Culling phenotypically inferior trees in seed production area enhances seed and seedling quality of <Emphasis Type="Italic">Acacia auriculiformis</Emphasis>

Improvement in seed and seedling quality of Acacia auriculiformis after culling phenotypically inferior trees was studied in a 6-year old seed production area (SPA). A 5-ha plantation was identified, of which 2.3 ha was converted into SPA. The initial stocking, 1 612 trees·ha⁻¹, was thinned down to 982 trees·ha⁻¹ based on growth characteristics. The following fruiting season, seeds were collected from 10 randomly selected trees in culled and non-culled stands, and seed physical characters, germination and seedling traits were assessed. Seed weight, seed thickness and percentage germination increased by 32.1%, 4.43% and 22.37%, respectively in the culled stand compared to the non-culled stand. Culling also increased the speed of germination, seedling dry weight and seedling vigor index. Heritability values were high for seed weight (0.974) and seed thickness (0.948) while medium values were observed for percentage germination (0.577) and total dry weight (0.534). Predicted genetic gain was 11.13% and 11.22% for seed weight and percentage germination, respectively. The actual gain was 32.1, 51.9 and 22.9% for seed weight, percentage germination and total dry matter, respectively. In conclusion, SPAs established by culling inferior trees could serve as sources of good quality seeds for reforestation programs until genetically improved seeds are made available.     

UV老化后氧化铁颜料着色木纤维-HDPE复合材料的性能变化

探讨了氧化铁颜料对木纤维．高密度聚乙烯复合材耐老化性能的改善作用。采用四种常用的氧化铁颜料与木纤维、高密度聚乙烯和其他加工助剂干混,并用自行设计的双螺杆／单螺杆双阶挤出机组制造木塑复合材料。对该木塑复合材料进行人工加速紫外循环老化处理,用CIE1976L^＊a^＊b^＊表色体系和ASTMD790标准分别对老化前后的材料进行测试,结果显示加入颜料以后木塑复合材料的抗弯弹性模量没有明显的变化,但是弯曲强度都有一定程度的提高。经过2000h人工加速紫外老化以后,不论是颜色要是力学性能都发生了明显的变化。铁红和铁黑着色的试样在整个老化过程中表现较好,颜料添加量约2．28％比较适宜。     

Small-scale forestry development in Leyte,Philippines: The central role of nurseries

This paper presents results of survey research into the role of the forestry nursery sector in the development of smallholder forestry in Leyte, Philippines. Seedling production in the province is basically carried out by three categories of nurseries: individual, communal and the government. Seedlings in the government nurseries are primarily raised for free distribution to landholders but the extension scheme fails to reach the majority of the smallholder farmers. Seedling demand of landholders is mostly catered for by the more numerous and accessible individual and communal nurseries. However, problems of capital outlay, sources and supply of germplasm, technical knowledge in nursery management for both timber and fruit trees and low sales are among the major impediments in the sustainability of small-scale nurseries. Most of the communal nurseries fail to sustain the operation after the withdrawal of supporting agencies. Knowledge on site-species matching is needed not only by small-scale nursery operators but also by the managers of government nurseries. It is concluded that the seedling industry in the province is not well established and there is a need to organise better the overall nursery system so as to improve the availability of seedlings and promote appropriate site and species combinations.     

Cattle distribution and behavior in southern-pine silvopasture versus open-pasture

Shade present in silvopasture systems could reduce heat stress associated with microclimatic conditions that characterize warm-weather portions of the year on the Coastal Plain of the Southeast USA. Objectives of this research were to: (1) quantify diurnal distribution patterns of landscape use and behavior of cattle in loblolly-pine (Pinus taeda) silvopasture versus open-pasture landscapes, and (2) relate observed differences in landscape use and cattle behavior patterns between the two pastures to differences in microclimatic conditions, and forage quantity and quality. The research was conducted in Chipley, Florida USA within a 5-ha cell of a loblolly-pine-bahiagrass (Paspalum notatum) silvopasture (tree age 20 year), and a 5-ha open bahiagrass pasture with unlimited access to an adjacent 1-ha wooded area. One-day observations of diurnal distribution and behavior of cattle were conducted in March, June, and September 2007; microclimatic conditions were measured, and forage quantity and quality were estimated within each landscape. Cattle utilized the landscape more evenly in the silvopasture versus the open-pasture and this difference was mainly attributed to reduced solar radiation recorded in the silvopasture. Grazing was the dominant behavior in the silvopasture while loafing was dominant in the open-pasture. Shade present in silvopasture appeared to reduce heat stress for cattle grazing during warm-weather portions of the year on the Coastal Plain of the Southeast USA. Further study is needed to determine how this reduction in heat stress influences cattle performance in southern-pine silvopasture, and the nature and extent of the interactions among animal distribution and behavior, microclimatic conditions, and forage characteristics in these systems.     

Influence of characteristics and extension of a forest road network on the supply cost of forest woodchips

A forest road network in northeastern Italy was explored by field investigations to evaluate the cost of covering annual demand of woodchips according to three scenarios. The first scenario (A) considered the current extent of the forest road network (mainly tractor road) and the associated qualitative characteristics; the second scenario (B) evaluated the possibility of increasing the availability of the technical amount of forest biomass by extending the forest road network by three tractor roads (3.9 km); the third scenario (C) considered the impact on woodchip supply of converting 9.3 km of tractor forest road into truck forest road. At a woodchip price of 60 € t⁻¹, the cost–supply curve of scenario C indicated a woodchip amount of 2886 t year⁻¹, which was 561 t year⁻¹ greater than scenario A and 161 t year⁻¹ greater than scenario B.     

Is it necessary to change the number of samples for different forest types when evaluating plant species richness? A case study in a forested landscape in central Japan

We demonstrate a method for evaluating the appropriate number of samples required to estimate plant species richness in different forest types within a forested landscape. In each of 36 plots (0.1 ha each) from 5 forest types (deciduous broad-leaved secondary forest and 4 categories of coniferous plantation classified according to stand age) in central Japan, 40 quadrats of 1 × 1 m were set in a regular pattern; the total number of quadrats in each forest type ranged from 200 to 400. In each plot, the number of observed species in 40 quadrats ranged from 60 to 80% of the number of species estimated by the rarefaction method for each forest type. Sampling 30 quadrats detected approximately 90% of the observed species in each plot that were detected using 40 quadrats. In specific functional groups (i.e., tall trees and weed species), the ratios of both tall trees and weed species to all species were at equilibrium for 30 or more quadrats. For fewer than 30 quadrats these ratios were highly variable. No significant differences were found among forest types in the ratio of the observed number of species in each plot to the estimated number of species calculated using the rarefaction method, and in sampling efficiency estimated by use of non-parametric estimators. We concluded that the number of samples does not need to be changed according to forest type or plantation stand age in the studied landscape, and that the method used to evaluate the number of samples could be useful.     

Environmental influence on urban rodent bait consumption

Anticoagulant poisoning is a common rodent control method in urban areas, but rodents may exhibit versatile feeding behavioural habits in varying environmental conditions. This study has been conducted to determine those environmental factors that could directly influence bait consumption and which therefore may affect an urban rodent control plan carried out with chemical methods. In the city of Bologna (Italy), 2500 bait stations have been monitored in various urban biotopes and the bait consumption studied in relation to several environmental factors, using both bivariate and multivariate analysis. Results reveal that the rodent patch distribution triggers the avoidance of baits placed outside of their home-range, hence the importance on bait placement. The logistic regression model confirms that vegetation, harbourage and water supplies are important variables in determining bait consumption, probably because they may spatially and temporarily facilitate the agoraphobic rodent movement, ensuring undisturbed bait consumption. The role of predators (dogs and cats) and food competitors (synanthropic birds) remains insignificant. However, bait eating invertebrates may consume part of the bait. For a proper rodent control plan the first real need is to minimize the alternative food sources, which may compete with baits. Weather conditions in which rodents could possibly pass unnoticed (fog and rainfall) may encourage bait consumption, vice versa with a cold climate. The considered environmental factors have satisfactorily explained bait consumption, highlighting the importance of human influence. The study of environmental factors may be useful in categorizing several site-specific conditions where rodent control efforts should be targeted, enhancing any intervention by matching the correct and specific strategy.     

Environmental influences on post-harvest natural regeneration of <Emphasis Type="Italic">Pinus pinaster</Emphasis> Ait. in Mediterranean forest stands submitted to the seed-tree selection method

Research on natural regeneration is crucial for the development of sustainable forestry practices, in light of the global climate changes taking place. In this study, 151 plots were sampled in six Pinus pinaster stands that were naturally regenerated by the seed-tree method in Mediterranean forests in central Spain. The objectives of the survey were to study the suitability of different forest stands designated for natural regeneration as well as to analyse seedling establishment and the relationship between regeneration and different site factors. Analysis of variance and multivariate analysis with canonical ordination techniques were employed. Full and partial redundancy analyses on a correlation matrix were used to carry out a direct gradient analysis of regeneration density as a function of site factors. Nearly all stands presented seedling densities over 2,000 seedlings ha⁻¹ and were thus found to be suitable for natural regeneration of Pinus pinaster by the seed-tree selection method. Significant variables that best explained total seedling and viable seedling density were spring and autumn precipitation of the year prior to establishment, spring and summer precipitation of the year of establishment and percentage cover of litter. There were no signs of competition between shrubs and seedlings, but a negative significant correlation with grass cover was observed. Pinus pinaster natural regeneration was successful with the seed-tree method, although it appeared to be highly dependent on climate and stand conditions.