Do wide crowns in arid woodland trees reflect hydraulic limitation and reduction of self-shading?

2014 ◽  
Vol 41 (12) ◽  
pp. 1221 ◽  
Author(s):  
Martín Escoto-Rodríguez ◽  
José M. Facelli ◽  
Jennifer R. Watling
Keyword(s):  
Arid Regions ◽  
Tree Height ◽  
Lateral Spreading ◽  
Light Limitation ◽  
Hydraulic Limitation ◽  
Trade Offs ◽  
Crown Shape ◽  
Horizontal Growth ◽  
Lateral Branches ◽  
Topographic Positions

In arid regions many tree species develop broad crowns. A number of hypotheses involve trade-offs between growth in height and horizontal spreading, but there is no explanation for the switch from vertical to horizontal growth during development. Using Acacia papyrocarpa Benth as a model, we measured tree height and crown shape across different sites and topographic positions. We also measured δ13C of phyllodes from crown tops and lateral spreading branches. Trees were significantly taller at the base of a hill, where water availability is typically greater, than on the adjacent steep hillslope. In contrast, δ13C from the treetops was not significantly different across this topographic gradient, despite variation in tree height. In addition, δ13C was higher at treetops than in lower, lateral branches. These observations are consistent with hydraulic limitation to tree height. The shape of mature and young crowns in open environments was not symmetrical. At all sites, branches were shortest, but tree crowns tallest, on south-facing (i.e. shadiest) aspect of crowns. This suggests that light limitation may also affect crown development. If upper branches become water-limited and lower branches light-limited, then middle lateral branches become the less-stressed part of the crown and may grow more, producing a broad crown.

scholarly journals Genetically based resistance to the white pine weevil in jack pine and eastern white pine

2010 ◽  
Vol 86 (6) ◽  
pp. 775-779 ◽  
Author(s):  
Alice Verrez ◽  
Dan Quiring ◽  
Thibaut Leinekugel Le Cocq ◽  
Greg Adams ◽  
Yill Sung Park
Keyword(s):  
Pinus Banksiana ◽  
Significant Proportion ◽  
Tree Height ◽  
Jack Pine ◽  
White Pine ◽  
Pissodes Strobi ◽  
Pine Weevil ◽  
Tree Resistance ◽  
Trade Offs ◽  
White Pine Weevil

White pine weevil (Pissodes strobi Peck) damage was evaluated in one white pine (Pinus strobus L.) and four jack pine(Pinus banksiana Lamb) half-sib family test sites to determine the role of tree genotype in resistance to the weevil. Halfsibfamily explained a significant proportion of the variation in weevil attack at all sites. Estimates of family (0.16-0.54)and individual (0.09-0.24) heritabilities of jack pine resistance to white pine weevil were moderate. Estimates of family(0.37) and individual (0.22) heritability of resistance of white pine to the weevil were also moderate when the percentageof test trees damaged by the weevil was relatively low, but were insignificant four years later when more than three-quartersof trees were damaged. Significant positive correlations between mean tree height and mean incidence of trees damagedby the weevil were observed for four of seven site-years but relationships were weak, suggesting that any cost, withrespect to height growth, to breeding weevil resistant trees may be small.Key words: Pinus, Pissodes strobi, trade-offs, tree improvement, tree resistance, white pine weevil.

Hydraulic limitation of tree height: a critique

2000 ◽  
Vol 14 (1) ◽  
pp. 4-11 ◽  
Author(s):  
P. Becker ◽  
F. C. Meinzer ◽  
S. D. Wullschleger
Keyword(s):  
Tree Height ◽  
Hydraulic Limitation

scholarly journals The evolution of competitive ability for essential resources

2019 ◽  
Author(s):  
Joey R. Bernhardt ◽  
Pavel Kratina ◽  
Aaron Pereira ◽  
Manu Tamminen ◽  
Mridul K. Thomas ◽  
...  
Keyword(s):  
Competitive Ability ◽  
Community Dynamics ◽  
Species Coexistence ◽  
Resource Competition ◽  
Environmental Gradients ◽  
Light Limitation ◽  
Major Question ◽  
Trade Offs ◽  
Resource Requirements ◽  
Competitive Abilities

AbstractCompetition for limiting resources is among the most fundamental ecological interactions and has long been considered a key driver of species coexistence and biodiversity. Species’ minimum resource requirements, their R*s, are key traits that link individual physiological demands to the outcome of competition. However, a major question remains unanswered - to what extent are species’ competitive traits able to evolve in response to resource limitation? To address this knowledge gap, we performed an evolution experiment in which we exposed Chlamydomonas reinhardtii for approximately 285 generations to seven environments in chemostats which differed in resource supply ratios (including nitrogen, phosphorus and light limitation) and salt stress. We then grew the ancestors and descendants in common garden and quantified their competitive abilities for essential resources. We investigated constraints on trait evolution by testing whether changes in resource requirements for different resources were correlated. Competitive abilities for phosphorus improved in all populations, while competitive abilities for nitrogen and light increased in some populations and decreased in others. In contrast to the common assumption that there are trade-offs between competitive abilities for different resources, we found that improvements in competitive ability for a resource came at no detectable cost. Instead, improvements in competitive ability for multiple resources were either positively correlated or not significantly correlated. Using resource competition theory, we then demonstrated that rapid adaptation in competitive traits altered the predicted outcomes of competition. These results highlight the need to incorporate contemporary evolutionary change into predictions of competitive community dynamics over environmental gradients.

scholarly journals Effect of Selected Pruning Methods to Obtain Straight Trunks on Container Grown Quercus shumardii Buckl.

1989 ◽  
Vol 7 (4) ◽  
pp. 123-125
Author(s):  
Adolph J. Laiche
Keyword(s):  
Growth Medium ◽  
Tree Height ◽  
Bud Break ◽  
Lower Trunk ◽  
Lateral Branches ◽  
Quercus Shumardii ◽  
Pruning Methods ◽  
Number Of Branches

Abstract Quercus shumardii seedling trees in 7.6 1 (2 gal) containers were selected with straight and crooked trunks and planted in 26 1 (7 gal) containers on March 13, 1987. Pruning treatments to trees with straight and crooked trunks were: (A) not pruned; (B) lower lateral branches on the trunk headed back; and trunks severed at 5 cm (2 in) on (C) March 30, 1987 or (D) May 13, 1987 with lower lateral branches arising on the forced new trunk headed back. Trees were allowed to branch normally above 91 cm (3 ft). The study was terminated October 19, 1987. Tree height and trunk quality of trees with straight trunks were not improved by pruning treatments. Height of trees with crooked trunks was not reduced by heading back laterals only, or by severing trunks on March 30, 1987. Trunk quality of trees with crooked trunks was substantially improved by all pruning treatments, although the resultant trunk quality was not equal to that of trees with straight trunks. Severing trunks 5 cm (2 in) above the growth medium and heading back lateral branches on the lower trunk reduced caliper and the number of branches above 91 cm (3 ft). Delaying severing of trunks approximately 6 weeks after bud break caused a further reduction of trunk caliper.

scholarly journals ACCURACY ASSESSMENT OF CROWN DELINEATION METHODS FOR THE INDIVIDUAL TREES USING LIDAR DATA

2016 ◽  
Vol XLI-B8 ◽  
pp. 585-588
Author(s):  
K. T Chang ◽  
C. Lin ◽  
Y. C. Lin ◽  
J. K. Liu
Keyword(s):  
Forest Canopy ◽  
Accuracy Assessment ◽  
Tree Height ◽  
Experimental Results ◽  
Estimation Methods ◽  
Surface Model ◽  
Individual Tree ◽  
Free Process ◽  
Crown Shape ◽  
Individual Trees

Forest canopy density and height are used as variables in a number of environmental applications, including the estimation of biomass, forest extent and condition, and biodiversity. The airborne Light Detection and Ranging (LiDAR) is very useful to estimate forest canopy parameters according to the generated canopy height models (CHMs). The purpose of this work is to introduce an algorithm to delineate crown parameters, e.g. tree height and crown radii based on the generated rasterized CHMs. And accuracy assessment for the extraction of volumetric parameters of a single tree is also performed via manual measurement using corresponding aerial photo pairs. A LiDAR dataset of a golf course acquired by Leica ALS70-HP is used in this study. Two algorithms, i.e. a traditional one with the subtraction of a digital elevation model (DEM) from a digital surface model (DSM), and a pit-free approach are conducted to generate the CHMs firstly. Then two algorithms, a multilevel morphological active-contour (MMAC) and a variable window filter (VWF), are implemented and used in this study for individual tree delineation. Finally, experimental results of two automatic estimation methods for individual trees can be evaluated with manually measured stand-level parameters, i.e. tree height and crown diameter. The resulting CHM generated by a simple subtraction is full of empty pixels (called "pits") that will give vital impact on subsequent analysis for individual tree delineation. The experimental results indicated that if more individual trees can be extracted, tree crown shape will became more completely in the CHM data after the pit-free process.

scholarly journals Growth features of apple varieties and forms with natural and compact crown types

2021 ◽  
Vol 845 (1) ◽  
pp. 012014
Author(s):  
A S Zemisov ◽  
A N Youshkov ◽  
N N Saveleva ◽  
L V Grigoreva ◽  
N V Borzykh ◽  
...  
Keyword(s):  
Tree Height ◽  
Cost Effective ◽  
Federal State ◽  
Scientific Center ◽  
Apple Varieties ◽  
Crown Volume ◽  
Crown Shape ◽  
The Rich ◽  
Growth Features ◽  
High Degree

Abstract This research explores the compactness of apple varieties and forms with different types of crown. Orchards on semi-vigorous rootstocks with density and high density planting systems are cost-effective in modern horticulture. For making such gardens, it is necessary to have trees with special compact crown shape. They ensure the high-quality fruits production, meeting the requirements of world standards. To date the most perspective apple varieties and forms for domestic intensive gardening from the rich gene pool of the Selection and Genetic Center of Federal State Scientific Institution «I. V. Michurin Federal Scientific Center» are identified. Varieties of folk domestic and foreign breeding took part in the creation of new genotypes. Apple varieties and promising forms (more than 160 genotypes), including from near and far abroad selection, were used as materials for crown features studying. We conducted our study by the following indicators: tree height, crown volume, “degree of compactness” and the shoot-forming ability. We found that the genotypes Sholokhovskoye, Zvezda Artemyeva, 25-7(11), 40-9(8), 36-8(21), 40-9(6), 8-7(72), 40-9(7), 36-8(17), 62-5(140) have optimal crown parameters. We recommend their use for industrial horticulture and further breeding to create restrained growth, low-volume crown, and a high degree of compactness varieties.

scholarly journals A Consumer Grade UAV-Based Framework to Estimate Structural Attributes of Coppice and High Oak Forest Stands in Semi-Arid Regions

2021 ◽  
Vol 13 (21) ◽  
pp. 4367
Author(s):  
Seyed Arvin Fakhri ◽  
Hooman Latifi
Keyword(s):  
Arid Regions ◽  
Tree Height ◽  
Growth Forms ◽  
Zagros Mountains ◽  
Zagros Forests ◽  
Forest Models ◽  
Random Forest Models ◽  
Quercus Brantii ◽  
Linear Regressions ◽  
Semi Arid

Semi-arid tree covers, in both high and coppice growth forms, play an essential role in protecting water and soil resources and provides multiple ecosystem services across fragile ecosystems. Thus, they require continuous inventories. Quantification of forest structure in these tree covers provides important measures for their management and biodiversity conservation. We present a framework, based on consumer-grade UAV photogrammetry, to separately estimate primary variables of tree height (H) and crown area (A) across diverse coppice and high stands dominated by Quercus brantii Lindl. along the latitudinal gradient of Zagros mountains of western Iran. Then, multivariate linear regressions were parametrized with H and A to estimate the diameter at breast height (DBH) of high trees because of its importance to accelerate the existing practical DBH inventories across Zagros Forests. The estimated variables were finally applied to a model tree aboveground biomass (AGB) for both vegetative growth forms by local allometric equations and Random Forest models. In each step, the estimated variables were evaluated against the field reference values, indicating practically high accuracies reaching root mean square error (RMSE) of 0.68 m and 4.74 cm for H and DBH, as well as relative RMSE < 10% for AGB estimates. The results generally suggest an effective framework for single tree-based attribute estimation over mountainous, semi-arid coppice, and high stands.

scholarly journals An Improved Tree Height Measurement Technique Tested on Mature Southern Pines

2008 ◽  
Vol 32 (1) ◽  
pp. 38-43 ◽  
Author(s):  
Don C. Bragg
Keyword(s):  
Tree Height ◽  
Real Point ◽  
Horizontal Distance ◽  
Height Measurement ◽  
Similar Triangle ◽  
Height Determination ◽  
Southern Pines ◽  
Crown Shape ◽  
Tangent Method ◽  
Similar Triangles

Abstract Virtually all techniques for tree height determination follow one of two principles: similar triangles or the tangent method. Most people apply the latter approach, which uses the tangents of the angles to the top and bottom and a true horizontal distance to the subject tree. However, few adjust this method for ground slope, tree lean, crown shape, and crown configuration, making errors commonplace. Given documented discrepancies exceeding 30% with current methods, a reevaluation of height measurement is in order. The sine method is an alternative that measures a real point in the crown. Hence, it is not subject to the same assumptions as the similar triangle and tangent approaches. In addition, the sine method is insensitive to distance from tree or observer position and can not overestimate tree height. The advantages of the sine approach are shown with mature southern pines from Arkansas.

scholarly journals Restoration of degraded grasslands, but not invasion by Prosopis juliflora, avoids trade-offs between climate change mitigation and other ecosystem services

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Purity Rima Mbaabu ◽  
Daniel Olago ◽  
Maina Gichaba ◽  
Sandra Eckert ◽  
René Eschen ◽  
...  
Keyword(s):  
Climate Change ◽  
Ecosystem Services ◽  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Climate Change Mitigation ◽  
Arid Regions ◽  
Prosopis Juliflora ◽  
Trade Offs ◽  
Change Mitigation ◽  
Semi Arid

AbstractGrassland degradation and the concomitant loss of soil organic carbon is widespread in tropical arid and semi-arid regions of the world. Afforestation of degraded grassland, sometimes by using invasive alien trees, has been put forward as a legitimate climate change mitigation strategy. However, even in cases where tree encroachment of degraded grasslands leads to increased soil organic carbon, it may come at a high cost since the restoration of grassland-characteristic biodiversity and ecosystem services will be blocked. We assessed how invasion by Prosopis juliflora and restoration of degraded grasslands in a semi-arid region in Baringo, Kenya affected soil organic carbon, biodiversity and fodder availability. Thirty years of grassland restoration replenished soil organic carbon to 1 m depth at a rate of 1.4% per year and restored herbaceous biomass to levels of pristine grasslands, while plant biodiversity remained low. Invasion of degraded grasslands by P. juliflora increased soil organic carbon primarily in the upper 30 cm and suppressed herbaceous vegetation. We argue that, in contrast to encroachment by invasive alien trees, restoration of grasslands in tropical semi-arid regions can both serve as a measure for climate change mitigation and help restore key ecosystem services important for pastoralists and agro-pastoralist communities.

Tree height and crown shape, as results of competitive games

1985 ◽  
Vol 112 (2) ◽  
pp. 279-297 ◽  
Author(s):  
Yoh Iwasa ◽  
Dan Cohen ◽  
Jesus Alberto Leon
Keyword(s):  
Tree Height ◽  
Crown Shape ◽  
Competitive Games
Sign in / Sign up

Export Citation Format

Share Document