21 research outputs found
Dynamics of canopy development of Cunninghamia lanceolata mid-age plantation in relation to foliar nitrogen and soil quality influenced by stand density
It has been generally accepted that different silvicultural practices affect the forest canopy morphology and structure. During forest establishment, many natural sites were converted to coniferous plantations in southern China. Retention of the canopy during stand conversion may be desirable to promote ecological function and meet conservation objectives. We tested the impact of planting density, foliar nitrogen and soil chemical properties on the canopy development of Chinese fir (Cunninghamia lanceolata) mid-age monoculture stands. Low density (1450 trees hmâ2 with planting spacing of 2.36 Ă 2.36 m), intermediate-density (2460 trees hmâ2 with planting spacing of 1.83 Ă 1.83 m) and high density (3950 trees hmâ2 with planting spacing of 1.44 Ă 1.44 m) stands were selected in Xinkou forest plantations in Sanming City, China. Canopy characteristics such as leaf area index (LAI), mean tilt angle of the leaf (MTA) and average canopy openness index (DIFN) were measured. Measurements were taken using LAI-2200 PCA. The results illustrated that stand density was the primal factor responsible in canopy structuring while soil chemical properties seem to play a secondary role for canopy dynamics. LAI increased from 3.974 m2 m-2 to 5.072 m2 m-2 and MTA increases from 34.8° to 48.7° as the stand density increased while the DIFN decreased from 0.1542 to 0.0902 with the increasing stand density but it was no significantly different in intermediate and high-density stands. Additionally, LAI and MTA were positively correlated to foliar nitrogen while the DIFN was negatively correlated. In general, soil available nitrogen, available phosphorus and soil pH were not significant to canopy parameters. The results presented provide guiding principles about the canopy dynamics distribution in varying stand densities from LICOR measurements in mid-age Chinese fir monoculture. Furthermore, this provides a base to study canopy dynamics at mature stage forests because of more senescence activities.This research was financially supported by the National Natural Science Foundation of China (31870614 and 30970451), the Forestry Peak Discipline Project of Fujian Agriculture and Forestry University, China (71201800716) and Postdoctoral research funding of Central South University of Forestry and Technology (70702-45200003)
DOES CROWN CLASS CLASSIFICATION IMPROVE THE INITIATION AND DEVELOPMENT ANALYSIS OF POST-FIRE PINUS BRUTIA STANDS?
The relationship between growth efficiency and individual tree leaf area index in an even-aged coast redwood (Sequoia sempervirens [Lamb. ex D. Don] Endl.) stand
BlattflĂ€che und StandflĂ€che wurden verwendet um die BlattflĂ€cheneffizienz und die StandflĂ€cheneffizienz fĂŒr einen 28 Jahre alten KĂŒstenmammutbaumbestand (Sequoia sempervirens [Lamb. ex D.Don] Endl.) in Scotia, Kalifornien, Vereinigte Staaten von Amerika, zu schĂ€tzen. 13 ProbeflĂ€chen mit 5 verschiedenen Behandlungsformen und einer KontrollflĂ€che wurden zweimal gemessen (2003-2007) auf Durchmesser, Höhe, Splintholz und Borkendicke was den GrundflĂ€chen- und Volumszuwachs ergab. Die projizierte BlattflĂ€che wurde ĂŒber die SplintholzflĂ€che fĂŒr jeden Baum bestimmt. Es war möglich die Koordinaten zu berechnen, da der Pflanzprozess sehr prĂ€zise erfolgte und fĂŒr FĂ€lle wo mehrere StĂ€mme auf einen Rasterpunkt fielen wurden spezielle Richtlinien erarbeitet. Die StandflĂ€chen wurden nach dem Verfahren von RĂMISCH (1995) berechnet. Die BlattflĂ€che erwies sich als starke Variable um GrundflĂ€chen- und Volumszuwachs vorherzusagen. Im generellen Modell nahm die BlattflĂ€cheneffizienz mit zunehmender BlattflĂ€che zu, jedoch wenn die relative Höhe konstant gehalten wurde nahm sie mit zunehmender BlattflĂ€che ab. Ab einer BlattflĂ€che von 300 m 2 bewahrte die BlattflĂ€cheneffizienz moderate Werte bei. Die StandflĂ€cheneffizienz nahm mit zunehmender StandflĂ€che in negativ exponentieller Form ab. FĂŒr beide Effizienzen gilt das eine höhere relative Höhe zu höheren Effizienzen fĂŒhrt. Die Theorie eines optimalen individuellen BlattflĂ€chenindex wurde in dieser Studie bestĂ€tigt. Sie beschreibt eine Optimumkurve der StandflĂ€cheneffizienz ĂŒber dem BlattflĂ€chenindex, welcher als VerhĂ€ltnis zwischen BlattflĂ€che und StandflĂ€che definiert ist.Leaf area and area potentially available were used to predict leaf area efficiency and area available efficiency for a 28 year old redwood (Sequoia sempervirens [Lamb. ex D.Don] Endl.) stand in Scotia, California, United States of America. 13 plots with 5 different treatments and a control were measured two times (2003-2007) for diameter, height, sapwood and bark thickness, which led to the basal area increment and the volume increment. The projected leaf area was predicted from the sapwood area from each tree. Coordinates of every individual tree could be calculated based on the very precise planting process and special guidelines for the handling of multiple trees per grid point. The area potentially available was calculated following the approach of RĂMISCH (1995). The leaf area was found to be a very powerful variable to predict basal area increment and volume increment. The leaf area efficiency was increasing with increasing leaf area for the general model, but decreasing when the relative height was held constant. For a leaf area of more than 300 m 2 the leaf area efficiency maintained moderate values. The efficiency of the area potentially available is declining in a negative exponential fashion with increasing area potentially available. Higher relative height led to higher efficiencies in both models. The theory of an optimum tree leaf area index could be confirmed in this study. This is an optimum curve of the available area efficiency over the leaf area index, where the leaf area index is defined as a ratio between the leaf area and the area potentially available.handed in by Martin GspaltlZsfassung in dt. SpracheWien, Univ. fĂŒr Bodenkultur, Masterarb., 2008(VLID)108348
Growth efficiency of individual trees
Es ist weitestgehend bekannt, dass die Bestandesdichte das Wachstum eines Bestandes direkt beeinflusst. Jedoch die Prozesse, die das Wachstum des Einzelbaumes beschreiben und in Summe das Bestandeswachstum ergeben sind noch weitestgehend unerforscht. Diese Dissertation versucht durch die Analyse der Wachstumseffizienz einzelner BĂ€ume einen Beitrag dazu zu leisten. Es werden drei verschiedene Effizienzen untersucht, welche alle vom jĂ€hrlichen Volumszuwachs ausgehen. Dieser Zuwachs wird in Relation zur baumindividuellen projizierten BlattflĂ€che (BlattflĂ€cheneffizienz), zum vom Einzelbaum absorbierten Licht (Lichtausnutzungseffizienz) und zur StandflĂ€che (StandflĂ€cheneffizienz) gesetzt. Zur Analyse dient ein Datensatz der Gemeinen Fichte (Picea abies (L.) Karst.), welcher vier gleichaltrige Paare verschiedener Wuchsklassen (Altholz, Baumholz und zwei Stangenhölzer) beinhaltet, und ein Paar ungleichaltriger BestĂ€nde. Jedes Paar besteht aus einer durchforsteten und einer undurchforsteten Variante. Mit Hilfe der KronenmantelflĂ€che und dem sozialen Status des Einzelbaumes wurden allometrische BlattflĂ€chenfunktionen entwickelt. Das detaillierte Kronenmodell MAESTRA wurde fĂŒr die Fichte parametrisiert und dazu verwendet, das vom Einzelbaum absorbierte Licht im photosynthetisch aktiven Bereich zu berechnen. Obwohl Unterschiede zwischen den BlattflĂ€chen- und den LichtverhĂ€ltnissen nachgewiesen wurden, zeigten die jeweiligen Effizienzen keine wesentlichen Unterschiede. Beide zeigten, dass BĂ€ume mit gröĂerem Schaftholzvolumen mehr Licht absorbierten (oder mehr BlattflĂ€che hatten), jedoch auch mehr Volumszuwachs pro Einheit absorbierten Lichts (BlattflĂ€che) leisten konnten. Die StandflĂ€chen wurden berechnet und mit der BlattflĂ€che gewichtet. Die StandflĂ€cheneffizienz der Fichte stieg mit zunehmender Dichte an, ohne einen Hinweis auf eine optimale Dichte. Als DichtemaĂ wurde der FlĂ€chen-Ausnutzungs-Index (VerhĂ€ltnis von BlattflĂ€che zu StandflĂ€che) verwendet.It is well known that forest density directly affects the growth of a forest. Still, very little is known about the processes that scale up the individual tree growth to the stand level. In an effort to bridge this gap, in this dissertation growth efficiency is analyzed at the individual tree level. In this work three different efficiencies are described, all of which use the annual volume increment as an increment measure. This increment can be put in relation to a trees projected leaf area (leaf area efficiency) to the amount of light which is absorbed by a tree (light use efficiency) and to the area that a tree may potentially occupy (available area efficiency). The analyses were mainly conducted on a Norway spruce (Picea abies (L.) Karst.) dataset which included four even-aged pairs of different growth classes (mature, immature and two pole-stage), and one pair of uneven-aged stands. Each pair included a thinned and an unthinned variant. Allometric leaf area equations were established which employed the crown surface area and a measure for the social status of a tree. The detailed three-dimensional crown model MAESTRA was parameterized for Norway spruce to determine the absorbed photosynthetically active radiation of an individual tree. Although it was possible to identify differences in the pattern of light to leaf area, the leaf area efficiency pattern did not differ from the light use efficiency pattern. Both revealed that larger trees, in terms of bole volume, received more light (or leaf area), but they were also able to produce more annual bole volume increment per unit of light (or leaf area). Areas potentially available were calculated and weighted by the leaf area. For Norway spruce we found that available area efficiency was increasing with increasing density, without displaying an optimum density. As a density measure we employed the area exploitation index which was calculated as the ratio of leaf area to area potentially available.submitted by Martin GspaltlAbweichender Titel laut Ăbersetzung der Verfasserin/des VerfassersWien, Univ. fĂŒr Bodenkultur, Diss., 2012OeBB(VLID)193112