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1.
Ying Yong Sheng Tai Xue Bao ; 32(2): 618-628, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33650372

RESUMEN

Southwestern China is an important ecologically resource area and ecologically fragile area in China, which plays an important role in the national project of "Clear Waters and Green Mountains". Based on land use data set with a 1 km spatial resolution and combined with land use transfer matrix, we analyzed the characteristics and driving forces of land use change in Southwest China from 2000 to 2015. Based on the MODIS remote sensing index, we calculated the vegetation coverage in Southwest China using the dimidiate pixel model, and analyzed the changes of the normalized vegetation index (NDVI) and vegetation coverage. Results showed that the main land types were woodland, cropland and grassland. The built-up land area increased by 5874 km2(55.8%), the cropland area decreased by 6211 km2, and grassland decreased by 2099 km2. From 2000 to 2015, the area that had been changed to built-up land was the largest, mainly from cropland (contributed 68.2%), woodland (contributed 19.2%) and grassland (contributed 13.1%). The transformed areas were mostly close to urban area. The area and rate for the transformation of cropland were 7079 km2 and 2.2% respectively, accounting for 46.0% of all the transferred out areas. Most of the woodland were transformed from grassland (61.8%), mainly distributed in central and southern Guizhou and western Yunnan. Both NDVI and vegetation coverage were significantly increased, indicating that the whole region was greening. NDVI of both natural vegetation and cropland increased significantly, while the NDVI of areas with expanded build-up land decreased. Therefore, natural vegetation and cropland dominated the vegetation change in this region. Results of the resi-dual analysis showed that both climate change and human activities contributed significantly to the greening trend.


Asunto(s)
Cambio Climático , Monitoreo del Ambiente , China , Bosques , Actividades Humanas , Humanos
2.
Appl Microbiol Biotechnol ; 99(13): 5709-18, 2015 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-25690313

RESUMEN

The quantitative importance of anaerobic ammonium oxidation (anammox) has been described in paddy fields, while the presence and importance of anammox in subsurface soil from vegetable fields have not been determined yet. Here, we investigated the occurrence and activity of anammox bacteria in five different types of vegetable fields located in Jiangsu Province, China. Stable isotope experiments confirmed the anammox activity in the examined soils, with the potential rates of 2.1 and 23.2 nmol N2 g(-1) dry soil day(-1), and the anammox accounted for 5.9-20.5% of total soil dinitrogen gas production. It is estimated that a total loss of 7.1-78.2 g N m(-2) year(-1) could be linked to the anammox process in the examined vegetable fields. Phylogenetic analyses showed that multiple co-occurring anammox genera were present in the examined soils, including Candidatus Brocadia, Candidatus Kuenenia, Candidatus Anammoxoglobus and Candidatus Jettenia, and Candidatus Brocadia appeared to be the most common anammox genus. Quantitative PCR further confirmed the presence of anammox bacteria in the examined soils, with the abundance varying from 2.8 × 10(5) to 3.0 × 10(6) copies g(-1) dry soil. Correlation analyses suggested that the soil ammonium concentration had significant influence on the activity and abundance of anammox bacteria in the examined soils. The results of our study showed the presence of diverse anammox bacteria and indicated that the anammox process could serve as an important nitrogen loss pathway in vegetable fields.


Asunto(s)
Compuestos de Amonio/metabolismo , Bacterias Anaerobias/crecimiento & desarrollo , Bacterias Anaerobias/metabolismo , Microbiología del Suelo , Verduras/crecimiento & desarrollo , Anaerobiosis , Bacterias Anaerobias/clasificación , China , Análisis por Conglomerados , ADN Bacteriano/química , ADN Bacteriano/genética , ADN Ribosómico/química , ADN Ribosómico/genética , Marcaje Isotópico , Datos de Secuencia Molecular , Nitrógeno/metabolismo , Oxidación-Reducción , Filogenia , ARN Ribosómico 16S/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Análisis de Secuencia de ADN
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