DOI: 10.5061/dryad.70rxwdc8b
title: The non-native Areca triandra palm is a potential threat to the Southwestern rainforests of Sri Lanka

description: The palm family is a major source of invasive plants because of their long
 history of introductions outside their native range in tropical and
 subtropical regions for their use as food and ornamentals. Areca triandra
 was introduced to Sri Lanka in 1867 through the Royal Botanic Gardens,
 Peradeniya and has been grown as an ornamental for over a century. To
 assess its potential invasiveness, we applied an invasiveness assessment
 protocol. Population and reproductive characteristics were studied in
 Meethirigala and Yagirala Forest Reserves. In each location, stems
 &gt; 1 m in height were sampled and crown cover was assessed in three
 plots of 400 m2 (20 × 20 m) and the ground layer &lt; 1 m height
 sampled through four 1 x 1 m quadrats within each 400 m2 (total of 24
 quadrats). Areca triandra accounted for 56 - 66% of stems &gt; 1 m
 height, 52 - 76% crown cover, and 64 - 77% of saplings and seedlings in
 the ground layer &lt; 1 m height. Clump formation was high with 30 -
 51% having 2 - 7 stems, compared to single stems of 12 - 26%. Fruit
 production was prolific, 140 - 250 fruits per infructescence, and each
 clump of multiple stems producing 1 - 3 infructescences. This resulted in
 a total of 250 - 440 fruits per clump, translating up to 8000 fruits per
 20 m × 20 m plot; bright red, (one-seeded) fleshy drupes attracted avian
 and mammalian frugivores, aiding seed dispersal. This species was
 colonized along the disturbed forest edges where it can compete with
 native species, exposing vulnerability of highly fragmented rainforests.
 This study shows that the species is naturalized in the southwest humid
 lowlands and can be considered a potential invasive emphasizing the need
 for urgent actions to manage this species.
description: # The non-native *Areca triandra* palm is a potential threat to the
 Southwestern rainforests of Sri Lanka
 [https://doi.org/10.5061/dryad.70rxwdc8b](https://doi.org/10.5061/dryad.70rxwdc8b) ## Description of the data and file structure This dataset contains statistical analyses and supplementary materials related to our study on the invasive potential of *Areca triandra* in Sri Lanka’s Southwestern rainforests. The data support our findings on species distribution, ecological impacts, and citizen science contributions for the investigation of this species in Sri Lanka. Supplementary materials include: Appendix 1: Invasiveness assessment protocol, Appendix 2: Species above 1 m height in the study plots, Appendix 3: Results from citizen science survey and Appendix 4: Data collected on infructescence of *Areca triandra*. ### Files and variables **Statistical Analysis:** To identify any significant difference between *A. triandra* and other species in each site (MFR and YFR) and height classes (≥ 1 m and &lt; 1 m) using independent two-sample tests. Analysis was conducted in R studio, the alpha value set at 0.05 for the significance level and box plots were generated to present the results. **Appendix 1:** Invasiveness assessment protocol (Criteria for categorizing invasive nonnative plants that threaten wildlands by Warner et al 2003) evaluated under three main criteria; Q.1. invasive potential, Q.2. reproductive potential and Q.3. ecological amplitude (A - High, B - Moderate, C - Low, D - Negligible, U - Unknown) **Appendix 2:** Species above 1 m height in the study plots in Meethirigala Forest Reserve (MFR 1, 2, and 3) and Yagirala Forest Reserve (YFR 1, 2, and 3) **Appendix 3:** Results from citizen science survey (Survey 1, Survey 2, Survey 3) of *Areca triandra* records in Sri Lanka conducted through the Facebook pages of ‘Flower of Sri Lanka' and ‘Medicinal plant identification’ with 130 participants. **Appendix 4:** Data collected on infructescence of *Areca triandra* in the study plots in Meethirigala Forest Reserve (MFR 1, 2, and 3) and Yagirala Forest Reserve (YFR 1, 2, and 3)