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Annual methane uptake by temperate semiarid steppes as regulated by stocking rates, aboveground plant biomass and topsoil air permeability
Author(s) -
CHEN WEIWEI,
WOLF BENJAMIN,
ZHENG XUNHUA,
YAO ZHISHENG,
BUTTERBACHBAHL KLAUS,
BRÜGGEMANN NICOLAS,
LIU CHUNYAN,
HAN SHENGHUI,
HAN XINGGUO
Publication year - 2011
Publication title -
global change biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.146
H-Index - 255
eISSN - 1365-2486
pISSN - 1354-1013
DOI - 10.1111/j.1365-2486.2011.02444.x
Subject(s) - steppe , grazing , temperate climate , overgrazing , environmental science , agronomy , stocking , growing season , topsoil , sink (geography) , grassland , zoology , ecology , soil water , biology , soil science , geography , cartography
Overgrazing‐induced degradation of temperate semiarid steppes may affect the soil sink for atmospheric methane (CH 4 ). However, previous studies have primarily focused on the growing season and on single grazing patterns. Thus, the response of annual CH 4 uptake by steppes compared with various grazing practices is uncertain. In this study, we investigated the effects of grazing on the annual CH 4 uptake by two typical Eurasian semiarid steppes (the Stipa grandis steppe and the Leymus chinensis steppe) located in Inner Mongolia, China. The CH 4 fluxes were measured year‐round using static chambers and gas chromatography at 12 field sites that differed primarily in grazing intensities. Our results indicated that steppe soils were CH 4 sinks throughout the year. The annual CH 4 uptake correlated with stocking rates, whereas the seasonality of CH 4 uptake was primarily dominated by temperature. The annual CH 4 uptake at all sites averaged 3.7±0.7 kg C ha −1 yr −1 (range: 2.3–4.5), where approximately 35% (range: 23–40%) occurred during the nongrowing season. Light‐to‐moderate grazing (stocking rate≤1 sheep ha −1 yr −1 ) did not significantly change the annual CH 4 uptake compared with ungrazed steppes, but heavy grazing reduced annual CH 4 uptake significantly (by 24–31%, P <0.05). These findings imply that easing the pressure of heavily grazed steppes (e.g. moving to light or moderate stocking rates) would help restore steppe soil sinks for atmospheric CH 4 . The empirical equations based on the significant relationships between annual CH 4 uptake and stocking rates, aboveground plant biomass and topsoil air permeability ( P <0.01) could provide simple approaches for the estimation of regional CH 4 uptake by temperate semiarid steppes.