松嫩平原盐碱化反演及其动态变化过程

[目的]监测2000—2013年来松嫩平原盐碱地时空演变过程,为松嫩平原盐碱地防治提供理论依据。[方法]以MODIS影像为主要数据源,结合野外实测样点建立回归模型,对松嫩平原土壤含盐量进行定量反演。将整个研究时期分为3个时段:时段1(2000—2004年),时段2(2004—2008年),时段3(2008—2013年)。[结果]时段1和时段2盐碱地面积增加,增加速度为5 109.75和2 240.62km2/a,同时盐碱化程度加剧;以2008年为转折点,时段3盐碱地面积减少,主要是轻度盐碱地的减少,但是盐碱化程度仍在加剧。[结论]松嫩平原的盐碱化趋势不容乐观,应该采取紧急措施防止盐碱化程度进一步恶化,保护松嫩平原的生态环境健康发展。     

基于遥感的2000－2009年三江平原北部耕地变化特征分析

该文以三江平原北部为研究区,基于遥感数据分析2000-2009年该区域耕地变化特征,旨在为土地整治、农田水利工程建设等耕地资源开发利用提供依据。结果显示:耕地面积由214.31增加至285.10万hm2,垦殖率升至67.3%,新增耕地主要为旱地;共有73.64万hm2土地被垦殖为耕地,主要来源为沼泽地、林地和草地,而同期退耕面积仅为2.84万hm2;58.67万hm2旱地转换为水田,9.06万hm2水田转换为旱地;水田呈现出集中分布的格局,占耕地总面积的比重升至30.10%;位于研究区东部北部的县市耕地增加较多,而位于西部南部的县市耕地增加的较少;今后该区域在农业发展特别是农田水利建设过程中,应加强水土资源优化配置研究,并主要通过土地整治来增加有效耕地面积。     

松嫩平原盐碱土理化性质与生态恢复

土壤盐碱化是世界性的土壤退化问题,给农业生产造了极大的损失。由于不合理的灌溉、过度使用化肥和植被破坏,土地盐碱化越来越严重。松嫩平原属于干旱—半干旱气候区,区内现有盐碱化土地373万hm2,是世界上三大片苏打盐碱地集中分布区域之一,而且重度盐碱化土地面积仍以每年1.4%的速度扩展[1]。过度放牧是导致松嫩平原草地次生盐渍化的主要原因。随着土地资源的紧张,人们尝试着各种方法改良盐碱地,包括工程改良、化学改良[2~6]和生物改良[7~10],但是成本太高。国内外关于固氮蓝藻的耐盐性考察已经有许多报道,包括耐盐藻对Na+的吸附[11~15]、渗透压调整[16~18]以及盐胁迫对蓝藻的生长、光合作用、     

川中典型紫色丘陵区表层土壤有机碳密度空间变异及影响因素

根据94个样点表层(0-20cm)土壤有机碳分析化验数据,运用地统计学方法研究川中典型紫色丘陵区清流河流域土壤有机碳密度的空间变异特征及其影响因素,结果表明,该区域表层土壤有机碳密度在4.60~59.59kg/m2之间,平均值为20.58kg/m2,变异系数为52.32%,属于中等变异强度;土壤有机碳密度总体分布呈团状或条带状分布,其中高值区(28.70kg/m2)主要位于研究区东部的大清河下游,并以此为中心,向北、西和南3个方向呈辐射状逐步降低;低值区(17.20kg/m2)主要分布在南部、西部和北部;研究区中部土壤有机碳密度多介于17.20~25.80g/m2。研究区域土壤有机碳密度与土壤母质、地形、土地利用方式、排灌方式和土壤质地等因素密切相关,在不同土壤母质、地形、土地利用方式、灌溉方式和土壤质地下土壤有机碳密度差异达极显著或显著水平。     

西南山区生态敏感区土地生态安全评价——以秀山县为例

研究综合应用数字高程模型(DEM)、遥感影像及土地利用现状更新调查等数据,应用地理信息系统(GIS),基于栅格对秀山县土地生态安全状况进行了评价和分析,为西南山区生态敏感区探索一种精确的生态安全评价方法。结果表明:秀山县土地生态安全状况可以分为安全、较安全、预警、中警4个级别,各级别的面积分别占21.23%,43.97%,21.81%,4.99%。其中土地生态安全级主要分布在中部平坝丘陵区;土地生态较安全级在全县均有分布,多分布在各区域坡度较小、海拔相对较低等位置;土地生态预警级主要分布在东部低山区南端、西部低山区、以及东部中山区和西部中山区中海拔相对较低的位置;土地生态中警级主要分布在东部中山区和西部中山区。综上,秀山县土地生态状况整体上良好,与实际情况相符合,今后应加强土地利用结构优化,提高土壤培肥力度,减少水土流失,以促进土地生态系统健康稳定发展。     

基于RS和GIS技术的坝上地区土地利用/覆盖动态监测

以1987年和1999年 TM遥感图像为数据源,在ERDAS8.4遥感图像处理软件和ArcInfo8.02地理信息系统软件的支持下,获取了坝上研究区两期土地利用/覆盖图.在此过程中,提出和建立了研究区土地利用/覆盖遥感图像分类体系;通过计算机自动分类和分类后人工解译纠错相结合的图像分类提取方案,提高了图像分类提取的效率和精度.动态监测结果表明从1987～1999年的12年期间,坝上地区土地利用/覆盖动态度由大到小的顺序为居民建设用地＞林地＞高覆盖度草地＞水体＞沙盐碱地＞低覆盖度草地＞耕地.其中面积增加的是居民地、林地、高覆盖草地和耕地;面积减少的是沙盐碱地、水体和低覆盖度草地.从1987～1999年的12年期间,研究区的沙盐碱地面积从1 985.89 km2减少到 1 250.75 km2,减少了37.02%,年动态度为-3.08%.坝上东部沙漠化得到遏制,而西部张北、康保一带沙盐碱化土地有所扩展.     

基于RS和GIS的黄河三角洲土地利用变化及生态安全研究——以东营市为例

基于RS和G IS技术,以东营市为例,研究黄河三角洲的土地利用变化及其结构特征,确定综合土地生态风险指数,然后通过系统采样、变异函数分析及空间插值对土地生态风险指数进行变量空间化,生成1996和2005年土地生态风险演变规律分布图。研究结果表明:近10年来东营市土地利用变化剧烈,居民工矿用地大幅增加,次生盐碱地所占比重较大,油田生产建设和生态环境保护矛盾比较突出;近10年来,生态风险重心已经由南部的广饶地区转移到中部的东营地区,生态风险有进一步恶化的趋势,区域内土地生态风险分布极其不平衡,具有明显的区域性特征。高风险区域为居民及工矿用地密集区,主要分布在中部的东营区;中风险区域主要分布在南部的广饶地区和土地盐碱化严重地区;低风险区主要分布在北部的河口区和垦利县的东部。最后针对土地生态风险分布格局,提出了生态环境安全的政策建议及改造措施。     

基于RS和GIS的黄河三角洲土地利用变化及生态安全研究——以东营市为例

基于RS和GIS技术,以东营市为例,研究黄河三角洲的土地利用变化及其结构特征,确定综合土地生态风险指数,然后通过系统采样、变异函数分析及空间插值对土地生态风险指数进行变量空间化．生成1996和2005年土地生态风险演变规律分布图。研究结果表明：近10年来东营市土地利用变化剧烈,居民工矿用地大幅增加,次生盐碱地所占比重较大,油田生产建设和生态环境保护矛盾比较突出;近10年来,生态风险重心已经由南部的广饶地区转移到中部的东营地区,生态风险有进一步恶化的趋势,区域内土地生态风险分布极其不平衡,具有明显的区域性特征。高风险区域为居民及工矿用地密集区,主要分布在中部的东营区;中风险区域主要分布在南部的广饶地区和土地盐碱化严重地区;低风险区主要分布在北部的河口区和垦利县的东部。最后针对土地生态风险分布格局,提出了生态环境安全的政策建议及改造措施。     

GIS支持下的滇西北地区泥石流灾害评价

滇西北地区泥石流区域分布受地貌、构造、岩性、气候和人类活动等诸多因素的影响和控制 ,在区域分布上表现出明显的地带差异性,泥石流灾害南部多于北部,西部多于东部.据本次调查,滇西北现有流域面积0.5 km2以上的泥石流沟690条.本文描述了用于地理信息系统识别和定量计算不同泥石流危险区的系统方法.对泥石流灾害评价表明研究区高度灾害区面积约5 413 km2,占全区面积的8.01%;中度灾害区面积约16 239 km2,占全区总面积的24.05%;低度灾害区面积24 907 km2,占全区面积的36.87%;无灾害区面积20 988 km2,占全区总面积的31.07%.所完成的泥石流灾害评价为全面反映灾情,确定减灾目标 ,优化防御措施,进行减灾决策提供了重要依据.     

松嫩平原西部地区土地利用/覆被变化的驱动力分析

利用1986年和2000年两期TM影像资料,在空间图形库系统支持下全面分析了松嫩平原西部地区土地利用/覆被数量变化和土地利用空间格局变化,揭示了近15年来研究区土地利用时空变化特征.表现为耕地、盐碱地从整体上呈现集中化,林地、草地不断破碎化.耕地与草地、草地与盐碱地空间相邻度增大,草地开垦和土地盐碱化日益严重.对不同经济类型区即农区、半农半牧区和牧区土地利用变化的社会经济因素的区域相似性和差异性分析表明,人口的压力、落后的畜牧业和经济利益驱动是近15年该区土地利用变化的主导因素.     

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