DOI: 10.5061/dryad.z8w9ghxk2
title: Total, foliar, and reproductive fine litter production for up to 38 years for four old-growth forests in central Panama

description: Forests sequester a substantial portion of anthropogenic carbon emissions.
 Many open questions concern how. We address two of these questions. Has
 leaf and fine litter production changed? And what is the contribution of
 old-growth forests? We address these questions with long-term records (≥10
 years) of total, reproductive, and especially foliar fine litter
 production from 32 old-growth forests. We expect increases in forest
 productivity associated with rising atmospheric carbon dioxide
 concentrations and, in cold climates, with rising temperatures. We
 evaluate the statistical power of our analysis using simulations of known
 temporal trends parameterized with sample sizes (number of years) and
 levels of interannual variation observed for each record. Statistical
 power is inadequate to detect biologically plausible trends for records
 lasting less than 20 years. Modest interannual variation characterizes
 fine litter production. More variable phenomena will require even longer
 records to evaluate global change responses with sufficient statistical
 power.  Just four old-growth forests have records of fine litter
 production lasting longer than 20 years, and these four provide no
 evidence for increases. Three of the four forests are in central Panama,
 also have long-term records of wood production, and both components of
 aboveground production are unchanged over 21 to 38 years. The possibility
 that recent increases in forest productivity are limited for old-growth
 forests deserves more attention. This data package contains previously
 unpublished data from four old-growth forests in central Panama. Data
 compiled from the published literature for another 28 forests and the R
 scripts required to recreate our analyses can be found here:
 https://smithsonian.dataone.org/view/urn:uuid:8bbcd334-059b-45b1-9b83-94b52abbd6f8.  
description: The data are dry masses of material collected by litter traps.
 The litter traps are open, 1-mm mesh bags supported 80 to 100 cm above the
 ground by PVC frames. We collect fallen material from traps each week at
 three sites (named BCI_Inceptisol, BCI_FDP, and BPSL) and each month at
 the final site (Gigante), Table 1 below provides site descriptions. We
 oven dry the collected material to constant mass at 60°C. We then separate
 and determine the dry mass of leaves, reproductive material, fine wood
 (&lt; 2 cm diameter), and unidentifiable material or
 "dust".    We summed the data over censuses
 within each year for each trap and present the sums by year and trap.
 Units are Mg ha<sup>-1</sup> yr<sup>-1</sup>.
 Years begin with the first census at each site and run from November 1985
 through October 2023 for the BCI_Inceptisol site, May 1997 through April
 2024 for the BPSL site, July 1998 through June 2023 for the Gigante site,
 and May 2013 through April 2024 for the BCI_FDP site. Fine litter fall is
 at its annual low during the rainy season from May through November in
 central Panama. There are 59 0.25 m<sup>2</sup> traps at the
 BCI_Inceptisol site, 64 0.5 m<sup>2</sup> traps at the BCI_FDP
 site, 40 0.5 m<sup>2</sup> traps at the BPSL site, and 12/20
 0.58 m<sup>2</sup> traps at the Gigante site, where 12/20
 indicates there were 12 traps from 1998 to February 2007 and 20 traps
 thereafter.  Rarely, fallen objects or vandals
 compromised traps. These rare occassions accounted for 0.02%, 0.06%,
 0.19%, and 0.13% of the trap-census combinations for the BCI_Inceptisol,
 BCI_FDP, BPSL, and Gigante sites, respectively. The lower values for the
 two BCI sites probably reflect the near total exclusion of potential
 vandals from Barro Colorado Island. When a trap was compromised, its value
 for that census was replaced by the mean value for functioning traps for
 the same census.  Table 1. Site descriptions. MAP refers to mean annual
 precipitation. Mean annual temperature is 26°C. Soil pH (in water), resin
 phosphorus (resin P), and total bases (sum of potassium, calcium, and
 magnesium) are for the upper 10 cm.  Site name Latitude Longitude Elev. (m) MAP (mm) Soil Order pH in water Resin P (mg P kg<sup>-1</sup>) Total bases (cmol<sub>c</sub> kg<sup>-1</sup>) Years since disturbance BCI Inceptisol 9°8'30"N 79°51'05"W 30 2620 Inceptisol 6.2 2.50 25.0 ~ 600 BCI FDP 9°9'20"N 79°51'15"W 180 2620 Oxisol 5.9 1.86 9.75 ~ 600 Gigante 9°6'31"N 79°50'37"W 50 2450 Oxisol 5.4 0.85 13.0 ~ 600 BPSL 9°16'48"N 79°58'30"W 120 3421 Oxisol 4.7 0.24 1.81 ~ 200 Additional site-specific methodological details can be found in the following articles: Puerta-Piñero C, Muller-Landau HC, Calderon O, Wright SJ. 2013. Seed arrival in tropical forest tree fall gaps. Ecology 94: 1552-1562. Wright, SJ, O Calderon, HC Muller-Landau. 2019. A phenology model for tropical species that flower multiple times each year. Ecological Research 34: 20-29. Wright SJ, Turner BL, Yavitt JB et al. 2018. Plant responses to fertilization experiments in lowland, species-rich, tropical forests. Ecology 99: 1129-1138. Wright, SJ, O Calderon. 2025. Statistical power and the detection of global change responses: The case of leaf production in old-growth forests. Ecology 106: in press.
description: # Total, foliar, and reproductive fine litter production for up to 38
 years for four old-growth forests in central Panama
 [https://doi.org/10.5061/dryad.z8w9ghxk2](https://doi.org/10.5061/dryad.z8w9ghxk2) The data set contains total, foliar, and reproductive fine litter production for four old-growth forests in central Panama. The data were collected with litter traps (see Methods). ## Description of the data and file structure The data consist of total, foliar, and reproductive fine litter production for four old-growth forests in central Panama. Table 1 presents site descriptions. The data are in one tab delimited file with 4415 rows and six columns. Each row holds data for a unique combination of the variables site, year, and trap. The six variables (columns), their definitions, and permissible values follow: site: Site names. The four values are BCI_Inceptisol, BCI_FDP, BPSL, and Gigante. year: Calendar year. Values are 1985-2023 for the site BCI_Inceptisol, 2013-2023 for BCI_FDP, 1997-2022 for BPSL, and 1998-2018 and 2020-2021 for Gigante. trap: Values are integers that uniquely identify traps within each site. total: total fine litter production. Units are Mg/ha/yr. Includes the variables 'lvs' and 'repro' plus fine wood (&lt; 2 cm diameter) and "dust" fractions. lvs: foliar fine litter production. Units are Mg/ha/yr. "NA" represents missing values (see below). repro: reproductive fine litter production. Units are Mg/ha/yr. "NA" represents missing values (see below). "NA" represents missing values. The only missing values are for the variables 'lvs' and 'repro' for the values 1998 and 2018 of the variable 'year' at the Gigante site. These values are missing because we only determined total mass for the first four monthly censuses in 1998 and the final four monthly censuses in 2018.The Covid-19 pandemic disrupted the Gigante census, with censuses scheduled for March through June 2020 cancelled. The year 2019 (July 2019 through June 2020) is therefore missing entirely for the Gigante site.