Ruminant production, especially in the tropics and developing countries suffers a setback when compared with the temperate and developed countries, which is attributable to the kinds of available feed resources in the...Ruminant production, especially in the tropics and developing countries suffers a setback when compared with the temperate and developed countries, which is attributable to the kinds of available feed resources in the region of production. In the tropics, ruminants are restricted to grazing on low-quality forages, crop residues and agro-industrial by-products with very little or no concentrate diets, which adversely affect the animals in exhibiting their full production potential. Considering this fact, there is an increasing interest in improving the digestibility of these feed resources. In recent years, researchers have explored several methods to enhance the functions of rumen microflora, improve digestion and fermentation processes, as well as increase bioavailability and utilization of nutrients through feed supplementation. This review aims to explore the positive effects of supplementation of ruminant diets with probiotics or botanical extracts and their metabolites on the productivity of the animals. Moreover, the functions of these non-pathogenic and non-toxic live microorganisms(probiotics) and plant biologically active compounds(botanical extract)are explored because of the ban on non-therapeutic use of antibiotics as growth promoters coupled with the critical preference of consumers to high quality and safe animal products. It has been reported that these alternative supplemental products have a beneficial impact on both animal health and productivity, which is affecting stabilization of rumen environment, inhibition of pathogenic bacteria proliferation in gastrointestinal tract, modulation of immune response, increase in fibre degradation and fermentation, nutrients availability and utilization, animal growth performance and milk production, among others. However,long-term in vivo studies are still required to determine the synergetic effects of these 2 safe supplemental products.展开更多
Leaf litter decomposition of liaotong oak (Quercus liaotungensis Koize) under temperate, subtropical and tropical forests was examined using a litter bag technique. Decomposition rates and release dynamics of nutrient...Leaf litter decomposition of liaotong oak (Quercus liaotungensis Koize) under temperate, subtropical and tropical forests was examined using a litter bag technique. Decomposition rates and release dynamics of nutrients Ca, Cu, Fe, K, Mg, Mn and P were observed separately at all three sites for I to 2 a periods. The leaf litter mass loss of liaotong oak was simulated with Olson's exponential model. Significant differences of leaf litter mass loss were found in forests of all three climate zones. Litter decomposition was accelerated with the increase of both annual mean precipitation and temperature. Our results agreed with other studies demonstrating that litter decomposition processes were greatly affected not only by soil organisms (including soil fauna and microorganisms), but also by chemical factors. These chemical factors were important for controlling the release of nutrients, especially elements of Fe and Mn. We also found that Fe and Mn content increased in semi-decayed leaf litter as litter mass decreased. This result was presumably due to chelating process which accumulated soil Fe and Mn ions into the decomposing litter. In conclusion, our study allowed us to determine the classification of the characteristics of different nutrient release patterns.展开更多
The summer of 1998 was characterised by a severe flood in East Asia. The possible linkages were examined among the anomalies in the tropics that may be associated with the severe flood. The anomalies of 1998 are obtai...The summer of 1998 was characterised by a severe flood in East Asia. The possible linkages were examined among the anomalies in the tropics that may be associated with the severe flood. The anomalies of 1998 are obtained by removing the climatology, which is the average of the ECMWF (European Centre for Medium Range Weather Forecasts) Re—Analysis (ERA) data over 15 years from 1979 to 1993, from the corresponding fields of 1998, which are obtained from the ECMWF operational analyses. In comparison to the results of Nitta (1990), it was found that there are considerable similarities in the atmospheric circulation anomalies between the summers of 1998 and 1988, in the tropics as well as in middle—high latitudes. It was shown that the atmospheric convection is slightly suppressed over the tropical western Pacific. In general, the suppressed convection corresponds to a negative anomaly of SST in the warm pool region. In the summers of 1998 and 1988, however, there are positive anomalies of SSTs in the tropical western Pacific, corresponding to the suppressed convection over there. This slightly suppressed convection may not provide a viable forcing mechanism for the severe flood in East Asia. It was postulated that the zonal wind anomalies in the tropics, in addition to the atmospheric convection over the tropical western Pacific, influence the position and intensity of the North Pacific subtropical high. In both summers of 1998 and 1988, while the stronger convection occurs over the warmer tropical Indian Ocean, the suppressed convection corresponds to the positive anomalies of SSTs in the tropical western Pacific. A possible explanation was given for the broken relationship between SSTs and OLR, (Outgoing Longwave Radiation) by analyzing the large—scale atmospheric circulation anomalies in the tropics. The heat fluxes at the surface in the warm pool of the tropical western Pacific and tropical Indian Ocean were also examined by using the ERA–15 data. To avoid the inconsistency between the ERA–15 and the op展开更多
木麻黄(Casuarina equisetifolia)人工林是我国东南沿海最重要的防护林类型,但近年来出现明显的衰退现象.以广东省电白县沿海4种林龄(3、6、13、18年生)木麻黄人工林为研究对象,比较不同林龄木麻黄人工林系统养分利用特征.研究表明,木...木麻黄(Casuarina equisetifolia)人工林是我国东南沿海最重要的防护林类型,但近年来出现明显的衰退现象.以广东省电白县沿海4种林龄(3、6、13、18年生)木麻黄人工林为研究对象,比较不同林龄木麻黄人工林系统养分利用特征.研究表明,木麻黄不同器官含碳量差别不大,枝与干含碳量(448-462 g kg-1)略高于叶与枯落叶含碳量(416-430g kg-1),细根含碳量最低(320-391 g kg-1),除细根外,不同器官含碳量也不随林龄的增加而变化.木麻黄细根生物量与沙地土壤有机碳积累没有统计上的相关性.木麻黄含氮水平(9.9-11.9 g kg-1)与本地区其它植物叶片含氮量相当,其生理活性最高的叶片与细根含氮量最高,两者具有相似的动态特征,生长旺盛的6年林含氮量最低.木麻黄叶片含磷量最高(0.66-0.89 g kg-1),其次是细根,枝干含磷量最低.木麻黄不同器官含磷量在旺盛生长期(6年)和衰老期(18年)最低.4个林龄土壤中,3年林土壤含磷量远高于其它林地,3年林较高的土壤磷导致了较高的土壤有机碳和氮含量,但所有林地土壤碳、氮含量总体水平极低,约为同地带正常土壤碳氮含量的1/10.土壤含氮量与植物叶片及细根含氮量有一定的相关性,但土壤磷与植物磷没有统计上的相关性.木麻黄不同器官碳氮比及碳磷比基本不随林龄而变化,只有叶片有激烈的动态特征,6年林叶片处于最高值.木麻黄对衰老叶中氮转移效率不高,约为18%-30%,磷转移率在43%-58%,木麻黄的氮磷转移率与土壤或体内养分水平没有统计上的相关性.因而,当地木麻黄氮磷养分水平低,幼龄快速生长阶段受氮磷养分限制,较老阶段受磷养分限制,沙地土壤养分水平极低,土壤碳汇功能差.展开更多
Increases in free tropospheric ozone over the past two decades are mainly in the Northern Hemisphere that have been widely documented,while ozone trends in the Southern Hemisphere(SH)remain largely unexplained.Here we...Increases in free tropospheric ozone over the past two decades are mainly in the Northern Hemisphere that have been widely documented,while ozone trends in the Southern Hemisphere(SH)remain largely unexplained.Here we first show that in-situ and satellite observations document increases of tropospheric ozone in the SH over 1990–2015.We then use a global chemical transport model to diagnose drivers of these trends.We find that increases of anthropogenic emissions(including methane)are not the most significant contributors.Instead,we explain the trend as due to changes in meteorology,and particularly in transport patterns.We propose a possible linkage of the ozone increases to meridional transport pattern shifts driven by poleward expansion of the SH Hadley circulation(SHHC).The SHHC poleward expansion allows more downward transport of ozone from the stratosphere to the troposphere at higher latitudes,and also enhances tropospheric ozone production through stronger lifting of tropical ozone precursors to the upper troposphere.These together may lead to increasing tropospheric ozone in the extratropical SH,particularly in the middle/upper troposphere and in austral autumn.Poleward expansion of the Hadley circulation is partly driven by greenhouse warming,and the associated increase in tropospheric ozone potentially provides a positive climate feedback amplifying the warming that merits further quantification.展开更多
文摘Ruminant production, especially in the tropics and developing countries suffers a setback when compared with the temperate and developed countries, which is attributable to the kinds of available feed resources in the region of production. In the tropics, ruminants are restricted to grazing on low-quality forages, crop residues and agro-industrial by-products with very little or no concentrate diets, which adversely affect the animals in exhibiting their full production potential. Considering this fact, there is an increasing interest in improving the digestibility of these feed resources. In recent years, researchers have explored several methods to enhance the functions of rumen microflora, improve digestion and fermentation processes, as well as increase bioavailability and utilization of nutrients through feed supplementation. This review aims to explore the positive effects of supplementation of ruminant diets with probiotics or botanical extracts and their metabolites on the productivity of the animals. Moreover, the functions of these non-pathogenic and non-toxic live microorganisms(probiotics) and plant biologically active compounds(botanical extract)are explored because of the ban on non-therapeutic use of antibiotics as growth promoters coupled with the critical preference of consumers to high quality and safe animal products. It has been reported that these alternative supplemental products have a beneficial impact on both animal health and productivity, which is affecting stabilization of rumen environment, inhibition of pathogenic bacteria proliferation in gastrointestinal tract, modulation of immune response, increase in fibre degradation and fermentation, nutrients availability and utilization, animal growth performance and milk production, among others. However,long-term in vivo studies are still required to determine the synergetic effects of these 2 safe supplemental products.
文摘Leaf litter decomposition of liaotong oak (Quercus liaotungensis Koize) under temperate, subtropical and tropical forests was examined using a litter bag technique. Decomposition rates and release dynamics of nutrients Ca, Cu, Fe, K, Mg, Mn and P were observed separately at all three sites for I to 2 a periods. The leaf litter mass loss of liaotong oak was simulated with Olson's exponential model. Significant differences of leaf litter mass loss were found in forests of all three climate zones. Litter decomposition was accelerated with the increase of both annual mean precipitation and temperature. Our results agreed with other studies demonstrating that litter decomposition processes were greatly affected not only by soil organisms (including soil fauna and microorganisms), but also by chemical factors. These chemical factors were important for controlling the release of nutrients, especially elements of Fe and Mn. We also found that Fe and Mn content increased in semi-decayed leaf litter as litter mass decreased. This result was presumably due to chelating process which accumulated soil Fe and Mn ions into the decomposing litter. In conclusion, our study allowed us to determine the classification of the characteristics of different nutrient release patterns.
基金the National Natural Science Foundation of China ! 49605065"National Key Programme for Developing Basic Sciences"! G19980409
文摘The summer of 1998 was characterised by a severe flood in East Asia. The possible linkages were examined among the anomalies in the tropics that may be associated with the severe flood. The anomalies of 1998 are obtained by removing the climatology, which is the average of the ECMWF (European Centre for Medium Range Weather Forecasts) Re—Analysis (ERA) data over 15 years from 1979 to 1993, from the corresponding fields of 1998, which are obtained from the ECMWF operational analyses. In comparison to the results of Nitta (1990), it was found that there are considerable similarities in the atmospheric circulation anomalies between the summers of 1998 and 1988, in the tropics as well as in middle—high latitudes. It was shown that the atmospheric convection is slightly suppressed over the tropical western Pacific. In general, the suppressed convection corresponds to a negative anomaly of SST in the warm pool region. In the summers of 1998 and 1988, however, there are positive anomalies of SSTs in the tropical western Pacific, corresponding to the suppressed convection over there. This slightly suppressed convection may not provide a viable forcing mechanism for the severe flood in East Asia. It was postulated that the zonal wind anomalies in the tropics, in addition to the atmospheric convection over the tropical western Pacific, influence the position and intensity of the North Pacific subtropical high. In both summers of 1998 and 1988, while the stronger convection occurs over the warmer tropical Indian Ocean, the suppressed convection corresponds to the positive anomalies of SSTs in the tropical western Pacific. A possible explanation was given for the broken relationship between SSTs and OLR, (Outgoing Longwave Radiation) by analyzing the large—scale atmospheric circulation anomalies in the tropics. The heat fluxes at the surface in the warm pool of the tropical western Pacific and tropical Indian Ocean were also examined by using the ERA–15 data. To avoid the inconsistency between the ERA–15 and the op
文摘木麻黄(Casuarina equisetifolia)人工林是我国东南沿海最重要的防护林类型,但近年来出现明显的衰退现象.以广东省电白县沿海4种林龄(3、6、13、18年生)木麻黄人工林为研究对象,比较不同林龄木麻黄人工林系统养分利用特征.研究表明,木麻黄不同器官含碳量差别不大,枝与干含碳量(448-462 g kg-1)略高于叶与枯落叶含碳量(416-430g kg-1),细根含碳量最低(320-391 g kg-1),除细根外,不同器官含碳量也不随林龄的增加而变化.木麻黄细根生物量与沙地土壤有机碳积累没有统计上的相关性.木麻黄含氮水平(9.9-11.9 g kg-1)与本地区其它植物叶片含氮量相当,其生理活性最高的叶片与细根含氮量最高,两者具有相似的动态特征,生长旺盛的6年林含氮量最低.木麻黄叶片含磷量最高(0.66-0.89 g kg-1),其次是细根,枝干含磷量最低.木麻黄不同器官含磷量在旺盛生长期(6年)和衰老期(18年)最低.4个林龄土壤中,3年林土壤含磷量远高于其它林地,3年林较高的土壤磷导致了较高的土壤有机碳和氮含量,但所有林地土壤碳、氮含量总体水平极低,约为同地带正常土壤碳氮含量的1/10.土壤含氮量与植物叶片及细根含氮量有一定的相关性,但土壤磷与植物磷没有统计上的相关性.木麻黄不同器官碳氮比及碳磷比基本不随林龄而变化,只有叶片有激烈的动态特征,6年林叶片处于最高值.木麻黄对衰老叶中氮转移效率不高,约为18%-30%,磷转移率在43%-58%,木麻黄的氮磷转移率与土壤或体内养分水平没有统计上的相关性.因而,当地木麻黄氮磷养分水平低,幼龄快速生长阶段受氮磷养分限制,较老阶段受磷养分限制,沙地土壤养分水平极低,土壤碳汇功能差.
基金supported by the National Natural Science Foundation of China(41475112,41375072,and 41530423)the National Key Research and Development Program of China(2017YFC0210102)+1 种基金supported by the Chinese Scholarship Councilsupport from the Atmospheric Chemistry Program of the US National Science Foundation
文摘Increases in free tropospheric ozone over the past two decades are mainly in the Northern Hemisphere that have been widely documented,while ozone trends in the Southern Hemisphere(SH)remain largely unexplained.Here we first show that in-situ and satellite observations document increases of tropospheric ozone in the SH over 1990–2015.We then use a global chemical transport model to diagnose drivers of these trends.We find that increases of anthropogenic emissions(including methane)are not the most significant contributors.Instead,we explain the trend as due to changes in meteorology,and particularly in transport patterns.We propose a possible linkage of the ozone increases to meridional transport pattern shifts driven by poleward expansion of the SH Hadley circulation(SHHC).The SHHC poleward expansion allows more downward transport of ozone from the stratosphere to the troposphere at higher latitudes,and also enhances tropospheric ozone production through stronger lifting of tropical ozone precursors to the upper troposphere.These together may lead to increasing tropospheric ozone in the extratropical SH,particularly in the middle/upper troposphere and in austral autumn.Poleward expansion of the Hadley circulation is partly driven by greenhouse warming,and the associated increase in tropospheric ozone potentially provides a positive climate feedback amplifying the warming that merits further quantification.
