DOI: 10.5061/dryad.0k6djhb90
title: Land-use legacies affect flower visitation network structure after forest restoration

description: Agricultural land use causes drastic changes to ecosystems, which persist
 after agricultural activity has stopped. One way to mitigate these impacts
 is through restoration of post-agricultural lands; however, the interplay
 between agricultural history and restoration remains poorly understood.
 This is particularly true for interactions among species. We investigated
 the effect of experimental restoration of longleaf pine (Pinus palustris
 Mill.) forests with differing land use histories on floral visitation
 networks. We found that restoration of open canopy conditions caused
 drastic increases in floral and floral visitor abundance and species
 richness. We found that after restoration, plots with no history of
 agriculture supported more specialized floral visitations and networks
 than in post-agricultural plots. These results illustrate large positive
 effects of forest restoration and flowering of understory plants and
 floral visitation, along with a persistent agricultural land-use legacy
 affecting the structure of floral visitation networks that is still
 evident 66 years after agricultural abandonment.
description: <strong>Study site and experimental
 design</strong> This study was conducted on the
 Savannah River Site, an 80,000 ha National Environmental Research Park in
 Aiken and Barnwell Counties, South Carolina, USA. It is a United States
 Department of Energy site with forest management conducted by the USDA
 Forest Service. Like much of the Southeastern United States, uplands at
 the Savannah River Site were historically dominated by longleaf pine
 (Pinus palustris Mill.) savannahs characterized by widely spaced canopy
 trees with a highly diverse groundcover plant community. Throughout its
 range, the vast majority (97%) of the area of this ecosystem has been lost
 to fire suppression and land conversion to agriculture. By middle of the
 20th century, the majority of the Savannah River Site was being used for
 agriculture. When the Savannah River Site was acquired by the federal
 government in 1951, approximately 6000 residents were relocated to
 surrounding areas, and all agricultural activity was abandoned. The Forest
 Service then planted loblolly (Pinus taeda L.) and longleaf pine
 plantations on agricultural fields for the next several
 decades.  Using aerial photography taken in 1951, we
 located eight sites which had been agricultural fields when the Savannah
 River Site was acquired and that were adjacent to stands of remnant
 longleaf pine savannahs. Remnant stands are defined as areas which have no
 known history of agricultural cultivation (i.e., tillage). In 2010 we
 established two pairs of one ha plots at each site (four 100 m × 100 m
 plots at each site, 32 plots total). Paired plots spanned across the
 land-use boundary between post-agricultural and remnant stands. In 2011,
 we randomly selected one half of the plots located in each land used type
 within a site (16 plots total) to undergo restoration. We thinned the
 canopy of the restoration plots to 10 large pine trees per hectare and
 planted longleaf pine seedlings. To promote grasses and forbs in the
 understory, herbicides were applied once in 2012 to control hardwood
 resprouts. The remaining plots received no restoration thinning or
 planting. Prescribed burning was also conducted across all plots
 regardless of restoration or land-use history type with either one or two
 burns being conducted in each experimental site between 2011 and
 2017. <strong>Floral visitation network
 sampling</strong> We assessed visitation to
 plants by insects three times in each plot during September and October of
 2017. Along a 50 by 10 m transect near the center of each plot, we either
 collected or recorded the count and identity of all floral visitors that
 we observed making contact with the reproductive parts of flowers,
 excluding spiders, thrips, and ants (no non-insect pollinators were
 observed). The transect was broken into 10 5×10 m subplots, and we spent
 three minutes collecting and observing in each subplot, spending a maximum
 of 30 minutes total per transect per observation period. If a subplot
 contained no open flowers, we noted this and moved to the next subplot. On
 sampling days, we conducted one observation period in the morning between
 8:00 am and 12:00 pm and another one in the afternoon between 12:00 pm and
 4:00 pm. We also recorded the approximate area covered by the blooms of
 each plant species within the 50×10 m transect once each sampling day. We
 increased the accuracy of the floral estimates by recording only the
 flowers present in one five by 10 m subplot at a time. We only assessed
 floral-visiting insect activity on sunny or partly cloudy days when wind
 gusts did not exceed 6 m/s and temperature was above 16° C. We identified
 insects to the lowest taxonomic level possible using published taxonomic
 revisions. Insect specimens are deposited in the J. B. Wallis / R. E.
 Roughley Museum of Entomology at the University of Manitoba, Canada. Some
 insects (380 individuals, 11% of total observations) which were observed
 but not collected could not be identified to species or morphospecies
 because of insufficient information. These interactions were dropped from
 the dataset and were not included in any of the results of the associated
 manuscript.
description: # Land-use legacies affect floral visitation network structure after
 forest restoration
 [https://doi.org/10.5061/dryad.0k6djhb90](https://doi.org/10.5061/dryad.0k6djhb90) ## Description of the data and file structure This data was collected for a floral visitation interaction network study conducted in the Remnant Project in 2017. The Remnant Project is a two-level split plot design experiment which crosses land-use history (history of tillage agricultural and no history of tillage) with restoration treatments (canopy thinning and no canopy thinning). The study was conducted on Savannah River Site in Aiken and Barnwell Counties, South Carolina, USA. ### Files and variables #### File: breland\_\_et\_al\_2024\_floral\_visitation\_interactions.csv **Description:** Host plant-floral visitor interactions data from eight experimental sites across the Savannah River Site collected in September and October of 2017. Each line of data is an individual insect floral visitor and the associated experimental plot and floral host information. ##### Variables * site: spatial blocks around the Savannah River Site in South Carolina that each include four one-hectare plots * plot_pair: the number associated with pairs of 1 hectare plots on each side of the land use boundary * stand_type: land-use history coded as either Remnant or Post-agricultural. Whether a 1 hectare plot is a remnant longleaf pine savanna with no history of agriculture (Remnant) or a plot was in tillage agriculture as of 1951 then abandoned and planted as pine plantation, (Post-agricultural). * treatment: restoration treatment coded as Unthinned or Thinned. Unthinned are not manipulated and Thinned had all but 10 trees per hectare removed in 2011. * plot_id: identifier for each unique one-hectare plot which contains the site, plot pair, and stand type. Stand type is coded as R for Remnant and M for Post-agricultural. For example, 17NW-1M is the plot that is in site 17NW, plot pair 1, and in the post-agricultural stand. * latitude_decimal: latitude in decimal degrees of the center point of the one-hectare plot where the interaction was observed * longitude_decimal: longitude in decimal degrees of the center point of the one-hectare plot where the interaction was observed * date: date that the interaction was observed * time: time, in 24 hour format, that the interaction was observed * collector: initials of person who observed and collected data about the interaction, SB=Sabrie Breland, EH=Elise Hanson, RH=Ross Hunter * host: plant species that insect was visiting the open flower of, species code for plant species (first three letters of the genus + first three letters of the species) * host_family: family of host plant species * host_genus: genus of host plant species * host_species: specific epithet of host plant species * host_genus_spp: full genus and species of host plant species * host_notes: notes taken in the field about identity of host plant species * group: type of floral visitor (bee, beetle, butterfly, fly, hemipteran, hymenoptera, moth, unknown, wasp) * family: family of floral visitor * genus: genus of floral visitor * species: species of floral visitor * subspecies: subspecies of floral visitor * authority:  taxonomic authority - name of the person or people who first described the taxon  * genus_species: genus and species of floral visitor * gender: gender of floral visitor #### File: breland\_et\_al\_2024\_floral\_cover.csv **Description:** Floral cover data from eight experimental sites across the Savannah River Site collected in September and October of 2017 ##### Variables * researcher: initials of person who collected data, SB=Sabrie Breland, EH=Elise Hanson, RH=Ross Hunter * date: date that the data was collected * site: spatial blocks around the Savannah River Site in South Carolina that each include four one-hectare plots * plotpair: the number associated with pairs of 1 hectare plots on each side of the land use boundary * stand_type: land-use history coded as either Remnant or Post-agricultural, whether a 1 hectare plot is a remnant longleaf pine savanna with no history of agriculture (Remnant) or a plot was in tillage agriculture as of 1951 then abandoned and planted as pine plantation (Post-agricultural) * treatment: restoration treatment coded as Unthinned or Thinned. Unthinned are not manipulated and Thinned had all but 10 trees per hectare removed in 2011. * plot_id: identifier for each unique one-hectare plot which contains the site, plot pair, and stand type. Stand type is coded as R for Remnant and M for Post-agricultural. For example, 17NW-1M is the plot that is in site 17NW, plot pair 1, and in the post-agricultural stand. * distance: location along a 50 meter transect where open flowers were observed. The 50 meter transect was located in the middle of an 100 meter transect used for previous research that ran from edge to edge of the plot perpendicular with the land-use boundary. Floral cover was measured from the 25 m line to the 75 m line. * species_code: plant species that was in flower. Species code for plant species (first three letters of the genus + first three letters of the species) * family: family of plant that was in flower * genus: genus of plant that was in flower * species: specific epithet of plant that was in flower * cover_cm2: estimate of cover in square centimeters of a flower, inflorescence, or group of flowers from plants that were encountered along the transect N/A : not applicable