Predicting the effects of hardwood competition on red pine seedling growth

1992 ◽  
Vol 22 (10) ◽  
pp. 1510-1515 ◽  
Author(s):  
Alan S. White ◽  
Katherine J. Elliott
Keyword(s):  
Leaf Area ◽  
Seedling Growth ◽  
Negative Impact ◽  
Ground Level ◽  
Red Pine ◽  
Area Index ◽  
Clear Cut ◽  
Site Characteristics ◽  
Early Effects ◽  
Highly Correlated

Pin cherry (Prunuspensylvanica L.f.) and striped maple (Acerpensylvanicum L.) are potentially important competitors of red pine (Pinusresinosa Ait.) planted on recently clear-cut hardwood sites. By experimentally manipulating initial competitor densities on 2.0-m2 plots, we were able to quantify and compare the effects of competitor species on red pine seedlings 2 years after planting on two sites in western Maine. Various measures of competitor biomass and leaf area index (LAI) were highly correlated; thus, we used LAI to quantify competitor abundance. On the site with poorer growth for both competitors and red pine, the only red pine variable significantly correlated with competitor LAI was specific leaf area (SLA) of current needles. On the site with better growth for all species, various measures of red pine biomass as well as diameter at ground level and SLA were significantly correlated with competitor LAI. Seedling height was not significantly correlated with competitor LAI at either site. Although there were no significant differences between competitor species in terms of their effect per unit of LAI, pin cherry tended to achieve much higher LAI (and biomass) than did striped maple and thus had a greater negative impact on red pine seedling growth. We conclude that general predictions of the early effects of competition under field conditions are possible, but that the strength of the relationships may be influenced by the extent to which microsite factors and site characteristics are incorporated.

Effect of previous cutting interval and of leaf area remaining after cutting on regrowth of Macroptilium atropurpureum cv. Siratro

1974 ◽  
Vol 14 (68) ◽  
pp. 343 ◽  
Author(s):  
RJ Jones
Keyword(s):  
Leaf Area ◽  
Practical Implication ◽  
Soluble Sugars ◽  
Ground Level ◽  
Fold Increase ◽  
Water Soluble ◽  
Hot Water ◽  
Lag Phase ◽  
Area Index ◽  
Plant Yield

Experiments with Siratro were conducted at Samford, south east Queensland to study the effects of previous cutting and defoliation treatments on regrowth. In the first experiment, swards of Siratro were cut at 7.5 cm above ground level every 4 weeks, every 8 weeks or cut once at 16 weeks during spring and summer. Regrowth of all treatments over ten weeks was measured after varying (by leaf removal) the stubble leaf area index (LAI) of the plots cut every four weeks. Pattern of regrowth yield was similar for all treatments with a pronounced lag phase after cutting. Regrowth yield after 10 weeks differed between treatments and was linearly related (P < 0.01 ) to residual LAI in the stubble at the start of regrowth. In the absence of stubble leaves, plots previously cut at 16 weeks or at 8 weeks yielded marginally more than those cut every 4 weeks. There were no marked treatment differences in gross root morphology other than a two fold increase in stolon rooting for the 16-week treatment. Nitrogen content of the roots (mean 1.38 per cent) was unaffected by treatment, but the per cent hot water soluble sugars were lower for the 16 week defoliation treatment than for the 8-week and the 4-week treatments. In the second experiment individual plants were cut to a uniform stubble every 4 weeks and either 0, 5, or 10 leaves were left. Dry weight of regrowth and stolon development were greatest when most leaves were left. Two thirds of the plants died after six cuttings with complete defoliation but none died when either 5 or 10 leaves were retained. Plant survival was not related to plant yield or degree of stoloniferous development. However, there was a strong correlation between stolon number and plant yield under this intensive cutting regime. The practical implication of the results in the management of Siratro is discussed.

scholarly journals Comparisons of Herbicide Treated and Cultivated Herbicide-Resistant Corn

2010 ◽  
Vol 2010 ◽  
pp. 1-7 ◽  
Author(s):  
H. Arnold Bruns ◽  
Hamed K. Abbas
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Growth Rates ◽  
Negative Impact ◽  
Growth Yield ◽  
Yield Component ◽  
Dry Matter Accumulation ◽  
Negative Effects ◽  
Area Index ◽  
Relative Growth Rates

Four glyphosate resistant corn (Zea maysL.) hybrids, a glufosinate-ammonium resistant hybrid, and a conventional atrazine resistant hybrid gown at Stoneville, MS in 2005, 2006, and 2007 with furrow irrigation were treated with their respective herbicides and their growth, yield, and mycotoxin incidence were compared with untreated cultivated plots. Leaf area index (LAI) and dry matter accumulation (DMA) were collected on a weekly basis beginning at growth stage V3 and terminating at anthesis. Crop growth rates (CRGs) and relative growth rates (RGRs) were calculated. Plots were later harvested, yield and yield component data collected, and kernel samples analyzed for aflatoxin and fumonisin. Leaf area index, DMA, CRG, and RGR were not different among the herbicide treated plots and from those that were cultivated. Curves for LAI and DMA were similar to those previously reported. Aflatoxin and fumonisin were relatively low in all plots. Herbicide application or the lack thereof had no negative impact on the incidence of kernel contamination by these two mycotoxins. Herbicides, especially glyphosate on resistant hybrids, have no negative effects on corn yields or kernel quality in corn produced in a humid subtropical environment.

Effects of defoliation management on the productivity of an irrigated Persian clover sward

1994 ◽  
Vol 34 (2) ◽  
pp. 205 ◽  
Author(s):  
CR Stockdale
Keyword(s):  
Leaf Area ◽  
Growth Rates ◽  
Ground Level ◽  
Maximum Growth ◽  
Fungal Disease ◽  
Area Index ◽  
Herbage Yield ◽  
Defoliation Treatment ◽  
Negative Effect ◽  
Persian Clover

A field experiment investigated the effects of frequency and height of defoliation on the productivity of an irrigated Persian clover (Trifolium resupinatum) sward. Combinations of 4 intervals of harvest (3, 6, 9, 12 weeks) and 2 heights of defoliation (to ground level or 5 cm above ground level) were used in a randomised block experiment, with 2 additional treatments of 4 and 18 weeks between harvests defoliated to ground level. Total herbage accumulation ranged from 8.46 to 13.90 t DM/ha and varied according to defoliation management. Except for the very short defoliation intervals, harvesting to 5 cm was less productive than harvesting to ground level. The effects of leaf area index, herbage yield, and infection with leaf fungal disease on growth rates were assessed. Leaf area had a positive effect, and fungal disease a negative effect, on herbage growth rates, while maximum growth rates in autumn-winter were achieved when herbage yield reached about 2.0 t DM/ha. Dead matter accumulation increased with the interval between harvests, and weeds invaded the plots at both the shortest and longest defoliation intervals. The quality of seed produced (seed weight) was not influenced by defoliation treatment (0.1112 g/100 seeds, on average). Defoliation interval was positively related to number of inflorescences and quantity of seed set, but height of defoliation did not significantly affect these variables. It was concluded that the optimum interval of harvest was 6-9 weeks. Height of defoliation had only minor effects, due to the small difference in residual dry matter between the treatments.

Biomass and Leaf-Area Estimates for Varnishleaf Ceanothus, Deerbrush, and Whiteleaf Manzanita

1987 ◽  
Vol 2 (4) ◽  
pp. 124-128 ◽  
Author(s):  
Thomas F. Hughes ◽  
Christopher R. Latt ◽  
John C. Tappeiner ◽  
Michael Newton
Keyword(s):  
Leaf Area ◽  
Site Occupancy ◽  
Basal Area ◽  
Stem Length ◽  
Stand Age ◽  
Leaf Biomass ◽  
Total Biomass ◽  
Regression Equations ◽  
Area Index ◽  
Highly Correlated

Abstract To help foresters assess site occupancy of seed-established stands of varnishleaf (Ceanothus velutinus var. laevigatus) deerbrush (Ceanothus integerrimus), and whiteleaf manzanita (Arctostaphylos viscida), we developed equations for estimating their aboveground biomass and leaf area. From 9 to 14 pure stands from 2 to 20 years old were selected for each species in southwest Oregon and northern California. Individual stems of Ceanothus species and whole bushes of manzanita were destructively sampled Regression equations for leaf and total biomass of manzanita plants and for stems of Ceanothus sp. showed that these variables were highly correlated with trunk or stem diameter (r² = 0.85 - 0.99). Total biomass, leaf biomass, and leaf area index (LAI) of stands can be estimated accurately from measurements of stem or trunk basal area (r² = 0.87 - 0.99). Stand age (yr) and average stem length (cm) are also reliable estimators (r² = 0.74 - 0.82). It appears that stands of varnishleaf attain a maximum LAI of 5.5 m²/m² by 7 years, whereas the maximum values for deer-brush and manzanita were 2.8 and 3.5, respectively, at about 15 years. Stands of all three species apparently continue to produce net biomass well beyond 16 years of age. West. J. Appl. For. 2(4):124-128, October 1987.

Estimating Leaf Areas of Cowpea and Soyabean Using Dry Weights of Terminal Leaflets

1980 ◽  
Vol 16 (2) ◽  
pp. 149-151 ◽  
Author(s):  
D. Nangju ◽  
S. B. C. Wanki
Keyword(s):  
Glycine Max ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Rapid Method ◽  
Vigna Unguiculata ◽  
Terminal Leaflet ◽  
Area Index ◽  
Trifoliate Leaf ◽  
Physiological Studies ◽  
Highly Correlated

SUMMARYLeaf area index is an important parameter in many agronomic and physiological studies, but its determination in cowpea (Vigna unguiculata) and soyabean (Glycine max) is difficult and time consuming. A simple and rapid method is described in which dry weights of the middle leaflets were used to predict leaf areas of cowpea and soyabean. This method was based on results which indicated that leaf dry weights were highly correlated to leaf areas and that the ratio between leaf area of the terminal leaflet and total area of a trifoliate leaf was constant, at least in some cultivars, giving ratios of 0.37 for cowpea and 0.33 for soyabean.

scholarly journals Projections of leaf area index in earth system models

2016 ◽  
Vol 7 (1) ◽  
pp. 211-229 ◽  
Author(s):  
Natalie Mahowald ◽  
Fiona Lo ◽  
Yun Zheng ◽  
Laura Harrison ◽  
Chris Funk ◽  
...  
Keyword(s):  
Climate Change ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Climate Change Impacts ◽  
Earth System ◽  
Area Index ◽  
System Models ◽  
Clear Cut ◽  
The Tropics ◽  
Earth System Models

Abstract. The area of leaves in the plant canopy, measured as leaf area index (LAI), modulates key land–atmosphere interactions, including the exchange of energy, moisture, carbon dioxide (CO2), and other trace gases and aerosols, and is therefore an essential variable in predicting terrestrial carbon, water, and energy fluxes. Here our goal is to characterize the LAI projections from the latest generation of earth system models (ESMs) for the Representative Concentration Pathway (RCP) 8.5 and RCP4.5 scenarios. On average, the models project increases in LAI in both RCP8.5 and RCP4.5 over most of the globe, but also show decreases in some parts of the tropics. Because of projected increases in variability, there are also more frequent periods of low LAI across broad regions of the tropics. Projections of LAI changes varied greatly among models: some models project very modest changes, while others project large changes, usually increases. Modeled LAI typically increases with modeled warming in the high latitudes, but often decreases with increasing local warming in the tropics. The models with the most skill in simulating current LAI in the tropics relative to satellite observations tend to project smaller increases in LAI in the tropics in the future compared to the average of all the models. Using LAI projections to identify regions that may be vulnerable to climate change presents a slightly different picture than using precipitation projections, suggesting LAI may be an additional useful tool for understanding climate change impacts. Going forward, users of LAI projections from the CMIP5 ESMs evaluated here should be aware that model outputs do not exhibit clear-cut relationships to vegetation carbon and precipitation. Our findings underscore the need for more attention to LAI projections, in terms of understanding the drivers of projected changes and improvements to model skill.

scholarly journals Coffee (Coffea arabica L,var. Castillo) seedling growth in Nariño, Colombia

2021 ◽  
Vol 38 (1) ◽  
pp. 62-74
Author(s):  
José Álvaro Castillo ◽  
Danita Andrade
Keyword(s):  
Growth Rate ◽  
Leaf Area ◽  
Seedling Growth ◽  
Block Design ◽  
Dry Weight ◽  
Climatic Conditions ◽  
Area Index ◽  
Environmental Variations ◽  
La Florida ◽  
Net Assimilation

Coffee is one of the most socioeconomically important crops worldwide. Currently, environmental variations due to climate change are affecting coffee development and growth. Therefore, it is important to evaluate areas that offer a different environment during seedling stage since it is fundamental for successful cultivation. Four municipalities located at different altitudes in the Department of Nariño were selected: La Florida (1879 m a.s.l.), Sandoná (1924 m a.s.l.), Consacá (2001 m a.s.l.), and La Unión (1417 m a.s.l.). The experiment was conducted as a randomized complete block design. Growth variables were measured for five months, including total height-TH, number of leaves-NL, total leaf area-LA, fresh weight-FW, and dry weight-W. The following indices were calculated from the variables recorded: relative growth rate-RGR, leaf area index-LAI, net assimilation rate-NAR, crop growth rate-CGR, leaf area duration-LAD, and leaf area ratio-LAR. The data related to TH, NL, W, and LA recorded during the last evaluation (120 days after being transplanted) showed differences between locations; the maximum values in TH, W and LA were recorded in La Union, while higher averages in NL were obtained in Sandoná. The index values for CGR, LAI, LAR, RGR, and LAD were higher in La Unión, while NAR was higher in La Florida. The results lead to conclude that there are differences in coffee seedling growth depending on the climatic conditions. Accordingly, the highest growth was observed in areas at lower altitudes; therefore, these are recommended for seedling establishment given the higher growth rate, especially that of leaves.

scholarly journals Apple Δ13C Discrimination Is Related to Shoot Ash Content

HortScience ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 213-216 ◽  
Author(s):  
D. Michael Glenn ◽  
Carole Bassett
Keyword(s):  
Leaf Area ◽  
Ash Content ◽  
Yearly Variation ◽  
Area Index ◽  
Grassland Species ◽  
Malus Sieversii ◽  
Period 2 ◽  
Highly Correlated ◽  
Relationship Of ◽  
The Relationship

Plant ash content has been highly correlated with plant water use efficiency (WUE) and Δ13C (Δ) in field crops and grassland species and proposed as a selection criteria for WUE. δ18O (δ) has also been correlated with transpiration in herbaceous plants. The objectives of the study were to 1) evaluate the relationship of shoot ash (ASH) with Δ and δ in ‘Empire’ apple over a 3-year period; 2) determine if yearly variation significantly affected the relationship of ASH with Δ and δ; and 3) evaluate the value of the relationship between ASH content with Δ and δ for a population of Malus sieversii. ‘Empire’ leaf area index (LAI) was negatively correlated with ASH content and positively correlated with Δ. Δ was negatively correlated with ‘Empire’ ASH. There were no yearly effects at a site. Within the Malus sieversii accessions, there was a grouping based on ASH that could be identified and this outlier group also had the lowest δ of the accessions. There were no correlations of leaf area, number, length, width, or stomata number with δ, Δ, or ASH for the Malus sieversii accessions. Rather than a substitute for Δ measurement in assessing WUE, ash content analysis adds an additional dimension to understanding the dynamics of WUE in apple. This work has identified a unique population of Malus meriting further study.

Alternative conifer release treatments affect leaf area index of competing vegetation and available light for seedling growth

1997 ◽  
Vol 73 (1) ◽  
pp. 83-89 ◽  
Author(s):  
Phillip E. Reynolds ◽  
Donald A. Buckley ◽  
James A. Simpson ◽  
Andrew M. Gordon ◽  
Donald A. Gresch ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Seedling Growth ◽  
Photosynthetically Active Radiation ◽  
Growing Season ◽  
Plant Succession ◽  
Trembling Aspen ◽  
Area Index ◽  
Active Radiation ◽  
Competing Vegetation

Leaf area index (LAI) of competing vegetation and photosynthetically-active radiation (PAR) for spruce seedling growth were measured during the first growing season after alternative conifer release treatments [brush saw, Silvana Selective, Release® (a.i., triclopyr) herbicide, Vision® (a.i., glyphosate) herbicide], and control (no treatment) were applied. Bareroot white [Picea glauca (Moench) Voss] and black [Picea mariana (Mill.) B.S.P.] spruce were planted between 1987 and 1991, and averaged 82 cm height in 1993 compared with 2.6 m for major competitors. Treatments were applied in 1993, the primary competitor being trembling aspen (Populus tremuloides Michx.). After the first growing season following treatments, LAI at seedling base differed (P = 0.002) among treatments, ranging from 2.04 (Vision®) to 3.88 (control) m2 m−2. The Vision® treatment had significantly lower LAI than the brush saw, Silvana Selective, and Release® treatments (means = 2.76,2.76, and 2.74 m2 m−2 respectively), and the control treatment had significantly greater LAI than all other treatments. LAI correlated well (r = 0.81) with measured competition levels, increasing as competition levels increased. Mean tip angle (MTA) did not differ among treatments, but was higher for the Vision® treatment, presumably because of lower deciduous tree and shrub cover. Available light (PAR) decreased as LAI increased r = −0.90). In 1994, few released seedlings were overtopped by competing vegetation, and available PAR at leader height was generally 100%. For control seedlings, available PAR at leader height varied among blocks, ranging from 20 to 50%. PAR at seedling base differed among treatments, was lowest (13%) for controls, highest (36%) for the Vision®, and intermediate (~ 26%) for all other treatments. Available PAR on a whole seedling basis (i.e. avg. of leader and base) ranged from 25% for control seedlings to 68% for seedlings released with Vision®. Key words: Fallingsnow Ecosystem Project, white spruce, black spruce, trembling aspen, Vision® (glyphosate), Release® (triclopyr), leaf area index (LAI), mean tip angle (MTA), competition indices, photosynthetically-active radiation (PAR), vegetation management, plant succession

Seedling growth in conifers and angiosperms: impacts of contrasting xylem structure

2005 ◽  
Vol 53 (8) ◽  
pp. 749 ◽  
Author(s):  
T. J. Brodribb ◽  
N. M. Holbrook ◽  
R. S. Hill
Keyword(s):  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Gas Exchange ◽  
Leaf Area ◽  
Seedling Growth ◽  
Light Adaptation ◽  
Efficient Production ◽  
Xylem Structure ◽  
Highly Correlated ◽  
Global Vegetation

Competitive interaction between conifers and angiosperms has moulded the structure of global vegetation since the Cretaceous. Angiosperms appear to enjoy their greatest advantage in the lowland tropics, an advantage often attributed to the presence of vessels in their xylem tissue. By monitoring the seedling growth of three members of the pan-tropical conifer family Podocarpaceae and three tropical angiosperm tree species, our aim was to determine whether these conifer and angiosperm seedlings showed distinct patterns of growth and light adaptation that might be attributed to the presence/absence of vessels. Angiosperm seedlings were consistently more efficient in terms of leaf area carried per unit stem investment, as well as more responsive to light climate than the conifer seedlings. Apparently linked to this were larger growth rate, stem hydraulic conductivity and stomatal conductance in the angiosperm sample. Stem hydraulic conductivity and maximum stomatal conductance were highly correlated among species and light treatments explaining the association between highly conductive vessel-bearing wood and high rates of gas exchange. We conclude that xylem vessels contribute to higher rates of gas exchange and more efficient production of leaf area in our sample angiosperms than in conifers. However, this advantage is limited by shade.

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