Get access

Dynamic and complex microclimate responses to warming and grazing manipulations

Authors

  • Julia A. Klein,

    1. Department of Environmental Science, Policy & Management, Division of Ecosystem Science, University of California, 151 Hilgard Hall, Berkeley, CA 94720 USA,
    Search for more papers by this author
  • John Harte,

    1. Department of Environmental Science, Policy & Management, Division of Ecosystem Science, University of California, 151 Hilgard Hall, Berkeley, CA 94720 USA,
    Search for more papers by this author
  • Xin-Quan Zhao

    1. Northwest Plateau Institute of Biology, Chinese Academy of Sciences, Xining, Qinghai 810001, China
    Search for more papers by this author

Julia A. Klein, Natural Resource Ecology Laboratory, Colorado State University, A206 NESB, Fort Collins, CO 80523-1499, USA, tel. +1 970 491 7715, fax +1 970 491 1965, e-mail: jklein@nrel.colostate.edu

Abstract

Synthesis efforts that identify patterns of ecosystem response to a suite of warming manipulations can make important contributions to climate change science. However, cross-study comparisons are impeded by the paucity of detailed analyses of how passive warming and other manipulations affect microclimate. Here we document the independent and combined effects of a common passive warming manipulation, open-top chambers (OTCs), and a simulated widespread land use, clipping, on microclimate on the Tibetan Plateau. OTCs consistently elevated growing season averaged mean daily air temperature by 1.0–2.0°C, maximum daily air temperature by 2.1–7.3°C and the diurnal air temperature range by 1.9–6.5°C, with mixed effects on minimum daily air temperature, and mean daily soil temperature and moisture. These OTC effects on microclimate differ from reported effects of a common active warming method, infrared heating, which has more consistent effects on soil than on air temperature. There were significant interannual and intragrowing season differences in OTC effects on microclimate. For example, while OTCs had mixed effects on growing season averaged soil temperatures, OTCs consistently elevated soil temperature by approximately 1.0°C early in the growing season. Nonadditive interactions between OTCs and clipping were also present: OTCs in clipped plots generally elevated air and soil temperatures more than OTCs in nonclipped plots. Moreover, site factors dynamically interacted with microclimate and with the efficacy of the OTC manipulations.

These findings highlight the need to understand differential microclimate effects between warming methods, within warming method across ecosystem sites, within warming method crossed with other treatments, and within sites over various timescales. Methods, sites and scales are potential explanatory variables and covariables in climate warming experiments. Consideration of this variability among and between experimental warming studies will lead to greater understanding and better prediction of ecosystem response to anthropogenic climate warming.

Ancillary