Physiological ecology - Original Paper

Oecologia

, Volume 168, Issue 2, pp 301-310

Nitrogen and water availability interact to affect leaf stoichiometry in a semi-arid grassland

  • Xiao-Tao LüAffiliated withState Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of Sciences
  • , De-Liang KongAffiliated withState Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences
  • , Qing-Min PanAffiliated withState Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences
  • , Matthew E. SimmonsAffiliated withState Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences
  • , Xing-Guo HanAffiliated withState Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese Academy of SciencesState Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences Email author 

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Abstract

The effects of global change factors on the stoichiometric composition of green and senesced plant tissues are critical determinants of ecosystem feedbacks to anthropogenic-driven global change. So far, little is known about species stoichiometric responses to these changes. We conducted a manipulative field experiment with nitrogen (N; 17.5 g m−2 year−1) and water addition (180 mm per growing season) in a temperate steppe of northern China that is potentially highly vulnerable to global change. A unique and important outcome of our study is that water availability modulated plant nutritional and stoichiometric responses to increased N availability. N addition significantly reduced C:N ratios and increased N:P ratios but only under ambient water conditions. Under increased water supply, N addition had no effect on C:N ratios in green and senesced leaves and N:P ratios in senesced leaves, and significantly decreased C:P ratios in both green and senesced leaves and N:P ratios in green leaves. Stoichiometric ratios varied greatly among species. Our results suggest that N and water addition and species identity can affect stoichiometric ratios of both green and senesced tissues through direct and interactive means. Our findings highlight the importance of water availability in modulating stoichiometric responses of plants to potentially increased N availability in semi-arid grasslands.

Keywords

C:N:P Precipitation regime Senesced leaves Steppe Stoichiometric ratios