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1.
The determination of tree age is an important issue for urban green planning, forestry and dendrology; finding non-destructive and quasi-non-destructive methods for this purpose is of great theoretical and practical importance. The resistance drilling method is quasi-non-destructive because the average diameter of an opening that remains after drilling does not exceed 3 mm. Do electrically recording resistance drills allow precise assessment of tree age? The aim of this study is to assess the accuracy of determining the number of tree rings based on an examination of this special kind of drilling resistance profiles for three tree species, the pine Pinus sylvestris L., the oak Quercus robur L., and the birch Betula pendula ROTH. In 2015 and 2016, 15 pine trees, 15 oak trees, and 15 birch trees were randomly selected. For each studied tree, a measurement was conducted using the electrically recording resistance drill IML-Resi E400 with a flat-tipped 1.5/3 mm steel needle (research sample), and an increment core was taken (reference sample). The drill used was not a real Resistograph®. The analysis of the E400-profiles underestimated the number of tree rings; the mean bias error (MBE) values were –6.5, –2.5, and –6.0 years for pine, oak, and birch, respectively. The proportion of investigated trees with less than five years difference between the research and reference samples varied from 38.4 (birch) to 66.7 (oak) percent. The accuracy of tree age determination was lowest for birch and highest for oak. The binomial generalised linear model (GLM) revealed that the most accurate tree age assessments were obtained from tree rings wider than 2 mm. The measurements clearly showed that the electrically recording resistance drill IML-Resi E400 enables a quick, although approximate, tree age assessment. Future research should concentrate on electronically regulating and recording drills, providing a higher spatial and signal resolution, and a stronger correlation to wood density. 相似文献
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<正> 中国干旱半干旱区面积占全国面积的52.5%,半壁河山是以水分胁迫为主导限制因子的特殊生态区。为了提高这一地区的造林质量,选择旱生和抗旱性强的树种造林是主要造林技术之一。对于如何评价和比较林木的抗旱性,传统方法多采用对林木生态环境因子及对林木生 相似文献
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The ability to predict species occurrences quickly is often crucial for managers and conservation biologists with limited
time and funds. We used measured associations with landscape patterns to build accurate predictive habitat models that were
quickly and easily applied (i.e., required no additional data collection in the field to make predictions). We used classification
trees (a nonparametric alternative to discriminant function analysis, logistic regression, and other generalized linear models)
to model nesting habitat of red-naped sapsuckers (Sphyrapicus nuchalis), northern flickers (Colaptes auratus),tree swallows (Tachycineta bicolor), and mountain chickadees (Parus gambeli) in the Uinta Mountains of northeastern Utah, USA. We then tested the predictive capability of the models with independent
data collected in the field the following year. The models built for the northern flicker, red-naped sapsucker, and tree swallow
were relatively accurate (84%, 80%, and 75% nests correctly classified,respectively)compared to the models for the mountain
chickadee (50% nests correctly classified). All four models were more selective than a null model that predicted habitat based
solely on a gross association with aspen forests. We conclude that associations with landscape patterns can be used to build
relatively accurate, easy to use, predictive models for some species. Our results stress, however, that both selecting the
proper scale at which to assess landscape associations and empirically testing the models derived from those associations
are crucial for building useful predictive models.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
选用10种树高曲线模型作为候选模型,以决定系数(R~2)、残差平方和(S_(se))和均方差(M_(se))作为模型优劣的评价指标,对小兴安岭天然林中的云杉(Picea asperata)、红松(Pinus koraiensis)、水曲柳(Fraxinus mandschurica)、椴树(Tilia tuan)4种树种的树高曲线模型进行优选。结果表明:云杉、红松和椴树的最优模型均为Logistic模型,水曲柳的最优模型为抛物线模型;云杉和红松两种针叶树种,最优模型的优势不明显,水曲柳和椴树两种阔叶树种最优模型的优势较明显;比较R~2的大小,得出较适合小兴安岭云杉和红松两种针叶树种的树高曲线模型(R~20.8),对小兴安岭阔叶树种的适用程度不具有普遍性,对椴树的适用性好(R~2最大达0.94),对水曲柳的适用性较差(R~20.8)。对水曲柳的树高进行分段研究得出:水曲柳在树高低于9 m时,树高曲线模型较适宜(R~20.8),其中抛物线模型为最优模型;树高较高时,没有适用的树高曲线模型。 相似文献
7.
Urban tree canopy cover (UTC) is a simple, and common, measure of urban forest resource. Urban infill development is likely to lead to losses in UTC under private tenure, at a time when local governments are setting ambitious targets to increase UTC overall. Simple, statistically rigorous methods are required to benchmark and track change in UTC, whilst identifying which land-use types or tenures experience change.We estimated UTC in six Melbourne suburbs in 2010 and 2015 by randomly sampling 2000 points across public land, public streetscapes and private land. We were able to detect a net change in UTC of <2% over five years to a 95% level of confidence. A significant net decrease in UTC (−2.4%) was only detected in one of the six suburbs. Two suburbs had a net increase in UTC by +2.7% over five years. On private land, there was often areas of UTC loss, but this was generally offset by canopy gain in other areas of the private realm as well as in streetscapes and public land. Losses in UTC on private land were mainly due to tree removal, with or without subsequent construction works.This study describes a simple, but statistically rigorous, method to quantify UTC change and the drivers of change in different land-use types and tenure. Despite studying two suburbs will high rates of infill development, only one suburb showed evidence of net UTC decrease. The ‘dynamic equilibrium’ in UTC, whereby canopy losses area approximately offset by concurrent canopy gain, means that ambitious targets being set by local governments to increase UTC may be difficult to achieve without changes in tree protection and infill development policy and planning. 相似文献
8.
台是中国传统建筑类型中非常有代表性的一种。台能够使人产生独特的感觉,主要因为高起、容纳人、上部开敞、可赏景的特征,并由这些特征导致了人在台上空间与在其它园林空间类型感觉不同。这些特征导致人置身台面上会两有种独特的感觉,其一,更接近天,更远离人世;其二,获得了极不同的视高体验。台这种建筑形式在现代已经极少出现了,但是其能形成良好的空间感所具备的特征对我们空间营造的工作仍然有极大的借鉴意义。 相似文献
9.
The aim of this study was to quantify street tree population dynamics in the city of Claremont, CA. A repeated measures survey (2000 and 2014) based on a stratified random sampling approach across size classes and for the most abundant 21 species was analyzed to calculate removal, growth, and replacement planting rates. Demographic rates were estimated using a hierarchical Bayesian framework. The community-level (all species) median growth rate was 1.41% per year (95% CI: 1.21–1.65%) with Pinus brutia and Pistacia chinensis growing significantly faster than the community-level median. The community-level median removal rate was 1.03% per year (95% CI: 0.66–1.68%), with no significant differences between species and the community-level medium. Once removed, only 7.2% (95% CI: 4.4–12.9%) were replaced annually. Presence of overhead utility lines influenced tree removal rates while age, diameter-at-breast-height, and prior tree condition influenced tree growth. Overall live aboveground biomass in sampled sites was 713.29 Mg in 2000 and increased to 877.36 Mg by 2014. Biomass gain from growth outweighed loss from removals nearly three-fold; replacement contributed 0.5% of the total biomass gain. We conclude that to increase the resilience of the street tree population will require 1) an increase in percent of full stocking or biomass stock and 2) a shift in the species palette to favor species less vulnerable to pests and expected disturbance from climate change and 3) ongoing monitoring to detect departures from baseline demographic rates. 相似文献
10.
牡丹5个管家基因的克隆及其在系统进化分析中的应用 总被引:1,自引:0,他引:1
利用RT-PCR技术从牡丹组7个野生种和1个栽培种中分别克隆得到泛素延伸蛋白基因(ubiquitin,UBI)、素环蛋白基因(cyclophilin,CYP)、肌动蛋白基因(Actin)、葡萄糖六磷酸脱氢酶基因(glucose-6-phosphate 1-dehydrogenase,G6PD)和β–微管蛋白基因(beta-tubulin,TUB)等5个管家基因的编码序列(coding sequence,CDS)。序列比对分析发现,5个管家基因序列均相对保守,其在牡丹7个野生种和1个栽培种中的保守性在99.04%~99.69%。利用5个管家基因分别构建了其在牡丹组8份材料中的系统进化树。5个系统进化树均将8份材料分成两组,即革质花盘亚组和肉质花盘亚组;由于5个管家基因核苷酸序列各自的保守性不同,在区分亚组成员间略有差异。综合分析5个管家基因构建的系统进化树可知,杨山牡丹(Paeonia ostii)和栽培牡丹(P.suffruticosa‘Luoyanghong’)常聚为一支,二者亲缘关系较近,因而推测杨山牡丹可能参与了栽培牡丹的形成;紫斑牡丹(P.rockii)和四川牡丹(P.decomposita)一直聚为一支,推测二者亲缘关系较近;黄牡丹(P.lutea)和紫牡丹(P.delavayi)一直聚为一支,推测这二者亲缘关系较近。狭叶牡丹(P.potaninii)与黄牡丹和紫牡丹分化较早,结合前人研究结果建议将狭叶牡丹作为一个独立的种。 相似文献