Effect of climate change on seasonal monsoon in Asia and its impact on the variability of monsoon rainfall in Southeast Asia

Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment.Although there are enough historical evidence to support the theory that climate change is a natural phenomenon,many research scientists are widely in agreement that the increase in temperature in the 20 th century is anthropologically related.The associated effects are the variability of rainfall and cyclonic patterns that are being observed globally.In Southeast Asia the link between global warming and the seasonal atmospheric flow during the monsoon seasons shows varying degree of fuzziness.This study investigates the impact of climate change on the seasonality of monsoon Asia and its effect on the variability of monsoon rainfall in Southeast Asia.The comparison of decadal variation of precipitation and temperature anomalies before the 1970 s found general increases which were mostly varying.But beyond the 1970 s,global precipitation anomalous showed increases that almost corresponded with increases in global temperature anomalies for the same period.There are frequent changes and a shift westward of the Indian summer monsoon.Although precipitation is observed to be 70%below normal levels,in some areas the topography affects the intensity of rainfall.These shifting phenomenon of other monsoon season in the region are impacting on the variability of rainfall and the onset of monsoons in Southeast Asia and is predicted to delay for 15 days the onset of the monsoon in the future.The variability of monsoon rainfall in the SEA region is observed to be decadal and the frequency and intensity of intermittent flooding of some areas during the monsoon season have serious consequences on the human,financial,infrastructure and food security of the region.

Ground-active arthropod responses to rainfall-induced dune microhabitats in a desertified steppe ecosystem,China

Different microhabitats along dune slope were found to affect the distribution of plant performances and soil properties in desertified ecosystems. However, the ground-active arthropod responses to rainfall-induced dune microhabitats were largely unknown in desertified regions. At dune top, midslope and bottom, ground-active arthropods were sampled by the method of pitfall traps in addition to the herbaceous and soil measurements during spring, summer and autumn from 2012 to 2013. Ground-active arthropod had a strong dynamics in time, seasonally and yearly in responses to rainfall-induced dune microhabitats and the variations were significant higher than those of soil and herbaceous properties. The abundance distribution of dominant taxa （i.e. Melolonthidae, Carabidae, Glaphyridae, Tenebrionidae and Formicidae families） among dune microhabitats was similar between seasons within the same year, whereas they differed markedly between two sampling years with varying rainfall patterns. A significant （P〈0.05） difference in total abundance, taxa richness and Shannon index among dune microhabitats was found only in certain season time, particularly in 2013; however, no significant （P〉0.05） differences were found among dune microhabitats when averaged on three sampling seasons within the year of either 2012 or 2013. In all, the taxonomical structure differed considerably from the community structure in ground-active arthropod response to rainfall-induced dune microhabitats. The spatial distribution of taxonomical groups among dune microhabitats was significantly affected by inter-annual rainfall changes, whereas that of community structure was affected by both intra- and inter-annual rainfall changes in desertified ecosystems.

Impacts of precipitation variation and soil and water conservation measures on runoff and sediment yield in the Loess Plateau Gully Region, China

The Loess Plateau of China has experienced a lengthy drought and severe soil erosion.Changes in precipitation and land use largely determine the dynamics of runoff and sediment yield in this region. Trend and mutation analyses were performed on hydrological data(1981–2012) from the Yanwachuan watershed in the Loess Plateau Gully Region to study the evolution characteristics of runoff and sediment yield. A time-series contrasting method also was used to evaluate the effects of precipitation and soil and water conservation(SWC) on runoff and sediment yield. Annual sediment yield declined markedly from 1981 to 2012 although there was no significant change in annual precipitation and annual runoff. Change points of annual runoff and annual sediment yield occurred in 1996 and 1997,respectively. Compared with that in the baseline period(1981–1996), annual runoff and annual sediment yield in the change period(1997–2012)decreased by 17.0% and 76.0%, respectively, but annual precipitation increased by 6.3%. Runoff decreased in the flood season and normal season, but increased in the dry season, while sediment yield significantly declined in the whole study period. The SWC measures contributed significantly to the reduction of annual runoff(137.9%) and annual sediment yield(135%) and were more important than precipitation. Biological measures(forestland and grassland) accounted for 61.04% of total runoff reduction, while engineering measures(terraces and dams) accounted for 102.84% of total sediment yield reduction. Furthermore, SWC measures had positive ecological effects. This study provides a scientific basis for soil erosion control on the Loess Plateau.