This paper presents the effects of alternative nitrogen management regimes on production of Eucalyptus in tropics and sub-tropics carried out in autumn,2011.The aim of the study was to review alternative nitrogen mana...This paper presents the effects of alternative nitrogen management regimes on production of Eucalyptus in tropics and sub-tropics carried out in autumn,2011.The aim of the study was to review alternative nitrogen management regimes that could enhance the positive effects and reduce negative effects of different Eucalyptus species in the perspective of smallholders.Literature review was used to survey the alternative nitrogen management regimes on eucalyptus trees.There was a significant improvement(P≤0.01)in mean annual increment(MAI)as measured at seven years of Eucalyptus tereticornis in the plots planted with only legume,pueraria and stylosanthes,compared to that of the control on altitude 150 m and rainfall of 2,000 mm at the age of seven years,The MAI of Eucalyptus urophylla and Eucalyptus camaldulensis in plots planted with beans and rice shows a significant improvement(P≤0.05)over the control treatment.Only the plots treated with nitrogen fertilizer 550 kg/ha showed significant improvement(P≤0.05)in terms of MAI of Eucalyptus nitens,compared to the control treatment.In general,it can be concluded that as these alternative management regimes enhance productivity of Eucalyptus woodlots,the challenge for the small-scale farmers is on how to manage them sustainably.Therefore,forest policies that take consideration of increasing production of Eucalyptus and managing biodiversity with reference to these alternative management regimes should be developed in tropics and sub-tropics.展开更多
The splitting of the Northern Hemisphere sub-tropical high (SH) during spring to summer and its possible mechanisms has been analyzed. Results indicate that the splitting of SH occurs over the Bay of Bengal to the Ind...The splitting of the Northern Hemisphere sub-tropical high (SH) during spring to summer and its possible mechanisms has been analyzed. Results indicate that the splitting of SH occurs over the Bay of Bengal to the Indo-China peninsula. However, remarkable contrast exists in the Hadley cell at the lower and upper levels over these sectors during March to May. The land surface sensitive/latent heating both play an important role, and decay the local Hadley cell over the Indo-China peninsula by enhancing the upwelling. In contrast, the dominant land surface sensitive heating over the Bay of Bengal only damages the low-level Hadley cell. Thus, the splitting of SH should occur over the Indo-China peninsula, rather than the Bay of Bengal at lower levels. In addition, the analysis suggests that the faster seasonal snow melting in the east of Indo-China peninsula can enhance the land surface sensitive heating atmosphere and weaken the local Hadley cell, such seasonal change benefits the splitting of the SH.展开更多
Accurate estimates of tree carbon, forest floor carbon and organic carbon in forest soils （SOC） are important in order to determine their contribution to global carbon （C） stocks. However, information about these ...Accurate estimates of tree carbon, forest floor carbon and organic carbon in forest soils （SOC） are important in order to determine their contribution to global carbon （C） stocks. However, information about these carbon stocks is lacking. Some studies have investigated regional and continental scale patterns of carbon stocks in forest ecosystems; however, the changes in C storage in dif- ferent components （vegetation, forest floor and soil） as a function of elevation in forest ecosystems remain poorly understood. In this study, we estimate C stocks of vegetation, forest floor and soils of a Pinus roxburghii Sargent forest in the Garhwal Himalayas along a gradient to quantify changes in carbon stock due to differences in elevation at three sites. The biomass of the vegetation changes drastically with increasing elevation among the three sites. The above-ground biomass （AGB） and below-ground biomass （BGB） were highest at site I （184.46 and 46.386 t·ha^-1 respectively） at an elevation of 1300 m followed by site II （173.99 and 44.057 t·ha^-1 AGB and BGB respectively） at 1400 m and the lowest AGB and BGB were estimated at site III （161.72 and 41.301t·ha^-1） at 1500 m. The trend for SOC stock was similar to that of biomass. Our results suggest that carbon storage （in both soil and biomass） is nega- tively correlated with elevation.展开更多
Soil CO<sub>2</sub> efflux is an ongoing process of respiration from soil;plant parts/ microbes below the ground to the atmosphere which is known for faster cycling of carbon sources. A large portion of ca...Soil CO<sub>2</sub> efflux is an ongoing process of respiration from soil;plant parts/ microbes below the ground to the atmosphere which is known for faster cycling of carbon sources. A large portion of carbon sequestered and fixed by forests is returned to the atmosphere through soil CO<sub>2</sub> efflux and multiple controlling parameters mainly temperature, precipitation, and growth factors interact with the soil CO<sub>2</sub> efflux variation. This study assessed the soil CO<sub>2</sub> efflux every month for consecutive 2-years (August 2015 to July 2017) by using the closed chamber method to determine the role of ecological parameters that govern the soil CO<sub>2</sub> efflux and its temporal modification in a sub-tropical mixed forest of central region in Nepal. The results of this study manifested that soil CO<sub>2</sub> efflux accounted 63.2% (y = 31.96e<sup>0.128x</sup>), 71.3% (y = 44.77e<sup>0.123x</sup>) and 64.5% (y = 44.11e<sup>0.117x</sup>) variations in soil temperature with significantly (p < 0.05) exponential positive relation in the year 2015/2016, 2016/2017 and the two years when merged. And the temperature sensitivity value (Q<sub>10</sub>) of the soil CO<sub>2</sub> efflux was 3.6, 3.4, and 3.2, respectively. Soil water content also expressed significantly (p < 0.05) positive exponential effect on soil CO<sub>2</sub> efflux and accounted 62.0% (y = 138.3e<sup>0.057x</sup>), 46.1% (y = 88.42e<sup>0.052x</sup>) and 40.5% (y = 133.1e<sup>0.0447x</sup>) in its variability in different years and the merged years. Evident variations of soil CO<sub>2</sub> efflux, soil temperature, soil water content, and litter were observed in the forest seasonally and inter-annually. Two years mean total annual soil CO<sub>2</sub> efflux of the forest was estimated at 904.76 g C·m<sup>-2</sup>·y<sup>-1</sup>. The study revealed that sub-tropical forests could be more influenced by precipitation regimes in progressing warm climates i.e. vulnerable to climate change, illustrating the comprehensive dynamics of the representative forest carbon cycle in the tropical region.展开更多
In this study, we investigated the specific gravity of wood samples collected from a total of 31 woody spe- cies, consisting of 20 trees, 10 shrubs and one species of bamboo from sub-tropical regions of Garhwal Himala...In this study, we investigated the specific gravity of wood samples collected from a total of 31 woody spe- cies, consisting of 20 trees, 10 shrubs and one species of bamboo from sub-tropical regions of Garhwal Himalayas, In- dia. Results show that among these woody species, the specific gravity of trees ranged from 0.34 for Erythrina suberosa to 0.83 for Albizia procera. For shrub species the specific gravity of Ricinus communis was 0.39 and that of Dodonaea viscosa 0.93. The average specific gravity of trees was 0.58 and of shrubs 0.66.展开更多
We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level...We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level data (recorded by a pressure-type water level gauge installed in a box culvert) and a discharge rating curve (derived from in situ observations). Water balance calculations for 2010 showed that the rainfall, runoff and evapotranspiration losses (= rainfall – runoff) were 3403.6 mm, 2285.7 mm and 1117.4 mm, respectively. This result was in agreement with previous results from other forested experimental catchments in this region. Direct runoff, as a proportion of event total rainfall, can be expressed by the empirical equation (Qdirect = 0.0048, Pevent 1.7971, R2 = 0.9599). When Pevent was 100 mm or less, the ratios of Qdirect to Pevent were less than 15% in general. When Pevent exceeded 100 mm, the ratios were 20% - 30%.展开更多
The study was conducted at Olericulture Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh during summer season of 2021 to see the performances of yield and yield-related components of twelve he...The study was conducted at Olericulture Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh during summer season of 2021 to see the performances of yield and yield-related components of twelve heat tolerant tomato hybrids. Significant variation was expressed for days to first harvest (101.0 - 108.0 days), while maximum number of fruits per plant was calculated in F<sub>1</sub> 2101 and F<sub>1</sub> 2201 (9.5), followed by F<sub>1</sub> 203, F1 2001, F<sub>1</sub> 2303, F<sub>1</sub> 2401 (9.0). The highest single fruit weight was estimated in F<sub>1</sub> 2501 (195.5 g), followed by F<sub>1</sub> 2101 (119.0 g), F<sub>1</sub> 2201 (113.8 g), while the range was 33.1 - 195.5 g. The range of fruit yield was 7.9 - 38.7 t/ha, while higher-yielding hybrids were viz., F<sub>1</sub> 203 (27.7 t/ha), F<sub>1</sub> 2101 (35.5 t/ha), F<sub>1</sub> 2201 (33.9 t/ha) and F<sub>1</sub> 2501 (28.7 t/ha). Maximum TSS was produced by F<sub>1 </sub>2501 (5.9%), followed by BARI Hybrid Tomato-8 (5.1%), F<sub>1</sub> 1101, F<sub>1</sub> 1903 (5.0%), with a range of 4.0% - 5.9%, while TYLCV infection and leaf sucking pest infestation varied from 0.0% - 10.0% and 3.3% - 16.7%, respectively. Thus, based on the performances of different yield and yield contributing traits, the hybrids, viz., F<sub>1</sub> 2101, F<sub>1 </sub>2201, F<sub>1 </sub>2501 may be selected to develop heat tolerant tomato hybrid varieties for the farmers of sub-tropical regions.展开更多
Here we use harmonic analyses to examine seasonal variations of China land rainfall, low-level winds, and atmospheric heating over East Asia during spring to summer and the associated subtropical summer monsoon activi...Here we use harmonic analyses to examine seasonal variations of China land rainfall, low-level winds, and atmospheric heating over East Asia during spring to summer and the associated subtropical summer monsoon activities. Our results indicate that the South China spring rainfall (SCSR) in March is the prophase of East Asian sub-tropical summer monsoon (EASSM), and the onset of EASSM and China summer rainy season starts in early April, characterized by the enhanced rainfall in South China and the seasonal reverse of zonal land-sea thermal contrast in sub-tropical East Asia. The EASSM onset is earlier than that of South China Sea summer monsoon, and it is active in east of 100?E and north of 20?N. Our analyses suggest that the subsequent heating appears over India-China Peninsula in March and South China in April and causes the low-level atmospheric warming and the zonal land-sea thermal contrast seasonal reverse in East Asian subtropics. The atmospheric heating over South China is the main force to drive the southwesterly winds, updrafts and strengthen the summer precipitation in South China.展开更多
文摘This paper presents the effects of alternative nitrogen management regimes on production of Eucalyptus in tropics and sub-tropics carried out in autumn,2011.The aim of the study was to review alternative nitrogen management regimes that could enhance the positive effects and reduce negative effects of different Eucalyptus species in the perspective of smallholders.Literature review was used to survey the alternative nitrogen management regimes on eucalyptus trees.There was a significant improvement(P≤0.01)in mean annual increment(MAI)as measured at seven years of Eucalyptus tereticornis in the plots planted with only legume,pueraria and stylosanthes,compared to that of the control on altitude 150 m and rainfall of 2,000 mm at the age of seven years,The MAI of Eucalyptus urophylla and Eucalyptus camaldulensis in plots planted with beans and rice shows a significant improvement(P≤0.05)over the control treatment.Only the plots treated with nitrogen fertilizer 550 kg/ha showed significant improvement(P≤0.05)in terms of MAI of Eucalyptus nitens,compared to the control treatment.In general,it can be concluded that as these alternative management regimes enhance productivity of Eucalyptus woodlots,the challenge for the small-scale farmers is on how to manage them sustainably.Therefore,forest policies that take consideration of increasing production of Eucalyptus and managing biodiversity with reference to these alternative management regimes should be developed in tropics and sub-tropics.
基金Project "863" (2002AA135360) Key Project from the National Natural Science Foundation ofChina (40135020)+2 种基金 National Natural Science Foundation of China (40375014) Funding Program for OutstandingYoung Teachers from the Ministry of Education Open Project from LASG of the Institute of AtmosphericPhysics of the Chinese Academy of Sciences
文摘The splitting of the Northern Hemisphere sub-tropical high (SH) during spring to summer and its possible mechanisms has been analyzed. Results indicate that the splitting of SH occurs over the Bay of Bengal to the Indo-China peninsula. However, remarkable contrast exists in the Hadley cell at the lower and upper levels over these sectors during March to May. The land surface sensitive/latent heating both play an important role, and decay the local Hadley cell over the Indo-China peninsula by enhancing the upwelling. In contrast, the dominant land surface sensitive heating over the Bay of Bengal only damages the low-level Hadley cell. Thus, the splitting of SH should occur over the Indo-China peninsula, rather than the Bay of Bengal at lower levels. In addition, the analysis suggests that the faster seasonal snow melting in the east of Indo-China peninsula can enhance the land surface sensitive heating atmosphere and weaken the local Hadley cell, such seasonal change benefits the splitting of the SH.
文摘Accurate estimates of tree carbon, forest floor carbon and organic carbon in forest soils （SOC） are important in order to determine their contribution to global carbon （C） stocks. However, information about these carbon stocks is lacking. Some studies have investigated regional and continental scale patterns of carbon stocks in forest ecosystems; however, the changes in C storage in dif- ferent components （vegetation, forest floor and soil） as a function of elevation in forest ecosystems remain poorly understood. In this study, we estimate C stocks of vegetation, forest floor and soils of a Pinus roxburghii Sargent forest in the Garhwal Himalayas along a gradient to quantify changes in carbon stock due to differences in elevation at three sites. The biomass of the vegetation changes drastically with increasing elevation among the three sites. The above-ground biomass （AGB） and below-ground biomass （BGB） were highest at site I （184.46 and 46.386 t·ha^-1 respectively） at an elevation of 1300 m followed by site II （173.99 and 44.057 t·ha^-1 AGB and BGB respectively） at 1400 m and the lowest AGB and BGB were estimated at site III （161.72 and 41.301t·ha^-1） at 1500 m. The trend for SOC stock was similar to that of biomass. Our results suggest that carbon storage （in both soil and biomass） is nega- tively correlated with elevation.
文摘Soil CO<sub>2</sub> efflux is an ongoing process of respiration from soil;plant parts/ microbes below the ground to the atmosphere which is known for faster cycling of carbon sources. A large portion of carbon sequestered and fixed by forests is returned to the atmosphere through soil CO<sub>2</sub> efflux and multiple controlling parameters mainly temperature, precipitation, and growth factors interact with the soil CO<sub>2</sub> efflux variation. This study assessed the soil CO<sub>2</sub> efflux every month for consecutive 2-years (August 2015 to July 2017) by using the closed chamber method to determine the role of ecological parameters that govern the soil CO<sub>2</sub> efflux and its temporal modification in a sub-tropical mixed forest of central region in Nepal. The results of this study manifested that soil CO<sub>2</sub> efflux accounted 63.2% (y = 31.96e<sup>0.128x</sup>), 71.3% (y = 44.77e<sup>0.123x</sup>) and 64.5% (y = 44.11e<sup>0.117x</sup>) variations in soil temperature with significantly (p < 0.05) exponential positive relation in the year 2015/2016, 2016/2017 and the two years when merged. And the temperature sensitivity value (Q<sub>10</sub>) of the soil CO<sub>2</sub> efflux was 3.6, 3.4, and 3.2, respectively. Soil water content also expressed significantly (p < 0.05) positive exponential effect on soil CO<sub>2</sub> efflux and accounted 62.0% (y = 138.3e<sup>0.057x</sup>), 46.1% (y = 88.42e<sup>0.052x</sup>) and 40.5% (y = 133.1e<sup>0.0447x</sup>) in its variability in different years and the merged years. Evident variations of soil CO<sub>2</sub> efflux, soil temperature, soil water content, and litter were observed in the forest seasonally and inter-annually. Two years mean total annual soil CO<sub>2</sub> efflux of the forest was estimated at 904.76 g C·m<sup>-2</sup>·y<sup>-1</sup>. The study revealed that sub-tropical forests could be more influenced by precipitation regimes in progressing warm climates i.e. vulnerable to climate change, illustrating the comprehensive dynamics of the representative forest carbon cycle in the tropical region.
文摘In this study, we investigated the specific gravity of wood samples collected from a total of 31 woody spe- cies, consisting of 20 trees, 10 shrubs and one species of bamboo from sub-tropical regions of Garhwal Himalayas, In- dia. Results show that among these woody species, the specific gravity of trees ranged from 0.34 for Erythrina suberosa to 0.83 for Albizia procera. For shrub species the specific gravity of Ricinus communis was 0.39 and that of Dodonaea viscosa 0.93. The average specific gravity of trees was 0.58 and of shrubs 0.66.
文摘We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level data (recorded by a pressure-type water level gauge installed in a box culvert) and a discharge rating curve (derived from in situ observations). Water balance calculations for 2010 showed that the rainfall, runoff and evapotranspiration losses (= rainfall – runoff) were 3403.6 mm, 2285.7 mm and 1117.4 mm, respectively. This result was in agreement with previous results from other forested experimental catchments in this region. Direct runoff, as a proportion of event total rainfall, can be expressed by the empirical equation (Qdirect = 0.0048, Pevent 1.7971, R2 = 0.9599). When Pevent was 100 mm or less, the ratios of Qdirect to Pevent were less than 15% in general. When Pevent exceeded 100 mm, the ratios were 20% - 30%.
文摘The study was conducted at Olericulture Division, Bangladesh Agricultural Research Institute, Gazipur, Bangladesh during summer season of 2021 to see the performances of yield and yield-related components of twelve heat tolerant tomato hybrids. Significant variation was expressed for days to first harvest (101.0 - 108.0 days), while maximum number of fruits per plant was calculated in F<sub>1</sub> 2101 and F<sub>1</sub> 2201 (9.5), followed by F<sub>1</sub> 203, F1 2001, F<sub>1</sub> 2303, F<sub>1</sub> 2401 (9.0). The highest single fruit weight was estimated in F<sub>1</sub> 2501 (195.5 g), followed by F<sub>1</sub> 2101 (119.0 g), F<sub>1</sub> 2201 (113.8 g), while the range was 33.1 - 195.5 g. The range of fruit yield was 7.9 - 38.7 t/ha, while higher-yielding hybrids were viz., F<sub>1</sub> 203 (27.7 t/ha), F<sub>1</sub> 2101 (35.5 t/ha), F<sub>1</sub> 2201 (33.9 t/ha) and F<sub>1</sub> 2501 (28.7 t/ha). Maximum TSS was produced by F<sub>1 </sub>2501 (5.9%), followed by BARI Hybrid Tomato-8 (5.1%), F<sub>1</sub> 1101, F<sub>1</sub> 1903 (5.0%), with a range of 4.0% - 5.9%, while TYLCV infection and leaf sucking pest infestation varied from 0.0% - 10.0% and 3.3% - 16.7%, respectively. Thus, based on the performances of different yield and yield contributing traits, the hybrids, viz., F<sub>1</sub> 2101, F<sub>1 </sub>2201, F<sub>1 </sub>2501 may be selected to develop heat tolerant tomato hybrid varieties for the farmers of sub-tropical regions.
基金supported by the National Natural Science Foundation of China (Grant Nos. 40921003 and 90711003)the Program of the Chinese Academy of Meteorological Sciences (Grant Nos. 2010Z003 and GYHY 200706005)
文摘Here we use harmonic analyses to examine seasonal variations of China land rainfall, low-level winds, and atmospheric heating over East Asia during spring to summer and the associated subtropical summer monsoon activities. Our results indicate that the South China spring rainfall (SCSR) in March is the prophase of East Asian sub-tropical summer monsoon (EASSM), and the onset of EASSM and China summer rainy season starts in early April, characterized by the enhanced rainfall in South China and the seasonal reverse of zonal land-sea thermal contrast in sub-tropical East Asia. The EASSM onset is earlier than that of South China Sea summer monsoon, and it is active in east of 100?E and north of 20?N. Our analyses suggest that the subsequent heating appears over India-China Peninsula in March and South China in April and causes the low-level atmospheric warming and the zonal land-sea thermal contrast seasonal reverse in East Asian subtropics. The atmospheric heating over South China is the main force to drive the southwesterly winds, updrafts and strengthen the summer precipitation in South China.
