洞庭湖湿地生态系统的保护与管理

为了维护洞庭湖湿地生态系统的自然平衡,使湿地生态系统和资源得到合理的利用与开发。本文阐述了洞庭湖区的湿地资源特征、自然保护区的情况,采用了SWOT分析法对加强洞庭湖湿地生态系统保护与管理进行了分析并针对洞庭湖区的湿地生态系统现状,提出了湿地生态系统保护与管理的建议。     

黄河三角洲自然保护区植被调查报告

黄河三角洲自然保护区植被调查报告赵延茂，吕卷章（山东黄河三角洲国家级自然保护区管理局）马克斌（东营市林业局）山东黄河三角洲国家级自然保护区（以下简称保护区）是一个新生的湿地生态系统。作为这一湿地生态系统基本而重要组成部分的植物资源，不仅可为鸟类提供食...     

黄河三角洲原生湿地存在问题及保护对策

1　湿地资源概况黄河三角洲是我国的三大三角洲之一 ,是继长江三角洲、珠江三角洲开发之后待开发的重要区域。由于黄河携带大量泥沙填海造陆 ,黄河三角洲形成了大面积宝贵的原生湿地 ,总面积约 45 0 0ｋｍ2 ,其中2 0 0 0ｋｍ2 的潮上带湿地 ,10 0 0Ｋｍ2 潮间带湿地和15 0 0ｋｍ2 的潮下带湿地。 1992年 10月经国务院批准 ,在原生湿地最具代表性的区域设立了 15 30ｋｍ2 的自然保护区。黄河三角洲自然保护区是以保护黄河口新生湿地生态系统和珍稀濒危鸟类为主体的湿地类型保护区。经国内外著名专家认证 ,该保护区是中国暖湿带保存最完整、最…     

黄河三角洲建立湿地生态补偿机制问题的探讨

湿地是重要的生态系统,其特殊的地位和作用受到越来越多的关注,建立湿地生态补偿制度将成为保护湿地的长效机制.本文以山东黄河三角洲国家级自然保护区为研究对象,概述了保护区基本情况和目前存在的主要问题,即工农业生产活动频繁,湿地退化严重,可持续发展能力较弱,保护管理水平有待提高.阐述了建立湿地生态补偿机制对保护湿地,持续利用湿地资源,充分实现公共资源的生态服务价值,达到可持续发展的必要性;并针对山东黄河三角洲国家级自然保护区的实际情况,提出建立相关法规条例,创建适合本地区的湿地生态补偿机制;同时强调加强监督管理和宣教工作,促进公众参与.     

加强黄河三角洲湿地保护 努力建成国际重要湿地保护的典范

黄河三角洲湿地是中国暖温带保存最完整、最广阔、最年轻的湿地生态系统,是东亚至澳大利亚、东北亚内陆和环西太平洋鸟类迁徙的重要中转站、越冬地和繁殖地。为了加强黄河三角洲湿地的保护,东营市人民政府于1990年12月批准建立黄河三角洲市级自然保护区;1991年11月被山东省政府批准为省级自然保护区;1992年10月被国务院批准为国家级自然保护区。     

加强黄河三角洲湿地保护努力建成国际重要湿地保护的典范

黄河三角洲湿地是中国暖温带保存最完整、最广阔、最年轻的湿地生态系统,是东亚至澳大利亚、东北亚内陆和环西太平洋鸟类迁徙的重要中转站、越冬地和繁殖地。为了加强黄河三角洲湿地的保护,东营市人民政府于1990年12月批准建立黄河三角洲市级自然保护区;1991年11月被山东省政府批准为省级自然保护区;1992年10月被国务院批准为国家级自然保护区。山东黄河三角洲国家级自然保护区位于山东省东营市境内的黄河入海口处,是以保护黄河口新生湿地生态系统和珍稀濒危鸟类为主体的湿地类型自然保护区,总面积15.3万公顷,其中核心区5.94万公顷,缓冲区1.12万公顷,实验区8.24万公顷。其区域分两部分：南部区域位于现行黄河入海口,面积10.45万公顷;北部区域位于1976年改道后的黄河故道入海口,面积4.85万公顷。     

湿地自然保护区调查技术与方法

本文介绍了当前湿地学科的体系框架、优先研究领域,着重概述了湿地自然保护区的相关调查技术,包括湿地自然状况、湿地野生动物资源、湿地植被和湿地周边状况利用保护调查技术等.     

黄河三角洲自然保护区原生湿地生态系统演化规律研究

黄河三角洲自然保护区是以保护黄河口新生湿地生态系统和珍稀濒危鸟类为主体的国家级自然保护区,自1992年10月经国务院批准建立以来,保护区加大科研力度,实行依法治区,加强湿地生态系统的恢复和重建,使这片新生湿地得到了有效保护,保护了这片新生湿地生态系统的典型性、完整性和科学性。但由于多年来油田在自然保护区实验区及毗邻区的开发,保护区的生态环境面临一定的负面影响,如不采取措施,长此下去,将会产生一系列生态和环境问题,使区域脆弱的生态环境更加脆弱。为了保护好这块国际重要湿地,多年来,我们加强了自然保护区生态环境演化监测…     

广德湿地保护分析与展望

通过对广德县湿地资源的调查、摸底、了解和分析,基本掌握了广德县湿地的生态环境、湿地资源类型、面积及自然分区,阐述了广德湿地自然保护区、湿地公园发展历程、发展现状、经验和问题,在分析广德县湿地资源及保护管理基本概况的基础上,对广德县湿地资源如何进一步加强保护管理拟定了短期、中期和长期目标,展望了广德县湿地资源保护和管理的美好前景,同时也为加大对广德县湿地资源保护和管理的力度,奠定和夯实了理论基础.     

泉州湾湿地生态旅游资源保护与开发刍议

泉州湾湿地是我国东南沿海典型湿地类型之一,其特殊的地理、自然条件和人类长期活动形成独特的湿地旅游资源,湿地多样性明显,但也伴随人为强度干预导致的景观脆弱性。为此,本文提出泉州湾湿地的保护和开发思路:①进行泉州湾湿地资源的本底调查,申报国家级湿地自然保护区;②制定湿地生态旅游发展规划,并逐步建立和完善生态旅游服务网络体系;③政府决策与社区参与相结合;④加强湿地旅游管理和环境影响评价。总之,泉州湾湿地旅游开发必须定位在生态旅游资源的保护开发,改变以往只重视其生产功能而忽视其生态、社会、文化功能的倾向,实现湿地资源的可持续利用。     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.     

qPCR quantification of Ophiognomonia clavigignenti‐juglandacearum from infected butternut trees under different release treatments

The use of a molecular assay for quantifying conidia of Ophiognomonia clavigignenti‐juglandacearum, the fungal pathogen responsible of butternut canker, was investigated. Purified DNA from conidia collected on glass fibre filters of a passive rain collectors was quantified using a TaqMan real‐time quantitative polymerase chain reaction (qPCR) assay. The qPCR assay could specifically discriminate the target species from all other North American known species of Ophiognomonia, and it was sensitive enough to repeatedly detect one conidium. A linear relationship between numbers of conidia and qPCR C_t values was determined, and used to assess the sporulation of the pathogen under trees that were released to promote their vigour. In total, 977 samples of field‐captured conidia from 49 trees, at two locations, and from two successive growing seasons were analysed. No significant difference of sporulation was observed under control and release treatments. However, our results demonstrated that qPCR assay was reliable for detecting and quantifying O. clavigignenti‐juglandacearum from environmental samples, which will be useful to assess further control methods for this disease.     

The potential of alley cropping in improvement of cultivation systems in the high rainfall areas of Zambia I. Chitemene and Fundikila

Three trials investigating the potential of alley cropping to improve the traditional systems of cultivation, chitemene and fundikila, in the Northern Province of Zambia are described. Flemingia congesta, Tephrosia vogelii, and Sesbania sesban, were grown in association with finger millet, groundnut, cowpea, and maize in various traditional cropping sequences. The indigenous species Tephrosia vogelii and Sesbania sesban were not able to withstand repeated pruning and the long following dry season, and were replaced with Calliandra calothyrsus, and Cassia spectabilis.Over a four year period, there was no benefit by alley cropping with any of the tree species on crop yields, and yields in alley crop treatments even dropped significantly below the control treatments in the fourth year, casting doubt on the potential of alley cropping for sustainable production. There was also no consistent effect on soil chemical characteristics in any of the trials. It was suggested that this lack of beneficial response to alley cropping was due to low tree biomass production low quality of prunings, and an inappropriate cropping sequence. There was no evidence that alley cropping contributed to enhanced nutrient recycling, despite substantial localised pools of soil nutrients, particularly in the chitemene, with which recycling could potentially occur.     

Toxicity of biocide GCSC-BtA on arthropod pests under different temperature conditions

The present research dealt with the toxicity of GCSC-BtA (Germany–China Scientific Cooperation-Bacillus thuringiensis-Abamectin), a new type biocide developed by conjugating a toxin from Bacillus thuringiensis (B.t.) with Abamectin from Streptomyces avermitilis, on arthropod pests under different temperature conditions. The results showed that GCSC-BtA possessed higher toxicity than B.t. crystal, Abamectin or Cypermethrin, with pest mortalities of 97.9, 93.7, 96.4, 82.3 and 96.7% for Tetranychus cinnabarinus (Boisd.) (Acari, Tetranychidae), Frankliniella occidentalis Pergande (Thys., Thripidae), Aphis fabae Scopoli (Hom., Aphididae), Plutella xylostella (L.) (Lep., Plutellidae) and Cameraria ohridella Deschka et Dimić (Lep., Gracillariidae), respectively. Toxicities of GCSC-BtA to T. cinnabarinus and P. xylostella decreased significantly at the older developmental stage with an exception that egg stage had the highest tolerance, in which LC₅₀s of GCSC-BtA were 0.0001, 0.0019 and 0.0708 mg/ml for nymph, adult and egg of T. cinnabarinus, and that 0.0399, 0.2035 and 0.9033 mg/ml for the 2nd instar larvae, 4th instar larvae and egg of P. xylostella, respectively. Also, the biocide was more effective to the lower stage of A. fabae than the higher one with LC₅₀s of 0.0023, 0.0086 and 0.0171 mg/ml against 1st instar nymph, 3rd instar nymph and adult, respectively. In general, toxicity of the new type of biocide was positively related to temperature against all the tested pests, except against T. cinnabarinus, where it was almost similar at the three temperature conditions. GCSC-BtA displayed significantly lower toxicities at 15/20°C than 20/25°C or 25/30°C against F. occidentalis, A. fabae, P. xylostella and C. ohridella. However, no significant difference was found in the toxicities against F. occidentalis, A. fabae and C. ohridella above 20°C, whereas toxicity against P. xylostella increased as temperature raised. Therefore, to achieve higher efficacy in the field, application rate and time should be devised according to these factors.