DOI: 10.5061/dryad.f4k16
title: Data from: Climate and landscape drive the pace and pattern of conifer encroachment into subalpine meadows

description: Mountain meadows have high biodiversity and help regulate stream water
 release following the snowmelt pulse. However, many meadows are
 experiencing woody plant encroachment, threatening these ecosystem
 services. While there have been field surveys of individual meadows and
 remote sensing-based landscape-scale studies of encroachment, what is
 missing is a broad scale, ground-based study to understand common regional
 drivers, especially at high elevations, where land management has often
 played a less direct role. With this study we ask: what are the climate
 and landscape conditions conducive to woody plant encroachment at the
 landscape scale, and how has historical climate variation affected tree
 recruitment in subalpine meadows over time? We measured density of
 encroaching trees across 340 subalpine meadows in the central Sierra
 Nevada, California, USA, and used generalized additive models (GAMs) to
 determine the relationship between landscape-scale patterns of
 encroachment and meadow environmental properties. We determined ages of
 trees in 30 survey meadows, used observed climate and GAMs to model the
 relationship between timing of recruitment and climate since the early
 1900s, and extrapolated recruitment patterns into the future using
 downscaled climate scenarios. Encroachment was high among meadows with
 lodgepole pine (Pinus contorta Douglas ex Loudon var. murrayana (Balf.)
 Engelm.) in the immediate vicinity, at lower elevations, with physical
 conditions favoring strong soil drying, and with maximum temperatures
 above or below average. Climatic conditions during the year of germination
 were unimportant, with tree recruitment instead depending on a 3-year seed
 production period prior to germination and a 6-year seedling establishment
 period following germination. Recruitment was high when the seed
 production period had high snowpack, and when the seedling establishment
 period had warm summer maximum temperatures, high summer precipitation,
 and high snowpack. Applying our temporal model to downscaled output from
 four global climate models indicated that the average meadow will shift to
 forest by the end of the 21st century. Sierra Nevada meadow encroachment
 by conifers is ubiquitous and associated with climate conditions
 increasingly favorable for tree recruitment, which will lead to
 substantial changes in subalpine meadows and the ecosystem services they
 provide.
description: SubalpineMeadowEncroachmentDataZip contains 8 data files: 1) MeadowData.csv is the primary data file, with the bulk of the data from the four years of field work; 2) TransectSummary.csv with metadata for individual transects within the 30 detailed survey meadows; 3) MeadowSummary.DetailedSurveys.csv with metadata for each of the 30 detailed survey meadow; 4) MeadowSummary.RapidAssessments.csv with summary data for 306 rapid assessment meadows; 5) MeadowSummary.Subalpine.csv with meadow characteristics for 1233 subalpine meadows in Yosemite National Park; 6) TreeCoresSummary.csv with summary data for 287 tree cores collected 2009-2011 in Yosemite National Park; 7) Cores.PICO.txt is a standard rwl file in decadal/Tucson format; 8) Recruitment.csv with historical recruitment data for the 19 of the 30 detailed survey meadows that each had at least 100 encroaching conifers.