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Keywords:bioclimatic model / Mediterranean forest / water availability / floristic analysis / PLS regression / Provence Abstract • Water availability is one of the main factors explaining flora composition and growth in Mediterranean regions, where it may decline with climate change.• Our goal was to develop a model for forest site assessment in Mediterranean environments, focusing on water availability to assess potential vegetation composition and productivity in any places, whatever their level of disturbance.• We designed a statistical model, using global climatic and geographic variables, as well as detailed local topographic and edaphic variables, to compute a bioclimatic index for Mediterranean forest environments. This model was calibrated in France with a flora index from 325 old forests. The model explained 80.3% of the flora index variance. The method fills a gap in existing models, bridging scales from the region to forest sites.• Beyond its theoretical aspect, it was designed to allow practical tools to be derived from it for decision-making and management, such as the assessment of climate change impact on vegetation, and of forest productivity. Its development and adaptation is possible in other Mediterranean regions, and in any region where water is one of the main limiting factors. Mots-clés :modèle bioclimatique / forêt méditerranéenne / disponibilité en eau / analyse floristique / régression PLS / Provence Résumé -Un nouveau modèle bioclimatique calibré à l'aide de la flore pour les milieux forestiers méditerranéens.• La disponibilité en eau est un des principaux facteurs contrôlant la composition et la croissance de la flore en région méditerranéenne. Elle devrait décroître avec le changement climatique.• Notre objectif était de développer un modèle pour l'analyse stationnelle des milieux forestiers mé-diterranéens. Basé sur la disponibilité de l'eau, il devait permettre l'évaluation de leur flore potentielle et de leur productivité, quel que soit leur état de perturbation.• Nous avons conçu un modèle statistique, utilisant conjointement des variables globales, climatiques et géographiques, et des variables locales topographiques et édaphiques pour calculer un indice bioclimatique adapté aux milieux forestiers méditerranéens. Ce modèle a été calibré en France sur 325 placettes de forêts âgées à l'aide d'un indice floristique dont il explique 80.3 % de la variance. Avec des échelles de travail allant en continu de la région à la station forestière, la méthode comble un vide dans la gamme des modèles existants.• Ce modèle ouvre des perspectives pour l'évaluation de l'impact du changement climatique sur la flore et de la productivité forestière. La méthode peut être adaptée à d'autres régions méditerranéennes et à toute région où le bilan hydrique est un des principaux facteurs limitants. * Corresponding author: michel.vennetier@cemagref.frArticle published by EDP Sciences Ann. For. Sci. 65 (2008) 711 M. Vennetier et al. INTRODUCTION ContextMediterranean forests of Europe and North Africa are...

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Effects of sampling time, species richness and observer on the exhaustiveness of plant censuses

Cited by 93 publications

References 13 publications

Decreasing deer browsing pressure influenced understory vegetation dynamics over 30 years

Decreasing deer browsing pressure influenced understory vegetation dynamics over 30 years

Unexpected long-range edge-to-forest interior environmental gradients

A new bioclimatic model calibrated with vegetation for Mediterranean forest areas

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