Soil greenhouse gas fluxes from different tree species on Taihang Mountain, North China

Abstract

Abstract. The objectives of this study were to investigate seasonal variation of greenhouse gas fluxes from soils on sites dominated by plantation (Robinia pseudoacacia, Punica granatum, and Ziziphus jujube) and natural regenerated forests (Vitex negundo var. heterophylla, Leptodermis oblonga, and Bothriochloa ischcemum), and to identify how tree species, litter exclusion, and soil properties (soil temperature, soil moisture, soil organic carbon, total N, soil bulk density, and soil pH) explained the temporal and spatial variation in soil greenhouse gas fluxes. Fluxes of greenhouse gases were measured using static chamber and gas chromatography techniques. Six static chambers were randomly installed in each tree species. Three chambers were randomly designated to measure the impacts of surface litter exclusion, and the remaining three were used as a control. Field measurements were conducted biweekly from May 2010 to April 2012. Soil CO 2 emissions from all tree species were significantly affected by soil temperature, soil moisture, and their interaction. Driven by the seasonality of temperature and precipitation, soil CO 2 emissions demonstrated a clear seasonal pattern, with fluxes significantly higher during the rainy season than during the dry season. Soil CH 4 and N 2 O fluxes were not significantly correlated with soil temperature, soil moisture, or their interaction, and no significant seasonal differences were detected. Soil organic carbon and total N were significantly positively correlated with CO 2 and N 2 O fluxes. Soil bulk density was significantly negatively correlated with CO 2 and N 2 O fluxes. Soil pH was not correlated with CO 2 and N 2 O emissions. Soil CH 4 fluxes did not display pronounced dependency on soil organic carbon, total N, soil bulk density, and soil pH. Removal of surface litter significantly decreased in CO 2 emissions and CH 4 uptakes. Soils in six tree species acted as sinks for atmospheric CH 4 . With the exception of Ziziphus jujube, soils in all tree species acted as sinks for atmospheric N 2 O. Tree species had a significant effect on CO 2 and N 2 O releases but not on CH 4 uptake. The lower net global warming potential in natural regenerated vegetation suggested that natural regenerated vegetation were more desirable plant species in reducing global warming.

Legume-based mixed intercropping systems may lower agricultural born N2O emissions

“…In a review study, Rochette and Jansen [26] summarized that legumes can increase N 2 O emissions during growth compared to evenly fertilized arable crops most likely due to the N release from the root exudates and decomposition of crop residues. Our study clearly agrees with Rochette and Jansen [26] and many others (e.g., [7,27]) that growing legumes as mono-crop can increase N 2 O fluxes compared to N-fertilized arable crops. On the other hand, seasonal N 2 O fluxes were 35 % lower in WFB (wheat mixed intercropped with faba bean) than in NWT (wheat as mono-crop) treatment.…”

“…During the first year, young plantations in agro-forestry domains generally have limited N and water uptake, while wheat and faba bean as arable crops are at their most productive growth stage specifically during May and June (growth rates are almost at their maximum during this period). Here, soil conditions seem to be more favorable specifically for denitrification in agro-forestry treatments than in soils planted with arable crops that may explain large N 2 O emissions [27]. The cumulative mean N 2 O emissions in agro-forestry treatments were about fivefold higher than in both WT and WFB treatments, and the latter was still more than twofold higher when compared to FB plots.…”

“…3) ) have been usually observed in young agro-forest ecosystems [7,27]. Almost all significant N 2 O fluxes occurred as daily peak N 2 O emissions and were measured only during the early summer period in 2014.…”

“…In contrast, in a review study, Rochette and Janzen [26] concluded that legumes can produce substantial N 2 O emissions. The cultivation of N 2 -fixing legume species (e.g., faba bean (Vicia faba L.) as arable crop or Robinia (Robinia pseudoacacia) as woody plant) could stimulate N 2 O emissions simply by increasing N input to soils, thus providing additional substrate for nitrification and denitrification [27]. Authors reported that faba bean could release 13 % of their fixed N as rhizodeposition [28].…”

Winter Soil CO2 Flux from Different Mid-Latitude Sites from Middle Taihang Mountain in North China

“…The grass vegetation is dominated by the mixed drought-resistant species of Artemisia sacrorum , Bothriochloa ischaemum and Themeda japonica ; shrub vegetation is dominated by Vitex negundo var. heterophylla ; and plantation vegetation is dominated by Populus tomatosa species [21], [22]. The region is characterized by short, cold, and dry winters, lasting approximately three months long from December to February, with varied snow cover.…”