杨凌大棚土壤微生物区系变化研究

为了研究杨凌地区大棚土壤微生物区系的变化规律,以当地0～11年的大棚土壤为研究材料,采用微生物培养的方法对大棚土壤微生物区系进行研究,结果显示:大棚土壤细菌、真菌数量随棚龄的延长而明显增加,而大棚土壤中放线茵数量变化规律并不明显;与大田土壤相比,大棚栽培的条件大幅提高了细菌数量,小幅度增加了真菌数量,却大幅降低了放线菌的数量,因此,大棚土壤微生物的总量和种类的多样性主要体现在细菌数量的增长上。土壤微生物是构成土壤肥力的重要因素,微生物做为评价土壤质量的生物学指标之一,对土壤培肥、作物栽培都具有重要的参考价值。土壤微生物主要聚集在表层土壤中,以微生物菌落的形式分布于土壤颗粒和有机质表层及植物根系,作物的根系所处的环境和其微生物的区系特点不仅为微生物提供稳定的土壤生态系,提供植物生存的营养元素,同时局部土壤环境的维持和污染的净化均可以看成是微生物生态的协调结果。大棚土壤由于复种指数高,肥水管理频繁,土壤中微生物的生长发育经常受到土壤的理化性状、土壤温度、土壤有机质含量、湿度、土壤pH值、土壤肥力水平等各因素的干扰,这些因素在很大程度上均会受到大棚耕作栽培措施的影响,影响到土壤微生物的数量,进而影响土传病害的发生程度和土壤肥力状况及作物的生长发育状况。因此本文对杨凌大棚土壤的微生物区系进行了研究,旨在分析大棚土壤微生物区系的分布特点。

根际土壤微生物变化对西洋参种植的影响

以陕西产地不同年限西洋参根际土壤微生物(包括解钾、解磷及自生固氮菌)为研究对象,通过对根际土壤微生物进行分离、培养、计数和鉴定,并对比栽参后的玉米轮作根际土壤微生物数量和类群的变化特征,研究了根际土壤微生物的动态变化对西洋参连续种植的影响。结果表明:与轮作根际土壤相比,随西洋参生长期的增加其根际土壤中细菌数量的变化不明显,但优势细菌种类减少;放线菌数量及种类均有不同程度的减少;引起西洋参病害的霉菌类群明显增加;解磷、解钾、自生固氮菌的比例明显失调。此种变化可引起土壤理化性质的改变,进而影响西洋参的连续种植情况。

浅谈影响鸡肠道微生物区系的因素

动物肠道的微生物菌群对动物的生命活动具有重要的作用,肠道菌群通过多种方式定植在动物的消化道内,在体内通过竞争方式获得生存的机会,与宿主建立了合作共赢的关系。但肠道的菌群也受到多种因素的影响而时刻保持着变化,为了保证菌群的稳定性,防止有害菌群获得优势地位,本文就影响菌群区系变化的研究成果进行总结,分析影响菌群变化的因素,提出维持鸡肠道菌群稳定的技术措施。

CO_2气调储粮技术对粮食真菌的抑制效果研究

进行了粮食在不同CO2 气体浓度、不同粮食水分、不同环境温度条件下储藏后的粮食真菌区系变化情况、尤其是在粮食水分较高、储藏温度较高的条件下CO2 对粮食真菌的抑制效果进行了实验室研究和绵阳CO2 气调库粮食真菌的区系变化实仓研究。研究结果表明 ,CO2 气调储粮方法对水分在 15 %以内的各种粮食上着生的粮食真菌于 15～ 35℃的温度范围内在较长时间内具有很好的抑制作用 ,可用于低水分粮的长期储藏 ;6 0 %高浓度的CO2 对水分在 15 %～ 16 %的高水分粮于 15～ 2 5℃温度范围短时间内 (品质较差的粮食 15天、品质较好的粮食 14 0天左右 )有较好的防霉作用 ,但粮食感官品质有所下降 ;35 %以下浓度的CO2 对高水分粮在 15～ 35℃温度范围内均不能较好地抑制粮食真菌的生长 ,粮食储藏一段时间后就发生霉变 ;CO2 不适宜于高水分粮在常温下的长期储藏 ,即使是 6 0 %以上浓度的CO2 也不能很好地抑制高水分粮上着生的引起粮食霉变的储藏性真菌。

How Well does BCC_CSM1.1 Reproduce the 20th Century Climate Change over China?

The historical simulation of phase five of the Coupled Model Intercomparison Project （CMIP5） ex- periments performed by the Beijing Climate Center cli- mate system model （BCC_CSM1.1） is evaluated regard- ing the time evolutions of the global and China mean sur- face air temperature （SAT） and surface climate change over China in recent decades. BCC CSM1.1 has better capability at reproducing the time evolutions of the global and China mean SAT than BCC_CSM1.0. By the year 2005, the BCC_CSM1.1 model simulates a warming am- plitude of approximately I℃ in China over the 1961- 1990 mean, which is consistent with observation. The distributions of the warming trend over China in the four seasons during 1958-2004 are basically reproduced by BCC CSM1.1, with the warmest occurring in winter. Al- though the cooling signal of Southwest China in spring is partly reproduced by BCC_CSM1.1, the cooling trend over central eastern China in summer is omitted by the model. For the precipitation change, BCC_CSM1.1 has good performance in spring, with drought in Southeast China. After removing the linear trend, the interannual correlation map between the model and the observation shows that the model has better capability at reproducing the summer SAT over China and spring precipitation over Southeast China.

Simulating Hydrologic Changes with Climate Change Scenarios in the Haihe River Basin

Climate change scenarios, predicted using the regional climate modeling system of PRECIS (providing regional cli-mates for impacts studies), were used to derive three-layer variable infiltration capacity (VIC-3L) land surface model forthe simulation of hydrologic processes at a spatial resolution of 0.25° × 0.25° in the Haihe River Basin. Three climatescenarios were considered in this study: recent climate (1961-1990), future climate A2 (1991-2100) and future climateB2 (1991-2100) with A2 and B2 being two storylines of future emissions developed with the Intergovernmental Panel onClimate Change (IPCC) special report on emissions scenarios. Overall, under future climate scenarios A2 and B2, theHaihe River Basin would experience warmer climate with increased precipitation, evaporation and runoff production ascompared with recent climate, but would be still likely prone to water shortages in the period of 2031-2070. In addition,under future climate A2 and B2, an increase in runoff during the wet season was noticed, indicating a future rise in theflood occurrence possibility in the Haihe River Basin.

Changes in Agricultural System as Farmers Adapt to Economic-Social and Climatic Changes in the Min Upriver Rural Areas in Western Sichuan,Southwestern China

Rapid economic growth in China has brought about great economic-social changes in rural areas, having considerable impact on the society in economy and environment. With a per capita possession of about 0.08 ha of cropland, Chinese farmers in rural areas adopt various ways in response to these changes in a bit to maintain their livelihood, wherein the agricultural system is facing one more options possible. To understand how rural communities have used different mechanisms to adapt to the economic and natural changes, we joined a survey in dry valleys of the Min upriver area under Maoxian county of western Sichuan province, southwestern China and visited the local people. Changes in the main crop cultivation have shown up an important means to keep up their household income. Farm households start seeking economic growth through diversified cultivating of cereal and economic crops in five lines, namely cereal, apple monoculture, apple and vegetables, plum and vegetables, mixed fruits and vegetables. These new lines mirror farmers' flexibility to cope with today's economic-social and climatic changes. The farming operation has changed all the more from a subsistence on grain to special agricultural products. Economic reforms in the early 1980 s motivated theprogress first in conversion of production from grain to fruits, and the desire to increase family income turned out to be an impetus for the subsequent events. At present, more farmers moving out of the rural areas, uneasy availability of labor force, increased opportunity cost of labors and their wages, increased farm size, and the urgent demand for the agricultural labor force, all these combine into the trend of the agricultural system of China on facing further economic-social reforms and reconstruction of the countryside across China.

Simulating Net Carbon Budget of Forest Ecosystems and Its Response to Climate Change in Northeastern China Using Improved FORCCHN

As dominant biomes,forests play an important and indispensable role in adjusting the global carbon balance under climate change.Therefore,there are scientific and political implications in investigating the carbon budget of forest ecosystems and its response to climate change.Here we synthesized the most recent research progresses on the carbon cycle in terrestrial ecosystems,and applied an individual-based forest ecosystem carbon budget model for China(FORCCHN) to simulate the dynamics of the carbon fluxes of forest ecosystems in the northeastern China.The FORCCHN model was further improved and applied through adding variables and modules of precipitation(rainfall and snowfall) interception by tree crown,understory plants and litter.The results showed that the optimized FORCCHN model had a good performance in simulating the carbon budget of forest ecosystems in the northeastern China.From 1981 to 2002,the forests played a positive role in absorbing carbon dioxide.However,the capability of forest carbon sequestration had been gradually declining during the the same period.As for the average spatial distri-bution of net carbon budget,a majority of the regions were carbon sinks.Several scattered areas in the Heilongjiang Province and the Liaoning Province were identified as carbon sources.The net carbon budget was apparently more sensitive to an increase of air temperature than change of precipitation.

Impacts of Climate Change on Forest Ecosystems in Northeast China

This paper reviews the studies and research on climate change impacts on the forest ecosystems in Northeast China. The results show that in the context of global and regional warming, the growing season of coniferous forests has been increasing at an average rate of 3.9 d per decade. Regional warming favors the growth of temperate broad-leaved forests and has a detrimental effect on the growth of boreal coniferous forests. Over the past hundred years, the forest edge of the cool temperate zone in the southern Daxing＇anling region has retreated 140 km northward. From 1896 to 1986, the northern boundary of broad-leaved forests in Heilongjiang province has extended northwestward about 290 km. Future climatic changes （until 2060） may lead to the northern deciduous needle forests moving out of China＇s territory altogether. The occurrence cycles of pests and diseases have shortened; their distribution ranges have expanded. The life cycle of tent caterpillars （Malacosoma neustria testacea Motschulsky） has shortened from 14-15 years in the past to 8-10 years now. The pine caterpillar （Dendrolimus tabulaeformis Tsai et Liu）, which has spread within western Liaoning province and the nearby areas, can now be found in the north and west. Lightning fires in the Daxing＇anling region have significantly increased since 1987, and August has become the month when lightning fires occur most frequently. Overall, the net primary productivity （NPP） of forest in Northeast China has increased. The NPP in 1981 was around 0.27 Pg C, and increased to approximately 0.40 Pg C in 2002. With the current climate, the broad-leaved Korean pine forest ecosystem acts as a carbon sink, with a carbon sink capacity of 2.7 Mg C hm-2. Although the carbon sink capacity of the forest ecosystems in Northeast China has been weakened since 2003, the total carbon absorption will still increase. The forest ecosystems in Northeast China are likely to remain a significant carbon sink, and will play a positive role in the mitigation of climate change.

Temporal and Spatial Variations of ET 0 and Sensitivity Coefficients in Spring-summer in Eastern Agricultural Areas of Qinghai,China

Reference crop evapotranspiration(ET 0) is a key parameter to calculate crop water requirements.In the paper,ET 0 during 1960-2005 was calculated with FAO-56 PM in eastern agricultural areas of Qinghai,China.Then the sensitivity coefficients of ET 0 to meteorological variables were estimated through the nondimensional partial derivative in FAO-56 PM.Results show that the mean annual ET 0 of the whole area is 904 mm,and ET 0 portrays a very significant decrease during the 46 years.In spatial,ET 0 decreases from southeast to northwest,firstly increases then decreases from southwest to northeast.Through sensitivity analysis,in spring the most sensitive variable is relative humidity,while in summer is temperature.The temperature,sunshine duration and wind speed sensitivity coefficients(S(TA),S(n),S(u)) are higher in middle areas as opposed to surrounding areas,while the relative humidity sensitivity coefficient(S(RH)) has an opposite distribution rule.

Climate Change Impacts on Central China and Adaptation Measures

In Central China, the obvious climate change has happened along with global warming. Based on the observational analysis, the climate change has significant effects, both positive and negative, in every field within the study area, and with the harmful effects far more prevalent. Under the A1B scenario, it is reported that temperature, precipitation, days of heat waves, and extreme precipitation intensity will increase at respective rates of 0.38℃ per decade, 12.6 mm per decade, 6.4 d and 47 mm per decade in the 21st century. It is widely believed that these climate changes in the future will result in some apparent impacts on agro-ecosystems, water resources, wetland ecosystem, forest ecosystem, human health, energy sectors and other sensitive fields in Central China. Due to the limited scientific knowledge and researches, there are still some shortages in the climate change assessment methodologies and many uncertainties in the climate prediction results. Therefore, it is urgent and essential to increase the studies of the regional climate change adaptation, extend the research fields, and enhance the studies in the extreme weather and climate events to reduce the uncertainties of the climate change assessments.

Current Developmental Impacts on the Qanats： Its Challenge and Maintenance in China

In China, Qanats are found solely in the Xinjiang Uygur Autonomous Region, this system has greatly contributed since long ago to local livelihood, especially agriculture. Today, there are around 600 Qanats in Xinjiang, located especially in Turpan and Hami pefectures. Uygur people are the main users of the Qanat, they are not only using the techniques of construction and maintenance but they are also integrating Qanat into their culture. Today, Qanats in China are facing more and more crises with the local developmental impacts from enlarging farmland, groundwater over-extraction, seasonal water shortages, costly management, and conflicts of the interest, etc.. According to some studies, the number of Qanats in Xinjiang was reduced from 1,784 in 1950 to 600 today, which are equivalent to a decline of 23 Qanats per eventually come to end in the coming decades if we do not have year. Consequently, many experts are concerned that Qanats will effective efforts for their maintenance. It is a fact that Qanat is still able to adapt to the local environment, the local livelihood and against climate change, it cannot be converted to other hydraulic system in the arid environment of Xinjiang so far, but it is also challenged by current developments, especially rising amount of water consumption and costly maintenance. This paper aims to discuss the currently situation of Qanats in Xinjiang of China and their protection and sustainable use in a context of current development of industry, urbanization and local environmental change.

Agroforestry Suggestions Based on Climatic Modeling

Indigenous agroforestry systems have been practiced for centuries in the Himalaya Mountains and adjoining regions.With the increase of climate change associated risks,enhanced understanding of the impact of climate change and related phenomena on the potential distribution of agroforestry is increasingly useful and necessary,for both maintaining and improving yield and ecosystem function.In particular,

气候变化与海洋生物多样性关系研究进展

气候变化与生物多样性的关系研究已经成为落实《生物多样性公约》的焦点议题,海洋生物多样性是生物多样性的重要组成部分,研究气候变化与海洋生物多样性的关系对于保护全球生物多样性具有重要意义。作者分析讨论了气候变化与太平洋鲱鱼(Clupea pallasi)等海洋生物目标物种、东海浮游动物等海洋生物群落结构、珊瑚礁和红树林等敏感海洋生态系统的关系以及动态生物气候封闭式模型预测方面的研究进展,提出了我国在该领域需要深入研究的问题和对策,包括重视目标物种研究、加强生物区系和群落结构研究、加大敏感海洋生态系统研究、开展长时间尺度海洋生物多样性研究、开展预测研究和基于地理信息系统的气候变化与海洋生物多样性关系研究等。

Regional distribution and diurnal variation of deep convective systems over the Asian monsoon region

Using 12 years of data from the Tropical Rainfall Measuring Mission(TRMM)-based Precipitation Radar(PR),spatial and diurnal variations of deep convective systems(DCSs)over the Asian monsoon region are analyzed.The DCSs are defined by a 20 dBZ echo top extending 14 km.The spatial distribution of DCSs genesis is also discussed,with reference to the National Centers for Environmental Prediction(NCEP)reanalysis data.The results show that DCSs occur mainly over land.They concentrate in south of 20°N during the pre-monsoon season,and then move distinctly to mid-latitude regions,with the most active region on the south slope of the Himalayas during monsoon season.DCSs over the Tibetan Plateau are more frequent than those in central-eastern China,but smaller in horizontal scale and weaker in convective intensity.DCSs in central-eastern China have more robust updrafts and generate more lightning flashes than in other Asian monsoon regions.The horizontal scale of DCSs over the ocean is larger than that over the other regions,and the corresponding minimum infrared(IR)brightness temperature is lower,whereas the convective intensity is weaker.Continental DCSs are more common from noon through midnight,and DCSs over the Tibetan Plateau are more frequently from noon through evening.Oceanic DCSs frequency has a weaker diurnal cycle with dawn maximum,and diurnal variation of DCSs over the tropical maritime continent is consistent with that over the continent.

The Distribution Patterns of Timberline and Its Response to Climate Change in the Himalayas

Himalayan region represents the highest and most diverse treeline over the world.As one of the most conspicuous boundaries between montane forests and alpine vegetation,the alpine timberline attracted the interest of researchers for many decades.However,timberline in the Himalayas is understudied compared with European counterparts due to remoteness.Here we review the distribution pattern of timberline and its climatic condition,the carbon and nutrient supply mechanism for treeline formation,and treeline shift and treeline tree recruitment under climate change scenarios.Growth limitation,rather than carbon source limitation is the physiological cause of timberline under the low temperature condition.Nutrient limitation and water stress are not the direct cause of timberline formation.However,more clear local limitation factors are need to integrate in order to enable us to predict the potential impacts and changes caused by human activity and related global change in this sensitive region.