福建省粮食作物气候-土壤生产力及人口承载量的研究

文章采用改进的农业生态区域法 ,计算全省 2 9个代表站水稻、小麦、甘薯 3种作物光温、气候及气候 -土壤生产力 ;将福建分成 6个农业自然区进行分析 ;根据对未来 2 0 1 0年及 2 0 5 0年人口、耕地的动态预测 ,计算各农业区农田的人口承载力。分析结果表明 :福建省目前、2 0 1 0年、2 0 5 0年人口分别为 32 6 1×1 0 4人、370 8× 1 0 4人、4 1 6 8× 1 0 4人 ,人均占有粮食分别为 31 1 2kg·a- 1 、30 9 2kg·a- 1 、32 6 3kg·a- 1 ,不足低消费水平 4 0 0kg·a- 1 ,若增加农业投入 ,未来的粮食能达到理想产量水平。为合理利用当地自然资源 ,明确农业投入方向和协调粮食需求平衡 ,提出对策及建议 :①建设旱涝保收田 ;②合理调整粮食布局 ,挖掘生物学产量潜力 ;③提高土壤肥力 ,促进作物高产 ;④改良品种 ;⑤严格限制非农业用地 ,控制人口增长。

Species-diversified plant cover enhances orchard ecosystem resistance to climatic stress and soil erosion in subtropical hillside

Naturally occurring plants in agroecosystem evidently play an important role in ecosystem stability. Field studies on the ecological effects of native plants conserved in orchard and their resistance to adverse climatic stress, and soil erosion were conducted from 1998 to 2001 in a newly developed Changshan-huyou (Citrus changshan-huyou Y.B. Chang) orchard. The experimental area covered 150 ha in typical red soil hilly region in southeastern China. The experimental design was a randomized complete block with six combinations of twelve plant species with four replications. All species used were native in the orchard. Plots were 15×8m^2 and separated by 2m buffer strips. Precipitation, soil erosion in rainstorm days and aboveground biomass of plant community when rainstorm days ended, soil temperature and moisture under various plant covers during seasonal megathermal drought period, antiscourability of soil with different root density under various simulated rainfalls were measured. Plant cover significantly decreased the daily highest and mean soil temperature and its daily variation in hot-drought season, but there was no significant difference of the alleviation among various plant covers. Plant covers significantly increased the soil moisture in seasonal megathermal drought period. Better moisture maintenance and soil erosion reduction was found when the plant species numbers in cover plant communities increased from one to eight. Higher root density in plant communities with higher species richness increased significantly the antiscourability of the soil. It was suggested that conserving plant communities with diversified native species could produce the best positive ecological effects on citrus orchard ecosystem stability.

Research Advance on Sod Culture in Peach Orchard

Sod culture in peach orchards is an advanced soil management. The significances of sod culture in peach orchard are introduced, as well as the sod ways. The effects of sod culture in a peach orchard on soil, microclimate and growth and development of peach tree, and disease, pest and weed are reviewed. The problems in sod culture in peach orchard in China are summarized. Sod culture could increase soil fertility, improve soil physical properties, relieve soil temperature change, increase soil microbial growth and soil enzyme activity, improve microclimate and fruit quality, reduce physiological disease, insect pests and weeds.

Obsevation for Epidermal Ultrastructure of Nostoc sphaeroides Kutzing under Scanning Electron Microscope

[Objective]The experiment aimed to explore a new way for observing surface structure of Nostoc sphaeroides Kutzing. [Method] The scanning electron microscope was used to observe the epidermal ultrastructure of wild and cultured Nostoc sphaeroides Kutzing. [ Result] The epidermis of wild and cultured Nostoc sphaeroides Kutzing showed mixture structure of fibril colloid which was reticular arranged. The difference between wild and cultured Nostoc sphaeroides Kutzing was that the outer epidermis of cultured Nostoc sphaeroides Kutzing had trichome distribution but the wild Nostoc sphaeroides Kutzing did not has such distribution. The obsevation results of under smaller than 10 μm by scanning electron microscope was touched thick and showed many folds and distortions. [ Conclusion] The scanning electron microscope was an effective way to study development of Nostoc sphaeroides Kutzing colony and it was worth popularizing.

Effects of Forest Gaps on Some Microclimate Variables in Castanopsis kawakamii Natural Forest

The objective of this study was to understand the effects of forest gap and variations in different seasons, gap size, locations and diurnal variations on forest microclimate and soil water content. Spatial and temporal distribution features oi air temperature （TA）, soil temperature （Ts）, relative humidity （h） and soil water content （ψ） were measured in Castanopsis kawakamii natural forest gaps created by a severe typhoon or fallen dead trees. The results showed that： （1） the variations of TA, h, and Tsin four seasons were extremely significant. The variations of ψ in four seasons were extremely significant except for those between spring and summer. （a） The diurnal variations of TA and Tswere expressed with a single peak curve. The diurnal variations of h and ψ presented a high-low-high trend （3） The variations of TA, h, and Ts were extremely significant among the large, medium and small gaps in C. kawakamii natural forest. Medium gaps had the highest TA and the lowest h while small gaps were jusl contrary to medium gaps. The variations of T were extremely significant for large, medium and small gaps except those between the medium and large gaps （4） The TA, h, Ts and ψ were decreased from the gap center, canopy gap, expanded gap to understory. These results will help further our understanding of the abiotic and consequent biotic responses to gaps in the mid-subtropical broadleaved forests, which also provide a theoretical basis for the scientific management and population restoration of C. kawakamii natural forest.

Carbon Turnover in a Crop Rotation Under Free Air CO_2 Enrichment (FACE)

Mostly based on assumptions derived from controlled-environment studies, predicted future atmospheric CO2 concentrations [CO2] are expected to have considerable impacts on carbon （C） turnover in agro-ecosystems. In order to allow the in situ examination of C-transformations in the plant-soil system of arable crop rotations under future [002], a free air carbon dioxide enrichment （FACE） experiment （550 μmol mol^-1 CO2） was started at Braunschweig, Germany in 1999. The crop rotation under investigation comprised winter barley, a cover crop （ryegrass）, sugar beets and winter wheat. Assessments of CO2 effects included the determination of above- and belowground biomass production, measurements of canopy CO2- and H2O- fluxes, soil microbial biomass and in situ soil respiration. The results obtained during the 1st crop rotation cycle （3 years） showed that for the selected crops elevated [CO2] entailed significant positive effects （P 〈 0.05） on aboveground （6%-14% stimulation） and belowground biomass production （up to 90% stimulation）, while canopy evapotranspiration was reduced. This resulted in increased soil water content. Also, depending on crop type and season, high CO2 stimulated in situ soil respiration （up to 30%）, while soil microbial biomass did not show significant respouses to elevated [CO2] during the first rotation cycle.

Trends in carbon sink along the Belt and Road in the future under high emission scenario

Over the past three decades,the drawdown of atmospheric CO_(2) in vegetation and soil has fueled net ecosystem production(NEP).Here,a global land-surface model(CABLE)is used to estimate the trend in NEP and its response to atmospheric CO_(2),climate change,biological nitrogen(N)fixation,and N deposition under future conditions from 2031 to 2100 in the Belt and Road region.The trend of NEP simulated by CABLE decreases from 0.015 Pg carbon(C)yr^(-2) under present conditions(1936–2005)to−0.023 Pg C yr^(-2) under future conditions.In contrast,the trend in NEP of the CMIP6 ensemble changes from 0.014 Pg C yr^(-2) under present conditions to−0.009 Pg C yr^(-2) under future conditions.This suggests that the trend in the C sink for the Belt and Road region will likely decline in the future.The significant difference in the NEP trend between present and future conditions is mainly caused by the difference in the impact of climate change on NEP.Considering the responses of soil respiration(RH)or net primary production(NPP)to surface air temperature,the trend in surface air temperature changes from 0.01℃ yr^(-1) under present conditions to 0.05℃ yr^(-1) under future conditions.CABLE simulates a greater response of RH to surface temperature than that of NPP under future conditions,which causes a decreasing trend in NEP.In addition,the greater decreasing trend in NEP under future conditions indicates that the C-climate-N interaction at the regional scale should be considered.It is important to estimate the direction and magnitude of C sinks under the C neutrality target.

Changes of Soil Erosion and Possible Impacts from Ecosystem Recovery in the Three-River Headwaters Region, Qinghai, China from 2000 to 2015

Soil erosion poses a great threat to the sustainability of the ecological environment and the harmonious development of human well-being.The revised universal soil loss equation(RUSLE)was used to quantify soil erosion in the Three-River Headwaters region(TRH),Qinghai,China from 2000 to 2015.The possible effects of an ecosystem restoration project on soil erosion were explored against the background of climatic changes in the study area.The model was validated with on-ground observations and showed a satisfactory performance,with a multiple correlation coefficient of 0.62 from the linear regression between the estimations and observations.The soil erosion modulus in 2010–2015 increased 6.2%,but decreased 1.2%compared with those in the periods of 2000–2005 and 2005–2010,respectively.Based on the method of overlay analysis,the interannual change of the estimated soil erosion was dominated by climate(about 64%),specifically by precipitation,rather than by vegetation coverage(about 34%).Despite some uncertainties in the model and data,this study quantified the relative contribution of ecological restoration under global climatic change;meanwhile the complexity,labor-intensiveness and long-range character of ecological restoration projects have to be recognized.On-ground observations over the long-term,further parameterization,and data inputs with higher quality are necessary and essential for decreasing the uncertainties in the estimations.

Effects of warming on soil respiration during the non-growing seasons in a semiarid temperate steppe

Aims The response pattern of terrestrial soil respiration to warming during non-growing seasons is a poorly understood phenomenon,though many believe that these warming effects are potentially significant.This study was conducted in a semiarid temperate steppe to examine the effects of warming during the non-growing seasons on soil respiration and the underlying mechanisms associated therewith.Methods This experiment was conducted in a semiarid temperate grassland and included 10 paired control and experimental plots.Experimental warming was achieved with open top chambers(OTCs)in October 2014.Soil respiration,soil temperature and soil moisture were measured several times monthly from November 2014 to April 2015 and from November 2015 to April 2016.Microbial biomass carbon(MBC),microbial biomass nitrogen(MBN)and available nitrogen content of soil were measured from 0 to 20 cm soil depth.Repeated measurement ANOVAs and paired-sample t tests were conducted to document the effect of warming,and the interactions between warming and time on the above variables.Simple regressions were employed to detect the underlying causality for the observed effects.Important Findings Soil respiration rate was 0.24μmol m^(−2) s^(−1) in the control plots during the non-growing seasons,which was roughly 14.4%of total soil carbon flux observed during growing seasons.Across the two non-growing seasons,warming treatment significantly increased soil temperature and soil respiration by 1.48℃(P<0.001)and 42.1%(P<0.01),respectively,when compared with control plots.Warming slightly,but did not significantly decrease soil moisture by 0.66%in the non-growing seasons from 2015 to 2016.In the non-growing seasons 2015–16,experimental warming significantly elevated MBC and MBN by 19.72%and 20.99%(both P<0.05),respectively.In addition,soil respiration responses to warming were regulated by changes in soil temperate,MBC and MBN.These findings indicate that changes in non-growing season soil respiration impact other components in the carbon cycle.Additionally,these findings facilitate projections regarding climate change–terrestrial carbon cycling.

Warming-driven migration of core microbiota indicates soil property changes at continental scale

Terrestrial species are predicted to migrate northward under global warming conditions,yet little is known about the direction and magnitude of change in microbial distribution patterns.In this continental-scale study with more than 1600 forest soil samples,we verify the existence of core microbiota and lump them into a manageable number of eco-clusters based on microbial habitat preferences.By projecting the abundance differences of eco-clusters between future and current climatic conditions,we observed the potential warming-driven migration of the core microbiota under warming,partially verified by a field warming experiment at Southwest China.Specifically,the species that favor low p H are potentially expanding and moving northward to medium-latitudes(25°–45°N),potentially implying that warm temperate forest would be under threat of soil acidification with warming.The eco-cluster of high-p H with high-annual mean temperature(AMT)experienced significant abundance increases at middle-(35°–45°N)to high-latitudes(>45°N),especially under Representative Concentration Pathway(RCP)8.5,likely resulting in northward expansion.Furthermore,the eco-cluster that favors low-soil organic carbon(SOC)was projected to increase under warming scenarios at low-latitudes(<25°N),potentially an indicator of SOC storage accumulation in warmer areas.Meanwhile,at high-latitudes(>45°N)the changes in relative abundance of this eco-cluster is inversely related with the temperature variation trends,suggesting microbes-mediated soil organic carbon changes are more responsive to temperature variation in colder areas.These results have vital implications for the migration direction of microbial communities and its potential ecological consequences in future warming scenarios.

Discovery and study of silver sulfate mineral in S_5 from the eastern suburb of Xi'an

The paleosol samples from the fifth layer of the loess profile at Renjiapo in the eastern suburb of Xi'an are observed and analyzed using electron microscope and energy spectrum. Minerals such as AgSO4 and molybdenum, which are rare to find and can indicate typical dry climate environment, are found in this layer of paleosol. Secondary mineral is usually granular form of ellipsoidal and crystallization, and has the characteristics of chemical precipitating crystallization of apertures and fracture. Molybdenum minerals have the characteristics of colloidal substances. There are two kinds of secondary minerals. One is silver sulfate mineral and the other is silver oxide mineral. The movement of secondary silver, molybdenum and cobalt minerals, new clay mineral, Fe2O3 and Al2O3 indicates that S5 has experienced strong chemical weathering and mineral dissolution during its development. Silver, molybdenum, and cobalt can be released from primary minerals. During that period, the precipitation was abundant in Xi'an where soil reached an acidity stage of chemical weathering. At the later development stage of paleosol in the lowest part of S5, warm and wet monsoon climate had changed to dry and non-monsoon climate. In the period of the formation of AgSO4, which is easier to dissolve than CaSO4, a dry and non-monsoon climate was present in the Guanzhong Plain. Strong evaporation resulted in the accumulation of SO42-in the soil water solution and the formation of AgSO4. At that time, summer monsoon of East Asia was weak and did not cross Qinling Mountains to reach Guanzhong Plain. And at that time, the precipitation in Xi'an was less than 300 mm, and it was drier then in Xi'an than at present in Lanzhou.

Soil Microbiological Activity and Carbon Dynamics in the Current Climate Change Scenarios:A Review

Microbial activities are affected by a myriad of factors with end points involved in nutrient cycling and carbon sequestration issues.Because of their prominent role in the global carbon balance and their possible role in carbon sequestration, soil microbes are very important organisms in relation to global climate changes. This review focuses mainly on the responses of soil microbes to climate changes and subsequent effects on soil carbon dynamics. An overview table regarding extracellular enzyme activities(EAA) with all relevant literature data summarizes the effects of different ecosystems under various experimental treatments on EAA. Increasing temperature, altered soil moisture regimes, and elevated carbon dioxide significantly affect directly or indirectly soil microbial activities.High temperature regimes can increase the microbial activities which can provide positive feedback to climate change, whereas lower moisture condition in pedosystem can negate the increase, although the interactive effects still remain unanswered. Shifts in soil microbial community in response to climate change have been determined by gene probing, phospholipid fatty acid analysis(PLFA),terminal restriction length polymorphism(TRFLP), and denaturing gradient gel electrophoresis(DGGE), but in a recent investigations,omic technological interventions have enabled determination of the shift in soil microbe community at a taxa level, which can provide very important inputs for modeling C sequestration process. The intricacy and diversity of the soil microbial population and how it responds to climate change are big challenges, but new molecular and stable isotope probing tools are being developed for linking fluctuations in microbial diversity to ecosystem function.

Soil Carbon Dynamics Under Changing Climate A Research Transition from Absolute to Relative Roles of Inorganic Nitrogen Pools and Associated Microbial Processes:A Review

It is globally accepted that soil carbon （C） dynamics are at the core of interlinked environmental problems, deteriorating soil quality and changing climate. Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen （N） availability and moisture-temperature interactions. This article reviews the management aspects of soil C dynamics in light of recent advances, particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate. Globally, drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability, resulting in a higher decomposition rate and a considerable decline in soil organic C （SOC） levels due to increased soil CO2 emissions, degraded soil quality, and increased atmospheric CO2 concentrations, leading to climate warming. Predicted climate warming is proposed to enhance SOC decomposition, which may further increase soil N availability, leading to higher soil CO2 effiux. However, a literature survey revealed that soil may also act as a potential C sink, if we could manage soil inorganic N pools and link microbial processes properly. Studies also indicated that the relative, rather than the absolute, availability of inorganic N pools might be of key importance under changing climate, as these N pools are variably affected by moisture-temperature interactions, and they have variable impacts on SOC turnover. Therefore, multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.