Shift in ectomycorrhizal community composition in Scots pine (Pinus sylvestris L.) seedling roots as a response to nickel deposition and removal of lichen cover

Scots pine seedlings were exposed to wet-deposited nickel (Ni) and removal of lichen cover in a dry heath Scots pine forest. Ni deposition affected the colonization of roots by indigenous ectomycorrhizal fungi in contrasting ways in intact and skimmed quadrats. Highest frequencies of tubercle morphotypes of ectomycorrhiza were found in quadrats exposed to 100 mg m⁻² year⁻¹ Ni in lichen covered treatment, while in skimmed quadrats these peaked after the treatment with 10 mg Ni m⁻² year⁻¹. Removal of the lichen layer increased the value of diversity index (H′) of ectomycorrhizal fungal community, probably due to the increase in the evenness of the morphotype distribution. Lichen removal seemed also to improve the condition of the short roots, as the frequencies of poor and senescent short roots were decreased by the removal.     

MODELING THE HYDROLOGIC IMPACTS OF FOREST HARVESTING ON FLORIDA FLATWOODS1

ABSTRACT: The great temporal and spatial variability of pine flat-woods hydrology suggests traditional short-term field methods may not be effective in evaluating the hydrologic effects of forest management. The FLATWOODS model was developed, calibrated and validated specifically for the cypress wetland-pine upland landscape. The model was applied to two typical flatwoods sites in north central Florida. Three harvesting treatments (Wetland Harvesting, Wetland + Upland Harvesting, and Control) under three typical climatic conditions (dry, wet, and normal precipitation years) were simulated to study the potential first-year effects of common forest harvesting activities on flatwoods. Long-term (15 years) simulation was conducted to evaluate the hydrologic impacts at different stages of stand rotation. This simulation study concludes that forest harvesting has substantial effects on hydrology during dry periods and clear cutting of both wetlands and uplands has greater influence on the water regimes than partial harvesting. Compared to hilly regions, forest harvesting in the Florida coastal plains has less impact on water yield.     

松材线虫对其携带的一株细菌繁殖和致病性的影响

采用黑松(Pinusthunbergii)无菌苗和愈伤组织的接种试验证明,松材线虫携带的洋葱伯克霍尔德氏菌(Burk-holderiacepacia)B619菌株的繁殖及对黑松的致病性受松材线虫的影响.进一步的研究表明,松材线虫的分泌物及死尸均可促进该菌株的生长繁殖和致病作用,且活线虫的促进作用比死尸更加显著,这可能是由于松材线虫提供给该菌株某些重要的营养物质.试验还发现,松材线虫分泌液经高温处理后对致病细菌繁殖的促进活性下降.表5参18     

改性生物炭对Ni~(2+)和Cu~(2+)的吸附

以废弃松木屑为原料制备了生物炭,采用六亚甲基四胺(HMTA)和/或CO2对其进行改性,并将其用于水中Ni2+和Cu2+的吸附。表征结果显示,以HMTA和CO2共同改性的生物炭BC1的表面积最小但表面含氧官能团含量最高。实验结果表明:生物炭经改性后,其吸附性能明显提高,且以BC1为最优;在不调节溶液p H、初始重金属离子质量浓度为50 mg/L、吸附剂加入量分别为2.0 g/L和1.0 g/L、吸附时间分别为360 min和240 min的优化条件下,BC1对Ni2+和Cu2+的去除率分别达到99.81%和95.88%;改性生物炭对Ni2+和Cu2+的吸附过程可以用Langmuir等温吸附模型来描述,而其吸附动力学具有拟二级动力学方程特征。     

改性松木锯末吸附富营养化水体中磷的研究

采用改性松木锯末作为吸附剂,对富营养化水体的模拟水样中的磷进行吸附去除研究。实验结果表明,改性松木锯末对磷的吸附作用主要发生在15 min内,吸附时间超过15 min吸附量趋于平衡状态;p H值由4.0上升到6.0,改性松木锯末对磷的去除率增长较快,由6.0上升到9.0,去除率基本处于稳定状态;磷浓度在0.5~5 mg/L的低浓度范围内,改性松木锯末对磷的去除率均可达到95%以上;改性松木锯末的最佳投加量为0.4 g/L。用Freundlich吸附等温线方程能准确地描述改性松木锯末对磷吸附的特征,吸附等温线方程为q=5.11 C~(1/0.523)。     

Plants with phytotoxic potential: Wollemi pine (Wollemia nobilis)

Herbicide resistance in annual ryegrass (ARG, Lolium rigidum) threatens the quality and yield of winter wheat crops in Australia, prompting research to discover novel natural plant compounds with herbicidal properties. Due to its novel nature and potentially interesting chemistry, the Australian native, Wollemi pine (Wollemia nobilis), was tested for its ability to suppress ARG growth and its feasibility for use in weed control strategies. The leaf extract of Wollemi pine significantly inhibited the growth of ARG and wild radish (Raphanus raphanistrum) in laboratory bioassays at concentrations above 1% extract. In soil trials, the 100% extract (100 g dried plant material/L) inhibited the dry weight of ARG by 25%. The addition of a wetting agent to the extract increased the suppression of ARG to 80% which was as phytotoxic as a 4-fold increase in the extract concentration (“400%” extract). Using bioassay-guided fractionation, the most phytotoxic fraction was identified and further analysed via GC/MS. Several compounds not previously identified in Wollemi pine leaf extracts have been identified, namely, 2-propylphenol, 3,4-dimethoxyphenol, 2-methoxybenzoic acid, vanillyl alcohol and isovanillic acid. These results suggest that Wollemi pine is an important potential source of compounds for the control of ARG and wild radish in winter crops.     

Studies on biological features of band pine forests in the intermontane Minusinsk Depression by methods of gradient analysis

The results of gradient analysis of band pine forests in the Minusinsk Depression are presented. Methods of DCA ordination and correlation analysis have been used to reveal specific features of phytocenotic diversity formation in forest communities growing in azonal habitats of this steppe depression and to test zonal and typological forest units for ecological integrity. The role of directly acting zonal and compensatory ecological factors and specific relationships between types of forest communities and ecological-topographic conditions in the main forms of relief are considered.     

Modelling soil carbon development in Swedish coniferous forest soils—An uncertainty analysis of parameters and model estimates using the GLUE method

Boreal forest soils such as those in Sweden contain a large active carbon stock. Hence, a relatively small change in this stock can have a major impact on the Swedish national CO₂ balance. Understanding of the uncertainties in the estimations of soil carbon pools is critical for accurately assessing changes in carbon stocks in the national reports to UNFCCC and the Kyoto Protocol. Our objective was to analyse the parameter uncertainties of simulated estimates of the soil organic carbon (SOC) development between 1994 and 2002 in Swedish coniferous forests with the Q model. Both the sensitivity of model parameters and the uncertainties in simulations were assessed. Data of forests with Norway spruce, Scots pine and Lodgepole pine, from the Swedish Forest Soil Inventory (SFSI) were used. Data of 12 Swedish counties were used to calibrate parameter settings; and data from another 11 counties to validate. The “limits of acceptability” within GLUE were set at the 95% confidence interval for the annual, mean measured SOC at county scale. The calibration procedure reduced the parameter uncertainties and reshaped the distributions of the parameters county-specific. The average measured and simulated SOC amounts varied from 60 t C ha⁻¹ in northern to 140 t C ha⁻¹ in the southern Sweden. The calibrated model simulated the soil carbon pool within the limits of acceptability for all calibration counties except for one county during one year. The efficiency of the calibrated model varied strongly; for five out of 12 counties the model estimates agreed well with measurements, for two counties agreement was moderate and for five counties the agreement was poor. The lack of agreement can be explained with the high inter-annual variability of the down-scaled measured SOC estimates and changes in forest areas over time. We conclude that, although we succeed in reducing the uncertainty in the model estimates, calibrating of a regional scale process-oriented model using a national scale dataset is a sensitive balance between introducing and reducing uncertainties. Parameter distributions showed to be scale sensitive and county specific. Further analysis of uncertainties in the methods used for reporting SOC changes to the UNFCCC and Kyoto protocol is recommended.