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11.
Seedling crops of gazania, geranium, marigold, mimulus, pansy, verbena and vinca were grown to 60% anthesis in three greenhouse temperature regimes: (a) 26 °C day/6 ± 3 °C night (LT), with a 16.5 °C mean daily temperature (MDT), (b) 26 °C day/17 ± 4 °C night, with a 21 °C MDT, and (c) variable day/night temperatures in response to heating and cooling by a phase change material energy storage module (PCM) with an 8 ± 2 °C night and a 16 °C MDT. Crops bloomed from 2 to 17 days earlier in the 26 °C/17 °C greenhouse. The morphological characteristics of all cultivars of gazania, mimulus, pansy and verbena, geranium and vinca were similar regardless of greenhouse temperature regime. Marigold diploid and triploid cultivars and mimulus were morphologically more variable than the other bedding plant species. Crops grown in the PCM and LT greenhouses had virtually identical morphological characteristics and bloomed in about the same number of days. Plant height was not affected by DIF environments in the greenhouses. The PCM and LT greenhouses had a similar MDT, but the distribution of numbers of hours of mean daily temperatures was different. 相似文献
12.
The objectives of this study were: (1) to relate the height growth pattern to the GIS-derived site index, (2) to construct various types of polymorphic height curves, and (3) to select the most accurate height curve for Japanese larch (Larix kaempferi). A total of 14 dominant trees were felled for stem analysis. Richards' function was first fitted to the height/age dataset recorded from stem analyses of 14 trees, and its parameters (i.e., A, k, and m) were then estimated for each sample tree. The relationship between parameter A and the GIS-derived site index was significant, while that of parameters k and m were not significant. The 12 height curve equation forms developed from the Richards' function were then fitted to the dataset consisting of 563 observations of height, age, and GIS-derived site index derived from 14 trees. All height curves were unbiased and provided an equally good fit. The shape of the height curves differed among sites of different site indices. These results indicated that Richards' function was sufficiently flexible to represent the polymorphic height growth pattern of Japanese larch. Finally, the best-fit height curve was selected so that accurate height growth predictions would be possible at any given age and site. 相似文献
13.
海南东寨港主要红树植物树高与胸径相关关系 总被引:1,自引:0,他引:1
采用相邻网格法在海南东寨港红树林保护区六个不同红树林群落中共布设六块有代表性的样地,测得454株海莲、129株无瓣海桑、112株海桑、198株秋茄树高与胸径,利用SAS9.0研究了树高(y)与胸径(x1)之间的相关关系。选出了适用于海莲树高预测的最佳回归方程为y=1.40334 0.49758x1 0.00399x12,适用于无瓣海桑、海桑树高预测的最佳回归方程分别为y/1=0.01732 1.10089/x1、y/1=0.01664 1.24603/x1,适用于秋茄树高预测的最佳回归方程为y=1.8165 x1 0.5230和lny=0.54906 0.54559lnx1。回归方程均达到极显著水平(P<0.01),其估计精度较高,均在93%以上,所建方程可用于计算各红树植物树高及其林分平均高。 相似文献
14.
An annual individual tree survival and growth model was developed for pure even-aged stands of maritime pine in Portugal, using a large data set containing irregularly time-spaced measurements and considering thinning effects. The model is distance-independent and is based on a function for diameter growth, a function for height growth and a survival function. Two approaches are compared for modeling annual tree growth. The first approach directly estimates a future diameter or height using well-known growth functions formulated in difference form. The second approach estimates diameter or height using a function in differential form estimating the increment over a year period. In both approaches, the function parameters were related to tree and stand variables reflecting the competition status of the tree as well as of a thinning response factor. Variable growth and survival rates were assumed in the modeling approaches. An iterative method was used to continuously update tree and stand attributes using a cut-off to convert the survival probability for a living or a dead tree. The individual tree diameter growth model and the survival probability model were fitted simultaneously using seemingly unrelated regression (SUR). Parameters of the height function were obtained separately as the number of observations for height was much lower than the number of observations for diameter, which may affect the statistical inference and the estimation of contemporaneous cross-equation error correlation inherent to the system of equations. PRESS residuals were used to evaluate the predictive performance of the diameter and the height growth functions. Additional statistics based in the log likelihood function and also in the survival probability were computed to evaluate the survival function. The second modeling approach, which integrates components of growth expansion and decline, performed slightly better than the first approach. A variable accounting for the thinning response that was tested proved to be significant for predicting diameter growth, even if the model already included competition-related explanatory variables, namely the basal area of trees larger than the subject tree. However, this thinning response factor was not significant for predicting height growth. 相似文献
15.
Katherine D. Heineman Ethan JensenAutumn Shapland Brett BogenriefSylvester Tan Richard RebarberSabrina E. Russo 《Forest Ecology and Management》2011,261(11):1820-1832
Tree height and crown allometries reflect adaptations for resource acquisition and structural stability, as well as plastic responses to a heterogeneous environment. While both light and soil resources limit growth and influence competitive responses in tropical forests, the effects of belowground resources on allometries are less understood, especially within the understory. To characterize outcomes of tree competition along an edaphic resource gradient, we quantified variation in height and crown allometries of six Bornean tree species from contrasting regeneration niches (light-demanding vs. shade-tolerant) on two soil habitats (clay-fine loam and sandy loam) within a 52-ha forest dynamics plot. Using empirically-fit allometric parameters and diameter growth rates from plot census data, we modeled tree height and crown area growth over the projected life span of each species. Based on resource competition theory, we hypothesized that tree species specializing on and populations of generalist species growing on the relatively moister, more fertile clay-fine loam soil habitat would have faster height and crown growth rates, compared to those on the sandy loam habitat, regardless of regeneration niche. Among soil specialists and within generalists of both genera, trees growing on clay-fine loam had taller stems and larger crowns at a given age and faster height and crown area growth rates at most sizes than trees on sandy loam. Differences in height and crown growth were driven by the faster diameter growth rates of trees on clay-fine loam, not by differences in height- and crown-diameter allometries, as trees on sandy loam were significantly taller at a given diameter, and differences in crown allometry were not consistent across soil habitats. Characterizing the height and crown growth responses of trees along resource gradients provides insight into the mechanisms that maintain diversity in tropical forests. Our results point to the importance of adaptive and plastic responses to both above and belowground resource availability in determining the allometric growth of trees and suggest that this diversity of responses may contribute tree species coexistence through competition-based trade-off mechanisms and variation in growth among individuals. Additionally, as the importance estimating natural carbon sequestration increases with the escalating effects of anthropogenic climate change, differences in tree growth and architecture across soil habitats also have implications for the approximation of forest carbon storage on heterogeneous tropical soils. 相似文献
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17.
金纹细蛾与苹小卷叶蛾是两种重要的果树害虫。通过调查金纹细蛾与苹小卷叶蛾两种性诱剂在苹果园中的试验效果,明确了金纹细蛾诱芯放置的最佳间距为20 m,最佳高度为1 m;苹小卷叶蛾诱芯放置的最佳间距为7.5 m,最佳高度为1.25 m。 相似文献
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19.
R. Snchez-Andrs S. Snchez-Carrillo M. Benítez A. Snchez-Lpez 《Soil & Tillage Research》2006,90(1-2):50-62
This study describes the changes in height and diameter in Quercus ilex trees grown on agricultural land in a semi-arid Mediterranean climate, in response to different soil management practices: mechanical weeding (MW), chemical weeding (CHW) and no treatment (NT); and compares trees grown from 1-year-old saplings and from acorns. After 6 years, trees that had been mechanically weeded were largest; for trees grown from saplings the average height was 120 cm and diameter was 3.83 cm, for trees grown from acorns average height was 100 cm and diameter was 2.56 cm. Soil organic matter increased in all managed plots while phosphorus, nitrate, and water content oscillated between years. The no treatment plot had the highest values for nitrate and organic matter while the chemical weeding plot had the highest level of phosphorus. Annual mean on C/N ratios were higher in the mechanical weeding (12.6 ± 3.3) followed by the chemical weeding (12.0 ± 1.6). Also mechanical weeding treatment showed the lowest soil water content throughout the study. An old tillage-induced compaction zone appeared in all plots at a depth of 12.5–17.5 cm with mechanical weeding causing the greatest compaction. However, no relationships were found with tree heights, neither with spatial compaction zoning. All trees showed the same growth pattern, whether raised from saplings or acorns and irrespective of soil management system. The height and diameter of trees were linked to the sum of height and diameter ratios from previous years. Our study shows that soil management does influence tree growth rate. Mechanical weeding should be considered for afforestation of agricultural lands with Q. ilex in semiarid Mediterranean lands. 相似文献
20.
采用层次分析法建立了高尔夫球场园林植物景观的评价系统。结果表明:深圳地区高尔夫球场植物群落树木的平均胸径与植物景观之间存在函数关系A=aD2+bD+c。当植物群落的平均胸径大约为22cm时,其景观的评价值最高,为91分。 相似文献