DOI: 10.5061/dryad.7wm37pw4d
title: Data from: Context-dependent forest elephant seed dispersal: Implications for pathways of elephant-driven patterns of biodiversity and carbon storage

description: Seed dispersal by frugivores facilitates plant reproduction, enhancing
 germination and seedling survival by reducing risks like diseases and
 predation under parent trees and potentially directing seeds to favorable
 sites. Elephants, in particular, are known to strongly impact forests via
 their seed dispersal patterns because of their ability to disperse many
 very large seeds across long distances. However, knowledge gaps related to
 spatio-temporal variability in animal diets, the types and traits of plant
 species dispersed, and the effectiveness of seed dispersal limit our
 ability to predict the magnitude of impact that seed dispersers have on
 plant communities. To better understand how elephant seed dispersal
 impacts forests, we present a year-long study of fruit availability,
 forest elephant diet, and seed dispersal across three sites in Gabon
 showing that: (i) While seeds were prevalent in dung, forest elephants are
 consuming fewer seeds than in previous studies (ii) There are significant
 between-site differences in the overall species composition of available
 fruits and dispersed seeds. (iii) Forest elephants predominately disperse
 seeds with high carbon storage potential, and the magnitude of carbon
 storage potential in elephant-dispersed seeds varies between sites. (iv)
 Forest elephants are effective dispersers of herbs and lianas – growth
 forms that are often underrepresented in studies of forest elephant seed
 dispersal – at two out of three of our sites. And (v) seedling emergence
 and persistence varied significantly across sites. Our results highlight
 the fundamental role of fruit availability as a driver of forest elephant
 diet and seed dispersal patterns, and the variability of
 elephant-dispersed species and functional composition among sites.
 Additionally, among-site variability in how elephants affect different
 plant growth types, carbon storage potential, and dispersal effectiveness
 indicates that predicting the effects of elephants on forest ecosystems
 depends on site-specific conditions
description: <strong>METHODS</strong>
 <strong>Data & observational
 design</strong> <em>Study
 Areas</em> We conducted this research in three
 protected areas in Gabon: Ivindo National Park, Loango National Park, and
 the Wonga Wongué Presidential Reserve. Ivindo National Park (2990
 km<sup>2</sup>) is covered by primary and secondary lowland
 humid tropical forests, is home to several major rivers (e.g., Ivindo
 River and Djidji River), and has many small forest clearings (called
 <em>bais</em>) throughout the forest (Vande weghe 2009).
 Loango National Park (1500 km<sup>2</sup>) has an
 ocean-to-lowland gradient of coastal savannas to inland forest and
 features several rivers and a small lagoon. Wonga Wongué Presidential
 Reserve (4281 km<sup>2</sup>) is a savanna-forest mosaic
 ecosystem consisting of 70% secondary forests that are dominated by
 <em>Aucoumea klaineana</em> and <em>Sacoglottis
 gabonensis</em>. Overall, the climate in Gabon is bimodal, with a
 major dry season from June–August and a minor dry season from
 December–February. The major dry season is cool and cloudy, which is
 atypical for dry seasons in tropical forests. Annual rainfall at these
 sites is approximately 1700 mm at Ivindo, 1750-1850 mm at Loango, and
 2000-2400 mm at Wonga Wongué. <em>Data
 collection</em> In each park, we conducted focal
 elephant follows on GPS-collared forest elephants (Fig. 1). We followed 40
 elephants, up to three days at a time, for a total of 138, 76, 136 follow
 days in Ivindo, Loango and Wonga Wongué, respectively. We worked with
 BaAka forest people to track the forest elephants between the hourly GPS
 locations ensuring we were following the elephant’s “true” path of
 movement. To avoid stressing the tracked elephants and to protect the
 field teams, follows were maintained a minimum of 1 hour behind the focal
 elephant. Focal follows occurred between February 2017 and April
 2018. To quantify fruit availability, we conducted
 fruit sampling along transects (fruit walks) at the beginning and end of
 each day during elephant follows. If the field team moved less than 100m
 in a day, only one fruit walk was conducted. On each transect, all fallen
 fleshy fruits encountered on a 2 × 50 m transect, perpendicular to both
 sides of the elephant’s trail, were recorded and abundance of fruits was
 noted. Fruits were identified to the lowest taxonomic level possible. Only
 fallen fruit was recorded as canopy fruit is mostly inaccessible to forest
 elephants and not representative of what elephants could be eating. If
 fruits could not be identified in the field, they were photographed or
 collected as samples, and species identification was verified via
 published guidebooks and online flora or by consulting a
 botanist. We characterized overall elephant diet and
 seed consumption by destructively searching every third fresh dung during
 elephant follows to determine the composition of different food sources.
 Only fresh dung was searched to minimize the possibility that it came from
 a non-focal elephant group member or that the dung had been disturbed by
 other animals (e.g., red river hogs, dung beetles). We quantified the
 relative abundance of fiber, leaf fragments, fruit, and seeds on a 4-point
 scale. We then identified all seeds greater than 1 cm to the lowest
 taxonomic level possible and counted their abundances. If seeds could not
 be identified in the field, they were photographed or collected as
 samples, and species identification was verified as above.
 We characterized community-level seedling germination and
 survival in elephant dung, we located fresh dung piles accessible from the
 field stations, independent of focal follows, and monitored dung piles
 until they disappeared. Upon discovery, half of each dung pile was
 destructively sampled, and any seeds were identified and counted using the
 same protocol as during focal follows, described above. The remaining half
 of the dung pile was left untouched. We revisited the dung piles
 approximately each week to each month, depending on the site. At each
 revisit, the abundance of seedlings observed in the dung was recorded. The
 majority of seedlings were not sufficiently identified (at least to family
 level), thus taxonomic information on seedlings are not included in this
 study.  <strong>Statistical
 analyses</strong> <em>Composition of
 available fruit and dispersed seeds</em> ​​To
 assess the variation in composition of fruit observed on transects and
 seeds observed in elephant dung between sites, we used the function
 <em>decostand</em> from the <em>vegan</em> package
 in R to produce Hellinger-transformed species-by-transect or
 species-by-dung abundance matrices. Then, we created two distance
 matrices, one for the transects and one for the dung piles, using an
 abundance-based Euclidean distance metric using the function
 <em>vegdist</em> from the R package
 <em>vegan</em>. We tested for between-site differences in the
 species composition of fruit on transects and seeds in dung, comparing the
 central location of composition groups for each site using a PERMANOVA
 test via the <em>adonis2</em> function and using pairwise
 PERMANOVA post-hoc tests to identify which sites were different from each
 other . We created visualizations of the community composition results
 with non-metric multidimensional scaling (NMDS) plotsusing the
 <em>ordiplot</em> function from the <em>vegan</em>
 package.  <em>Plant growth types and carbon
 storage potential of dispersed seeds</em> To
 characterize the plant growth types of dispersed seeds in dung, we
 categorized dispersed seeds from our species list as herbs, lianas, or
 trees using information from published guidebooks and online herbaria. We
 used this information to explore between-site differences in plant growth
 types of seeds dispersed in elephant dung, by calculating the proportion
 and count of seeds from tree, liana, and herbaceous species in each dung
 pile. To estimate the carbon storage potential of
 elephant-dispersed seeds, we compiled information about taxon-specific
 wood density values for our species list of available fruits and dispersed
 seeds, using the Global Wood Database. This database contains published
 wood density information (mass per unit volume) of adult trees. For our
 dataset, wood density was obtained at the lowest specific taxonomic level
 possible (family = 5, genus = 15, species = 26) because wood density tends
 to show a phylogenetic signal. To explore between-site differences in
 carbon storage potential, we used these taxon-specific wood density values
 to calculate the community-weighted mean carbon storage potential of
 available fruits per transect and dispersed seeds per dung pile.
 We tested for differences in plant growth types and carbon
 storage potential between sites using Kruskal–Wallis H tests and post-hoc
 Dunn’s tests. Differences between sites were considered significant for
 values of p &lt; 0.05. <em>Emergence and
 persistence of seedlings in dung</em> To explore
 between-site differences in the germination success of seeds in elephant
 dung, we calculated the number of seeds and seedlings in each elephant
 dung pile. We then tested for differences between sites using
 Kruskal–Wallis H tests and post-hoc Dunn’s tests. Differences between
 treatments were considered significant for values of p &lt; 0.05. To
 explore between-site differences in the temporal patterns of seedling
 germination and survival, we then calculated the number of seedlings in
 dung on the first monitoring date, the last monitoring date, and the
 monitoring date with the highest number of seedlings. We identified the
 average temporal trajectory of seedling flush and persistence for each
 site, and identified the peak day of seedling flush post-dispersal for
 each site.
description: # Data from: Context-dependent forest elephant seed dispersal:
 Implications for pathways of elephant-driven patterns of biodiversity and
 carbon storage
 [https://doi.org/10.5061/dryad.7wm37pw4d](https://doi.org/10.5061/dryad.7wm37pw4d) ## Description of the data and file structure ## Abstract/Summary Seed dispersal by frugivores facilitates plant reproduction, enhancing germination and seedling survival by reducing risks like diseases and predation under parent trees and directing seeds to favorable sites. This process supports forest diversity, restoration, and carbon sequestration while aiding in plant genetic flow and the colonization of new areas. However, knowledge gaps related to spatio-temporal variability in animal diets, the types and traits of plant species dispersed, and the effectiveness of seed dispersal limit our ability to predict the magnitude of impact that seed dispersers have on plant communities. We present a year-long study of fruit availability, forest elephant diet, and seed dispersal across three sites in Gabon showing that (i) while seeds were prevalent in dung, forest elephants are consuming fewer seeds than in previous studies, (ii) there are significant between-site differences in the overall species composition of available fruits and dispersed seeds, (iii) forest elephants are effective dispersers of herbs and lianas (oft-ignored plant growth forms) at two out of three of our sites, (iv) forest elephants predominately disperse seeds with high carbon storage potential, and the magnitude of carbon storage potential in elephant-dispersed seeds varies between sites, and (v) seedling emergence and persistence varied significantly across sites. Our results highlight the fundamental role of fruit availability as a driver of forest elephant diet and seed dispersal patterns, and the variability of elephant-dispersed species and functional composition among sites. Additionally, among-site variability in how elephants affect different plant growth types, carbon storage potential, and dispersal effectiveness indicates that predicting the effects of elephants on forest ecosystems depends on site-specific conditions. ### Files and variables ## Description of the data and file structure Note on missing values: Across all datasets, cells coded as NA indicate that no data were collected for that entry (i.e., the information was not available, not observed, or not recorded). These do not represent “not applicable” values. ### Description: *A. "Diet_Dung_Final.csv" contains the overall description of different food types in elephant dung piles* Site - site where dung pile was located Observer - researcher who collected the data Sheet - physical sheet the data was collected on Year - year the data was collected in Month - month the data was collected in Day - day the data was collected on Hour - hour the data was collected on Minute - minute the data was collected on Dung - ID of individual dung pile Fiber - relative abundance score (0-4) of fiber present in dung pile LeafFrag - relative abundance score (0-4) of leaf fragments present in dung pile Fruit - relative abundance score (0-4) of fruit present in dung pile Seeds - relative abundance score (0-4) of seeds present in dung pile NoSpp - number of species present in dung pile Focal - the name or individual ID of the focal elephant followed Comments - notes from data collection Posix - GPS data lon - longitude lat - latitude time - time information from the GPS data sym - symbol on GPS cmt - comments and notes from GPS data *B. "Diet_Seed_Final.csv" contains information about species and counts of seeds in destructively-sampled elephant dung piles* Site - site where dung pile was located Observer - researcher who collected the data Sheet - physical sheet the data was collected on Year - year the data was collected in Month - month the data was collected in Day - day the data was collected on Hour - hour the data was collected on Minute - minute the data was collected on Dung - ID of individual dung pile SppNo - number of species in dung pile Spp - name of species in dung pile No - number of whole seeds Pieces - number of pieces of seeds BrknPcs - number of broken pieces of seeds Comments - notes from data collection Posix - GPS data lon - longitude lat - latitude time - time information from the GPS data sym - symbol on GPS cmt - comments and notes from GPS data *C. "Fruit_Walk_Final.csv" contains information about species and counts of fruit on transects* Site - site where dung pile was located Posix - GPS data Month - month the data was collected in Observer - researcher who collected the data Sheet - physical sheet the data was collected on time - time information from the GPS data WPT - transect individual ID lon - longitude lat - latitude Hab - categorical description of 31 different habitats Obs - kind of observation on fruit walk transects Species - species name of fruit No - number of fruits observed Mat - maturity categories for fruit. "IMT" = immature, "MAT" = mature, "unk" = unknown Ripe - ripeness categories for fruit. "R" = ripe, "U" = unripe, "unk" = unknown State - state categories for fruit. "C" = chewed, "I" = intact, "P" = partial Comments - notes from data collection *D. "SS_Seed_Final.csv" contains information about counts and numbers of seeds in non-destructively sampled dung piles* Site - site where dung pile was located Observer - researcher who collected the data Sheet - physical sheet the data was collected on Year - year the data was collected in Month - month the data was collected in Day - day the data was collected on Dung - ID of individual dung pile lon - longitude lat - latitude NoSeedSpp - number of species of seeds in dung pile SeedSpp - name of seed species in dung pile NoIntact - number of whole seeds TotalPcs - number of pieces of seeds BrknPcs - number of broken pieces of seeds Comments - notes from data collection *E. "SS_Dung_Final.csv" contains information about seedling survival dung (time0) in non-destructively sampled dung piles* Site - site where dung pile was located Observer - researcher who collected the data Sheet - physical sheet the data was collected on Year - year the data was collected in Month - month the data was collected in Day - day the data was collected on Dung - ID of individual dung pile lon - longitude lat - latitude TotalBoli - total number of boli in dung pile NoSearched - number of boli sampled NoBoli - the id number of the boli that was sampled Fiber - relative abundance score (0-4) of fiber present in dung pile LeafFrag - relative abundance score (0-4) of leaf fragments present in dung pile Fruit - relative abundance score (0-4) of fruit present in dung pile Seeds - relative abundance score (0-4) of seeds present in dung pile NoSpp - number of species present in dung pile Comments - notes from data collection Touched - info about whether dung pile/seeds had been touched during sampling SeedlingSpp - names of species for seedlings present in dung piles NoSeedlingSpp - numbers of seedlings present in dung piles Posix - GPS data *F. "SS_Return_Final.csv" contains information about seedling survival dung (time1/2/3/n/etc.) in non-destructively sampled dung piles* Site - site where dung pile was located Observer - researcher who collected the data Sheet - physical sheet the data was collected on Year - year the data was collected in Month - month the data was collected in Day - day the data was collected on Dung.ID - ID of individual dung pile lon - longitude lat - latitude Comments - notes from data collection Touched - info about whether dung pile/seeds had been touched during sampling SeedlingSpp - names of species for seedlings present in dung piles NoSeedling - numbers of seedlings present in dung piles Posix - GPS data ### spp lists *G. "fruit.walk.spp_dec21.csv" contains corrected and verified species names for all fruit species in the Fruit_Walk_Final.csv dataset* fruit.walk.spp - species name from fruit.walk data as recorded spp2 - updated species names based on verifications from online herbaria and guidebooks type - categorical type of each species = "herb", "liana", "palm", "tree" tree - binary variable describing if a species was a tree (1/0) herb - binary variable describing if a species was a herb (1/0) liana - binary variable describing if a species was a liana (1/0) palm - binary variable describing if a species was a palm (1/0) link - link to species name from online herbarium source (mostly from Plants of the World Online from Kew Gardens) note - any notes about species that came up during the name verification process *H. "diet.seed_spp.list_dec16.csv" contains corrected and verified species names for all seed species in the Diet_Seed_Final.csv dataset* spp - species name from fruit.walk data as recorded spp2 - updated species names based on verifications from online herbaria and guidebooks type - categorical type of each species = "herb", "liana", "tree" tree - binary variable describing if a species was a tree (1/0) herb - binary variable describing if a species was a herb (1/0) liana - binary variable describing if a species was a liana (1/0) link - link to species name from online herbarium source (mostly from Plants of the World Online from Kew Gardens) note - any notes about species that came up during the name verification process *I. "spp_list_biomass_2apr2024_v2.csv" contains information about species, genus, and family for all of the species in the ESD data* spp1 - species name from fruit.walk data as recorded spp2 - updated species names based on verifications from online herbaria and guidebooks family - taxonomic family group for each species *I. "ss.seed.spp_dec22.csv" contains corrected and verified species names for all the seedlings in the SS_Seed_Final.csv dataset* ss.seed.spp - species name from fruit.walk data as recorded spp2 - updated species names based on verifications from online herbaria and guidebooks type - categorical type of each species = "herb", "liana", "tree" tree - binary variable describing if a species was a tree (1/0) herb - binary variable describing if a species was a herb (1/0) liana - binary variable describing if a species was a liana (1/0) link - link to species name from online herbarium source (mostly from Plants of the World Online from Kew Gardens) note - any notes about species that came up during the name verification process X - more notes *J. "ss.return.spp_dec22.csv" contains corrected and verified species names for all the seedlings in the SS_Return_Final.csv dataset* ss.return.spp - species name from fruit.walk data as recorded spp2 - updated species names based on verifications from online herbaria and guidebooks type - categorical type of each species = "herb", "liana", "tree" tree - binary variable describing if a species was a tree (1/0) herb - binary variable describing if a species was a herb (1/0) liana - binary variable describing if a species was a liana (1/0) link - link to species name from online herbarium source (mostly from Plants of the World Online from Kew Gardens) note - any notes about species that came up during the name verification process id.weird - notes about funky species identifications *K. "fw.list.missing.dates.IV.LO.csv" contains information about missing dates from ivindo and loango in fruit walk data* site - site where data was collected wpt - transect individual ID date.format - date data was collected on (MM/DD/YY) day - day the data was collected on month - month the data was collected in year - year the data was collected in