DOI: 10.5061/dryad.np5hqc05h
title: Drought intensity and duration interact to magnify losses in primary productivity

description: Terrestrial ecosystem productivity losses are expected to magnify over
 time with increased drought duration, a likely future scenario. Yet, some
 ecosystems appear resistant to progressive losses in productivity with
 multi-year drought. We quantified the combined effects of drought duration
 and severity on aboveground productivity in 74 grasslands and shrublands.
 Productivity declined 29% when drought severity was within the range of
 historic variability, with little evidence for progressive loss over time.
 Resistance was lost when drought severity was extreme (≤ 1-in-100-year
 likelihood). When extreme drought occurred over consecutive years,
 productivity losses increased 3-fold. Our results portend a shift in
 ecosystem behavior under future drought scenarios – from maintenance of
 reduced functioning over time to progressive and profound loss of
 functioning as drought duration and severity increase.
description: # Drought severity interacts with duration to erode ecosystem resistance
 Dataset DOI: [10.5061/dryad.np5hqc05h](10.5061/dryad.np5hqc05h) ###
 Description of the Data and File Structure The structure of this
 repository is relatively simple, with one R script (code_for_submission.R)
 that uses data from five .csv files to reproduce results and figures from
 the publication. The datasets can all be linked by the site_code column,
 which serves as a unique identifier for each site in the study. ###
 `data.anpp.summary.csv` * site_code – Unique identifier for each site *
 year – Year of data collection * drtsev.1 to drtsev.4 – Drought severity
 calculated from precipitation in drought treatment plots for various time
 intervals before sampling * n_treat_years – Number of years since
 treatments started * map – Site-reported mean annual precipitation *
 habitat.type – Standardized habitat type of the site * e.n, prev_e.n,
 prev_e.n2, prev_e.n3 – Extreme/nominal status for different time windows
 prior to sampling * PctAnnual – Percent of pretreatment cover of annual
 plant species * Ann_Per – Indicates whether the site is annual- or
 perennial-dominated * ipcc_regions – Reference region per [IPCC
 guidelines](https://www.ipcc-data.org/guidelines/pages/ar5_regions.html) *
 mean_mass * ppt.1 – Precipitation for 0–365 days before sampling *
 anpp_response – Productivity response ratio * anpp_response.error – 95% CI
 for productivity response ratio * anpp_response.se – Standard error for
 productivity response ratio * percent.reduction, percent.reduction.error,
 percent.reduction.se – Percent productivity reduction and associated error
 estimates * n_treat_days – Number of treatment days * type ###
 `ai_pet_04-18-2022.csv` * site_code, site_id,site_worldclim_id – Site
 identifiers * MAT_v2, MAT_RANGE_v2 – Mean annual temperature and range
 (°C) * ISO_v2 TEMP_VAR_v2 – Iso/anisohydry index and temperature variation
 * MAX_TEMP_v2, MIN_TEMP_v2 – Max and min temperatures (°C) *
 ANN_TEMP_RANGE_v2 – Annual temperature range (°C) * TEMP_WET_Q_v2,
 TEMP_DRY_Q_v2, TEMP_WARM_Q_v2, TEMP_COLD_Q_v2 – Seasonal temperatures (°C)
 * MAP_v2, MAP_WET_M_v2, MAP_DRY_M_v2, MAP_VAR_v2 – Mean annual and
 seasonal precipitation (mm) * MAP_WET_Q_v2, MAP_DRY_Q_v2, MAP_WARM_Q_v2,
 MAP_COLD_Q_v2 – Seasonal precipitation (mm) * PET, RAIN_PET – Potential
 evapotranspiration * AI – Aridity index * Insulation – Average annual
 insulation ### `climate_mean_annual_by_site_v2.csv` * site_code – Unique
 identifier for each site * ppt_max_event, ppt_mean_event – Size of the
 largest and mean precipitation events (mm) * days_half_ppt – Days to reach
 half of annual precipitation * daily_ppt_d, yearly_ppt_d – Intra- and
 interannual precipitation variability (D metric) * n_wet_days – Number of
 precipitation events per year * MAP – Mean annual precipitation (mm/yr) *
 avg_dryspell_length – Days between wet events * ppt_95th_percentile_size –
 Size of the top 5% of precipitation events * cv_ppt_intra – Intra-annual
 precipitation variability (CV) * cv_ppt_inter – Interannual precipitation
 variability (CV of annual totals) * seasonality_index – Calculated as per
 Walsh and Lawler (1981): SI = sum(abs(x - Ri/12)) / Ri, where x is monthly
 ppt, Ri is annual ppt ### `gain_losses.csv` * site_code, year,
 n_treat_years – Site ID, year, and treatment duration * measure – Metric
 calculated (e.g., richness, abundance) * RR – Response ratio * trt – All
 drought (used in RR calculation) * map, MAP – Mean annual precipitation
 (reported vs. MSWEP) * drtseverity – Drought severity (0–365 days prior to
 sampling) * PctAnnual, PctGrass – Pretreatment cover percentages *
 cv_ppt_inter, seasonality_index – Precipitation variability and
 seasonality * MAT2 – Mean annual temperature * richness – Species richness
 * deltaabund – Change in abundance ### `site_sand_from_soilgrid.csv` *
 site_code – Unique identifier for each site * sand_mean – Average sand
 percentage (all depths) * sand0_5, sand5_15, sand15_30, sand30_60,
 sand60_100 – Sand content by soil depth (cm) ### Sharing / Access
 Information Please contact the authors if you are interested in using
 these data. The data are free to reuse, but reaching out beforehand
 ensures proper understanding of context and best practices for use.