DOI: 10.5061/dryad.ghx3ffbwn
title: Data from: Higher avian biodiversity, increased shrub cover, and proximity to continuous forest may reduce pest insect crop loss in small-scale oil palm farming

description: One of the key ecosystem services offered by avian biodiversity within
 agricultural landscapes is natural predation. Nonetheless, the current use
 of biological control agents such as farmland birds in oil palm
 plantations is relatively limited. The present study aimed to assess the
 potential roles of avian biodiversity, particularly insectivores which
 provide natural predation against oil palm herbivorous insects. We also
 investigated the influence of local- and landscape-scale variables on
 foliage damage (crown or frond). Our data showed that crown damage
 decreased with increasing farmland bird richness (overall and
 insectivore), shrub cover, dried biomass, and elevation, but increased
 with epiphyte cover, oil palm height, and distance to continuous forest.
 Frond damage was negatively related to bird richness (overall,
 insectivore, and non-insectivore) and non-insectivore abundance,
 elevation, and shrub cover, while increased with insectivorous abundance,
 epiphyte cover, oil palm height, and distance to continuous forest. We
 also found that plantations (≥ 50 ha) were more susceptible to foliage
 damage from pest insects than smallholdings (&lt;50 ha). There was no
 evidence that indicated the influence of forest patches on foliage damage.
 Our study highlights the economic value of conserving biodiversity, most
 notably, farmland birds and continuous forests with respect to biological
 control of defoliating pests and maintaining yield productivity in oil
 palm cultivation. Growers, particularly major plantation companies should
 make oil palm farming more biodiversity-friendly in order to increase the
 number of biological control agents such as birds.
description: <strong>Study design and foliage damage
 assessments</strong> Foliage damage assessments
 were conducted at 30 predetermined sampling points established at each
 study site, totalling 180 sampling points across all study sites. All
 points were spaced at &gt;500m apart to maximise spatial coverage.
 Foliage damage assessments were made based on the approach used by
 previous studies (e.g., Gilbert & Gregoire, 2003, Priwiratama et
 al., 2019; Ruslan et al., 2019). At each sampling point, eight oil palms,
 located within a 20 m radius from the centre of the sampling point were
 selected for the herbivorous pests (e.g., bagworms) damage inspection at
 two levels, namely crown and frond. Crown damage evaluations were
 conducted through visual inspections (using binoculars) to assess the
 extent of herbivorous pests affecting the entire foliage. The value
 representing crown damage at each sampling point was derived from the
 averaged percentage values of damage observed on eight selected palms.
 Damage observed from the frond base to lower crowns was categorized as
 ranging from 0% to 50%, damage extending to middle crowns was classified
 between 50% and 75%, and damage reaching upper crowns was classified
 between 75% and 100%. Frond damage caused by herbivorous pests was
 visually inspected on the 17th frond using a standard assessment method.
 The value representing frond damage for each sampling point was derived
 from the averaged percentage values observed on the eight selected palms
 (0% - no damage to 100% - severe damage). Evaluating oil palm health and
 productivity through the analysis of the 17th frond is a well-established
 method employed by agronomists (see, Rendana et al., 2015; Irvanto et al.,
 2022; Peng et al., 2022). In a nutshell, crown and frond evaluation
 indicate the coarse-scale (overall foliage damage) and fine-scale
 (detailed foliage damage) assessment, respectively.
 <strong>Bird sampling</strong> A
 10-minute point count was conducted at each sampling point where foliage
 damage assessments were conducted. All observed or heard birds within 50
 metres of the point's centre were recorded. All point counts were
 conducted in the morning between 0700 – 1030 hours, during good weather.
 Recorded birds through vocalisations and sightings were identified to
 species and bird data were sorted and grouped into two groups, namely
 insectivores and non-insectivores based on local bird guides (e.g., Wells
 1999, 2010; Robson 2011; Billerman et al., 2020). We determined bird
 overall richness, insectivorous bird richness, non-insectivorous richness,
 bird overall abundance, insectivorous bird abundance and non-insectivorous
 bird abundance from the surveys. <strong>Local-
 and landscape-scale variables </strong> We
 measured nine local- and landscape-scale variables at each sampling point.
 The values corresponding to the local-scale variables were obtained by
 calculating the average of four readings conducted within a 50 m x 50 m
 vegetation plot at each sampling point. These measured variables include,
 i) height of oil palm measured using Haga Altimeter, ii) grass cover -
 refers to coverage percentage (%) of herbaceous plants with narrow leaves
 estimated within 1m x 1m quadrat established on harvesting paths, iii)
 shrub cover - refers to coverage percentage (%) of perennial woody plants
 with stems and branches estimated within 1m x 1m quadrat established on
 harvesting paths, iv) canopy cover – refers to average percentage (%) of
 shade, v) epiphyte cover – refers to average percentage (%) of epiphyte
 persistence on oil palm trunk, vii) dried biomass – refers to weight (kg)
 of organic matter, debris, and litter cover (e.g., pruned fronds) on
 interplanting rows, and viii) elevation  - refers to altitude measured
 above sea level (m). Landscape-scale variables measured in this study
 include, i) distance to the continuous forest – refers to the shortest
 measured distance (km) to a forest fragment that exceeds 10,000 hectares
 in size and ii) distance to the forest patch – refers to the shortest
 measured distance (km) to a forest fragment that under 10,000 hectares in
 size (Hazwan et al., 2022; Oon et al., 2023). Landscape-scale variables
 were measured using the ruler tool in QGIS.
description: # Data From: Higher avian biodiversity, increased shrub cover, and
 proximity to continuous forest may reduce pest insect crop loss in
 small-scale oil palm farming
 [https://doi.org/10.5061/dryad.ghx3ffbwn](https://doi.org/10.5061/dryad.ghx3ffbwn) ## Description of the data and file structure This dataset comprises foliage damage assessments conducted on oil palm at 180 sampling points across Peninsular Malaysia. Additionally, the dataset encompasses bird data as well as local- and landscape-scale variables gathered from each sampling point. File name: Data-JAPPL-2023-00856.xlsx Data-specific information: 1. Number of variables: 22 2. Number of cases/rows: 180 3. Variable list: * Site: Location where data is collected (Banting, Tanjung Karang, Sabak Bernam, Kemayan, Segamat, or Besout) * Management: Oil palm management regime (industrial plantation or smallholding) * Point: Number assigned to each sampling point (point 1 - point 180) * Year: Year when data is collected * Crown damage: Foliage damage assessed at crown level (percentage, %) * Frond damage: Foliage damage assessed at frond level (percentage, %) * Oil palm height: Mean height of oil palms (metre, m) * Grass cover: Coverage percentage of herbaceous plants with narrow leaves (percentage, %) * Shrub cover: Coverage percentage of perennial woody plants with stems and branches (percentage, %) * Dried biomass: Weight of organic matter, debris, and litter cover (kilogram, kg) * Epiphyte cover: Coverage percentage of epiphyte persistence on oil palm trunk (percentage, %) * Canopy cover: Average percentage of shade (percentage, %) * Distance to forest patch: Shortest measured distance to a forest fragment under 10,000 hectares in size (kilometre, km) * Distance to continuous forest: Shortest measured distance to a forest fragment that exceeds 10,000 hectares in size (kilometre, km) * Elevation: Altitude measured above sea level (metre, m) * Bird richness (overall): Total number of bird species recorded during point count * Bird abundance (overall): Total number of birds recorded during point count * Bird richness (insectivore): Total number of insectivorous bird species recorded during point count * Bird abundance (insectivore): Total number of insectivorous birds recorded during point count * Bird richness (non-insectivore): Total number of non-insectivorous bird species recorded during point count * Bird abundance (non-insectivore): Total number of non-insectivorous birds recorded during point count.