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1.
? Context
There are many stand property–density relationships in ecology which represent emergent properties of plant populations. Examples include self-thinning, competition–density effect, constant final yield, and age-related decline in stand growth. We suggest that these relationships are different aspects of a general framework of stand property–density relationships.? Aims
We aim to illustrate the generalities and ecological implications of stand property–density relationships, and organize them in a comprehensive framework.? Methods
We illustrate relationships between stand property and density (1) at one point in time, (2) over time, and (3) independent of time. We review the consequences of considering different variables to characterize stand property (mean tree size, mean tree growth, stand growth, stand yield, stand leaf area).? Results
We provide a framework that integrates the broad categories of stand property–density relationships and individual expressions of these relationships. For example, we conclude that constant final yield is a special case of the growth–growing stock relationship for life forms were yield is a reasonable approximation of growth (non-woody plants).? Conclusion
There is support in the literature for leaf area being broadly integrative with respect to various expressions of stand property–density relationships. We show how this is and suggest implications for plant population ecology and forest management. 相似文献2.
The antifungal effects of citral, eugenol, nerolidol and α-terpineol on Trichophyton mentagrophytes were investigated. Citral over 0.1 mg/ml strongly inhibited the hyphal growth of T. mentagrophytes, and the antifungal activity of α-terpineol was less effective. The morphological changes of the fungus exposed to the terpenes were observed by electron microscopy. The hyphae were distorted and collapsed at 0.2, 0.4 and 1 mg/ml of eugenol, nerolidol and α-terpineol respectively, and cell membrane and organelles were irreversibly damaged at 0.2 mg/ml citral. 相似文献
3.
Li Zhou Limin Dai Shaoxian Wang Xiangtong Huang Xinchuang Wang Lin Qi Qingwei Wang Guowei Li Yawei Wei Guofan Shao 《Annals of Forest Science》2011,68(5):953-958
Introduction
The old-growth forests on Changbai Mountain have been well protected from human activities and provide a living laboratory for studying forest carbon sequestration under natural environmental conditions. 相似文献4.
Chemical investigation of the stems of Erythrina fusca Lour. led to the isolation of three new pterocarpans, named fuscacarpans A–C (1−3), together with fourteen known compounds, sandwicensin (4), erythribyssin A (5), erythrabissin I (6), demethylmedicarpin (7), eryvarin D (8), erypoegin I (9), hydroxycristacarpone (10), orientanol A (11), scandenone (12), genistein (13), liquiritigenin (14), isoliquiritigenin (15), vestitone (16) and 3,7,4′-trihydroxyflavone (17). Structures 1−3 were elucidated by spectroscopic and chemical methods. The isolates were evaluated for antibacterial, antiplasmodial and cytotoxic activities. 相似文献
5.
Two new cyclopentene dialdehydes, tabebuialdehydes A and B (1 and 2) and a new dihydrocyclopenta[c]furan monoaldehyde, tabebuialdehyde C (3), along with ten known compounds were isolated from the roots of Tabebuia rosea. The structures of all isolated compounds were elucidated through their physical properties and by the use of spectroscopic methods, as well as comparisons with previous literature data. Moreover, all isolated compounds were evaluated for their cytotoxicity (KB and HeLa cell lines). Compounds 6, 7 and 9 showed significant cytotoxicity against both KB and HeLa cells with IC50 values of 1.35 and 1.15, 0.53 and 0.77, 1.79 and 0.73 μg/mL, respectively. 相似文献
6.
Aoife B. Dillon Colm P. MooreMartin J. Downes Christine T. Griffin 《Forest Ecology and Management》2008
Hylobius abietis is the most important pest of replanted coniferous sites in Northern Europe, where feeding by adult weevils can result in up to 100% mortality of seedlings. Field trials were conducted with the aim of reducing H. abietis populations developing in Sitka spruce stumps by increasing pressure from natural enemies (top–down pressure), and reducing the quality of stumps for development (bottom–up pressure). Top–down pressure was applied through inundative treatment of stumps with entomopathogenic nematodes (Heterorhabditis downesi or Steinernema carpocapsae). Bottom–up pressure was applied by treating stumps with the wood colonising fungus Trichodermakoningii. Natural levels of parasitism of H. abietis by the parasitoid Bracon hylobii and the effect of applied agents on B. hylobii were also investigated. Heterorhabditis downesi parasitised more immature weevils than S. carpocapsae, and significantly reduced numbers of adults emerging from stumps compared to controls. Entomopathogenic nematodes did not significantly impact on populations of B. hylobii, and over three sites the effects of both agents were additive. Stumps modified by application of the fungus (bottom–up pressure) did not have fewer H. abietis developing in, or emerging from them; however, development of H. abietis was more advanced in these stumps, and the success of natural enemies was differentially affected. T.koningii facilitated B. hylobii while having the opposite effect on entomopathogenic nematodes, suggesting that it affected the outcome of competition between the nematodes and the parasitoid. 相似文献
7.
Guoyu Li Yanhai Zhang Bingyou Yang Yonggang Xia Yanlong Zhang Shaowa Lü Haixue Kuang 《Fitoterapia》2010
Three new oleanane bidesmosidic triterpenoid saponins, named leiyemudanosides A–C (1–3) were isolated from the roots of Caulophyllum robustum Maxim. Their structures were established by chemical and detailed spectroscopic analysis as 3-O-α-l-arabinopyranosyl-caulophyllogenin-28-O-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (1), 3-O-β-d-glucopyranosyl-(1 → 3)-α-l-arabinopyranosyl-caulophyllogenin-28-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (2), and 3-O-β-d-glucopyranosyl-(1 → 3)-α-l-arabinopyranosyl-echinocystic acid-28-O-α-l-rhamnopyranosyl-(1 → 4)-β-d-glucopyranosyl-(1 → 6)-β-d-glucopyranosyl ester (3), respectively. 相似文献
8.
Tetsuji Itoh Yoshikazu Sato Tsutomu Mano Ryûtarô Iwata 《Journal of Forest Research》2009,14(2):117-122
We examined 24 microsatellite markers to
select those most suitable for individual identification
and parentage tests of brown bears
(Ursus arctos)
based on statistical parameters and experimental error
using liver samples (38 issues) from nuisance bears killed
in the Akan–Shiranuka Region, eastern Hokkaido, Japan from
1996 to 2006. We found seven microsatellite markers suitable
for identifying individuals (G1A, G10B, G10L, UarMU5, UarMU23,
UarMU50, and UarMU51; probability of identity
P
id = 3.17
× 10−7; probability of identity of
sibs P
id-sib
= 2.23 × 10−3), 12 microsatellite
markers suitable for parentage testing when one parent is
known [G1A, G1D, G10B, G10L, G10P, UarMU5, UarMU23, UarMU50, UarMU51,
UarMU59, UarMU61, and UarMU64; probability of excluding one parent
(PE I = 0.9991)], and 15 microsatellite markers for parentage
testing when neither parents are known [three markers added to
the above: G10M, G10X, and UarMU9;
probability of excluding both parents (PE II = 0.9869)]. 相似文献
9.
A simultaneous estimation procedure for the parameters of two functions, i.e., the maximum size–density line and the self-thinning
curve, is presented to predict stand development for fast-growing tropical species. This procedure assumes that the rate of
periodic reduction in stand density with increasing quadratic mean diameter on a logarithmic scale (r) will increase inversely proportionally to the distance from the maximum size–density line and consequently equals the slope
of the line at distance 0. Under this assumption, the maximum size–density line can be incorporated into the self-thinning
curve to form an integrated equation with three parameters: k and m, the slope and constant of the maximum size–density line, and a, the rate of reduction of r of the self-thinning curve. These parameters are estimated simultaneously using measurement data on stand density, quadratic
mean diameter, and the corresponding r. This procedure was evaluated by application to two data sets: 186 measurements of Acacia mangium and 95 measurements of Paraserianthes falcataria, for which the parameters k and m have previously been calculated. The parameters estimated using this procedure were in good agreement with previous ones
based on the A. mangium data set, and the differences found for the P. falcataria data set were also small, within the error variances. Therefore, it is concluded that the proposed procedure would give almost
the same estimates from a single calculation step as the previous procedure that required two separate calculation steps. 相似文献
10.
Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at 23 different European test sites under different exposure
conditions (in total 27 test sets). The material climate in terms of wood moisture content (MC) and wood temperature was automatically
monitored over a period of up to 7 years and compared with the progress of decay. The overall aim of this study was to establish
dose–response relationships between climate factors and decay as a basis for the service life prediction of wood. The “Scheffer
Climate Index” based on weather data collected at official meteorological stations at the different test sites poorly correlated
with the corresponding decay progress and was therefore not a suitable tool for estimating site-specific decay potential.
In contrast, the use of the combined material climatic parameters MC and wood temperature led to a feasible dose–response
function and turned out to be a useful basis for service life prediction of wood. 相似文献
11.
Introduction
Korean pine (Pinus koraiensis) is a dominant tree species in the cold temperate mixed forest zone in eastern Eurasia. Its seeds are food sources for wildlife but have become an important and marketable part of the economy for local communities. 相似文献12.
• Introduction
Size-density relationships define the maximum number of stems that even-aged stands of a given species can hold in relation to the mean size of trees. They are used to derive stand density measures and are useful tools used to control tree mortality. 相似文献13.
The competition–density (C–D) effect for non-self-thinning Populus deltoides and Populus × euramericana plantations from 3 to 9 years was analyzed using the reciprocal equation of the C–D effect. The C–D effect was well described
by the reciprocal equation, and with the progress of time the C–D curve, on logarithmic coordinates, of the P. × euramericana plantations shifted upward faster than that of the P. deltoides plantations. With increasing physical time t, the biological time τ, i.e. the integral from zero to t of the coefficient of growth λ(t) in the general logistic curve with respect to t, increased rapidly during early growth stages and the increases in τ gradually became slow during later growth stages. This trend was more evident in the P. deltoides plantations than in the P. × euramericana plantations. The coefficients A and B included in the reciprocal equation were calculated at each growth stage. With increasing τ, the coefficient A, the reciprocal of which means the asymptote of yield (=wρ) at a given growth stage, increased abruptly to a maximum value and then tended to decrease gradually to a constant level.
On the other hand, the coefficient B, the reciprocal of which means the asymptote of mean stem volume at a given growth stage, decreased exponentially and tended
to be close to zero with increasing τ. The λ(t) decreased with increasing stand age, whereas the final yield Y(t) defined as W(t) ρ, where W(t) is the asymptote of w in the general logistic growth curve, increased gradually with increasing stand age. The differences in coefficients A, B, and λ(t) between the two species were reported. 相似文献
14.
15.
Balsam fir (Abies balsamea [L.] Mill.), which is widely used for floral greenery, is an important source of nontimber forest products (NTFP) from the northern forests of North America. Nonetheless, additional information is needed to refine and revise commercial tip-harvesting management guidelines to promote sustainable forest management. Therefore, a study was initiated to: (a) examine the socioeconomic impacts of and anticipate the potential biological responses to four contrasting harvesting practices; (b) discuss the implications of the results for the relevance and applicability of some specifications of management guidelines; and (c) assess the compatibility of tip harvesting while pursuing an objective of timber production. 相似文献
16.
Mingshi Li Chengquan Huang Wenjuan Shen Xinyu Ren Yingying Lv Jingrui Wang Zhiliang Zhu 《林业研究》2016,27(6):1329-1341
Forest losses or gains have long been recognized as critical processes modulating the carbon flux between the biosphere and the atmosphere. Timely, accurate and spatially explicit information on forest disturbance and recovery history is required for assessing the effectiveness of existing forest management. The major objectives of our research focused on testing the mapping efficacy of the vegetation change tracker (VCT) model over a forested area in China. We used a new version of VCT algorithm built upon the Landsat time series stacks (LTSS). The LTSS consisted of yearly image acquisitions to map forest disturbance history from 1987 to 2011 over the Ning-Zhen Mountains, Jiangsu Province of east China. The LTSS consisted of TM and ETM+ scenes with different projections due to distinct data sources (Beijing remote sensing ground station and the USGS EROS Center). The validation results of the disturbance year maps showed that most spatial agreement measures ranged from 70 to 86 %, comparable with the VCT accuracies reported for many places in USA. Very low accuracies were identified in 1995 (38.3 %) and 1992 (56.2 %) in the current analysis. These resulted from the insensitivity of the VCT algorithm to detect low intensity disturbances and also from the mis-registration errors of the image pairs. Major forest disturbance types existing in our study area were identified as agricultural expansion (39.8 %), urbanization (24.9 %), forest management practice (19.3 %), and mining (12.8 %). In general, there was a gradual decreasing trend in forest cover throughout this region, caused principally by China’s economic, demographic, environmental and political policies and decisions, as well as some weather events. While VCT has largely been used to assess long term changes and trends in the USA, it has great potential for assessing landscape level change elsewhere throughout the world. 相似文献
17.
W. A. Shehata S. S. Abou-Elkhair A. A. Youssef F. N. Nasr 《Journal of pest science》2003,76(6):155-158
Abstract The biology of two important lepidopterous pests, Prays oleae Bernard and Palpita unionalis Hübner, was studied. The target pests were reared on olive plants, Oleae europaea L. (Oleaceae) under laboratory conditions for two successive generations, from March to June 2002. For P. oleae, the duration of larval stage development in the first generation was 21.4 ± 0.18 days at 19.3–20.9 °C, 65–68 % R.H, while in the second generation it was 14.8 ± 0.10 days at 20.8–24.2 °C, 65–69 % R.H. The number of eggs laid per female ranged from 58 to 109 eggs in the first generation, and from 47 to 113 in the second. The larval stage duration of P. unionalis was 16.3 ± 0.12 days at 16.8–22.9 °C, 65–69 % R.H. and 15.5 ± 0.12 days at 21.6–25.5 °C, 66–69 % R.H. for the first and second generations, respectively. Also, the number of eggs laid per female ranged from 630 to 653 eggs, and from 425 to 493 eggs in the second generation under the same previous laboratory conditions. P. oleae laid eggs at night mostly singly on flower-buds, more on the calyx. than on the petals. The larvae mined on leaves and damaged groups of flowers. P. unionalis adults were active at night, laid eggs singly at twilight usually on the lower surface of foliage. Larvae fed on leaves spinning several leaves together to form shelter for the pupa. 相似文献
18.
Satomi Koretsune Kenji Fukuda Zhaoyang Chang Fuchen Shi Atsushi Ishida 《Journal of Forest Research》2009,14(2):88-94
We studied the importance of effective rainfall for interannual variation in water use efficiency (WUE) and tree-ring growth
of Chinese pine (Pinus tabulaeformis Carr.) and black locust (Robinia pseudoacacia L.) by examining correlations of seasonal precipitation with annual values of stable carbon isotope ratio (δ13C) and tree-ring width in early and late wood. The correlations with precipitation were examined for each month and for periods
of all possible lengths from 2 to 22 months starting from January of the previous year to October of the current year. The
period with the highest correlation was adopted as the most effective rainfall season for interannual variations in WUE and
tree-ring width. In early wood, precipitation during the dry season (October to May) before the growing season was negatively
correlated with δ13C in pine trees and positively correlated with ring width in pine and locust trees. In late wood, rainfall during the growing
season in the current year was negatively correlated with δ13C in pine and locust trees, and positively correlated with ring width in locust trees. Our results demonstrated the differences
in the water use strategies of pine and locust trees. The δ13C in pines indicated higher WUE and more conservative water use than in locust trees. Precipitation during the dry season
affected the interannual variation in WUE and tree-ring growth in pine and locust trees, indicating that rainfall during the
dry season is important for carbon gain and tree-ring growth during the following growing season. 相似文献
19.
《Scandinavian Journal of Forest Research》2012,27(3):241-249
The Brinell hardness and equilibrium moisture content (EMC) were measured from thinning-aged silver birch wood. Wood material both from the trees harvested in the first commercial thinning and from trees remaining on site after the thinning was included. The average Brinell hardness was 19.40 MPa. It correlated significantly with the basic density of wood. With respect to the distance from the pith, the Brinell hardness of air-dried wood was higher than that of artificially dried wood. The average EMC of the conditioned (20°C, 65% relative humidity) wood was 12.0%. The EMC of the wood also varied, with the EMC being higher for air-dried wood than for kiln-dried wood. EMC was the highest at a distance of 30–40 mm from the pith, decreasing towards both pith and log surface. Seasonal variation in both the Brinell hardness and the EMC of the wood was found. It was presumed to be a consequence of season-dependent physiological changes in trees. 相似文献
20.
《Scandinavian Journal of Forest Research》2012,27(6):544-553
Abstract The National Forest Inventory (NFI) is an important resource for estimating the national carbon (C) balance. Based on the volume, biomass, annual biomass increment and litterfall of different forest types and the 6th NFI in China, the hyperbolic relationships between them were established and net primary production (NPP) and net ecosystem production (NEP) were estimated accordingly. The results showed that the total biomass, NPP and NEP of China's forests were 5.06 Pg C, 0.68 Pg C year?1 and 0.21 Pg C year?1, respectively. The area-weighted mean biomass, NPP and NEP were 35.43 Mg C ha?1, 4.76 Mg C ha?1 year?1 and 1.47 Mg C ha?1 year?1 and varied from 13.36 to 79.89 Mg C ha?1, from 2.13 to 9.15 Mg C ha?1 year?1 and from ?0.16 to 5.80 Mg C ha?1 year?1, respectively. The carbon sequestration was composed mainly of Betula and Populus forest, subtropical evergreen broadleaved forest and subtropical mixed evergreen–deciduous broadleaved forest, whereas Pinus massoniana forest and P. tabulaeformis forest were carbon sources. This study provides a method to calculate the biomass, NPP and NEP of forest ecosystems using the NFI, and may be useful for evaluating terrestrial carbon balance at regional and global levels. 相似文献