泾河中上游流域土地利用格局变化与驱动因子分析

利用RS和GIS技术和景观生态学的方法，对泾河中上游流域1986～2000年的景观特征及其动态变化进行了研究。通过计算多样性指数、优势度、破碎化指数、分离度等指标，进行了土地利用格局变化分析，并对该区域土地利用变化的主导因子进行了分析，认为该区土地利用／土地覆被变化的驱动力主要为：自然因素、经济因素、人口压力及宏观政策等，并互相影响、互相制约，共同影响流域景观格局的变化。     

霍林河流域下游沿岸近50年土地利用/覆被变化研究

以干旱半干旱脆弱区霍林河流域下游沿岸为研究靶区，利用1954年和1964年地形图．1986，1996和2000年的TM遥感影像作为基本信息源，在GIS支持下，建立土地利用空间数据库。引用空间测算模型和累计转换概率，分析不同时段各土地利用／覆被类型的动态和转换变化，揭示霍林河流域下游沿岸近50年土地利用／覆被变化过程及规律。耕地和草地是霍林河流域下游沿岸的主要土地利用／覆被类型，次之为盐碱地，湿地和林地比例较小，居民地和沙裸地最小。耕地和草地始终相反的幅度变化方向说明二者密切的相互转换关系；人居地和盐碱地始终一致的幅度变化方向则说明人类干扰活动是研究区盐碱地面积扩张变化的一个主要因素；沙裸地最快的转移速度预示着研究区沙化状况有较大的改善空间；耕地最慢的转移速度体现出其作为研究区基质的功能；草地较高的转移速度使其丧失了研究区第二大土地利用覆被类型的地位。霍林河流域下游沿岸各土地利用／覆被类型之间的转换变化具有显著的差异性，同一土地利用／覆被类型在转出和转人土地利用／覆被类型及其转换量上的表现不同，且随时间推移亦发生变化，转出的减少作用和转人的增加作用相叠加决定着研究区不同时段各土地利用／覆被类型的动态变化。     

黄河小浪底水库蓄水前后库周土地覆被变化研究

选取黄河小浪底水库库周1993年和2000年TM遥感影像进行土地覆被变化分析,绘制出蓄水前后的土地利用现状图,计算出土地覆被变化的转移矩阵和景观结构的控制指标,分别从土地利用类型、空间景观结构特征及土地变化过程等方面进行了研究.研究结果表明:小浪底水库的施工和蓄水对库周的土地利用变化和空间景观结构的改变没有太大影响;由于林地向耕地和其它土地覆被类型转变,使得1993～2000年的模地类型由有林地向耕地转化     

京郊半城子水库流域土地利用及景观格局变化分析

运用遥感与地理信息系统技术,对半城子水库流域2000年和2005年的2期遥感影像数据进行解译判读,结合土地利用动态度模型和景观生态学数量方法分析了流域土地利用和景观格局的变化。结果表明:①2000-2005年间,流域土地利用类型发生了一定变化,但林地始终是流域主导土地利用类型;②研究期内,半城子水库流域土地利用年变化速度为1.30%,其中阔叶林是最稳定的土地利用类型,其他土地是最活跃的土地利用类型;③类型水平上格局指数显示针叶林斑块形状最复杂,混交林的异质性较高;④景观水平的格局指数显示,区域景观破碎化程度加剧,多样性增加,均匀度增强。     

东江流域2001-2013年土地利用/覆被类型变化的时空特征及成因

[目的]区分人类活动和自然环境变化对东江流域土地利用/覆被类型变化的贡献率,为优化流域土地利用方式、保护流域生态环境和支持粤港澳大湾区建设提供有益的信息和科技支撑。[方法]基于时间序列的遥感影像土地利用/覆被类型栅格数据,结合区域经济发展、土地利用评价指标体系和灰色关联分析,量化东江流域2001-2013年间土地利用/覆被类型变化的时空特征和成因。[结果]①随着时间推移,东江流域土地利用/覆被类型格局由常绿阔叶林、草地和耕地共同主导型转变为常绿阔叶林主导型;②研究期内不同土地利用/覆被类型变化差异明显,灌丛、混合林、常绿阔叶林和草地变化剧烈且相互之间转化频繁,水域、耕地和城镇用地面积变化相对平缓;③非城镇用地转化空间差异显著,耕地的转化程度表现为：下游 > 上游 > 中游;④人口增加、城市建设、技术革新和经济增长是推动东江流域土地利用/覆被类型发生变化的主要原因。[结论]总体来说,最近10 a多东江流域的土地利用/覆被类型变化有利于流域生态环境和水资源的保护,进而有助于粤港澳大湾区的建设。     

流沙河流域土地利用变化研究

流域土地利用/土地覆被变化是区域土地利用变化研究的重要内容。通过数字化1965年的地形图和对1976年、1988年、2003年三期L andsatM SS/TM/ETM卫星影像的解译得到西双版纳流沙河流域土地利用信息,进而在A rc G IS的支持下,采用土地利用转移矩阵和几种景观指数,结合该区域民族分布和传统习俗对流域土地利用变化进行分析。结果表明:流域的自然条件决定了土地利用的空间分布格局,但民族传统习俗的影响也很大:靠近坝区的山区居民以傣族为主,人口密度较大,森林覆盖率却较高;距离坝区较远的山区,主要是山地民族,人口密度小,但森林覆盖率也小,民族因素对森林以及其他土地利用类型的影响要大于人口因素。政策对土地利用的时间变化影响较大,从1965~2003年,流域的土地利用/土地覆被发生了很大变化,1965年、1976年、1988年和2003年4年中流域的主要土地利用类型都是有林地,但有林地面积在减少,受人类活动影响较大的土地利用类型面积在增加,人类活动对土地利用的干扰增强,土地开发利用强度有增大的趋势。     

黄土丘陵区土地利用变化动态与景观格局分析——以彭阳县为例

在退耕还林背景下研究土地利用/覆盖变化及其对景观格局的影响对宁南山区土地资源可持续利用和生态环境重建具有重要意义。以多时相Landsat TM/ETM 4期遥感影像数据为基础,借助GIS技术和景观生态学方法,分析彭阳县1991—2010年的土地利用变化动态及景观格局变化。结果表明:在研究时段内,彭阳县林草地面积持续增加的同时耕地和未利用土地持续减少;景观格局变化主要表现为景观破碎化程度、斑块混合分布程度、多样性指数和均匀度指数均呈先增加后减小的趋势,各斑块间连通性呈先减小后增加的趋势,景观形状趋于复杂;区域发展规划是该区2000年以后土地利用及景观变化的主要驱动力。     

天目湖流域土地利用的动态变化及其景观响应

采用遥感、地理信息系统及景观分析的方法研究了天目湖流域1984年、1995年、2000年、2004年4个时段土地利用／覆盖变化及其景观响应。结果表明：20年来天目湖流域土地利用变化的阶段特征明显,2000-2004年这一时段的土地利用变化最为剧烈,共有14．75％的土地类型发生了变化,年均变化率为3．68％,且近期开发的空间范围广、强度大;各种景观指数对土地利用／土地覆盖变化呈明显的时空响应;迎湖地区景观格局指数的变化最为剧烈,背湖地区较为平缓;人湖河流流域的景观指数空间分异较为明显,下游地区变化较大,而其上游相对较小;土地利用变化剧烈的时段与近几年水质恶化的趋势相呼应。     

黄土高原丘陵区景观特征与景观指数粒度效应研究

选取黄土丘陵沟壑区高家沟流域为研究区,基于遥感图像绘制流域土地利用景观图,利用GIS相关软件以及景观格局分析软件Fragstats,计算高家沟流域的景观格局指数,并在景观水平上对指数的粒度效应进行了研究.结果表明:草地为高家沟流域土地利用类型的主体,园地稀少,各土地利用类型布局分散,斑块形状较复杂,土地利用结构不够合理;粒度变化对景观指数的计算具有重要影响,各景观指数均具有明显的粒度效应,不同的景观指数随粒度增加表现出不同的变化趋势:(1)景观指数随粒度的增加有明显的下降趋势;(2)景观指数随粒度的增加变化趋势不明显,或上升或下降,并呈现出一定的波动性.高家沟流域景观分析的适宜粒度范围为75～120m.     

艾比湖流域气溶胶光学厚度与土地覆被景观格局关联分析

土地覆被-景观格局直接或间接影响大气环境,了解大气环境对土地覆被-景观格局的响应,对维护和改善生态环境具有重要的意义。该研究基于环境一号卫星HJ-1B CCD数据,研究艾比湖流域土地覆被-景观格局与气溶胶光学厚度(aerosol optical depth,AOD)的关联关系,首先通过CCD数据反演AOD,然后利用分维数分析和贡献分析方法,定量分析土地覆被-景观格局对AOD的影响。结果表明:1)研究区AOD主要集中于绿洲及人口集聚区,从绿洲的中心到绿洲边缘气溶胶光学厚度逐渐降低,且在南部山区集聚呈带状;2)流域平均AOD与景观指数PD、ED、LSI和AI之间均存在着高度相关性,且景观的组成和空间结构都影响着流域AOD的空间分布;3)通过分维数分析,可知耕地和盐渍地的AOD密度从高值中心到外边界下降,但在其他的土地覆被类型上变化相反,盐渍地和耕地是流域主要空气污染的贡献者;4)应用贡献分析法进一步阐明了耕地和盐渍地可以增加空气污染,而林草地的效果相反。土地覆被变化和人类活动是影响艾比湖流域AOD空间分布主要原因,对AOD与土地覆被-景观格局变化的定量研究可以使研究者更好地了解AOD与土地覆被-景观格局的关系,进一步为土地政策的制定和土地利用规划提供参考。     

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.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

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.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

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.