Abstract
Water use efficiency is an important indicator of drought tolerance of
plants. The response was still unclear of water use efficiency to
different grazing intensity and its adaptive mechanisms in alpine
meadow. Here, we analyzed water use efficiency of plant dominant
species, coexisting species and functional group level plants to grazing
intensity by δ13C index in alpine meadow. Furthermore,
this study revealed the driven factors of water use efficiency combined
available nitrogen, soil bulk density, soil organic carbon, soil water
content and evapotranspiration. Grazing increased plants
δ13C by 3.37%. Moderate grazing significantly
increased the δ13C of Gramineae by 4.84%
(P<0.05), and increased δ13C of Cyperaceae,
Leguminosae, and Forb by 3.45%, 0.81%, and 1.40% respectively. Some
dominant species and coexisting species have the highest
δ13C value under moderate grazing. This study
indicated that moderate grazing significantly improved the water use
efficiency of alpine meadows. Path analysis resulted showed that the
water use efficiency was negatively correlated with evapotranspiration
(P<0.05), soil water content, soil organic carbon, and soil
bulk density. It was positively correlated with available nitrogen. Our
study provides new insights that moderate grazing help to increase water
use efficiency in alpine meadows. In addition, evapotranspiration may be
the main driving factor affecting the water use efficiency of alpine
meadow.
KEYWORDS: alpine meadow, grazing activity, water use efficiency,
δ13C