DOI: 10.6086/d1kd6r
title: Data from: Incorporating temporal dynamics to enhance grazing management outcomes for a long-lived species

description: Identifying successful management strategies for long-lived species is
 challenging, especially in fluctuating environments, because the response
 of individual vital rates and overall growth rates to management action
 can vary over time. A demographic approach that isolates the impact of
 management and environment on individual vital rates, and assesses their
 importance for growth rate over time, can indicate whether and why a
 management strategy is successful. Here we take a demographic approach to
 assess the success of grazing management for the perennial grass Stipa
 pulchra, the state grass of California and a focus of conservation
 efforts. We tracked S. pulchra populations in paired grazed and ungrazed
 plots over six years, which included an historic drought and an El Niño
 rain year, and calculated summary transition matrices for the main effects
 of year, grazing, and year x grazing interaction for each site. We
 averaged these summary transition matrices to calculate population growth
 rates, l, for the main effects of year, grazing, and year x grazing and
 used life table response experiment (LTRE) analysis to compare how
 individual vital rates contributed to differences in l between grazed and
 ungrazed plots over time. Overall we found that grazing was a successful
 management strategy; grazed populations maintained a positive average
 population growth rate whereas ungrazed populations declined. We found
 that grazing had a larger positive effect on growth rates in wet years
 than drought years. This was because grazed populations benefited from a
 greater contribution of adult growth immediately following the end of the
 drought compared to ungrazed populations, and from adult survival
 thereafter. Synthesis and applications. Although Stipa pulchra is the
 focus of many management efforts, the use of grazing for management is
 contentious, and there have been few studies that take a demographic
 approach to understanding S. pulchra responses over time. Our results
 indicate that conservation and restoration efforts should move beyond
 recruitment to focus on adult growth and survival for overall population
 success. To this end, moderate grazing can be a successful strategy to
 maintain S. pulchra populations and is particularly important in wet years
 to promote plant growth.
description: Annual transition values for individual Stipa plants from 2014
 through 2019 (JAppl_VC_20141516171819.csv) All values were measured for
 Stipa pulchra individuals at the Vasco Caves Regional Preserve and Los
 Vaqueros Watershed, Byron, CA. Please see Larios & Hallett 2022
 for details of experimental design and data collection.
 Column metadata secondYear = The second year
 of the transition (e.g., 2015 indicates the change from 2014 to
 2015) Site = The name of the grazed and ungrazed pair
 of plots (Plot10, Plot15, Plot2, PlotBN, PlotBS, PlotNCow) within the
 Vasco Caves Regional Preserve or Los Vaqueros Watershed. Plot10, Plot15,
 and Plot2 included previously established grazing exclosures, the rest
 were established at the beginning of the experiment. All grazed plots were
 sheep grazed except in PlotNCow, which was cattle grazed. See Larios
 & Hallett 2022 for site details Plot = The name
 of the plot within a pair. G indicates a grazed plot, U indicates
 ungrazed Treatment = Whether the plot was grazed or not
 (coded as Grazed and Ungrazed) Transect = The transect
 within the plot, named by the distance in meters from the initial transect
 (transect 0) Subplot = The subplot within a transect,
 named by distance in meters along the transect Individ2
 = A unique number for each individual Stipa plant found within a
 subplot Grazer = Which type of grazer was in the grazed
 treatment (coded as either Sheep or Cow) stage = The
 stage class of the individual Stipa plant in the first year of the
 transition (e.g., if secondYear is 2015, stage refers to the life stage in
 2014). stage is coded as either seedling (when the individual was observed
 as a seedling in the first year), continuous (when the individual was a
 juvenile or adult in the first year), or NA (when the individual did not
 appear until the second year) stageNext = The stage
 class of the individual Stipa plant in the second year of the transition
 (e.g., the same year as secondYear). stageNext is coded as either seedling
 (when the individual was observed as a seedling in the second year),
 continuous (when the individual was either a juvenile or adult), or dead
 (when the individual was present in the first year but not in the
 second) size = The area in cm2 of the individual Stipa
 plant in the first year of the transition sizeNext =
 The area in cm2 of the individual Stipa plant in the second year of the
 transition surv = Whether the individual survived the
 transition from the first to second year, coded as a binary (0 if the
 individual did not survive, 1 if it did) offspringNext
 = Whether the individual was offspring that appeared in the second year of
 the transition (coded as NA if the individual was present in the first
 year, and sexual if the individual was a seedling in the second
 year) fec = Whether the individual produced seeds in
 the second year, coded as a binary (0 if the individual did not produce
 seeds, 1 if it did) fec1 = The number of culms the
 individual produced in the second year if it produced seeds
 seed = The average estimated number of seeds per culm produced
 for Stipa plants within that plot pair Transition
 Matrices for six populations that were either grazed or ungrazed over five
 transition periods from 2014 to 2019 (JAppl_Stipa Matrices_2014_2019.csv)
 All probabilities were estimated from the censused data reported in the
 annual transition values file entry (JAppl_VC_20141516171819.csv). Please
 see Larios & Hallett 2022 for details of experimental design and
 data collection. Column metadata
 secondYear – The second year of the transition (e.g., 2015
 indicates the change from 2014 to 2015) Treatment -
 Whether the plot was grazed or not (coded as Grazed and
 Ungrazed) Site - The name of the grazed and ungrazed
 pair of plots (Plot10, Plot15, Plot2, PlotBN, PlotBS, PlotNCow) within the
 Vasco Caves Regional Preserve or Los Vaqueros Watershed. Plot10, Plot15,
 and Plot2 included previously established grazing exclosures, the rest
 were established at the beginning of the experiment. All grazed plots were
 sheep grazed except in PlotNCow, which was cattle grazed. See Larios
 & Hallett 2022 for site details sdlg_sdlg –
 Transition probability for seedlings staying seedlings
 juv_sdlg - Transition probability for juvenile
 fecundity adult_sdlg - Transition probability for adult
 fecundity sdlg_juv - Probability for seedlings
 transitioning to juveniles juv_juv - Transition
 probability for juveniles staying juveniles adult_juv -
 Probability for an adult to regress to a juvenile
 sdlg_adult - Probability for seedlings transitioning to
 adults juv_adult - Probability for juveniles
 transitioning to adults adult_adult - Transition
 probability for adults staying adults