Continuous measurements of radial variation in Eucalyptus pauciflora Sieb. ex Spreng

1969 ◽  
Vol 17 (2) ◽  
pp. 191 ◽  
Author(s):  
JW Green
Keyword(s):  
Environmental Variables ◽  
Growth Curves ◽  
Growing Season ◽  
Radial Variation ◽  
Continuous Data ◽  
Seasonal Growth ◽  
Total Period ◽  
Regression Techniques ◽  
Diurnal Fluctuations ◽  
General Explanation

Improvised dendrographs of the Fritts type were used to make continuous chart records of radial variation in trees of Eucalyptus pauciflora at two altitudinal sites where, in addition, concurrent observations were made of some environmental variables. The total period of observation was 186 days, which was presumed to cover the main growing season. Continuous data were digitized by means of a stripchart converter and the converted data used to replot curves and to extract daily values of variables. Broadly sigmoid seasonal growth curves were found to be modified by a period of reduced growth in the hottest part of summer, by irregular fluctuations apparently related to precipitation, and by regular diurnal fluctuations. Unreversed increases in radius immediately following some falls of rain suggested that rapid cell growth occurred at times of high tissue hydration. An attempt to find a general explanation of daily radial variation in terms of certain environmental variables by means of multiple regression techniques was not successful. The results reflected to some extent the effects of precipitation referred to above, but the order of importance of significant variables was inconsistent between trees and between altitudes.

scholarly journals Ozone deposition into a boreal forest over a decade of observations: evaluating deposition partitioning and driving variables

2012 ◽  
Vol 12 (24) ◽  
pp. 12165-12182 ◽  
Author(s):  
Ü. Rannik ◽  
N. Altimir ◽  
I. Mammarella ◽  
J. Bäck ◽  
J. Rinne ◽  
...  
Keyword(s):  
Boreal Forest ◽  
Water Vapour ◽  
Environmental Variables ◽  
Total Ozone ◽  
Explanatory Power ◽  
Growing Season ◽  
Sink Strength ◽  
Ozone Deposition ◽  
Air Space ◽  
Flux Measurements

Abstract. This study scrutinizes a decade-long series of ozone deposition measurements in a boreal forest in search for the signature and relevance of the different deposition processes. The canopy-level ozone flux measurements were analysed for deposition characteristics and partitioning into stomatal and non-stomatal fractions, with the main focus on growing season day-time data. Ten years of measurements enabled the analysis of ozone deposition variation at different time-scales, including daily to inter-annual variation as well as the dependence on environmental variables and concentration of biogenic volatile organic compounds (BVOC-s). Stomatal deposition was estimated by using multi-layer canopy dispersion and optimal stomatal control modelling from simultaneous carbon dioxide and water vapour flux measurements, non-stomatal was inferred as residual. Also, utilising the big-leaf assumption stomatal conductance was inferred from water vapour fluxes for dry canopy conditions. The total ozone deposition was highest during the peak growing season (4 mm s−1) and lowest during winter dormancy (1 mm s−1). During the course of the growing season the fraction of the non-stomatal deposition of ozone was determined to vary from 26 to 44% during day time, increasing from the start of the season until the end of the growing season. By using multi-variate analysis it was determined that day-time total ozone deposition was mainly driven by photosynthetic capacity of the canopy, vapour pressure deficit (VPD), photosynthetically active radiation and monoterpene concentration. The multi-variate linear model explained the high portion of ozone deposition variance on daily average level (R2 = 0.79). The explanatory power of the multi-variate model for ozone non-stomatal deposition was much lower (R2 = 0.38). The set of common environmental variables and terpene concentrations used in multivariate analysis were able to predict the observed average seasonal variation in total and non-stomatal deposition but failed to explain the inter-annual differences, suggesting that some still unknown mechanisms might be involved in determining the inter-annual variability. Model calculation was performed to evaluate the potential sink strength of the chemical reactions of ozone with sesquiterpenes in the canopy air space, which revealed that sesquiterpenes in typical amounts at the site were unlikely to cause significant ozone loss in canopy air space. The results clearly showed the importance of several non-stomatal removal mechanisms. Unknown chemical compounds or processes correlating with monoterpene concentrations, including potentially reactions at the surfaces, contribute to non-stomatal sink term.

scholarly journals Environmental Controls of Diurnal and Seasonal Variations in the Stem Radius of Platycladus orientalis in Northern China

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 784 ◽  
Author(s):  
Manyu Dong ◽  
Bingqin Wang ◽  
Yuan Jiang ◽  
Xinyuan Ding
Keyword(s):  
Environmental Factors ◽  
Air Temperature ◽  
Water Status ◽  
Growing Season ◽  
Northern China ◽  
Climate Impacts ◽  
Radial Variation ◽  
Critical Threshold ◽  
Platycladus Orientalis ◽  
Environmental Controls

Fine-resolution studies of stem radial variation over short timescales throughout the year can provide insight into intra-annual stem dynamics and improve our understanding of climate impacts on tree physiology and growth processes. Using data from high-resolution point dendrometers collected from Platycladus orientalis (Linn.) trees between September 2013 and December 2014, this study investigated the daily and seasonal patterns of stem radial variation in addition to the relationships between daily stem radial variation and environmental factors over the growing season. Two contrasting daily cycle patterns were observed for warm and cold seasons. A daily mean air temperature of 0 °C was a critical threshold that was related to seasonal shifts in stem diurnal cycle patterns, indicating that air temperature critically influences diurnal stem cycles. The annual variation in P. orientalis stem radius variation can be divided into four distinct periods including (1) spring rehydration, (2) the summer growing season, (3) autumn stagnation, and (4) winter contraction. These periods reflect seasonal changes in tree water status that are especially pronounced in spring and winter. During the growing season, the maximum daily shrinkage (MDS) of P. orientalis was positively correlated with air temperature (Ta) and negatively correlated with soil water content (SWC) and precipitation (P). The vapor pressure deficit (VPD) also exhibited a threshold-based control on MDS at values below or above 0.8 kPa. Daily radial changes (DRC) were negatively correlated with Ta and VPD but positively correlated with relative air humidity (RH) and P. These results suggest that the above environmental factors are associated with tree water status via their influence on moisture availability to trees, which in turn affects the metrics of daily stem variation including MDS and DRC.

Seasonal Growth Rates of Mooneye (Hiodon tergisus) from the Assiniboine River

1976 ◽  
Vol 33 (9) ◽  
pp. 2078-2082 ◽  
Author(s):  
C. L. Glenn
Keyword(s):  
Linear Function ◽  
Growth Rates ◽  
Growing Season ◽  
Seasonal Growth ◽  
Summer Growth

Length increments, calculated from fish measured at capture and from estimates of back-calculated lengths at time of formation of the most peripheral scale annulus, were used to determine the growing season and seasonal growth rates of mooneye (Hiodon tergisus). Data from 670 fish indicate that mooneye grow rapidly from June to mid-August with little or no growth occurring during other months. Length increased as a linear function during summer. Summer growth rates of 0.89, 0.58, 0.49, 0.44, 0.23, and 0.16 mm/day were estimated for fish aged I–VI, respectively.

Mental Growth from Six to Sixty in an Institutionalized Mentally Retarded Sample

1979 ◽  
Vol 45 (2) ◽  
pp. 643-646 ◽  
Author(s):  
A. B. Silverstein
Keyword(s):  
Growth Rate ◽  
Sex Differences ◽  
Growth Curves ◽  
Growing Season ◽  
Mentally Retarded ◽  
Chronological Age ◽  
Initial Growth ◽  
Initial Growth Rate ◽  
Longitudinal Method

The semi-longitudinal method was used to trace changes in the mental ages of 906 institutionalized mentally retarded subjects as a function of chronological age, and equations were fitted to the resulting growth curves. Sex differences proved to be relatively slight. The higher levels of retardation had a higher initial growth rate and a more pronounced decline at higher age levels than did the lower levels, but they did not have a longer growing season. In all but the last respect, the findings resembled those obtained by Fisher and Zeaman (1970).

scholarly journals A Spatial Approach for Modeling Amphibian Road-Kills: Comparison of Regression Techniques

2021 ◽  
Vol 10 (5) ◽  
pp. 343
Author(s):  
Diana Sousa-Guedes ◽  
Marc Franch ◽  
Neftalí Sillero
Keyword(s):  
Geographically Weighted Regression ◽  
Environmental Variables ◽  
Linear Models ◽  
Model Performance ◽  
Regression Trees ◽  
Additive Models ◽  
Boosted Regression Trees ◽  
Weighted Regression ◽  
Road Kill ◽  
Regression Techniques

Road networks are the main source of mortality for many species. Amphibians, which are in global decline, are the most road-killed fauna group, due to their activity patterns and preferred habitats. Many different methodologies have been applied in modeling the relationship between environment and road-kills events, such as logistic regression. Here, we compared the performance of five regression techniques to relate amphibians’ road-kill frequency to environmental variables. For this, we surveyed three country roads in northern Portugal in search of road-killed amphibians. To explain the presence of road-kills, we selected a set of environmental variables important for the presence of amphibians and the occurrence of road-kills. We compared the performances of five modeling techniques: (i) generalized linear models, (ii) generalized additive models, (iii) random forest, (iv) boosted regression trees, and (v) geographically weighted regression. The boosted regression trees and geographically weighted regression techniques performed the best, with a percentage of deviance explained between 61.8% and 76.6% and between 55.3% and 66.7%, respectively. Moreover, the geographically weighted regression showed a great advantage over the other techniques, as it allows mapping local parameter coefficients as well as local model performance (pseudo-R2). The results suggest that geographically weighted regression is a useful tool for road-kill modeling, as well as to better visualize and map the spatial variability of the models.

scholarly journals A descriptive model o Scots pine (Pinus silvestris) L. seedling's growth during the first growing season

2015 ◽  
Vol 45 (1–2) ◽  
pp. 143-158
Author(s):  
Teresa Gowin ◽  
Leokadiusz Ubysz
Keyword(s):  
Scots Pine ◽  
Dry Matter ◽  
Growth Curves ◽  
Dry Weight ◽  
Growing Season ◽  
Logistic Growth ◽  
Descriptive Model ◽  
Relative Growth ◽  
Pine Seedlings ◽  
Net Assimilation

Scots pine seedlings were grown in pots from seed under outside conditions. Plant material was harvested ten times in fortnight periods, throughout the growing season. At each harvest, each plant was divided into particular organs and their dimensions as well as fresh and dry weight were determined. Seasonal course of growth of particular organs as well as changes in specific leaf area and distribution of dry matter between shoot and root were investigated. Net assimilation rate (NAR) and relative growth rate (RGR) were calculated from the fitted logistic growth curves.

The growth of three tropical pasture grasses on the mid-north coast of New South Wales

1975 ◽  
Vol 15 (76) ◽  
pp. 637 ◽  
Author(s):  
DR Kemp
Keyword(s):  
New South ◽  
New South Wales ◽  
Irrigation Treatment ◽  
Growth Curves ◽  
High Growth ◽  
North Coast ◽  
Seasonal Growth ◽  
South Wales ◽  
Pasture Grasses ◽  
Kikuyu Grass

The yields and seasonal growth curves of kikuyu grass, (Pennisetum clandestinum) setaria, (Setaria anceps cv. Kazungula) and broadleaf paspalum (Paspalum wettsteinii), were determined over a three year period at Taree (lat. 32�s) New South Wales with or without irrigation and under nil, 170 or 680 kg N ha-1 yr-1 (nil, low and high N). Annual forage yields averaged 1300, 51 00 and 13,000 kg DM ha-1 at nil, low and high N respectively. Kikuyu grass yields were significantly less than setaria or broadleaf, especially at low N. Both the apparent recovery of nitrogen and the efficiency of dry matter production by kikuyu grass were less than the other grasses. Yields from the irrigated plots were similar to the dryland plots due largely to a generally favourable rainfall pattern. During short dry periods the extra yield from irrigation was less than from the application of nitrogen. The patterns of seasonal growth were similar for each species at any one nitrogen rate and irrigation treatment. The growing season (>5 kg DM ha-1 day-1) without nitrogen, was only four to six months, commencing in late spring. This was increased to eight months at low N (October to May) and nine months (September to May) with high N. The mean period of high growth rates (>60 kg DM ha-1 day-1) over summer was nil at nil N, only six days at low N but increased to 154 days at high N. Winter growth was negligible.

Leaf conductance of four species growing in a subarctic marsh

1988 ◽  
Vol 66 (7) ◽  
pp. 1367-1375 ◽  
Author(s):  
Peter Lafleur
Keyword(s):  
Environmental Variables ◽  
Vapour Pressure Deficit ◽  
Woody Species ◽  
Growing Season ◽  
Distinct Pattern ◽  
Leaf Conductance ◽  
Coastal Marsh ◽  
James Bay ◽  
Maximum Conductance ◽  
Measurement Period

This paper describes measurements of leaf conductance made with a diffusion porometer on four wetland species growing in a coastal marsh on James Bay. The measurement period covered most of the growing season. In general, leaf conductance for the sedge, Carex paleacea, was larger than for three woody species, Alnus rugosa, Salix bebbianna, and Salix discolor. No distinct pattern was observed in maximum conductance throughout the growing season; however, leaf conductance demonstrated distinct diurnal trends for all species. The response of leaf conductance to various environmental variables was examined and it was found that conductance of all species was most strongly related to the atmospheric vapour pressure deficit. Two models for predicting leaf conductance from environmental variables showed moderate success.

scholarly journals Analysis of cambial activity and formation of wood in Quercus robur L. under conditions of a floodplain forest

2012 ◽  
Vol 49 (No. 9) ◽  
pp. 412-418 ◽  
Author(s):  
P. Horáček ◽  
J. Šlezingerová ◽  
L. Gandelová
Keyword(s):  
Quercus Robur ◽  
Ecological Factors ◽  
Growth Curves ◽  
Growing Season ◽  
Cambial Activity ◽  
Wood Formation ◽  
Floodplain Forest ◽  
Pedunculate Oak ◽  
Total Production ◽  
The Social

The analyses of the activity of cambium and the study of the increment of wood during one growing season of pedunculate oak (Quercus robur L.) under conditions of a floodplain forest is provided. The following parameters were studied: the beginning and end of the cambial activity, differentiation of wood fibres (libriform) and vessels and analysis of the total increment of wood during vegetation in dominant (D), co-dominant (CD) and subdominant (SD) trees in relation to ecological factors of the environment. The course of wood formation corresponds to typical growth curves which are modified by factors of the environment (mean daily temperature, precipitation, soil water supply). The rate of growth is limited by factors of the environment and under the lack of some of them it is reduced resulting in the decrease in the total production of cells. Oak is a species sensitively responding to the period of drought which is particularly manifested in wood increment in subdominant trees. Sufficient supplies of water during spring months accelerate the formation of early wood including differentiation of spring vessels as corroborated by the results. The total formation of wood is dependent not only on the characteristics of the respective growing season but particularly on the social position of trees in the stand.

Seasonal growth of black spruce and tamarack roots in an Alberta peatland

1993 ◽  
Vol 71 (2) ◽  
pp. 359-360 ◽  
Author(s):  
Timothy S. S. Conlin ◽  
Victor J. Lieffers
Keyword(s):  
Root Growth ◽  
Key Words ◽  
Picea Mariana ◽  
Black Spruce ◽  
Growing Season ◽  
Plant Roots ◽  
Larix Laricina ◽  
Soil Cores ◽  
Seasonal Growth

Seasonal growth of black spruce (Picea mariana Mill. BSP) and tamarack (Larix laricina (Du Roi) K. Koch) roots in an Alberta peatland were assessed by measuring growth into emplaced soil cores that did not contain plant roots. Five cores were positioned 1 m from the base of each tree and 10 replicates of this treatment were used for each species. Sequential lifting of these cores during the growing season showed that root growth by these species did not begin until midsummer. Tamarack root growth was restricted to August and September, while black spruce root growth continued into October. Key words: flooding, Larix laricina, peatland, phenology, Picea mariana, temperature, root growth.

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