嵩山景区旅游活动对土壤组成和性质的影响

旅游活动对景区土壤的影响研究始于20世纪70年代。众多学者研究了游客踩踏对景区土壤的影响,指出景区土壤板结、雨水下渗减少[1~5]。Joy等[6]提出了旅游活动对土壤-植被系统可能带来的种种冲击,如硬度增大、土壤结构破坏、植被覆盖度下降等。Sun[7]和Douglas[8]指出,旅游活动可使地面径流增加,引起水土流失。Cilimburg[9]研究发现,旅游活动可导致景区局部土壤有机质含量减少,病原体增多,微生物活性降低。Eden等[10]研究发现,旅游活动使景区土壤含水量下降,硬度增大,有机质含量减少,植物种类及覆盖度明显降低。Cer-man[11]和Willian[12]的研究也发现,旅游活     

干枯植被覆盖对公路沿线地表风沙流结构的影响

[目的] 以内蒙古S105草原公路沿线地表为研究对象,探讨挟沙风作用下干枯植被覆盖度对风沙流结构的影响,旨在为防治公路两侧土壤风蚀提供理论参考依据。[方法] 采用风洞模拟试验,在0%,20%,40%和50%覆盖度水平下测定输沙率。[结果] 在挟沙风作用下,输沙率随干枯植被覆盖度的增大而递减,最大输沙率点的高度层不断上升。覆盖度为0%时,输沙率随高度的增加呈指数函数规律降低;覆盖度为20%,40%和50%时,输沙率随高度的增加呈递减→递增→递减→趋于平缓的变化规律;在85 mm高度以下符合多项式函数关系,85 mm高度以上符合指数函数关系。随覆盖度的增大总输沙量递减,最大抗风蚀效率达65.73%。[结论] 干枯植被覆盖显著影响地表风沙流结构,可削弱挟沙风侵蚀力,是抑制公路沿线地表土壤风蚀沙化的有效措施。     

漓江风景区土壤生态环境对旅游干扰的响应

[目的] 探索广西壮族自治区桂林市漓江风景区土壤生态环境因子对旅游干扰的响应规律，为合理开发与保护漓江风景区旅游资源提供科学依据。[方法] 采用野外调查和室内分析方法，对比不同干扰程度下漓江风景区土壤环境指标的差异，分析旅游干扰对漓江风景区土壤生态环境的影响。[结果] 在旅游活动干扰下，土壤硬度明显增加，5个系列土壤坚实度平均值增加15.55倍，土壤颜色的明度和彩度增加，容重平均增幅为33.43%；枯枝落叶层厚度和土壤自然含水率下降，土壤有机质、土壤全氮、碱解氮、有效磷以及有效钾含量平均降幅分别达到61.31%，61.58%，32.21%，72.08%和36.26%。[结论] 在旅游干扰下漓江风景区土壤生态环境发生阶段性变化，供试区土壤出现不同程度退化，土壤综合肥力下降，土壤结构变差，进而将对景区植被和景观带来影响，因而应从管理和技术等方面采取有效措施，以减弱旅游干扰对漓江风景区土壤生态环境的负面影响。     

旅游干扰对贺兰山典型草原生物多样性及土壤性质的影响

[目的]探讨旅游干扰对贺兰山典型草原生物多样性及土壤性质的影响,进一步理解旅游干扰的生态影响效应与机制,为风景区资源与环境的保护管理提供参考。[方法]采用样方法对贺兰山景区主要游览线路两侧植物群落及其土壤进行了调查,分析了不同强度旅游干扰(低度旅游干扰,中度旅游干扰,重度旅游干扰)对植物群落及其土壤性质的影响。[结果](1)旅游干扰显著降低了植被覆盖度、枯落物含量、丰富度指数、均匀度指数和多样性指数(p0.05);(2)旅游干扰对土壤理化性质具有较大影响,土壤容重随着干扰强度的增加而增加,含水量和电导率随着干扰强度的增加而降低;(3)在旅游干扰条件下,土壤微生物量碳和氮变化幅度较大,对旅游干扰表现最为敏感;(4)随着旅游干扰强度的增加,土壤有机碳、全氮、碱解氮和微生物量碳、氮均明显降低,全钾和有效钾随干扰强度的增加而增加;(5)旅游干扰区域土壤养分指标相关性基本与对照区域相一致,土壤全量养分均与其对应的有效养分呈极显著正相关(p0.01)。[结论]中度旅游干扰并没有影响植被属性;旅游干扰对土壤性质有一定影响,而此影响并没有改变土壤养分因子之间的相互作用效应。     

引黄济青工程沿线生态因子1990-2020年时空变化特征

[目的]以引黄济青工程为研究对象,探究其通水1990-2020年间沿线生态因子的时空变化规律,为该区生态环境的保护和治理提供依据.[方法]采用遥感技术对土地利用/覆盖、植被指数及覆盖度、地表温度、土壤干湿度等因子1990-2020年的时空演变特征展开研究,深入探究工程运行后沿岸生态环境的变化.[结果]区域内水域、绿地、...     

以土地利用为基础的安徽省生态评价遥感信息模型

[目的]建立更科学合理的生态评价遥感信息模型,为研究区的可持续发展提供参考依据。[方法]利用NDVI(归一化植被指数)和像元二分模型监测植被覆盖度作为地表植被覆盖信息的评价指标;用热惯量法反演研究区的土壤含水量作为研究区地表植被覆盖信息与土壤肥力的评价指标;采用目视解译获得土壤质地的编码分布图并进行影像化处理,将土壤中物理性黏粒含量作为评价土壤板结情况指标;利用线性光谱混合分解模型提取研究区的裸地比率作为土地荒漠化程度的评价指标。[结果]从土地利用的角度构建了生态评价指标体系,建立了以像元为单位的生态评价定量化遥感信息模型。[结论]植被覆盖度因子对研究区生态评价的影响程度相对较大;在生态评价过程中本研究新建模型总体评价精度比传统方法提高了15%。     

放牧干扰对荒漠草原土壤和植被的影响

放牧是草原生态系统最主要的干扰因子之一,影响着草地生态系统植被和土壤的生态进程。以宁夏盐池县荒漠草原区为研究对象,根据地表植被以及地表羊粪的积累量设置6个放牧干扰梯度,分别为CK、T1、T2、T3、T4、T5,运用方差分析、回归分析研究了植被和土壤对不同放牧干扰的响应。结果表明：地上生物量、枯落物、植被覆盖度随着放牧干扰强度的加大呈现先增加后减小的趋势,支持了＂中度干扰理论＂;随着放牧干扰强度的增大,土壤水分随之增加,土壤容重则无显著变化;土壤有机碳与全氮随放牧干扰的变化趋势大致相同,二者有很强的曲线线性关系,C/N的变化趋势与有机碳的变化规律稍有不同,C/N和地上生物量都与地表羊粪量有显著的曲线线性关系,表明地表羊粪量对土壤碳氮分布及草地生产力有着很强的影响,体现了有机碳与全氮含量变化的复杂性及各因子之间的互作效应。     

黄河流域甘肃段植被覆盖度时空变化及对气候因子的响应

[目的]分析黄河流域甘肃段2000—2018年植被覆盖度变化的时空演变规律,探讨该区域植被覆盖度的变化对气候的响应机制,为该区域生态环境与社会经济的协调可持续发展和进一步落实生态环境保护、建设及恢复提供科学依据。[方法]基于2000—2018年的MODIS NDVI数据、气象数据,采用线性趋势分析和相关性分析等方法,对黄河流域甘肃段植被覆盖度的时空变化特征及与气候因子之间的关系进行分析。[结果]①空间上,近19 a研究区植被覆盖度自西南向东北在不断降低,以甘南州的植被覆盖状况最好;植被覆盖度改善面积占36.64%,主要分布于兰州市北部、临夏州、定西市、庆阳市、平凉市大范围区域、天水市南部等,而退化面积占4.2%,主要集中于甘南州等地区。②时间上,研究区植被覆盖度以2013年为界呈现"先持续增加后波动减少"的变化趋势,但整体在不断增加;以平凉市的增加速度最快,平均每年增长0.96%。③研究区植被覆盖度对降水量变化的响应敏感,与降水量呈现显著的正相关关系。[结论]研究区植被覆盖度空间差异明显,2000—2018年植被以改善为主,降水是影响这些区域植被改善的有利因素,降水状况的改善对研究区生态环境建设与修复至关重要。     

2000-2012年鄂尔多斯禁牧区植被覆盖度变化监测

[目的]评估鄂尔多斯实施禁牧、休牧政策以来获得的成效。[方法]以MODIS长时间序列的植被指数产品为数据源,利用像元二分模型研究了2000—2012年植被生长期5—9月份鄂尔多斯禁牧区的植被覆盖度及其时空变化特征。并采用转移矩阵的方法,分析了年度间植被覆盖度高低变化的方向。[结果]研究区植被覆盖度自东向西逐渐减小,东部高于西部,北部高于南部;2000—2012年研究区植被覆盖度总体呈上升趋势,均有低等级植被覆盖度向高等级植被覆盖度转化的趋势;2008—2012年植被恢复状况比2000—2004年和2004—2008年这两个阶段更优。[结论]禁牧政策使研究区植被长势逐年改善,禁牧、休牧政策对草原生态恢复起到了良好的作用。     

新疆策勒县固定沙地骆驼刺带状平茬对地表蚀积变化的影响

[目的]在对新疆策勒绿洲—沙漠过渡带绿洲边缘的固定沙地风蚀风积变化研究基础上,结合地表风速变化分析,探讨骆驼刺带状平茬和地形等对地表蚀积变化影响及其规律。[方法]采用插钎法、地形测量法、风速野外观测等方法。[结果]春季骆驼刺平茬初期,由于地表植被覆盖度大量减少,平茬带和保留带内地表主要以风蚀为主。夏季随着植被覆盖度的增加,地表主要以风积为主,地势较低、植被稀疏地表以轻微风蚀为主,秋季地表植被盖度基本保持最大和稳定,同时风力的减弱明显地减少了地表的风蚀量和风积量,地表主要以风积为主。[结论]春季骆驼刺带状平茬4m保留3m宽度利用方式不能有效地抵御地表风蚀危害,而夏秋季具有较好的防护效益。     

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.     

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.