A probability model for root and butt rot in Picea abies derived from Norwegian national forest inventory data

Root rot in Norway spruce (Picea abies (L.) Karst.) causes substantial economic losses to the forestry sector. In this study, we developed a probability model for decay at breast height utilizing 18,141 increment cores sampled on temporary plots of the Norwegian National Forest Inventory. The final model showed a good fit to the data and retained significant relationships between decay and a suite of tree, stand and site variables, including diameter at breast height, stand age, altitude, growing season temperature sum (threshold 5°C), and vegetation type. By comparing model predictions with recorded decay at stump height in an independent data set, we estimated a proportionality function to adjust for the inherent underestimation of total rot that will be obtained by applying a probability model derived from increment cores sampled at breast height. We conclude that the developed model is appropriate for national and regional scenario analyses in Norway, and could also be useful as a tool for operational forestry planning. This would however require further testing on independent data, to assess how well the new model predicts decay at local scales.     

蒙药植物肋柱花种子萌发条件研究

选用不同的发芽床和浸种温度对肋柱花种子进行发芽试验,以期找出适于种子发芽的前期处理条件,为提高其繁殖效率,更为进一步制定种子质量检验方法提供理论依据。采用培养皿发芽法,研究不同发芽床类型和浸种温度对肋柱花种子发芽的影响。结果表明：砂上培养条件下种子发芽率和发芽指数最高,种子腐烂率最低,而砂间培养种子腐烂率最高;40℃浸种温度处理下种子的发芽率最高,随着浸种温度升高,发芽率逐渐降低。肋柱花种子适宜发芽条件为浸种温度为40℃,砂上为种子发芽最适发芽床。     

种球大小及播深对半夏产量与珠芽腐烂率的影响

以清水旱半夏为材料,观察了种球大小及播深对半夏产量与珠芽腐烂率的影响。结果表明,半夏产量与播种深度和种球大小之间具有显著的线性关系,产量与播深呈负相关,与种球大小呈正相关;珠芽腐烂程度随播深、种球的增大而加重。     

Dynamics of large woody debris in small streams disturbed by the 2001 Dogrib fire in the Alberta foothills

We investigated the temporal dynamics of large woody debris (LWD) in five headwater streams before and after the 2001 Dogrib fire in the foothills of Alberta. The density of LWD varied from 5 to 41 logs per 50 m of stream reach and accounted for 19.4 ± 5.1 m³ ha⁻¹ (mean ± standard error) of wood in the riparian zones and 114.1 ± 30.1 m³ ha⁻¹ of wood in the bankfull margins of the stream channel. Individual logs averaged 18.9 ± 1.15 cm in diameter, 5.5 ± 0.7 m in length, and 0.2 ± 0.02 m³ in volume. Logs became significantly shorter in decay classes II–IV. Bridges were longer than partial bridges, which were longer than loose and buried LWD. Individual log volume was greatest for bridges, but not significantly different among other position classes. Bridges and loose LWD contributed little to stream morphology and function; however, 55% of partial bridges and all buried logs contributed to sediment storage, channel armouring, or riffles and pools in the stream channel.     

Leaf litter decomposition of dominant tree species of Namdapha National Park,Arunachal Pradesh,northeast India

Rates of weight loss and nutrient (N and P) release patterns were studied in the leaf litter of the dominant tree species (Ailanthus grandis, Altingia excelsa, Castanopsis indica, Duabanga sonneriatioides, Dysoxylum binectariferum, Mesua ferrea, Shorea assamica, Taluma hodgsonii, Terminalia myriocarpa and Vatica lancefolia) of a tropical wet evergreen forest of northeast India. Nitrogen and phosphorus mineralization rate and decay pattern varied significantly from species to species. In general, the decay pattern, characterized by using a composite polynomial regression equation, exhibited three distinct phases of decay during litter decomposition—an initial slow decay phase (0.063% weight loss day⁻¹), followed by a rapid decay phase (0.494% weight loss day⁻¹) and a final slow decay phase (0.136% weight loss day⁻¹). The initial chemical composition of the litter affected decomposition rates and patterns. Species like D. sonneriatoides, D. binectariferum, and T. hodgsonii with higher N and P content, lower carbon and lignin content, and lower C:N ratio and lignin:N ratio exhibited relatively faster decomposition rates than the other species, for example M. ferrea, C. indica and A. grandis. A slow decay rate was recorded for species such as M. ferrea, C. indica, and A. grandis. The initial N and P content of litter showed significant positive correlations with decay rates. Carbon and lignin content, lignin:N, and C:N showed significant negative correlations with decay rates. Soil total N and P, and rainfall, soil temperature, and soil moisture had positive correlations with decay rates. The rapid decomposition rates observed in comparison with other different forest litter decay rates confirm that tropical wet evergreen forest species are characterized by faster decomposition rates, indicating a faster rate of organic matter turnover and rapid nutrient cycling.     

不同防腐剂处理马尾松边材防腐性能研究

利用扫描电镜(SEM)分析了马尾松边材素样以及6种防腐剂处理马尾松边材在被褐腐菌侵染后的降解情况,采用同步热分析(TGA-DSC)研究了试样热解特性、各反应阶段热动力学参数等。研究表明:当热解温度升高到600℃时,各试样失重率从小到大依次为10%丙酮<10%蒸馏水<马尾松素样<4%樟脑<10%乙酸乙酯<10%甲醇<4%氨溶烷基铜铵(ACQ),最大失重量越大则对应试样防腐剂的防腐效果越好。各试样的热解在低温区(260~380℃)和高温区(380~600℃)分别满足一级和二级反应动力学方程。各试样活化能从一级反应到二级反应阶段均出现不同程度减小。试样浸渍的防腐剂防腐效果越好,其褐腐后的纤维素含量保留得就越多,则对应试样的一级热解反应活化能越高。     

TWP防腐剂处理橡胶木的防腐效果

TWP防腐剂以满细胞法处理的橡胶木,经露天气干2至9个月,用试剂显色法测定药剂透入深度。对4～6cm厚的板材药剂全部渗透,外层15mm硼酸当量(BAE)占木材绝干重0.20%以上。经耐腐性试验测定,用TWP处理的橡胶木属耐腐级,但野外耐腐性较差。此外,还探讨了板材不同深度的耐腐效力     

Breakdown of barrier zones and prediction of the spread of discolouration and decay resulting from stem wounds in Eucalyptus regnans and E. obliqua

In Eucalyptus regnans and E. obliqua a rapid increase in the spread of defects (discolouration and decay) was observed more than 14 years after wounding. This increase was due to a breakdown of the barrier zone and the subsequent spread of defects into wood formed after wounding. Satisfactory relationships predicting defect extent using time since wounding could not be derived.     

Biomass conversion factors (density and carbon concentration) by decay classes for dead wood of Pinus sylvestris, Picea abies and Betula spp. in boreal forests of Sweden

For estimating the amount of carbon (C) in dead wood, conversion factors from raw volume per decay class to dry weight were developed using three different classification systems for the species Norway spruce (Picea abies L. Karst), Scots pine (Pinus sylvestris L.) and birch (Betula pendula Roth and B. pubescens Ehrh) in Sweden. Also the C concentration in dead wood (dry weight) was studied. About 2500 discs were collected from logs in managed forests located on 289 temporary National Forest Inventory (NFI) sample plots and in 11 strips located in preserved forests. The conversion factors were based on an extensive data compilation with a wide representation of different site-, stand-, species- and dead wood properties and were assumed to represent the population of fallen dead wood in Sweden. The density decreased significantly by decay class and the range in density for decay classes was widest for the NFI decay classification system, suggesting this to be the most suitable. The C concentration in dead wood biomass increased with increasing decay class and in average Norway spruce (P. abies) showed a lower C concentration than Scots pine (P. sylvestris). The average dead wood C store of Swedish forests was estimated to 0.85 Mg C/ha.     

Physical and chemical characteristics of the blackened portion of Japanese persimmon (Diospyros kaki)

The heartwood of the Japanese persimmon tree (Diospyros kaki) becomes black on rare occasions and has been highly esteemed as a substitute for ebony. We attempted to clarify how the physical, mechanical, chemical, and biodegradation properties differ between sapwood and blackened heartwood. The specific gravity, equilibrium moisture content, modulus of rupture, and modulus of elasticity in the blackened heartwood were higher, and the loss tangent was lower, than those in sapwood. Furthermore, the blackened portion was more resistant to fungal and termite attacks. A section of heartwood was dark-brown, and the specific gravity and mechanical properties of this portion were slightly lower than those in sapwood. The dark-brown portion was speculated to be a sign or interrupted state of fungal attack. The blackening substance was bound tightly to cell wall components and could not be extracted with any of the organic solvents used. The findings of trace element analysis using inductively coupled plasma-mass spectrometry showed that the boron content was markedly high in the blackened portion. The findings obtained here suggest a role of boron in the antifungal properties and the blackening phenomenon of Japanese persimmon.Part of this work was presented at the 50th Annual Meeting of the Japan Wood Research Society, Kyoto, April 2000