共查询到20条相似文献，搜索用时 31 毫秒
1.
| – |
• Multivariate statistical analysis was used to define different developmental stages for stone pine (Pinus pinea L.) considering tree size and cone production, without site-specific information. 相似文献
2.
| – |
• Construction cost (g glucose g−1), chemical composition and morphology of leaves of beech (Fagus sylvatica L.) and two co-occurring valuable broadleaved species (sycamore maple — Acer pseudoplatanus L. — and ash — Fraxinus excelsior L.) were investigated along a horizontal light gradient (3–60% of above canopy radiation) and from top to bottom within the
crowns in a fairly even-aged mixed-species thicket established by natural regeneration beneath a patchy shelterwood canopy. 相似文献
3.
| – |
• Increased mortality of Scots pine (Pinus sylvestris L.) and spreading of deciduous trees are observed in the Swiss Rhone valley. Previous research identified climate change
effects as main drivers of this trend. On the local scale, we hypothesize that legacies from past anthropogenic disturbances
are superimposed on climate effects. 相似文献
4.
| – |
• This study investigated the short-term changes in neutral genetic variation that would occur if a mature, second-growth,
black walnut (Juglans nigra L.) stand was harvested following either a diameter-limited or value-limited cutting regime. 相似文献
5.
| – |
• Considerable progress has been made recently to promote glue-laminated beams of European beech (Fagus sylvatica L.) for load-bearing structures in engineering. However, further investigations into the bond durability are required. The
objective of the present study was to analyse material and manufacturing factors and their combination to improve the resistance
in delamination tests as required for the use in building service class 1. 相似文献
6.
| – |
• We studied the differences in branch characteristics along the stems of six different genetic entries of 20 year old Scots
pines (Pinus sylvestris L.) grown at different spacing (current stand density range 2000–4000 trees ha−1) in central Finland. Furthermore, we studied the phenotypic correlations between yield, wood density traits and branch characteristics.
All the genetic entries had Kanerva pine (plus tree S1101) as a father tree, whereas the mother tree represented Finnish plus
trees from southern, central and northern Finland. 相似文献
7.
| – |
• We present the results of a two-year (2007–2008) greenhouse study investigating the effect of water availability and nitrogen
fertilization on the growth, biomass partitioning, and foliar nutrient content of Abies fraseri (Pursh) Poir. 相似文献
8.
| – |
• Vène wood (Pterocarpus erinaceus Poir.) is currently the favorite wood for manufacture of xylophone in Mali. A dynamic analysis method with free boundary
conditions, known as BING, was used to determine the main acoustic properties: specific dynamic modulus (E
L
/ρ), damping coefficient or internal friction (tan δ), sound radiation coefficient (SRC) and peak response (PR). 相似文献
9.
| – |
• The Spanish fir (Abies pinsapo Boiss.) is a conifer endemic to southern Spain and belongs to a Mediterranean basin group of firs considered to be relict.
Megagametophyte storage proteins are a useful tool for the evaluation of genetic variability due to the haploid nature of
megagametophytes in conifers. 相似文献
10.
Pinus brutia Ten. subspecies brutia, which occurs in the Eastern Mediterranean region, is the main forest species in Syria and important for multi-purpose forestry.
In this study, 6,631 10-year past growth diameter increment measurements were taken in 83 temporary sample plots. The current
breast height diameter of all trees was measured and a sample of trees was measured for height and age. The plots were placed
so as to capture the whole range of variation in site quality, stand age and stand density. The data were used to develop
the following models:
| •
|
Dominant height model: the guide curve method was used to fit an anamorphic site index model between stand age and dominant
height. 相似文献
11.
| – |
• Paternity was established in a field trial of Abies nordmanniana with open-pollinated (OP) offspring from a clonal seed orchard (CSO) comprising 23 clones. 相似文献
12.
The germination of common alder ( Alnus glutinosa (L.) Gaertn.) and downey birch ( Betula pubescens Ehrh.) seeds is often poor in bare-root nurseries. The effect of a variety of seed coverings and a few seed pretreatments
on seedling emergence was examined in this study in an attempt to address this problem. Seeds of each species were sown in
trays containing nursery soil, covered with grit, gravel, sand, combinations of these coverings, a hydromulch or a sealed
plastic cloche and then incubated for 6 weeks at 17–20°C. The grit combined with sand or gravel, the hydromulch and the cloche
increased seedling emergence when compared with the standard grit. In another experiment, seeds of each species were fully
imbibed (FI) (>50% moisture content, MC), as per standard practice, or adjusted to target MC (TMC) (30–35% MC) levels, and
then chilled to release dormancy. Some seeds of each MC treatment were primed at 20°C for 2 days following chilling, after
which all seeds were evaluated in laboratory tests and a nursery trial. Germination potential of the FI seeds declined in
the lab tests by the second test date, which was reflected in low seedling emergence in the nursery in birch. The primed FI
seeds of alder germinated most rapidly in the nursery, but other effects were not significant. Seedling emergence was better
in the nursery in response to the TMC than the FI pretreatment in birch.
相似文献
13.
| – |
• The aim of our work was to homogenise the meteorological dataset of German ICP Forests Level II sites (n = 73) by the aid of interpolations based on climate data from the German meteorological network (DWD). 相似文献
14.
| – |
• Radiata pine (Pinus radiata D. Don) is the main exotic plantation tree species grown in New Zealand for wood production and as such represents a significant
component of the terrestrial carbon cycle. 相似文献
15.
| – |
• We aimed to better understand the genetic architecture of growth in E. globulus undergoing inbreeding by comparing families from selfing (SELF), open pollination (OP) and unrelated polymix crossing (POL)
of common parents. Stem diameter at breast height (DBH) was assessed at 4, 6 and 10 years after planting in a field trial. 相似文献
16.
| – |
• The effect of water stress on host selection and performance during the shoot feeding phase, by the Mediterranean pine shoot
beetle Tomicus destruens, was studied. 相似文献
17.
| – |
• The search for alternative fiber resources is receiving worldwide attention for the potential role of these fibers in climate
and forest restoration. Among bamboos, Bambusa balcooa is generally preferred for industrial use due to its rapid growth, excellent flexibility and tensile strength. The aim of
this study is to establish a non-invasive and efficient method of screening superior fiber quality from the wild gene pool
of B. balcooa. 相似文献
18.
In this paper we analyzed the dry matter yields (DM) produced in an agroforestry trial consisting of pine trees grown over (1) Control (bare ground), (2) ryegrass/clovers ( Lolium perene/Trifolium spp.), (3) ryegrass only, and (4) lucerne ( Medicago sativa) during the third growing season between 1992 and 1993. In addition these pastures were grown alone in separate plots in the open. The results show that: | 1. |
Pasture yields during the one-year period in the agroforestry plots were little affected by the presence of trees although there were seasonal trends: yields were generally unaffected or increased in summer, but reduced in spring as a result of tree shade. Total pasture yield during the one-year period was in the following order: lucerne > ryegrass/clovers > ryegrass. This trend was the exact opposite of that shown by the above-ground tree weight which was reduced in the pasture ground covers by between 16 and 52%. The reduction in tree weights was associated with reduced soil moisture availability arising from competition with the pasture species. Thus the relationship between the yields of trees and pasture species in the agroforestry plots was reciprocal.
| | 2. |
The combined DM for both the trees and pastures in the agroforestry plots during the one-year period was in the following order: lucerne (20 t ha–1) > ryegrass/clovers (16 t) > ryegrass (11 t) > control (6 t) which was consistent with the total water used and photosynthetically active radiation (PAR) intercepted. The trees accounted for 55, 44, 34 and 24% of water used respectively in control, ryegrass, ryegras/cclovers and lucerne ground covers. The balance was largely accounted for by pasture transpiration, except in the control where soil evaporation was significant. The fraction of intercepted PAR accounted for by the trees followed a similar trend to that of the water used.
| | 3. |
The crop coefficient for water use efficiency (k) (Pa) was 2.3 for radiata pine, 3.6 for ryegrass/clovers, 2.8 for ryegrass and 4.8 for lucerne. The DM produced per unit of water used (kg mm–1 ha–1) during the one-year period was 24.5 for radiata pine, 41.1 for lucerne, 30.0 for ryegrass/clovers and 23.1 for ryegrass. Radiation use efficiency (g DM MJ–1 m–2) was 1.33 for pine, 1.83 for ryegrass/clovers, 1.49 for ryegrass and 2.34 for lucerne.
| | 4. |
The land equivalent ratio (LER), i.e. the sum of ratios of DM produced by the plant species in the agroforestry plots to those produced in the sole plots, was 1.95 for ryegrass, 1.71 for ryegrass/clovers and 1.45 for lucerne ground covers.
| | 5. |
These results indicate the susceptibility of pasture species to shading and interception of rainfall by the tree crowns (aboveground interactions), and the trees to competition for soil moisture (underground interaction).
|
相似文献
19.
| – |
• Plantation forestry in Zambia is based mainly on non-native Eucalyptus and Pinus species and constitutes an important component of the country’s economy. The productivity of these plantations is, however,
threatened by several factors, including fungal pathogens that reduce timber quality and cause tree mortality. 相似文献
20.
| – |
• We studied the effects of acorn cotyledon loss by insect damage and artificial excision on germination and seedling survival
of Quercus variabilis, to determine whether insect infestation decreases acorn germination and seedling establishment; and to what extent cotyledon
damage can affect acorn germination and seedling establishment. 相似文献
|
|
| | | | | | | | | | | | | | | | |
