粮食生产潜力短期预测的“趋势-波动模型”的验证

应用全国、31个省、6个典型地区和16个典型县的数据对粮食生产潜力短期预测的"趋势-波动模型"进行了系统性的验证和讨论。研究结果表明:(1)预测误差大小反映短期生产潜力的预测精度,预测误差大的主要原因是经济发达地区高产农田被大量占用和(或)蔬菜、水果种植面积大幅度增加而短期内使粮食单产下降;(2)小趋势修正方法是"趋势-波动模型"中不可缺少的一部分,它能将大趋势预测不能包括的短期如气象因素、科技投入、社会因素等影响纳入预测中,提高预测精度;(3)就我国近些年来的实际情况而言,越是经济发达的地区短期生产潜力的波动越大;同样发达地区短期潜力存在增加-下降-回升阶段;(4)就短期生产潜力预测精度而言:国家级大于省级、省级大于地区级、地区级大于县级;不同省、不同地区、不同县之间预测精度差别比较大,这与境内气候的互补性和农田抗御自然灾害的能力有关。     

哈巴湖自然保护区草地植被数量波动探讨

植被波动是植被动态的一种表现形式,该文在生态学、统计学基础上,结合草地植被特征,采用专家权重法构建草地植被波动测度公式,以哈巴湖自然保护区为例,研究2006—2010年草地植被数量波动及波动率,从数量特征上对草地植被波动进行探讨。结果表明:哈巴湖自然保护区植被波动率正向波动2007年最大,为0.381,是近年来植被生长状况最好的一年;负向波动以2009年的-0.350的绝对值最大,表明2009年是近年来植被生长状况最差的一年。草地植被数量的波动,一定程度上反映了该年度植被生长状况,为草地经营管理和植被恢复提供了便利,同时也为预测未来草地植被变化提供了依据。     

基于经验模态分解的中国粮食单产波动特征及影响因素

探索中国粮食单产的多尺度波动特征及其影响因素,进而有针对性地采取措施来稳定和提高粮食单产对保障中国粮食安全有重要意义。该文对1978-2012年中国粮食及其主要构成作物稻谷、小麦和玉米的单位面积产量,利用经验模态分解方法进行了多尺度波动分解,并分析了改革开放以来中国粮食单产波动的多尺度特征及其主要影响因素。结果表明:1)应用经验模态分解方法可以将1978年以来中国的粮食和三大作物的单产分解为1个趋势项和2个波动项,分别反应了科技、政策和气候对于中国粮食单产波动的影响。其中技术趋势为主导,2个尺度的波动都较小。2)粮食趋势单产年增长率从1997年前的2.28%下降到之后的0.69%,明显放缓。稻谷的趋势单产与粮食走势最为接近,但1997年以后几乎走平。玉米和小麦的趋势单产增速1997年后虽有所下降,但目前上升依然明显。3)中期波动项包括了3个完整的周期和1个进行中的周期,且与中国粮食政策的重大调整及其所产生的后效在时段上具有很好的一致性。总体看粮食生产领域政策的影响大于气候的影响,但不同作物对各种政策的响应也有所不同,土地、税收、补贴、奖励和保险政策的普惠性和同步性较价格政策更强。小麦的中期波动率明显大于其他作物,显示其对政策更加敏感。4)粮食单产的短期波动率为1.80%,其中玉米为3.38%,高于小麦(2.55%)和稻谷(1.06%),显示中国的粮食生产系统有较强的抵御气象灾害的能力,但玉米防灾能力不及稻谷和小麦。5)综合长期趋势和中短期波动来看,3大作物中稻谷最为稳产。稻谷的主要问题是1998年以后单产的趋势产量上升乏力,玉米的主要问题是短期波动较大,受气象灾害的影响大,而小麦的政策波动大于玉米和稻谷。当前中国的农业已经进入了新的发展阶段,农业政策的调整势在必行,该研究结果可为新阶段农业宏观调控政策的制定提供决策依据。     

吉林省玉米价格波动总体特征及趋势分析

粮食价格波动历来受到国内外专家的高度重视,吉林省作为玉米生产大省和加工业大省,对其玉米价格波动进行研究显得很有必要。本文先就吉林省玉米价格波动的历史背景做一简单回顾,然后就玉米价格波动的总体特征进行描述性统计分析：首先,将其与全国平均水平及其他玉米主产省进行比较,得出吉林省玉米价格波动的特,最;其次,测算价格波动的主要指标,并对波动指数进行细致分析,从而得出吉林省玉米价格波动的特征。最后,通过线性回归模型,就吉林省价格波动的长期和短期趋势展开研究,并给予展望。     

土壤水力特性异质性对土壤排水影响的瞬态随机分析

土壤剖面水分入渗及再分布对生态和水文建模十分重要,而土壤异质性导致垂向的导水率值差异非常大。因此,该文假设在单位梯度下,用微扰法和运动波模型并结合随机分析研究一维瞬态土壤剖面排水的问题。采用Brooks-Corey模型,设饱和导水率和模型参数为随机变量。结果表明:1)饱和导水率方差增大对排水过程具有减缓的作用,有效饱和导水率较小;2)土壤导水率异质性越大,土壤蓄水能力越强;3)比较模型参数的波动与饱和导水率方差和模型参数的协方差,饱和导水率方差对排水影响更大;4)田间排水试验的结论与模型预测相一致。研究可为以长期自我维持的生态系统和高田间持水量为目标的土壤复垦提供依据。     

浑南区尖山小流域SCS-CN方法初损率研究

土壤侵蚀受降雨径流作用影响显著,科学准确的对降雨径流进行分析是开展水土流失治理和综合效益评估的重要内容。SCS-CN模型因具备高效、简单等优点被广泛应用于降雨径流模拟分析中,初损率是决定SCS-CN法地表径流预测的重要参数,是影响模拟精度的关键因素。以浑南区尖山小流域为研究对象,将径流模拟结果与该流域8场降雨数据资料进行对比分析,通过对初损率的取值研究探讨了SCS-CN方法的适用性和可靠性。研究表明:模型理论初损率λ为0. 2时的径流预测效果良好,而对于尖山小流域初损率λ为0. 3时的模型效率系数明显增大,径流预测精度得到显著提高,模型预测结果与实测值保持较高的一致性,可适用于相似流域的径流预测研究。     

水位波动条件下土层中硝态氮迁移转化数值模拟

将溶质运移方程、一维饱和-非饱和土壤水分运动控制方程和Kool-Parker滞后模型联立耦合,建立了地下水位波动条件下土层中硝态氮迁移转化模型。采用有限元数值分析方法,模拟了在地下水位波动条件下硝态氮的迁移过程且与室内土柱实验结果进行对比。结果表明,所建模型的模拟结果与室内土柱实验结果吻合,地下水位波动对硝态氮迁移转化影响显著,其浓度随水位的下降而上升,随浓度的上升而下降。水位波动幅度越大,其浓度波动范围越大。所建数学模型能较好反应硝态氮随水位波动的迁移转化规律。     

基于改进持续法的短期风电功率预测

为了有效减轻风能波动对电网的影响,提高风电在电力市场中的竞争力,风电功率预测研究具有重要意义。该文提出了基于小波变换的改进持续法,对短期风电功率预测进行研究。该方法首先利用小波变换将原始风速信号分解为高频部分和低频部分,针对高频信号相邻的两个数据之间相似度较低,波动较大的特点,采用滑动平均法进行预测,而低频信号仍然采用持续法预测,最后通过小波重构以及风电功率特性曲线转换得到风电功率预测值。与原持续法相比较,平均相对误差由17.10%降至11.81%,平均绝对误差由39.58 kW降至23.48 kW,有效地提高了短期风电功率预测的精度,具有一定的实际应用价值。     

近40年来我国粮食产量变化特征初步分析

根据我国粮食产量资料及影响因子的时间变化特征，分析了近４０年来粮食产量的变化特征及其与各影响因子的关系。结果表明：近４０年来，我国粮食总产和单产逐步提高，单产对总产平均年际波动的影响很大。技术水平对单产的影响呈平稳、逐步加速增长的变化趋势，社会因素的影响呈较为连续的三峰型波动，气象条件的影响年际差异很大，其作用约占单产平均年际波动的一半。从预报的角度看，预测天气、气候因素对作物的影响是准确预测作物产量的关键。     

农田重金属污染长期演变LIVE模型构建

  目的  我国农田重金属污染较为突出,严重威胁农产品安全。防范农田土壤重金属的长期累积增加、实现农田土壤可持续的安全利用,是保障粮食安全生产的重要前提。然而现有政策管理框架与实践重点关注已污染农田土壤的风险管控与修复,侧重重金属污染农田的高效、短期安全利用,对重金属浓度在较长时间尺度内的动态变化重视不足。针对农田重金属长期的演变规律,亟需建立有效的预测方法,为相关政策的制定提供决策支撑。  方法  基于重金属元素的入流与出流特征分析与质量衡算,构建了农田土壤重金属演变规律预测的LIVE（Long-term Influx Versus Efflux）模型。通过选取典型参数,模拟浅层与深层农田土壤中镉（Cd）、砷（As）典型污染物的长期演变规律。  结果  农田重金属的变化规律可分为单向、波动、突变等多种形式。进一步结合长期观测数据,对不同演变规律的形成原因进行了探讨。  结论  在各入流项与出流项相对恒定的理想情形下重金属的积累存在单向性特征;水通量的波动性间接导致了污染物积累的波动性特征;通过人为控源,可以明显遏制乃至扭转重金属元素的积累,使污染物含量呈现突变性特征。该模型能够为重金属污染农田土壤长期、有效的安全利用提供相应依据。     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

Einfluss der düngungsmethoden auf die entwicklung von zuckerrübenkrankheiten

Während neunjähriger (1994-2002) Untersuchungen in der Versuchsanstalt Ba?cyny (Fahlerde, Fall-Gleyboden, ausgebildet aus leichtem Lehmboden) wurde der Befall mit Krankheiten an der Zuckerrübe in Abhängigkeit von der Düngungsmethode bewertet. Folgende Methoden wurden angewendet: A - Mineraldünger, B - Stalldung und Mineraldünger, C - Stroh-, Gründung und Mineraldünger, D - Kompostdünger und Biopräparate (ökologische Düngung). Auf den Objekten A, B, C wurden bei konstanter Phosphor-Kalium-Düngung die Stickstoffgaben von 0 bis 180 kg.ha^?1 differenziert. Auf dem ökologischen Objekt D ohne Mineraldünger wurden statt Stickstoff die Biopräparate P₅₀₀ und P₅₀₁ verabreicht. Der geringste Befall von Krankheiten wurde an der Zuckerrübe auf jenem Objekt festgestellt, das mit Kompost und den Biopräparaten gedüngt worden war. Im Rahmen der konventionellen Düngungsmethoden wurde allgemein die höchste Intensität der Krankheiten an der mit Stroh, Gründung und Mineraldünger gedüngten Zuckerrübe beobachtet. Ausnahmen von dieser Regel bildete das Vorkommen von echtem Mehltau und Keimlingsfäule. Auf den Objekten A, B, C nahm die Intensität der Krankheiten mit der Steigerung der Stickstoffgabe zu. Auch die auf Objekt D verabreichten Biopräparate stimulierten die Entwicklung der Krankheiten. The effect of various fertilization methods on the diseases of sugar beet was estimated on the basis of nine-year studies (1994-2002) conducted in the Experimental Production Farm in Ba?cyny on loess-based, sedimentary-gley, light-clay soil. The following fertilization methods were applied: A - mineral fertilization, B - mineral and manure fertilization, C - straw, green manure and mineral fertilization, D - ecological compost and biodynamic preparations fertilization. In the objects A, B and C fertilized with phosphorus and potassium, various doses of nitrogen ranging from 0 to 180 kg/ha^?1 were used. In the ecological object D, where mineral fertilization was not used, biodynamic preparations P₅₀₀ and P₅₀₁ were applied instead of nitrogen. The lowest ratio of the diseases of sugar beet was observed in the object fertilized with the compost and biodynamic preparations. In view of the conventional fertilization methods, generally the highest incidence of diseases was noted in the sugar beet fertilized with straw, green manure and mineral fertilizers. The exception was the occurrence of powdery mildew and the black leg. In objects A, B and C the incidence of the diseases increased with the increase in nitrogen doses. The applied biodynamical preparations in the object D stimulated the development of diseases too.     

Prospects for control of Pythium damping-off of lettuce with Trichoderma,Gliocladium and Enterobacter spp.

Summary Damping-off of lettuce (Lactuca sativa) caused by Pythium ultimum was studied in pots containing a non-sterile potting mix in the glasshouse. Fifty P. ultimum sporangia g^-1 compost reduced the plant stand to 15% and shoot dry weight to 18%, but this reduction was totally prevented by applying Trichoderma harzianum at 2×10⁵ viable propagules g^-1 potting mix. Gliocladium virens and Enterobacter cloacae also alleviated the damping-off. E. cloacae did not adversely affect the action of the fungal antagonists. The co-existence of the bacterial and fungal antagonists was revealed on the root surface and inner surface of the testa by scanning electron microscopy, indicating the compatibility of the biocontrol agents.     

细菌、真菌及植物氮营养信号研究进展

氮素吸收代谢是所有生物生命活动的核心部分,因此,各种生物对氮的吸收与同化过程都有精细的调节。这种调节依赖于生物对体内氮素状况信号及体外（生长介质中）氮素信号的感受。过去几十年中,在细菌、真菌中已经对氮素营养信号有了较好的研究,而植物中则相对缓慢,但也有了一定的认识。本文重点比较细菌、真菌及植物中氮信号系统的组成,以期为进一步认识植物中的氮信号接受与转导系统提供启示。     

Aircraft operations near concentrations of birds in Antarctica: The development of practical guidelines

Aircraft operations have the potential to disturb and to impact negatively on bird life. A gradient of increasing behavioural response is evident in birds when exposed to increasing aircraft stimulus. The most major disturbance is likely to lead to impacts on the health, breeding performance and survival of individual birds, and perhaps bird colonies. A process of revision to policies on aircraft operations contained in management plans for a number of specially protected areas in Antarctica by the United Kingdom, accompanied by consultations made within the scientific community through the Scientific Committee on Antarctic Research (SCAR) and with operational interests through the Council of Managers of National Antarctic Programmes (COMNAP) resulted in new guidelines being adopted by the Antarctic Treaty Consultative Parties in June 2004. The principal recommendations of the guidelines are that bird colonies should not be overflown below 2000 ft (∼610 m) above ground level and landings within 1/2 nautical mile (∼930 m) of bird colonies should be avoided wherever possible. These guidelines are less stringent and less specific than those that were recommended by the SCAR specialist group on birds, and represent a compromise to accommodate operational needs. While the adoption of clear and consistent guidelines for the operation of aircraft in Antarctica is welcome in that this provides practical advice that is likely to reduce incidences of close aircraft/bird encounters, there remains insufficient knowledge of the interactions between aircraft and birds in Antarctica, and the consequent impacts on individual birds and on bird populations. It is important, therefore, that the guidelines adopted are considered interim, and should be kept under scrutiny with revisions made as new and improved research results appear.     

The abundance of heterocystous blue-green algae in rice soils and inocula used for application in rice fields

Summary Algal populations were quantified (as colony-forming units [CFU] per square centimetre) in 102 samples of rice soils from the Philippines, India, Malaysia and Portugal, and in 22 samples of soil-based inocula from four countries. Heterocystous blue-green algae (BGA) were present in all samples. Nostoc was the dominant genus in most samples, followed by Anabaena and Calothrix. In soils, heterocystous BGA occurred at densities ranging from 1.0 × 10² to 8.0 × 10⁶ CFU/cm² (median 6.4 × 10⁴) and comprised, on average, 9% of the total CFU of algae. Their abundance was positively correlated with the pH and the available P content of the soils. In soil-based inocula, heterocystous BGA occurred at densities ranging from 4.6 × 10⁴ to 2.8 × 10⁷ CFU/g dw (dry weight), comprising only a moderate fraction (average 13%) of the total algae. In most soils, the density of indigenous N₂-fixing BGA was usually higher than that attained by applying recommended rates of soil-based inoculum. Whereas research on the practical utilization of BGA has been mostly directed towards inoculation with foreign strains, our results suggest that attention should also be given to agricultural practices that enhance the growth of indigenous strains already adapted to local environmental conditions.Maître de Recherches ORSTOM (France), Visiting Scientist at IRRI