黄土区大型露天煤矿废弃地植被恢复过程中的植被动态

生境再造与植被恢复是黄土区露天矿生态重建的核心 ,其中植被恢复是生态重建的保证。以我国平朔安太堡露天煤矿为例 ,采用野外调查、统计分析相结合的方法 ,对 1 985～ 2 0 0 1年矿区植被恢复过程中的植被动态进行研究。结果表明 :该区的人工植被经过演变 ,植物种的组成发生较大变化 ,由单一的物种组成结构逐渐发展为复杂的物种组成结构 ,并逐渐趋于动态的平衡。通过研究同一植物在不同配置模式下的生长情况 ,以及它们之间的相互影响 ,得出该区人工植被的较好模式为 :刺槐×油松×柠条、刺槐×油松、刺槐×沙棘和刺槐纯林。首次运用多样性指数、生态优势度、均匀度 ,对该区主要复垦植被群落进行分析 ,进一步预测了人工植被的演替方向 :刺槐林→刺槐林、沙棘林→沙棘林、沙棘×刺槐→刺槐、刺槐×油松→刺槐×油松和刺槐×油松×柠条→刺槐×油松×柠条。     

矿山废弃地生态重建研究进展

提出了今后需要加强研究的几个问题 :(1)加强干旱半干旱地区矿山废弃地生态重建的理论与实践研究 ;(2 )筛选与培育耐重金属污染和超富集重金属的植物物种 ;(3)加强西部矿山废弃地共性问题的研究与探讨 ,即如何根据植物与土壤的关系将矿业废弃地划分为不同的类型 ,并在此基础上研究不同类型的废弃地与植物的相互关系 ,进而探讨出必要的人工辅助措施 ,这将是今后矿山废弃地生态重建机制研究的重点。     

Effects of watering regime and depth of burial on seedling emergence of four dominant psammophytes in the Mu Us sandy land, Inner Mongolia, China, and relevance to revegetation of a desertified region

Four dominant psammophyte species are air-seeded in attempts to revegetate the Mu Us sandy land in Inner Mongolia, but seedling emergence is low. This study sought to clarify the behaviour of seedling emergence under different water supply and sand burial regimes to improve the technology of air seeding. Seeds were buried in sand at depths of 0, 0.5, 1, 1.5, 2, 3 and 5 cm and supplied one time with 2.5, 5, 7.5, 10, 15, 20, 30 or 40 mm of water or with 2.5 mm once every 3 days for 30 days. Our study showed that a 0.5-cm burial depth and under 10- to 20-mm single-watering regimes resulted in highest seedling emergence percentage and rate of these four species. All emerged seedlings of Caragana korshinskii , Hedysarum laeve and Artemisia ordosica died under 2.5, 5 and 7.5 mm of watering, respectively, but seedling mortality was <50% when the single-watering regime was >10 mm. In the field, germination of the four species increased from the top of the dune to the middle of the leeward side and then to the bottom. Based on precipitation pattern in the Mu Us sandy land, our study indicates that 0.5-cm burial depth and a single-watering regime of >7.5 mm is the threshold condition for seedling emergence.     

Regenerating Topsoil Functionality in Four Drastically Disturbed Soil Types by Compost Incorporation

The low water-holding capacity and low nutrient levels of roadcuts in northern California cause many of these disturbed areas to remain chronically barren. Yard waste compost was incorporated into four nonvegetated substrates found along roadcuts (decomposed granite [DG], lahar, serpentine, and sandstone) in order to regenerate topsoil infiltration, water-holding capacity, and nutrient availability. Soil physical and chemical properties, as well as the vegetative response of a native perennial grass, were compared between treatments (non-tilled, tilled, and tilled with compost amendment). Tillage and compost addition decreased soil bulk density compared to the non-tilled treatment, and the compost treatment increased the soil carbon and nitrogen contents compared to the non-tilled and tilled treatments. Tillage alone resulted in an increase in saturated hydraulic conductivity in soils that did not contain a large amount of coarse fragments. Tillage also reduced sediment loss in all soils except the DG. Foliar C¹³ content did not predict water stress consistently between treatments. The incorporation of yard waste compost increased plant available water in coarse but not in fine-textured soils, and aboveground plant biomass was significantly greater in the compost treatment than in either of the other treatments. Although the incorporation of yard waste compost generated the greatest revegetation success, tillage alone may be a sufficient treatment if residual soils have adequate nutrient levels.     

Enhancing the early performance of the leguminous shrub Retama sphaerocarpa (L.) Boiss.: fertilisation versus Rhizobium inoculation

We have investigated the effect on growth of fertilisation versus biological nitrogen fixation by rhizobial nodules in Retama sphaerocarpa(L.) Boiss, a leafless leguminous shrub native to the Iberian Peninsula and North-West Africa that has generated interest for revegation of dry Mediterranean habitats. Our main objective was to optimise the formation of root nodules under nursery conditions and to evaluate their influence on the first year of seedling growth in comparison with standard fertilisation. Seedlings of R. sphaerocarpa from two Spanish localities were grown under two levels of fertilisation, and half of each were inoculated with rhizobia isolated from adult Retama, Cytisus and Adenocarpusplants in the field. Although some promiscuity was observed, nodulation was significantly successful with specific rhizobia. At the end of the experiment, highly fertilised plants were taller and heavier and exhibited larger photosynthetic rates than either nodulated or non-nodulated plants under low fertilisation. High fertilisation enhanced seedling growth but inhibited both the nodulation and the nitrogenase activity of the nodules. Thus, physiological differences between nodulated and non-nodulated plants were observed in the low but not in the high fertilisation treatment. Nitrogen uptake and use was enhanced by root nodules, which translated into enhanced photosynthesis and growth. Since inoculation is simple, environmentally friendly and cheap, and nodulated plants are more likely to overcome transplant stress than non-nodulated ones, our results suggest that inoculation together with low, background fertilisation (instead of high fertilisation) should be used when producing high quality seedlings of this autochthonous Mediterranean shrub.     

生物土壤结皮的生态功能

荒漠化土壤或多或少地存在着结皮现象 ,导致结皮的产生有物理、化学和生物的因素 ,其中由不同种类的苔藓、地衣、藻类、真菌以及细菌等生物组成成分与其下层很薄的土壤共同形成的一个复合的生物土壤层 ,也就是所谓的生物土壤结皮在荒漠地区最具生态意义。组成生物土壤结皮的藻类、苔藓和地衣是常见的先锋拓殖植物 ,不仅能在严重干旱缺水、营养贫瘠、生境条件恶劣的环境中生长繁殖 ,并且能通过其生活代谢方式影响并改变环境 ,在防风固沙、防止土壤侵蚀、改变水分分布状况等方面更是扮演着重要角色。土壤的生态演替过程 ,往往是组成物种由低等…     

Effects of substrate coarseness and exposure on plant succession in uranium-mining wastes

Speciesturnover and speed of primary revegetation on uranium-mining spoils aredescribed from the Centre-West part of Spain. Four 21-yr-old successional seresdiffering in substrate-grain size (broken/unbroken waste) andslope orientation (North/South) are compared. Qualitative andquantitative changes in species composition and the time required for recoveryof a terminal stage are analysed, using an undisturbed pasture as reference.Revegetation succession is faster on the broken waste and on the North slope.Moreover, there is a combined effect of both abiotic factors on the pattern andduration of revegetation succession. 195 plant taxa are recorded showing one offour patterns of change: (1) 'pioneer';(2) 'intermediate'; (3) 'latecoloniser'; (4) 'fluctuating'. Multivariateanalysisallows us to identify species following each of these patterns on eachsubstrate.     

Interaction of lime,organic matter and fertilizer on growth and uptake of arsenic and mercury by Zorro fescue (Vulpia myuros L.)

The Sulphur Bank Mercury Mine (SBMM) is an abandoned open pit mine located on the eastern shores of Clear Lake, California. Revegetation efforts have been difficult because the mine-soils at SBMM have low pH, low fertility and elevated As and Hg concentrations. In a greenhouse study, we examined the interactions of lime, N, P and OM additions with respect to plant growth, and As and Hg uptake. Three selected acidic mine-soils from the site containing high (164 mg/kg) (S-H), medium (123 mg/kg) (S-M) and low (31 mg/kg) (S-L) total As content were planted to the Eurasian annual grass, Zorro fescue (Vulpia myuros L.). The Hg concentrations for these soils varied between 1700 and 3000 mg/kg with S-L > S-H S-M. A factorial design used 3 soils, 2 lime, 2 N, 2 P and 2 OM treatments with treatments replicated three times. Multiple regression analyses indicated a strong relationship between As plant uptake, root length density (RLD) and soluble As. A highly significant linear relationship between Hg uptake and RLD for plants growing on the three soils illustrated the importance of plant root characteristics in influencing Hg uptake. Soluble As decreased in the order S-H > S-M > S-L in positive correlation with P and DOC but in inverse relationship to oxalate extractable Fe. Lime and OM additions correlated negatively with soluble Hg and Hg tissue concentration due to either Hg adsorption to OM or to inorganic surfaces. Addition of lime increased dry matter yield and Hg uptake in all three soils.     

Potential Use of Uniola paniculata Rhizome Fragments for Dune Restoration

Abstract Uniola paniculata (sea oats) rhizomes uprooted by hurricanes and deposited as wrack could be salvaged and replanted in dune restoration. To test this unexplored technique, percent tiller emergence was observed for 4 years from U. paniculata rhizomes replanted after submersion in seawater; air exposure of 0, 1, 3, 5, 7, and 11 days; freshwater rinse; and reburial in pots (watered) or on the beach (with or without supplemental water). In addition, U. paniculata rhizomes uprooted by Hurricane Georges were experimentally planted, and effects of soil salinity and moisture on emergence were tested in the greenhouse. Tiller emergence declined with increasing length of air exposure and decreasing size of rhizome. Tiller survival was enhanced by rainfall, rinsing with salt or fresh water during exposure and immediately after planting or supplemental beach watering. Although emergence was not reduced by soil salinity of 1,800 μS/cm, emergence was reduced by soil salinity of 5,800 μS/cm. Across the 4 years of the study tiller emergence from treated rhizomes varied considerably. U. paniculata rhizomes lost bud viability after 3–5 days of beach exposure, unless fresh water from rainfall, wet burlap storage, or watering was applied within 3 days. Bud viability was extended through 11 days when supplied with water. Thus, reburial within 3–11 days after a storm is a viable restoration technique.