Extrapolated species accumulation curves.

<p>Species accumulation curves for remnant and control plots, for all stems ≥5 cm DBH. All species accumulation curves are extrapolated to 76 individuals, the greatest number of individuals found in one plot (min individuals in a plot  = 30, mean  = 53.6). White dots indicate mean species richness for all remnant or control plots. The dashed line allows for comparison of remnant and control plot means.</p

Effect of remnant tree or site on species structure and diversity.

<p>ANOVA results are shown for basal area, seedling density, tree density, light, species richness, species diversity, species evenness, and pairwise similarity to old-growth forest (df  = 1 and residual df  = 28 for all). Results with significant p-values are shown in bold.</p

Remnant Trees Affect Species Composition but Not Structure of Tropical Second-Growth Forest

<div><p>Remnant trees, spared from cutting when tropical forests are cleared for agriculture or grazing, act as nuclei of forest regeneration following field abandonment. Previous studies on remnant trees were primarily conducted in active pasture or old fields abandoned in the previous 2–3 years, and focused on structure and species richness of regenerating forest, but not species composition. Our study is among the first to investigate the effects of remnant trees on neighborhood forest structure, biodiversity, and species composition 20 years post-abandonment. We compared the woody vegetation around individual remnant trees to nearby plots without remnant trees in the same second-growth forests (“control plots”). Forest structure beneath remnant trees did not differ significantly from control plots. Species richness and species diversity were significantly higher around remnant trees. The species composition around remnant trees differed significantly from control plots and more closely resembled the species composition of nearby old-growth forest. The proportion of old-growth specialists and generalists around remnant trees was significantly greater than in control plots. Although previous studies show that remnant trees may initially accelerate secondary forest growth, we found no evidence that they locally affect stem density, basal area, and seedling density at later stages of regrowth. Remnant trees do, however, have a clear effect on the species diversity, composition, and ecological groups of the surrounding woody vegetation, even after 20 years of forest regeneration. To accelerate the return of diversity and old-growth forest species into regrowing forest on abandoned land, landowners should be encouraged to retain remnant trees in agricultural or pastoral fields.</p></div

Appendix A. Species contributions to standing biomass and biomass dynamics.

Species contributions to standing biomass and biomass dynamics

Supplement 1. Data on tree dynamics during secondary succession and wood specific gravity in northeastern Costa Rica.

<h2>File List</h2><div> <p><a href="Chazdon_data.txt">Chazdon_data.txt</a> (MD5: 05f10c673d870ea6e647a56b3ea7b67d)          Permanent plot data</p> <p><a href="Chazdon_meta.txt">Chazdon_meta.txt</a> (MD5: 90757c3a3ffd54b096105814f2296c86)          Information on the plots</p> <p><a href="WSG_data.txt">WSG_data.txt</a> (MD5: 210cd495964e565b31d2efb1a0135bb8)          Data on wood specific gravity</p> </div><h2>Description</h2><div> <p>This supplement includes the raw data of the permanent sample plots (Chazdon_data.txt), along with information on the characteristics of the plots (Chazdon_meta.txt), as well as data on wood specific gravity (WSG) for 92 tropical tree species from La Selva, Costa Rica. </p> <p><i>Note:</i> Robin Chazdon should be contacted before using the data set, to sign a data-use agreement, and to receive the latest version of the data, as updates and corrections (e.g., to species names) are continuously made. </p> <p>Additional data on WSG is available from Plourde et al. (<i>in press</i>). Average, species-specific WSG was measured as the ratio of dry mass to green volume, from cores or discs of trees ranging from 5–60 cm DBH for each species. Green volume was measured with the water displacement method, then wood samples were dried at 103–105°C for 24–48 hours before dry mass was determined (Plourde et al., <i>in press</i>). See Plourde et al. (<i>in press</i>) for more details on the methodology.</p> <p>Additional information on some of the columns in Chazdon_data.txt:</p> <p>StemID – The first number is the site code. The three digits after the first hyphen refer to the subplot number (1-100). The digits after the second hyphen indicate the number of an individual tree within each subplot. If multiple stems are separated below 1.3 m height they are marked separately. Each StemID is unique.  </p> <p>DBH.1997-2013 – Diameter at 1.3 m height, or above buttresses or stem irregularities for each year.</p> <p>DBH2.2012-2013 – Second diameter measurement higher in the stem when the point of measurement was changed because of the formation of buttresses or stem irregularities.</p> </div

Appendix A. A table showing annualized changes in density and mortality rates of common tree species in four 1-ha second-growth monitoring plots from 1997–2003.

A table showing annualized changes in density and mortality rates of common tree species in four 1-ha second-growth monitoring plots from 1997–2003

Appendix A. A table of reproductive traits for 366 species in 10 wet tropical forests.

A table of reproductive traits for 366 species in 10 wet tropical forests

Appendix A. Top 10 tree species for each of the treatment plots.

Top 10 tree species for each of the treatment plots

Appendix B. A generalization of Good-Turing sample coverage theory.

A generalization of Good-Turing sample coverage theory

Appendix C. Other models for the relative abundances of the undetected species.

Other models for the relative abundances of the undetected species