黄土丘陵区不同植被恢复模式对沟谷地土壤碳氮磷元素的影响

选取黄土丘陵区3种代表性植被恢复模式的沟谷地样地:人工刺槐(Robinia pseudoacacia)林沟谷地(G-Rp),人工柠条(Caragana korshinskii)灌丛沟谷地(G-Ck)和天然草地沟谷地(G-Ng).通过分析沟谷地5个坡位样带的土壤样品,评价了不同植被恢复模式对沟谷地土壤碳氮磷元素的影响.结果表明:3种植被恢复模式对沟谷地土壤有机碳和全氮的含量及储量具有显著的改善作用,对土壤全磷含量及储量略有减少的影响,其中柠条灌丛沟谷地土壤磷相对于对照(坡耕地)减少达显著差异(P<0.05);土壤碳氮磷的含量及储量在沟谷地的空间分布存在显著差异(P<0.05),总体呈由上到下递增趋势(除G-Rp沟底);沟谷地土壤碳氮元素间呈正向和极显著的线性相关关系(P<0.0001).在黄土丘陵区沟谷地地貌单元实施植被恢复,可显著地提高沟谷地土壤的碳汇和氮素储量.     

植被恢复对建筑垃圾填埋场土壤理化性质变化的影响研究

对徐州市九里山建筑垃圾填埋场人工造林恢复植被后的土壤理化性质进行研究的结果表明,恢复样地土壤孔隙度增大,土壤密度减小,土壤pH呈下降趋势,土壤有机质和土壤全氮水平显著增加。但土壤全磷和有效磷含量随植被的生长呈降低趋势,原因可能为当土壤中有效磷含量不能满足植物根系吸收时,植物根系会分泌一些有机酸来活化土壤中的磷元素供植物吸收。土壤全钾含量没有显著差异,速效钾含量随着植被的生长而降低。     

Enhancement of revegetation on construction fill by fertilizer and topsoil application: Effect on mycorrhizal infection

The influence of topsoil and fertilizer application on denuded road construction sites was evaluated to assess its contribution to improvement of vegetation re-establishment. the study sites were within a mixed hardwood and conifer forest on crushed, unweathered subsurface material with low fertility and low biological activity. Topsoils were removed from the site, stockpiled and reapplied to the site after construction. the effect of topsoil amendment on plant growth, soil fertility, mycorrhizal infection and an index of microbial biomass were measured in field and greenhouse experiments. Plant growth on the topsoil amended field plots were greatly increased relative to treatments with fertilizer but no topsoil. Three years after establishment, dry weight production on the plots without topsoil treatment was about 40 per cent of the plots treated with topsoil. Greenhouse experiments were designed to compare fresh, dried and stockpiled topsoil. These experiments indicated that storage of the harvested topsoil for five months in a stockpile had minor effects on plant growth, soil fertility, mycorrhizal infection and microbial biomass. Topsoil volumes had to exceed 20 per cent of the total soil volume to achieve statistically significant benefits and higher ratios showed greater benefit. the percentage of mycorrhizal infection was greatest in topsoil treatments without fertilizer. the addition of fertilizer increased growth but reduced the percentage of roots forming mycorrhizae. When the total weight of infected roots was calculated, however, infection was found to be greatest with a moderate level of fertilizer (equivalent to approximately 27 kg N ha⁻¹ and 39 kg P ha⁻¹), and was less in both higher fertilizer treatments and in unfertilized treatments. Topsoil amendment increased microbial biomass nitrogen but fertilizer treatment did not.     

Salinity tolerance and mycorrhizal responsiveness of native xeroriparian plants in semi-arid western USA

Restoration of salt-affected soils is a global concern. In the western United States, restoration of salinized land, particularly in river valleys, often involves control of Tamarix, an introduced species with high salinity tolerance. Revegetation of hydrologically disconnected floodplains and terraces after Tamarix removal is often difficult because of limited knowledge regarding the salinity tolerance of candidate native species for revegetation. Additionally, Tamarix appears to be non-mycorrhizal. Extended occupation of Tamarix may deplete arbuscular mycorrhizal fungi in the soil, further decreasing the success of revegetation efforts. To address these issues, we screened 42 species, races, or ecotypes native to southwestern U.S. for salinity tolerance and mycorrhizal responsiveness. As expected, the taxa tested showed a wide range of responses to salinity and mycorrhizal fungi. This variation also occurred between ecotypes or races of the same species, indicating that seed collected from high-salinity reference systems is likely better adapted to harsh conditions than seed originating from less saline environments. All species tested had a positive or neutral response to mycorrhizal inoculation. We found no clear evidence that mycorrhizae increased salinity tolerance, but some species were so dependent on mycorrhizal fungi that they grew poorly at all salinity levels in pasteurized soil.     

不同植被措施下排土场边坡细沟发育时空特征

为明确不同恢复年限植被措施对煤矿排土场边坡水土流失的防治效应,采用样方调查法,以内蒙古准格尔旗永利煤矿矿区排土场边坡为研究对象,以裸露边坡(CK)为对照,研究不同恢复年限(1a、3a、5 a)的沙柳方格+沙棘+沙打旺(SHA)和沙柳方格+沙打旺(SA)2种措施对细沟发育的影响。结果表明:(1)1a时CK、SHA与SA措施细沟宽度均集中分布在4～8 cm,细沟深度均集中分布在2～4 cm;3 a时CK、SHA与SA措施细沟宽度则集中分布在4～8 cm、8～12 cm、4～8 cm,细沟深度均集中分布在4～6 cm;5 a时CK与SHA措施细沟宽度均集中分布在8～12 cm,而细沟深度则集中分布在4～6 cm和8～14 cm;(2)CK(1～5 a)、SHA措施(1～5 a)和SA措施(1～3 a)的细沟平均宽分别为7.57～11.35 cm、7.58～13.31 cm和5.57～6.14 cm,细沟平均深分别为3.38～6.23 cm、4.19～10.34 cm、2.59～4.24 cm,三者的细沟平均宽深比分别为2.39、2.12和2.05,平均细沟密度分别为1.52～5.25 m·m...     

Plant and spider communities benefit differently from the presence of planted hedgerows in highway verges

Road verges should play a crucial role as a refuge for native flora and fauna in human dominated landscapes. However, the influence of construction choices, such as plantation of woody species, on the biodiversity supported by roadsides has received little attention, although the presence of hedgerows in roadsides is likely to enhance their role as a refuge, notably for woodland species. Using standardised methods, we assessed the impact of planted hedgerows on two taxonomic groups (plants and spiders) inhabiting highway verges within an intensive agricultural landscape. We examined community richness, taxonomic and functional composition in sites with and without planted hedgerows. At the site level, the response of plant and spider communities to the presence of planted hedgerows differed markedly: hedgerows were associated with significantly higher plant richness (higher α-diversity), but similar spider richness. Plant communities in sites without hedgerows appeared as a subset of communities in sites with hedgerows, whereas spider communities in non-planted sites were complementary to that of planted sites (increased β-diversity). The presence of planted hedgerows was also associated with increased taxonomic and functional trait diversity at the landscape level (γ-diversity), through an increased β-diversity in both plants and spiders. Our results thus suggest that a mosaic of planted hedgerows and grassland habitats is crucial for the maintenance of biodiversity at a landscape scale. By providing information for road practitioners and policy makers regarding their potential impact on biodiversity, these results have important direct implications for the management of road networks.     

Mineral composition of iron chlorotic citrus limon L. leaves

A field experiment was conducted to evaluate the effect of iron (Fe) chlorosis on the mineral composition of lemon tree leaves cultivated in calcareous soil in the region of Murcia, Spain. A Fe‐polyflavonoid was employed as fertilizer to control Fe deficiency. The evolution of the leaf content in Fe, potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), phosphorus (P), manganese (Mn), and zinc (Zn) was monitored during all the sampling cycle. A high correspondence between total Fe and chlorophyll content could be appreciated. A multivariance analysis was performed with the data obtained, showing that Fe was correlated with P, Mn, and K.     

Properties of Urbic Anthrosols from an abandoned shunting yard in the Ruhr area, Germany

The soil conditions of an abandoned shunting yard in the Ruhr area were studied to find the most important factors influencing plant growth and nutrient cycling. The chemical and physical conditions of five Urbic Anthrosols with different development histories were compared with those of a nearby Calcic Cambisol under agricultural use. In the second half of the 19th century, the ground level of the shunting yard site was raised about 2 m. The soils are now mainly Regosols, mostly well drained in the topsoil. The coarse material contents (>2 mm), which are up to 100% in base layers of railway tracks, and the quality of the man-made substrates (crushed rock, slags, ashes, coke) are the most important factors influencing plant growth. Poor physical structure and low contents of fine fraction (<2 mm) lead to low water storage. Together with a low available nutrient stock, these properties lead to poor establishment of vegetation. The burning of coal by steam engines produced highly polluted ashes that fill pore spaces in the railway ballast layers. All the investigated fine substrata of the shunting yard layers exhibit a higher magnetic susceptibility than the rural soil. The ashes still contain unburned coal so that, although the total organic C content of the man-made soils reaches 37%, the wide C:N ratio does not indicate the actual quality of humic substances. The acid neutralization potential of the topsoil layers of the shunting yard will be consumed by acidic atmospheric deposition within a few decades, whereas in the surrounding Calcic Cambisols, it will take more than a thousand years. This may cause further problems of groundwater quality, as the heavy metals will become more soluble. The low soil quality makes such sites suitable for vegetation species that cannot compete in the surrounding very eutrophic agricultural landscape.     

Edge geometry influences patch-level habitat use by an edge specialist in south-eastern Australia

We investigated patterns in habitat use by the noisy miner (Manorina melanocephala) along farmland-woodland edges of large patches of remnant vegetation (>300 ha) in the highly fragmented box-ironbark woodlands and forests of central Victoria, Australia. Noisy miners exclude small birds from their territories, and are considered a significant threat to woodland bird communities in the study region. Seventeen different characteristics of edge habitat were recorded, together with the detection or non-detection of noisy miners along 129 500-m segments of patch edge. Habitat characteristics ranged from patch-level factors related to patch-edge geometry to site-level floristic factors. Backward (stepwise) logistic regression analyses were used to identify habitat characteristics that were associated with the occupancy of a site by noisy miners. After accounting for the effects of spatial autocorrelation on the occurrence of noisy miners along edges, we identified projections of remnant vegetation from the patch edge into the agricultural matrix (e.g., corners of patches, peninsulas of vegetation) and clumps of trees in the agricultural matrix within 100 m of the edge as significant predictors of the occupancy of edges by noisy miners. This relationship was also confirmed in two other geographically and floristically distinct habitats within Victoria. The use of edges with projections by noisy miners may confer advantages in interspecific territorial defence. In light of these results, we advocate revegetation strategies that attempt to enclose projections within 100 m of the edge, with fencing placed out to this new boundary, to reduce the likelihood of colonisation and domination of an edge by noisy miners. Our study highlights the need for greater consideration to be given to the patterns in habitat use by aggressive edge specialists, particularly in relation to patch-edge geometry and other human-induced components of landscapes.     

Simple modelling to assess if offsets schemes can prevent biodiversity loss, using examples from Australian woodlands

Offset schemes are advocated as a way that continued development and environmental restoration can be achieved concurrently. We used a simple modelling approach to evaluate proposed offsets schemes, with scenarios that required offsetting the impacts of clearing woodlands either by revegetation of cleared land or by improving the habitat value of degraded woodland. Each simulation used the attribute table of a single GIS polygon layer to obtain data and record results. We investigated the likely consequences of these schemes for three groups of species with different foraging resource requirements: shrub-dependent; canopy-dependent and old tree-dependent. Only the shrub-dependent group, whose requirements could be rapidly grown, saw increases in suitable habitat in the landscape within our 30 year simulations. The habitat of the canopy-dependent group initially declined but began to increase towards the end of some simulations, while the old tree-dependent group’s habitat declined. When a simple measure of spatial configuration was considered further differences between the schemes were highlighted. The simulation results demonstrate that assessing only the eventual benefit score of a scheme can hide the losses sustained by some elements of biodiversity. We recommend this type of simple modelling approach as the first step in determining whether a proposed offsets scheme is worth investigating further. In particular, the ability to represent the scheme’s predicted consequences as maps and graphs assists decision makers in judging whether the scheme has sufficient merit to warrant a full assessment and subsequent implementation; or needs some adjustments to achieve its aims, or is seriously flawed.