Models for the establishment and height development of naturally regenerated Pinus sylvestris in Finnish Lapland

Abstract

The study focused on constructing models for the establishment and seedling height development of naturally regenerated seedling stands in the natural regeneration of Scots pine by the seed-tree method in Lapland, northern Finland. Modelling was used to describe the dynamics of the regeneration process and to analyse the principal ecological factors and management activities influencing regeneration success. Models for the density of seedling stands were developed with the generalized linear mixed model method. The most significant variables affecting seedling establishment were elevation, time since the establishment cutting, the interaction of forest site type and site preparation, and stoniness. The results indicated that the average stocking level tends to remain unsatisfactory on moist, fertile site types without site preparation. Seedling height development was modelled as a function of age using the linear mixed model. Age explained 97% of the variance of seedling height. Other independent variables in the model were effective temperature sum, site preparation and the presence or absence of seed trees.     

Genetic control and age‐related changes of juvenile growth characters in Picea abies

In full‐sib families of Picea abies (L.) Karst. (Norway spruce) the dynamics of juvenile growth and the inheritance of the most important growth characters were analysed in six growth periods in climate chambers followed by two additional growing seasons in a nursery. The full‐sib families were of French and North Swedish origin including both within and between provenance crosses. All growth rhythm characters changed over time. For instance, number of days to budbreak increased, whereas days to budset decreased, as growth periods advanced. Concurrent with the changes in growth rhythm, free growth decreased with increasing age. Half of the total variation for different growth rhythm characters within a growth period could in most cases be explained by provenance effects. Early selection is, therefore, meaningful to reduce damage by frost and mortality. Furthermore, the actual distances between family means decreased substantially with increasing age, and the actual length of the shoot elongation period decreased from 31 days during the second growth period to 16 days during the sixth. We suggest therefore that selection together with some treatment in the nursery that alters the growth rhythm of the seedlings are the best ways to increase frost resistance. Tree height was influenced by a set of complex gene actions that changed over time. Provenance effects were important during the first two growth periods. Subsequently, non‐accumulative within provenance family variance took over. If this pattern holds true in general, juvenile selection for height growth in Norway spruce cannot be made as early as that for growth rhythm.     

扭黄茅竞争对金沙江干热河谷区滇榄仁幼苗早期生长的影响

滇榄仁为金沙江干热河谷特有的一级标志种,常与乡土草本植物扭黄茅形成"稀树草丛"景观。长期以来,滇榄仁幼苗极少能在自然群落中成功建植。为了探讨扭黄茅竞争对滇榄仁幼苗早期生长和存活的影响,通过室内盆栽实验人为控制滇榄仁幼苗与扭黄茅之间的竞争强度,研究了扭黄茅竞争对滇榄仁幼苗形态、生物量积累与分配以及叶片数量与大小等特征的影响。结果表明,扭黄茅竞争严重限制了滇榄仁幼苗的早期生长。当存在扭黄茅竞争时,滇榄仁幼苗的生物量分配格局发生了较大变化,根冠比变化范围为0.42 0.62之间。无论滇榄仁幼苗延后定居、同时定居或提前定居,其根系长度以及生物量干质量均会因为受到限制而缩短或减少。然而,定居时间在滇榄仁幼苗存活与生长状况中扮演了一个极为重要的角色。提前定居时,滇榄仁幼苗根冠比远高于同时定居和延后定居时,且其根冠比不受扭黄茅竞争强度的显著影响,表现出了较强的竞争力。     

Underplanting oil palm with cocoa in Ghana

Mature oil palms at the Oil Palm Research Institute at Kusi, Ghana were underplanted with cocoa to study the feasibility of mixed cropping of the two crops under West African conditions. The oil palm trees used in this trial were planted in 1970 and had achieved maximum canopy formation. Three triangular spacings of the oil palms used were 8.7, 9.9 and 10.5 m. The cocoa was underplanted in June 1988 at a spacing of 2.4 m triangular using mixed hybrids. There were no significant differences in oil palm yield between plots with cocoa and the controls. There was no appreciable damage to the cocoa trees from falling palm fronds and fruits during harvesting or pruning. Cocoa seedling growth and yield were significantly better under the oil palm spaced at 9.9 or 10.5 m triangular than under oil palm space at 8.7 m triangular.     

柳树优良品系区域性试验

在柳树引种对比试验的基础上,对所选出的５个生长快,干形好,抗逆性强的品（系）种于１９９６￣１９９８年在全省４个气候类型区进行了区域性试验。结果表明：Ｊ１７２、Ｊ１９４、Ｊ３６９柳除武威试点外,其余各点均表现出极强的速生性,定植３年后最大单株高９．９ｍ,最大胸径１２．８ｃｍ;准噶尔柳和青刚柳在武威和临夏表现出良好的速生性。５个品系在临夏杨柳蛀干害虫为害区,经１０年观察未见蛀干害虫为害。     

沙地油松幼龄林造林试验及其生长状况研究

通过对沙地油松造林试验及其生长状况研究，结果显示：采取覆膜加土措施进行沙地油松栽植，能提高沙地油松的造林成活率。沙地油松在栽植9年以后，胸径平均每年增长0．60cm；高生长在前3年生长缓慢，5年以后树高以每年30-40cm的速度生长。油松主根系长仅为1m；水平侧根多且发达，主要分布在20-40cm深处。     

不同施肥方法对毛竹林冠下多花黄精生长的影响

试验于2013～2015年期间在毛竹林冠下种植多花黄精,连续2年选用氯化钾复合肥采用穴施、环状沟施、放射状沟施3种不同施肥方法和不施肥（对照）进行毛竹林冠下多花黄精生长效果对比试验,结果表明：放射状沟施的多花黄精的各项生长量指标最高,平均保存率、平均地径、平均高度、平均根茎重量分别达94.9%、0.62 cm、65.1 cm、1389.62 kg/hm2;各项指标分别比环状沟施高出4.5%、12.7%、9.2%、16.3%,比穴施高出9.5%、26.5%、26.9%、22.5%,比不施肥（对照）高出24.5%、67.6%、58.8%、82.9%。     

Mixed Forests as a Part of Sustainable Forestry in Southern Sweden

Abstract

We review and discuss the applicability of mixed stands in the context of sustainable forestry in southern Sweden. This is done from a silvicultural perspective regarding aspects such as regeneration, pre-commer-cial thinnings, production, economy, damage and policy implications. The paper is based on literature reviews and on studies performed in southern Sweden or under comparable conditions. After considering the underlying mechanisms, we find that it is possible to establish a mixed stand in the regeneration phase and sometimes even to a lower cost compared to monocultures. To keep the mixture, or to create it, with pre-commercial thinnings is, however, often more expensive. The reviewed studies, together with a new simulation, show that the effect on productivity of mixed stands compared to monocultures is minor. Some positive effects on damage (i.e., decreased levels) in mixed stands have been found. The economy and the policy implications of mixed stand management were found to be dependent on the specific stand and situations. A general finding was that research and knowledge of managing mixed stands, as compared to monocultures, are limited, which in turn could limit the applicability of mixed stand management.     

红松优树子代树高生长的遗传测定

对红松自然分布区内３个亚区、９个地点、１０８株优树子代１０年生树高测定的结果表明,亚区间和家系／地点／亚区间差异显著、极显著,北亚区在带岭生长表现最好;亚区、地点／亚区、家系／地点／亚区间遗传力分别为０８３６、０５３７、０３６５。     

Predicting lumber grade and by-product yields for Scots pine trees

The purpose of this study was to develop models for estimating yields of lumber grades and by-products of individual Scots pine (Pinus sylvestris L.) trees using stem and crown dimensions as explanatory variables. Two separate data sets were used: (1) one simulated by the process-based growth model, PipeQual, which provides information about stem form and branch properties. The model was used to predict the 3D structure of Scots pine stems from thinning regimes of varying intensity and rotation periods and (2) an empirical data set with detailed 3D measurements of stem structure. The stems were sawn using the WoodCim sawing simulator and the yields and grades of the individual sawn pieces, as well as by-products, were recorded. The sawn timber was classified on A, B, C and D-grades for side and centre boards separately (Nordic Timber grading). By-products were pulpwood, sawmill chips, sawdust and bark.