Long-term gravel–sand mulch affects soil physicochemical properties, microbial biomass and enzyme activities in the semi-arid Loess Plateau of North-western China

Author(s):  
Yang Qiu ◽  
Yajun Wang ◽  
Zhongkui Xie
2013 ◽  
Vol 61 (1) ◽  
pp. 29 ◽  
Author(s):  
Ling-Ping Zhao ◽  
Gao-Lin Wu ◽  
Zhi-Hua Shi

Offspring recruitment is an important part of population dynamics, as well as for plant-community structure and succession. One generality regarding grasses and fire is that clonal grasses tolerate fire extremely well and in most cases reach their maximum production in the immediate post-fire years. One qualification to this statement is that post-fire offspring, recruitment mode is very important. However, respective data are scare in the semiarid perennial steppe. We studied the relative importance of asexual v. sexual recruitment in the post-fire recovery in semiarid steppe on the Loess Plateau of north-western China. We observed differences in regeneration strategy after different times post-fire (burnt in 2008, burnt in 1999, and no fire history for at least 30 years). Results showed that fire significantly increased offspring recruitment numbers, but not species richness. The increase of asexual recruitment after a fire made a major contribution to the increase of total offspring number. Meanwhile, there was no significant difference for the ratio of asexual to sexual recruitment among sites with different times since fire. The asexual to sexual recruitment ratio was significantly different for different species, with some species not recruiting offspring via sexual recruitment. Our results indicated that seedling recruitment contributed little to post-fire recovery of the perennial-steppe community. Lack of sexual recruitment is not related to fire management but to inherent traits of the occurring plants.


2020 ◽  
Vol 12 (18) ◽  
pp. 7494
Author(s):  
Lan Mu ◽  
Lan Fang ◽  
Yuhong Liu ◽  
Chencheng Wang

The changing climate represents a large challenge for farmers, and adaptation responses are necessary to minimize impacts. Mixed approaches, which involve the analysis of meteorological data, web-based surveys, and face-to-face interviews, explore producers’ barriers and pressing needs to enhance climate resilience based on the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) approach in semi-arid north-western China. According to the main categories of farming activity, 85 crop farmers, 68 animal farmers, and 81 agro-tourism operators were interviewed. We found that most of the producers perceived climate impacts, and they encountered multiple adaptation obstacles, of which institutional and normative obstacles were more serious, such as farmers unable to obtain resources or government incentives, lacked scientific, and efficient coping measures. The survey also observed that crop farmers had a pressing need for agricultural subsidies, while animal farmers and agro-tourism operators had a strong enabler for animal housing infrastructure and credit facilities, respectively. Given the heterogeneity of the context and climate change experience of different categories of farmers, it is necessary to formulate flexible adaptation strategies and adjust them according to specific climate stress and farming conditions. To achieve the Sustainable Development Goals and implement the 2015 Paris Agreement, policymakers should plan and introduce appropriate adaptation strategies to minimize the adverse effects of climate change such as improving irrigation and weather forecasting system through technological advancement, cost reduction of farm inputs, ensuring availability of information, providing agricultural subsidies to the farmers, and increasing the access to agricultural markets.


2012 ◽  
Vol 16 (3) ◽  
pp. 893-910
Author(s):  
X. Xiao ◽  
H. C. Zuo ◽  
Q. D. Yang ◽  
S. J. Wang ◽  
L. J. Wang ◽  
...  

Abstract. The energy observed in the surface layer, when using eddy-covariance techniques to measure turbulent fluxes, is not balanced. Important progress has been made in recent years in identifying potential reasons for this lack of closure in the energy balance, but the problem is not yet resolved. In this paper, long-term data that include output of tower, radiation, surface turbulence flux and soil measurement collected from September 2006 to August 2010 in the Semi-Arid Climate Change and Environment Observatory, Lanzhou University, in the semi-arid Loess Plateau of Northwest China, were analysed, focusing on the seasonal characteristics of the surface energy and the factors that have impact on the energy balance closure (EBC). The analysis shows that (1) the long-term observations are successful; the interaction between the land and the atmosphere in semi-arid climates can be represented by the turbulent transport of energy. In addition, even though the residual is obvious, this suggests that the factors that impact the EBC are stable, and their seasonal variations are identical. The analysis also shows that (2) four factors have obvious impact on the EBC: the diverse schemes for surface soil heat flux, the flux contribution from the target source area, the low-frequency part of the turbulence spectra, and the strength of atmospheric turbulence motion. The impact of these four factors on the EBC are similar in all seasons. Lastly, the results indicate that (3) atmospheric turbulence intensity is a very important factor in terms of its impact on the EBC. The relative turbulence intensity, RIw, characterises the strength of atmospheric turbulence motion, and is found to exert a noticeable impact on the EBC; in all seasons, the EBC is increased when the relative turbulence intensity is enlarged.


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