DOI: 10.5061/dryad.x95x69pt4
title: Light quality and spatial variability influences on seedling regeneration in Hawaiian lowland wet forests

description: Tropical forest understories tend to be light-limited. The red-to-far-red
 ratio (R:FR) is a useful and reliable index of light quality and its
 spatial variability can influence competition between native and
 non-native seedlings. While percent light transmittance has been
 quantified in some Hawaiian lowland wet forests (HLWF), no information
 exists on how the spatial distribution of understory light varies in
 relation to species invasion, or if patterns of seedling regeneration and
 light are linked. We measured the R:FR of light in the understory to
 assess light quality in three HLWF forest types: native-dominated,
 partially-invaded, and Psidium cattleyanum- (strawberry guava) dominated
 to quantify light quality in the understory (0-50 cm height). We also
 identified relationships between light quality and native and non-native
 seedling presence, diversity, and abundance. Together, these data can help
 to determine the restoration potential of HLWF. Linear mixed-effect
 modeling showed that native-dominated forests had significantly greater
 R:FR than P. cattleyanum-dominated forests, demonstrating a transformation
 in the light environment with increased invasion. Heterogeneity in R:FR
 varied more across sites than among forest types. In both native-dominated
 and partially-invaded forests, there were more native seedlings in the
 low-quality R:FR (0.0 – 0.40) category and fewer in the medium- (0.41 –
 0.70), and high- quality (≥ 0.71) light categories than would be expected
 by chance, and there were no native seedlings in the P.
 cattleyanum-dominated forests. Native-dominated forests had greater
 species richness and abundance of native seedlings than the
 partially-invaded forests, likely due to propagule availability. However,
 the spatial clustering of seedlings, the mismatch of native seedlings in
 light environments less suitable, and a considerable proportion of open
 high-quality microsites, highlights that conditions are not optimal for
 native species in HLWF in the long-term. Synthesis and applications The
 native-dominated and partially-invaded forests still hold conservation
 value, despite variation among sites. Seedling additions could be targeted
 to different R:FR environments and at different spatial scales, but the
 lack of a strong relationship between R:FR and seedling number suggests
 that other factors besides light quality should be considered in seedling
 enrichment or other management activities.
description: <strong>STUDY SITES</strong> See
 Table 1 of corresponding publication for list of the 9 lowland wet forest
 sites.   
 <strong>LIGHT QUALITY DATA COLLECTION AND SPATIAL
 PATTERNS</strong>   At
 each site (n=9), we established a 20 x 80 m plot with an internal grid
 system measuring 5 x 5 m. This led to 85 points for data collection per
 site. Light quality measurements taken with a SKR 110 Red / Far-red sensor
 (SKYE Instruments, London, UK), at five height categories. In a few cases
 a fallen log or other barrier precluded sampling at a given point/height
 combination (n = 20 missing points). The collected R:FR light data were
 assigned local coordinates (x,y,z origin for each plot arbitrarily set at
 100/100/0m) and imported into a GIS software program (ArcGIS Pro 3.2,
 ESRI, Redlands, CA). See corresponding publication for more
 details  
 <strong>SEEDLING PATTERNS</strong>
   All woody seedlings were identified to
 species, and fern and grass species were grouped together as native or
 non-native morphospecies. See corresponding publication for
 details.   
 <strong>STATISTICAL ANALYSES</strong>
   See corresponding publication for
 details.
description: # Reference Information ## Provenance for this README * File name:
 README_Dataset-LightQualitySeedlingRegeneration_v0.1.0.txt * Authors:
 Rebecca Ostertag * Other contributors: Jodie Rosam, Laura Warman, Ryan
 Perroy, Susan Cordell * Date created: 2024-05-21 * Date modified:
 2024-05-22 ## Dataset Version and Release History * Current Version: *
 Number: 1.0.0 * Date: 2024-05-22 * Persistent identifier:
 [https://doi.org/10.5061/dryad.x95x69pt4](https://doi.org/10.5061/dryad.x95x69pt4) * Summary of changes: n/a * Embargo Provenance: n/a * Scope of embargo: n/a * Embargo period: n/a ## Dataset Attribution and Usage * Dataset Title: Data for the article "Light quality and spatial variability influences on seedling regeneration in Hawaiian lowland wet forests" * Persistent Identifier: [https://doi.org/10.5061/dryad.x95x69pt4](https://doi.org/10.5061/dryad.x95x69pt4) * Dataset Contributors: * Creators: Jodie R Rosam, Laura Warman, Rebecca Ostertag, Ryan Perroy, Susan Cordell * Date of Issue: 2024-05-22 * Publisher: University of Hawaii at Hilo * License: Use of these data is covered by the following license: * Title: CC0 1.0 Universal (CC0 1.0) * Specification: [https://creativecommons.org/publicdomain/zero/1.0/](https://creativecommons.org/publicdomain/zero/1.0/); the authors respectfully request to be contacted by researchers interested in the re-use of these data so that the possibility of collaboration can be discussed. * Suggested Citations: * Dataset citation: &gt; Rosam, J.R., L. Warman, R. Ostertag, R. Perroy, and S. Cordell. 2024. Data for the article "Light quality and spatial variability influences on seedling regeneration in Hawaiian lowland wet forests", Dryad, Dataset, [https://doi.org/10.5061/dryad.x95x69pt4](https://doi.org/10.5061/dryad.x95x69pt4) * Corresponding publication: &gt; Rosam, J.R., L. Warman, R. Ostertag, R. Perroy, and S. Cordell. 2024. Light quality and spatial variability influences on seedling regeneration in Hawaiian lowland wet forests. Journal of Applied Ecology. Accepted. DOI: XXXX ## Contact Information * Name: Rebecca Ostertag * Affiliation: Department of Biology, University of Hawaii at Hilo * ORCID ID: [https://orcid.org/0000-0002-5747-3285](https://orcid.org/0000-0002-5747-3285) * Email: [ostertag@hawaii.edu](mailto:ostertag@hawaii.edu) * Address: Department of Biology, University of Hawaii at Hilo, 200 W. Kawili Street, Hilo, HI 96720 --- # Additional Dataset Metadata ## Acknowledgements * Funding sources: This work was carried out with supported from the National Science Foundation Graduate Research Fellowship to JRR, with logistical support and field support from SERDP grant number RC-2117 to RO. ## Dates and Locations * Dates of data collection: Field data collected in 2014 * Geographic locations of data collection: Hawaii Island (see Table 1 in corresponding publication) --- # Methodological Information * Methods of data collection/generation: see corresponding publication for details --- # Data and File Overview ## Summary Metrics * File count: 2 * Total file size: 235 KB * Range of individual file sizes: 77 bytes - 158 KB * File formats: .csv ## Naming Conventions * File naming scheme: files with the "Raw" in the name denote files that are the data without any manipulation, and files with "Averaged" in the name denote files used for the main analysis. ## Table of Contents * RFR_Seedlings_Raw_Data.csv * RFR_Averaged_By_Heights.csv --- # File/Folder Details ## Details for: RFR\_Seedlings\_Raw\_Data.csv * Description: a comma-delimited file containing the raw data of the ratio of red-to-far red (R:FR) light and the number of seedlings for 85 points located in the field per study site. * Format(s): .csv * Size(s): 158 KB * Dimensions: 3826 rows x 11 columns * Variables: * Forest_Type: 1 = native-dominated, 2 = partially-invaded, 3 = Psidium cattleyanium-dominated; see corresponding publication for details * Site: Names of sites that we used internally, without Hawaiian diacritical marks * Site_Code: Numbers 1-9 to represent the 9 sites * Forest_Description: Native = native-dominated forest; Partial = partially-invaded forest; Psidium = Psidium cattleyanum-dominated forest * Point: Numbers 1-85. Each site had a grid of 85 points at which data were collected * Height: Data were taken in 5 different height classes above the ground. 1 = 0-10 cm, 2 = 11-20 cm, 3 = 21-30 cm, 4 = 31-40 cm, 5 = 41-50 cm * No_seedlings_total: Total number of seedlings found at the point * No_native_seedlings: Total number of seedlings of native species found at the point; see Table S3 in corresponding publication for species list * No_non-native_seedlings: Total number of non-native species found at the point; see Table S3 in corresponding publication for species list * RFR: Red-to-far-red ratio taken with SKR 110 Red / Far-red sensor (SKYE Instruments, London, UK) * R:FR_Group: R:FR values organized by light quality group; 1 = ≤0.40, 2 = 0.41-0.70, 3 = ≥ 0.71 * Missing data codes: coded as NA, places where it was not possible to take a measurement in the field Details for: RFR_Averaged_By_Heights.csv --- * Description: a comma-delimited file containing the data of the ratio of red-to-far red (R:FR) light for 85 points located in the field per study site, with the R:FR values averaged across the 5 height categories found at each of the 85 points. * Format(s): .csv * Size(s): 77 KB * Dimensions: 766 rows x 13 columns * Variables: * Forest_Type: 1 = native-dominated, 2 = partially-invaded, 3 = Psidium cattleyanium-dominated; see corresponding publication for details * Site: Names of sites that we used internally, without Hawaiian diacritical marks * Site_Code: Numbers 1-9 to represent the 9 sites * Forest_Description: Native = native-dominated forest; Partial = partially-invaded forest; Psidium = Psidium cattleyanum-dominated forest * Point: Numbers 1-85. Each site had a grid of 85 points at which data were collected * RFR_Ht_Avg: Red-to-far-red (R:FR) ratio taken with SKR 110 Red / Far-red sensor (SKYE Instruments, London, UK), averaged across the five height classes above the ground at which data were (1 = 0-10 cm, 2 = 11-20 cm, 3 = 21-30 cm, 4 = 31-40 cm, 5 = 41-50 cm). See file RFR_Seedlings_Raw_Data.csv for original data at each height * SD_Ht_Avg: Standard deviation of the red-to-far-red (R:FR) ratio taken with SKR 110 Red / Far-red sensor (SKYE Instruments, London, UK), averaged across the five height classes above the ground at which data were (1 = 0-10 cm, 2 = 11-20 cm, 3 = 21-30 cm, 4 = 31-40 cm, 5 = 41-50 cm). See file RFR_Seedlings_Raw_Data.csv for original data at each height * CV_Ht_Avg: Coefficient of variation of red-to-far-red (R:FR) ratio taken with SKR 110 Red / Far-red sensor (SKYE Instruments, London, UK), averaged across the five height classes above the ground at which data were (1 = 0-10 cm, 2 = 11-20 cm, 3 = 21-30 cm, 4 = 31-40 cm, 5 = 41-50 cm). See file RFR_Seedlings_Raw_Data.csv for original data at each height * R:FR_Group: R:FR values organized by light quality group; 1 = ≤0.40, 2 = 0.41-0.70, 3 = ≥ 0.71 * logRFR_Ht_Avg: log transformation base 10 of the RFR_Ht_Avg variable, log (1+ RFR_Ht_Avg) * SqrtRFR_Ht_Avg: square root transformation of the RFR_Ht_Avg variable, sqrt (RFR_Ht_Avg) * logCV_Ht_Avg: log transformation base 10 of the CV_Ht_Avg variable, log (CV_Ht_Avg) * SqrtCV_Ht_Avg: square root transformation of the CV_Ht_Avg variable, sqrt (CV_Ht_Avg) * Missing data codes: coded as NA, places where it was not possible to take a measurement in the field