The use of seasonal dambos for crop production is potentially associated with increase demission of GHGs such as nitrous oxide , carbon dioxide and methane . Nonetheless, the impact of dambo cultivation on GHG emissions is yet to be evaluated.The production Corresponding author. of rice, which is one of the major crops grown in dambos, has been associated with elevated GHG emissions, particularly CH4.Specifically,soil disturbance during dambo cultivation and application of fertilisers that influence microbial processes, soil organic carbon storage and turnover also affect GHG emissions from wetlands.However,to date there are no studies that have evaluated the use of conservation tillage practices on SOC storage and GHG emissions from dambos in Zimbabwe.In Zimbabwe, as in most of Sub-Saharan Africa, there are very few studies that have explored GHG emissions from cropped agricultural lands particularly dambos. There are a few reported studies the central and southern Africa regions e.g. Taylor et al.

The contributions of dambos of central and southern Africa to global CH4, carbon dioxide and N2O missions are mainly estimates as there have been very few measurements and there is a risk that a very important source of GHGs is being overlooked.This has been the case because of several reasons,among them; high research costs, limited funding, limitation of analytical infrastructure and trained personnel.The objective of the study was to quantify GHG emissions from seasonal wetland rice under different tillage systems, using static chambers. Northern China is always considered as a dry region comparing to the southern China. Especially in winter,a dry lasting cold weather dominates in the north.However,the northern China turned to be rich in precipitation in January 2018. The research region, called Region hereafter, is defined by the rectangle limitation comprising northern part of the farming-pastoral ecotone and Hulunbuir Grass-land, because both of the mentioned areas are economically relied on winter precipitations for crops growth, pasturage and tourism business. Up to date,many research are focused on the environment changes of such grassland ecosystem due to natural impact factors such as climate change, precipitation, grazing,fire and drought.The present research focuses on precipitation factor on the forest-grassland transition zone. Over the past 30 years from1988 to 2018, the maximum winter precipitation amount of the Region is no more than 100 mm, meanwhile in January 2018 that exceeds 400 mm.

This abnormal phenomenon attracts attention. For winter heavy precipitations, several studies are investigated worldwide. Single winter heavy precipitation occurred incentral Japan in January 2016. It is found that the occluding cyclones are the main cause of the heavy precipitations. Cold air out breaks, passing by of extra tropical cyclones are also causes of winter heavy precipitations in Japan. In addition, typical winter monsoon pressure patterns also contribute to the inland heavy precipitations in Japan. Along the coast of the Sea of Japan, local-scale depressions and local convergences caused by land breezes are factors for heavy winter precipitations . Studies on heavy winter precipitations in Japan caused by extratropical cyclones further provide information on root causes. The result is that the combination of the warm conveyor belt, the cold conveyor belt and the dry air intrusion is vital in the contribution of the heavy precipitations .Moving to areas above the southeast Canada and the northeast United States,North Atlantic Oscillation is the major cause of the heavy winter precipitation.The positive North Atlantic Oscillation induces less precipitations, while the negative North Atlantic Oscillation causes twice as many heavy precipitation events as the former .

In eastern Canada, studies show that the winter precipitations are poorly correlated with the North Atlantic Oscillation.In aspect of sea surface temperature influences, existing studies show that theme so scale of that can give a remote influence on atmospheric river land falling,leading to heavy precipitations along the west coast of North America . In addition, heavy winter precipitations in the west mountainous topography of America is also caused by the moisture originating from the Pacific, and transporting upwards through the mountains . For a heavy precipitation event in January 2008 in Iran, a deep low trough above the north of the Caspian Sea caused by a blocking system drives the thermal and moisture gradients . For summer heavy precipitations in Utah, both direct and indirect synoptic factors are important. Moreover, the humidity shift above the Atlantic Ocean plays acrucial role . In Romania, positive North Atlantic Oscillation and blocking phenomenon over the Atlantic-European sector can cause winter precipitations to decrease . Global warming is another key contributor to extratropical cyclones,leading to the increase of the precipitation intensity .