Growth response to thinning and its relation to site resources in Eucalyptusregnans

1995 ◽  
Vol 25 (1) ◽  
pp. 69-80 ◽  
Author(s):  
P.W. West ◽  
G.H.R. Osier

The factors determining individual tree growth response are examined during the 4 years following thinning in experiments in even-aged, 8- or 12-year-old regrowth Eucalyptusregnans F. Muell. forest at two sites in southern Australia. At one site, a vigorous understorey dominated by a sedge developed after the thinning. At that site, light-use efficiency by the trees was unaffected by thinning and the aboveground biomass production by the trees in the thinned stand was substantially less than that in the unthinned stand. At the other site, little understorey developed, light-use efficiency by trees in the thinned stand was greater than that in the unthinned stand, and aboveground biomass production was unaffected by thinning even though the leaf weight of the thinned stand was far below that of the unthinned stand. Where the understorey developed, it was concluded that it competed successfully with the trees for water, thereby reducing production in the thinned stand when compared with the unthinned stand. The individual tree growth response that occurred in the thinned stand at that site appeared to be due soley to the extra light available to individual trees following the canopy opening. Where the understorey did not develop, it was concluded that individual tree growth response was due not only to the extra light available to individual trees but also to the increased availability of belowground resources, most probably soil water. Application of a pre-existing stand growth model suggested that at that site the tendency for increased growth resulting from extra water availability in the thinned stand was just balanced by decreased growth due to lower radiation absorption by the reduced canopy, so that net production was unaffected by thinning.

2019 ◽  
Vol 65 (6) ◽  
pp. 784-795
Author(s):  
Jeffrey S Ward ◽  
Jessica Wikle

AbstractSix study areas were established in 80–125-year-old upland oak stands on average sites to compare stand and individual tree growth response following two active treatments (B-level thinning, crop tree) with an unmanaged control. Initial stocking of 104 percent was reduced to 62 percent and 60 percent on the B-level and crop-tree-management plots, respectively. Approximately 7,200 board feet per acre (International ¼) were harvested on the actively managed plots with upland oaks accounting for 81 percent of pre- and 86 percent of residual stand. Eleven-year diameter and volume growth of oak sawtimber trees was greater on actively managed plots. Growth response increased with degree of release and was maintained for the length of the study. Because of the increased individual tree growth of oaks in response to release, stand volume growth of oak sawtimber did not differ between treatments. In contrast to an 11-year decline of poletimber stocking on unmanaged plots, poletimber stocking increased on managed plots as diameter growth increased in response to partial release. This may increase difficulty of regenerating oak in the future. For those mature red oak stands where traditional regeneration prescriptions will not be implemented or will be delayed, commercial harvests can be conducted without compromising stand volume growth of oak.


2009 ◽  
Vol 39 (12) ◽  
pp. 2437-2449 ◽  
Author(s):  
Klaus J. Puettmann ◽  
Anthony W. D’Amato ◽  
Ulrich Kohnle ◽  
Jürgen Bauhus

This study investigated the individual-tree diameter response of mature silver fir ( Abies alba Mill.) to reproduction harvests (Femelschlag: an irregular group shelterwood method) on six sites in the Black Forest, Germany. On each site, four different treatments were applied, including a control treatment and short-, medium, and long-term regeneration periods aimed at the complete removal of overstory trees within 20, 35, and 50 years, respectively. These treatments created a wide variety of growing conditions for individual trees. Relationships between relative diameter growth and stand-level and neighborhood interaction indices were evaluated. Growing conditions for individual trees in control conditions were best characterized using Lorimer’s index for a 16 m radius neighborhood. Equations predicting tree growth in control stands underpredicted initial growth of trees after harvesting operations, suggesting a release effect that is not captured by postharvest density. This effect was larger for smaller trees and influenced by removal intensity. Growth response to density reductions was also influenced by previous harvests. Our results suggest that the growth response of mature trees to reproduction harvests may become an important consideration when increased emphasis is placed on managing for long-term regeneration periods.


1985 ◽  
Vol 15 (1) ◽  
pp. 18-22 ◽  
Author(s):  
T. M. Ballard ◽  
N. Majid

The use of pretreatment increment can lead to improved estimates of individual and average tree growth response to fertilization, by helping to adjust for site as well as stand structure differences between fertilized and control areas. It has applications in research using either single-tree or plot fertilization, and also in estimating responses to operational fertilization. Particularly useful equations are R = Af − (Bf)av(Au/Bu) and I = av(Af/Bf) − av(Au/Bu), where R is an estimate of the absolute magnitude of individual tree growth response to fertilization; A and B are increment after and before fertilization, and f and u denote fertilized and unfertilized trees, respectively; av signifies the average of several replicates; and I is an index of whether response has occurred. Equations were evaluated by examining branch length increment data from foliar spray application of iron and copper to Pinuscontorta Dougl. (lodgepole pine) and of nitrogen and iron to Pseudotsugamenziesii (Mirb.) Franco (Douglas-fir).


2001 ◽  
Vol 154 (1-2) ◽  
pp. 261-276 ◽  
Author(s):  
Julian C. Fox ◽  
Peter K. Ades ◽  
Huiquan Bi

1992 ◽  
Vol 22 (5) ◽  
pp. 660-666 ◽  
Author(s):  
Paul C. Van Deusen

A number of recent studies have shown reduced stand-level and individual-tree growth in natural loblolly pine (Pinustaeda L.) stands in the southeastern United States. This study uses increment cores from dominant and codominant trees to determine if individual-tree growth has changed from 1915 to 1985. The cores are grouped for comparison by first sorting on the basis of median stand age and then further sorting these groups of cores by individual-tree age. These trees experienced increasing basal area increments from the mid-1940s into the mid-1970s, after which growth rates returned to preincrease levels. These data support recent findings of growth reductions, but also indicate previously unreported growth increases preceding the growth decreases. These and supplemental permanent plot data suggest that stand dynamics is a viable hypothesis for explaining these growth trends.


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