DOI: 10.5061/dryad.6450hv3
title: Data from: The mechanisms affecting seedling establishment in restored savanna understories are seasonally dependent

description: 1. Globally, agricultural land is increasingly being abandoned with over
 200 million hectares recovering from agricultural use. Regeneration of
 plant communities sharply differ in their structure and composition after
 agricultural impacts, yet the mechanisms underpinning these dramatic
 changes are poorly understood. It is critical to determine the relative
 importance of abiotic and biotic factors that limit plant establishment
 and success during the recovery process. In particular, belowground
 competition for resources in soils impacted by former agricultural uses
 may play an especially important role in limiting plant establishment.
 Yet, belowground competition is generally studied less than aboveground,
 especially in the context of land-use history. 2. We compare plant
 establishment with and without belowground competition in the context of a
 large-scale experiment manipulating land-use histories (i.e., with and
 without a history of agriculture) and restoration of historical vegetation
 structure (i.e., thinned and unthinned canopy trees) and determine how
 life stage and the local environment (e.g., soil water holding capacity,
 vegetation cover) impact this relationship. 3. For three of our four
 target species, belowground competition strongly limited establishment
 success, but did not interact with land-use history and canopy thinning
 directly. Instead, land-use history and canopy thinning interacted to
 affect establishment during germination and survival in spring, while
 belowground competition limited growth during the summer. The strength of
 belowground competition was affected by local resources, but the
 directionality of this relationship depended on agricultural history and
 canopy thinning. 4. Synthesis and application: Overall, we recommend
 confronting land-use legacies by overcoming dispersal limitation with seed
 additions (even in degraded sites) and ensuring that belowground
 structures are managed during restoration, especially in summer. In
 addition, managers should consider how the relationship between local
 resources and belowground competition at individual sites might depend on
 land-use history or canopy thinning.
description: SorensonAndDamschen2019_Compaction_TubeLevelCompaction measurements were collected on either side (10cm away) of each tube using a penetrometer. The penetrometer was pushed into the soil at a constant rate and the pressure reading in pounds per square inch at 15cm depth was recorded.SorensonAndDamschen2019_EndingBiomass_IncludingZeros_TubeLevelThe whole-plant biomass of each plant collected from root excluder tubes. This datafile was generated in R to include a zero value for all potential seedlings. Because we thinned the number of seedlings in the spring to two per each species, each tube had the potential to contain eight individuals. Most tubes did not contain the maximum number of seedlings. We only collected data ending biomass data on individuals in the tubes. I was useful to have a datafile with all possible outcomes with zeros for those without a value."SorensonAndDamschen2019_EndingPlantMeasurements_NoZeros_TubeLevelAt the end of the summer, each tube was extracted, cut open, soil sprayed out, and seedlings with roots gently disentangled from other roots. Individuals were dried, separated into roots stems and leaves and weighed to the nearest one-hundredth of a mg. Stems length was also measured."SorensonAndDamschen2019_LightIntensity_TubeLevelLight intensity was taken using a 0.7m long light intensity meter bar. Measurements were taken on cloudless days with clear skies. Six measurements were taken at each tube. Two measurements were taken at taken at 45-degree angles to the edges of the subplot edge at three different heights: 5, 15, and 25cm.SorensonAndDamschen2019_MidSummerPresenseAndHeight_TubeLevelMidsummer Survival and height of seedlings was recorded July 12–15. Each tube was visited, each seedling was identified with a colored pin, and seedling length was measured with a ruler to the nearest 0.1 cm.SorensonAndDamschen2019_SpeciesCodeKeyWhile collecting data we used a six-letter code system that typically is comprised of the first three letters of both the genus and specific epithet. Some codes do not match species names, but the names reported are the correct names. If species were identified only to genus, only the genus is reported with sp. For some large genera, we identified species into morphogroups within the genus. In this case, we used the first three letters of the genus followed by SP and a number. We used names from Radford, A. E., Ahles, H. E., & Bell, C. R. (1968). Manual of the vascular flora of the Carolinas. Univ of North Carolina Press. We checked spelling and current name usage using the R package taxize (Scott Chamberlain and Eduard Szocs (2013). taxize - taxonomic search and retrieval in R. F1000Research, 2:191. URL: http://f1000research.com/articles/2-191/v2.) using " iPlant_TNRS" as the source, unless otherwise noted.SorensonAndDamschen2019_SpringPresenceAndHeight_TubeLevelLate Spring Survival and height of seedlings was recorded May 27–June 5. Each tube was visited, each seedling was identified and marked with a colored pin, and seedling length was measured with a ruler to the nearest 0.1 cm. Each tube was checked for burning. Thatch level was visually recorded into categories by percent cover (and depth for level 4).SorensonAndDamschen2019_TreeDBH_SubplotLevelSurrounding canopy trees were measured for each subplot by recording species ID, distance from subplot, and diameter at breast height (DBH). Basal area was calculated from dbh. Data was recorded May 27–June 5. Each tube was visited, each seedling was identified and marked with a colored pin, and seedling length was measured with a ruler to the nearest 0.1 cm. Each tube was checked for burning. Thatch level was visually recorded into categories by percent cover (and depth for level 4).SorensonAndDamschen2019_VegetationSurvey_SubplotLevelAndTubeLevelThe vegetation surrounding the root excluder tubes was recorded by measuring the plot attributes and herb community at the tube level and the shrub community at the subplot level. To measure plot attributes, a 0.5mx0.5m pvc quadrat was placed with each root excluder tube in the center and the edges aligned with the edges of the subplot. Within this quadrat, the overall %cover of: all plants from a bird’s eye view (Green), leaf litter (Litter), woody debris (Woody), bare ground (Bare), and moss and fungus (Non-Vasc) were recorded. Additionally, % cover of each species of plant that hung into the quadrat was visually estimated. %cover of each species was estimated even if a leaf of a different species overtopped it, but not for a conspecific. To measure the shrub community, a 3mx3m quadrat was placed with the subplot at the center and %cover of each species was visually estimated. This file has, admittedly poor data structure, but is easy to subset using the column data type column DT.SorensonAndDamschen2019_WaterHoldingCapacity_TubeLevelTwo 15cm deep, 2cm wide soil cores were collected from opposite sides of each tube (5cm away) and mixed. Each sample was placed in a tin container with a perforated bottom and placed in a shallow water bath just deep enough for the soil to wick water up into the soil and saturate it. Saturated and oven dried weights were used to calculate how much water each sample could hold. This was relativized to the dry mass of the soil.AllFilesMetadataContains data description and field descriptions of all datasets.metadata.txt