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 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.

A simple dynamic model of photosynthesis in oak leaves: coupling leaf conductance and photosynthetic carbon fixation by a variable intracellular CO2 pool

2004 ◽  
Vol 31 (12) ◽  
pp. 1195 ◽  
Author(s):  
Steffen M. Noe ◽  
Christoph Giersch
Keyword(s):  
Carbon Fixation ◽  
Calvin Cycle ◽  
Target Function ◽  
Vapour Pressure Deficit ◽  
Co2 Assimilation ◽  
Leaf Conductance ◽  
Co2 Partial Pressure ◽  
Sink Term ◽  
Essential Components ◽  
Oak Leaves

Modelling the diurnal course of photosynthesis in oak leaves (Quercus robur L.) requires appropriate description of the dynamics of leaf photosynthesis of which diurnal variations in leaf conductance and in CO2 assimilation are essential components. We propose and analyse a simple photosynthesis model with three variables: leaf conductance (gs), the CO2 partial pressure inside the leaf (pi), and a pool of Calvin cycle intermediates (aps). The environmental factors light (I) and vapour pressure deficit (VPD) are used to formulate a target function G(I, VPD) from which the actual leaf conductance is calculated. Using this gs value and a CO2 consumption term representing CO2 fixation, a differential equation for pi is derived. Carboxylation corresponds to the sink term of the pi pool and is assumed to be feedback-inhibited by aps. This simple model is shown to produce reasonable to excellent fits to data on the diurnal time courses of photosythesis, pi and gs sampled for oak leaves.

scholarly journals Evapotranspiration from a riparian fen wetland

2005 ◽  
Vol 36 (2) ◽  
pp. 121-135 ◽  
Author(s):  
H.E. Andersen ◽  
S. Hansen ◽  
H. E. Jensen
Keyword(s):  
Driving Forces ◽  
Radiant Energy ◽  
Vapour Pressure Deficit ◽  
Open Water ◽  
Absolute Magnitude ◽  
Growing Season ◽  
Agricultural Landscapes ◽  
Water Evaporation ◽  
Evaporative Demand ◽  
Fine Grained

Evapotranspiration rates were measured in a riparian fen wetland dominated by vascular vegetation and surrounded by open agricultural areas and forests. The wetland is situated on a floodplain in central Denmark. Measurements were taken throughout the growing season (April–September) of 1999. Evapotranspiration rates were higher than those published for most other wetland types, with an average of 3.6 mm d−1 during the growing season and a peak rate of 5.6 mm d−1. Daily average evapotranspiration was 110% of Penman's potential open water evaporation. Evapotranspiration was the dominant sink in the energy balance of the wetland studied. During the day, evapotranspiration accounted for 82% of the available radiant energy, Rn. Due to the presence of deposited fine-grained sediments, soil-water availability was kept high at all times which resulted in moderate canopy resistances, rc (overall mean =32 s m−1). Evapotranspiration was controlled by a combination of driving forces: Rn, saturation vapour pressure deficit, D, and rc. It is hypothesized that the results presented in this study are conditioned by the proximity of the wetland to drier upland areas. During periods with high evaporative demand and low precipitation, warm, dry air is formed over the upland areas and wetland evapotranspiration rates are enhanced by local advection. Indicative evidence for the hypothesis is presented. Although the absolute magnitude of the results reported is only directly relevant to similar sites in Denmark, the processes and controls described are considered to be representative of riparian wetlands subjected to frequent flooding and/or with a high groundwater table, with vascular vegetation, and which are narrow corridors in open agricultural landscapes.

Vegetation patterns in James Bay coastal marshes. III. Salinity and elevation as factors influencing plant zonations

1989 ◽  
Vol 67 (10) ◽  
pp. 2967-2974 ◽  
Author(s):  
J. C. Earle ◽  
K. A. Kershaw
Keyword(s):  
Salt Marsh ◽  
Salinity Gradient ◽  
Detrended Correspondence Analysis ◽  
Distribution Patterns ◽  
Environmental Data ◽  
Plant Distribution ◽  
Coastal Marsh ◽  
James Bay ◽  
Factors Influencing ◽  
Community Types

Plant zonations and selected environmental variables were studied in a subarctic coastal marsh at Ekwan Point, James Bay, Ont. Eight distinct community types were identified using two-way indicator species analysis classification (TWINSPAN). These were interpreted as a primary successional sequence. The eight communities were found to conform closely to the classical marsh zonations based on elevation and tidal influence: (1) lower salt marsh, (2) middle salt marsh, (3) upper salt marsh, (4) saline meadow, (5) freshwater meadow, and (6) freshwater fen. Environmental data collected along the vegetation transects indicated that changes in elevation and soil-water salinity probably influence species distributions. A species ordination using detrended correspondence analysis (DECORANA) revealed several trends in plant distribution patterns. Consideration of the environmental affinities of species separated along three ordination axes suggested that salinity and elevation, water content, and soil texture were probably important factors influencing successional processes in the marsh during at least the last century. An inverse salinity gradient, which has been reported at many sites along the west coast of Hudson and James bays, was not found at Ekwan Point.

Diversity of woody species 10 years after four harvesting treatments in the oak–pine type

1992 ◽  
Vol 22 (8) ◽  
pp. 1179-1183 ◽  
Author(s):  
James W. McMinn
Keyword(s):  
Species Richness ◽  
Woody Species ◽  
Growing Season ◽  
Dormant Season ◽  
Pine Stands ◽  
Whole Tree

Oak–pine stands in the Upper Piedmont of Georgia were whole-tree harvested to 10- and 2.5-cm DBH limits in both the dormant and early growing season, then allowed to regenerate spontaneously with no further perturbations. After 10 years, stands harvested in the early growing season exhibited higher diversity than those harvested in the dormant season. After the dormant-season harvests, 10-cm-limit stands tended to be more diverse than 2.5-cm-limit stands. The harvest disturbance primarily affected evenness, rather than species richness.

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.

Modelling stomatal conductance in a northern deciduous forest, Chalk River, Ontario

1994 ◽  
Vol 24 (5) ◽  
pp. 904-910 ◽  
Author(s):  
J. Harry McCaughey ◽  
Antonio Iacobelli
Keyword(s):  
Stomatal Conductance ◽  
Least Squares ◽  
Environmental Variables ◽  
Deciduous Forest ◽  
Vapour Pressure Deficit ◽  
Multiple Linear Regression Model ◽  
Nonlinear Least Squares ◽  
Global Solar Radiation ◽  
White Birch ◽  
Conductance Data

Modelling results of stomatal conductance of trembling aspen (Populustremuloides Michx.) and white birch (Betulapapyrifera Marsh.) are reported. Stomatal conductance for the two species was related to global solar radiation, vapour pressure deficit, and air temperature using both linear and nonlinear least squares approaches. Both approaches provided an equally poor fit when relating the large scatter of stomatal conductance data to each of the environmental variables separately. However, an additive, multiple linear regression model and a multiplicative, nonlinear least squares model were able to explain between 50 and 62% of the variability in stomatal conductance when all three environmental variables were included in the models. The two models were able to track changes in stomatal conductance from one half-hour period to the next.

Combining management based indices with environmental parameters to explain regional variation in soil carbon under dryland cropping in South Australia

Soil Research ◽  
2013 ◽  
Vol 51 (8) ◽  
pp. 738 ◽  
Author(s):  
Lynne M. Macdonald ◽  
Tim Herrmann ◽  
Jeffrey A. Baldock
Keyword(s):  
Environmental Variables ◽  
Explanatory Power ◽  
Regional Scale ◽  
South Australia ◽  
Vapour Pressure Deficit ◽  
Environmental Parameters ◽  
Decomposition Processes ◽  
Historical Management ◽  
Broad Scale

Identifying drivers of variation in soil organic carbon (OC) at a regional scale is often hampered by a lack of historical management information. Focusing on red-brown-earth soils (Chromosol) under dryland agriculture in the Mid-North and Eyre Peninsula of South Australia, our aims were 2-fold: (i) to provide a baseline of soil OC stocks (0.3 m) and OC fractions (mid-infrared predictions of particulate, humus, and resistant OC in 0.1 m samples) in cropping and crop-pasture systems; and (ii) to evaluate whether the inclusion of management-based indices could assist in explaining regional-level variation in OC stocks and fractions. Soil OC stocks in both regions varied ~20 Mg ha–1, with higher OC stocks in the Mid-North (38 Mg ha–1) than the Eyre Peninsula (29.1 Mg ha–1). The humus OC fraction was the dominant fraction, while the particulate OC was the most variable. Environmental variables only partially explained soil OC variability, with vapour pressure deficit (VPD) offering the greatest potential and likely acting as an integrator of temperature and moisture on plant growth and decomposition processes. Differences between broad-scale cropping and crop–pasture systems were limited. In the Mid-North, variability in soil OC stocks and fractions was high, and could not be explained by environmental or management variables. Higher soil OC concentrations (0.1 m) in the Eyre Peninsula cropping than crop–pasture soils were largely accounted for in the particulate OC fraction and are therefore unlikely to represent a long-term stable OC pool. Use of the management data in index format added some explanatory power to the variability in OC stocks over the main environmental variables (VPD, slope) within the Eyre Peninsula cropping soils only. In the wider context, the management data were useful in interpreting differences between regional findings and highlighted difficulties in using uninformed, broad-scale management categories.

scholarly journals PERFORMANCE PRODUCTION OF STRAWBERRY IN ENVIRONMENT CULTIVATED WITH FIG TREE

2017 ◽  
Vol 39 (4) ◽  
Author(s):  
HELOISA FERRO CONSTÂNCIO MENDONÇA ◽  
EUNICE OLIVEIRA CALVETE ◽  
ROSIANI CASTOLDI DA COSTA ◽  
ALEXANDRE AUGUSTO NIENOW
Keyword(s):  
Woody Species ◽  
Growing Season ◽  
The Other ◽  
Lower Percentage ◽  
Camino Real ◽  
Fig Tree ◽  
Fruit Plants ◽  
Fig Trees ◽  
Production Period ◽  
Strawberry Cultivars

ABSTRACT The use of protected environment in horticulture has been increasingly used as it provides increased precocity and productivity, in addition to produce outside the normal growing season. Both woody species such as herbs are possible to cultivate in this environment. However fruit plants occupy large spaces with a short production period. The study aimed to test whether strawberry genotypes present different production peaks in cultivated environment with fig trees. The treatments consisted of strawberry cultivars Aromas, Albion, Camino Real, Camarosa and Ventana distributed in delineation of randomized blocks with four replications and with a population of 10 plants m-2. It was recorded precocity in cultivars Albion, Camarosa and Ventana, because they started flowering at 63 days after planting. Aromas and Camino Real were characterized as late. Aromas achieved greater total number of fruit, but with a lower percentage of commercial fruits in relation to the other cultivars. Peak production for all cultivars was found when there was an accumulation 2008 °C day -1, corresponding to the month of November. There were differences in performance production between strawberry cultivars conducted in the environment with fig tree, with different production peaks.

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