Devenirs militants:Introduction

Présenter un dossier sur l’engagement qui mette sur le même plan les pratiques militantes dans les partis politiques, les organisations syndicales, le monde associatif et plus généralement les entreprises de mouvement social, pourra paraître osé. C’est que, pendant longtemps, le militantisme a été pensé sous les seules espèces du travail partisan et syndical, dans un contexte où la définition de la participation politique demeurait étroitement cantonnée à l’action dite « conventionnelle ». [Premier paragraphe de l'article

Global island dataset

The data are described in detail in SI Materials and Methods in the supporting information of the paper (Weigelt et al. 2013, PNAS) and in the ReadMe file

Global maps of (A) Native species richness (<i>N</i>), (B) Anthropogenic species richness (<i>ASR</i>), (C) Anthropogenic species richness (<i>ASR</i>) relative to <i>N</i>, (D) total anthropogenic species loss (<i>ASL</i>) + anthropogenic species increase (<i>ASI</i>) relative to <i>N</i>, (E) <i>ASL</i> relative to <i>N</i>, (F) <i>ASI</i> relative to <i>N</i>, (G) <i>ASL</i>, (H) <i>ASI</i>, (I) exotic species invasions (<i>IS</i>), (J) <i>IS</i> relative to <i>N</i>.

<p>All maps in Eckert IV global equal area projection.</p

Global relationships between (A) anthropogenic species loss (<i>ASL</i>) and increase (<i>ASI</i>), (B) anthropogenic (<i>ASR</i>) and native (<i>N</i>) species richness, (C) <i>N</i> and population density, (D) Habitat loss (<i>HL</i>; fraction of habitat lost to land use) and population density, (E) <i>ASL</i> and population density and (F) <i>ASI</i> and population density, (G) <i>ASL</i> and <i>HL</i>, and (H) <i>ASI</i> and <i>HL</i>.

<p>Points represent regional landscape cells, colored by anthrome class. Thick black lines are regressions with <i>R</i>² at lower right; thin dashed black lines are upper and lower regression models from sensitivity analysis. Thick dashed black lines indicate <i>X</i> = <i>Y</i> in (A) and (B) and smoothed curve fit to data in (I).</p

phylo_sumatra

The phylogeny used in the paper in newick format

metrics_sumatra

The community data used in the paper in csv format

Species accumulation curves based on forest floor-based sampling of epiphytes.

<p>A) Brazilian core transects (n = 30). B) Brazilian edge transects (n = 30). C) Panamanian transects, excluding ferns and aroids (n = 36). D) Panamanian transects, all species (n = 36). Solid curves give the mean number of species based on 100 randomized samplings, dashed curves the 95% CI. Horizontal lines indicate the number of species present in the canopy of the transects (thin lines), in the study site (thick lines, same estimate for both Brazilian study sites) and on substrate < 10 cm in diameter (dot line, in c and d). See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128019#pone.0128019.s007" target="_blank">S1 Table</a> for the list of species found in the transects and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128019#pone.0128019.s008" target="_blank">S2 Table</a> for species lists found in the study sites. Note that the Brazilian study sites showed curves leveling off, whereas the Panamanian site revealed a slightly steeper curve in agreement with the higher number of species.</p

Branchfall as a Demographic Filter for Epiphyte Communities: Lessons from Forest Floor-Based Sampling

<div><p>Local variation in the abundance and richness of vascular epiphytes is often attributed to environmental characteristics such as substrate and microclimate. Less is known, however, about the impacts of tree and branch turnover on epiphyte communities. To address this issue, we surveyed branches and epiphytes found on the forest floor in 96 transects in two forests (Atlantic rainforest in Brazil and Caribbean rainforest in Panama). In the Brazilian forest, we additionally distinguished between edge and core study sites. We quantified branch abundance, epiphyte abundance, richness and proportion of adults to investigate the trends of these variables over branch diameter. Branches <2 cm in diameter comprised >90% of all branches on the forest floor. Abundance and richness of fallen epiphytes per transect were highest in the Brazilian core transects and lowest in the Panamanian transects. The majority of epiphytes on the floor (c. 65%) were found attached to branches. At all three study sites, branch abundance and branch diameter were negatively correlated, whereas epiphyte abundance and richness per branch, as well as the proportion of adults were positively correlated with branch diameter. The relationship between branch diameter and absolute epiphyte abundance or richness differed between study sites, which might be explained by differences in forest structure and dynamics. In the Panamanian forest, epiphytes had been previously inventoried, allowing an evaluation of our surveying method by comparing canopy and forest floor samplings. Individuals found on the forest floor corresponded to 13% of all individuals on branches <10 cm in diameter (including crowns), with abundance, richness and composition trends on forest floor reflecting canopy trends. We argue that forest floor surveys provide useful floristic and, most notably, demographic information particularly on epiphytes occurring on the thinnest branches, which are least accessible. Here, branchfall acts as an important demographic filter structuring epiphyte communities.</p></div

Summarizing scheme of the expected trends with increasing branch diameter.

<p>We expect a decrease in water stress, mechanical disturbance and branch abundance with an increasing branch diameter. These drivers plus the increase in branch age should lead to higher epiphyte colonization and survival and an increase in epiphyte abundance, richness and proportion of adults per branch.</p

Branch abundances as a function of branch diameter.

<p>A) Brazilian core transects (n = 30). B) Brazilian edge transects (n = 30). C) Panamanian transects (n = 36). Box-plots show the median as central line, the first and third quantiles as the bottom and top box limits, 1.5 interquantile range as whiskers, and outliers as circles. Solid lines show fits from GAMMs with 95% CI indicated by dashed lines.</p