Effects of thinning intensities on tree water use, growth, and resultant water use efficiency of 50-year-old <i>Pinus koraiensis</i> forest over four years

Park, Juhan,Kim, Taekyu,Moon, Minkyu,Cho, Sungsik,Ryu, Daun,Seok Kim, Hyun Elsevier Scientific Pub.Co 2018 Forest ecology and management Vol.408 No.-

<P><B>Abstract</B></P> <P>This study investigated the effects of thinning intensities on tree water use and growth of 50-year-old Korean pine forests for four years. Thinning was conducted with two intensities (light thinning, heavy thinning, and control) in March 2012. Tree water use was estimated from sap flux density using Granier-type thermal dissipation sensors on 84 of total 103 trees. Tree diameter growth was measured in 97 trees with a dendrometer and converted to aboveground biomass increment using an allometric equation. Sap flux density increased initially in both thinning groups, but the effects of light thinning decreased over time. In the heavy thinning plot, sap flux density was stimulated for the entire study period. While light-thinning affected little on tree growth, tree diameter growth significantly increased from second year and this enhancement increased with time in the heavy-thinning plot. The tree diameter and growth rate were positively correlated in the light-thinning plot and negatively correlated in the heavy-thinning plot. The enhancement of sap flux density and diameter growth caused higher tree water use and tree level aboveground net primary productivity in heavy-thinning plot. Due to higher water use in the heavy thinning plot, increase in tree-level water use efficiency was observed in the high growth year only. Our results indicate that physiological responses of trees differed depending on thinning intensity and heavy thinning is an appropriate management practice for mature pine plantations.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Heavy thinning enhanced water use and growth of individual <I>Pinus koraiensis</I> trees. </LI> <LI> Tree level water use efficiency was not improved by thinning. </LI> <LI> In the light-thinning plot, larger trees grew more than smaller trees and the trend was opposite in heavy-thinning plot. </LI> <LI> Heavy thinning is an appropriate management practice in a mature forest. </LI> </UL> </P>

블루베리 인력적화 시기와 방법이 과실특성에 미치는 영향

김홍림,채원병,김진국,이목희,이한철,김승희,곽용범 한국환경농학회 2019 한국환경농학회지 Vol.38 No.3

BACKGROUND: Increase in the ratio of small berries in blueberry production decreases the farmers’ profits due to weakening market competitiveness and lowering harvest efficiency. One of the reasons for increased small berries is over fruit-load. For improving productivity and competitiveness of blueberry in Korea, hand-thinning can be applied to increase fruit quality before the developing adequate chemical thinning methods. This study was conducted to investigate the proper timing and methods for floral buds thinning in rabbiteye blueberry. METHODS AND RESULTS: Eight years old bushes of rabbiteye bluberries ‘Brightwell’ as a primary cultivar and ‘Powderblue’ as a pollinizer were used for this study. Fruit size distribution by leaf-to-fruit ratio was investigated by counting the number of leaves and fruits in canes of 127 ‘Brightwell’ plants whose fruit set varied. Fifty percent of flowers/floral buds were removed in four different floral buds stages such as bud swell, late pink bud, full bloom, and petal fall, and the consumed time for thinning and fruit characteristics were recorded to investigate the effect and proper timing of floral buds thinning. Fruit weight and soluble solids content tended to increase in proportion to leaf-to-fruit ratio and the production of the number of fruits less than 13 mm in diameter decreased when leaf-to-fruit ratio was more than 2.5. Manual floral buds thinning by hands was fastest in full bloom stage and slowest in bud swelling stage. In all cultivars, fruit size was significantly smaller in non-thinning treatment than thinning, and there was, however, no significant difference in total fruit yield. The number of fruits less than 13 mm in diameter increased in both cultivars as floral buds thinning was delayed. Consumed time for picking 90% berries out of total berries per bush was shortest in full bloom stage thinning in ‘Brightwell’ and bud swelling, full bloom thinning in ‘Powderblue’. These were 25 and 20 days faster than no thinning, respectively. CONCLUSION: Although the effect of floral buds thinning varied depending on the cultivars, our results confirmed that floral buds thinning was effective for the early intensive harvesting and the increase of the large fruit ratio and the harvesting productivity. Also, in order to increase thinning efficiency, it is recommended to remove the flower buds before the full bloom stage.

숲가꾸기 산물의 적재형태에 따른 산불위험성 비교 분석

이시영,이명욱,이해평 한국화재소방학회 2008 한국화재소방학회논문지 Vol.22 No.1

The effect of thinned trees which are produced from forest thinning on forest fire was studied in this work. To investigate the effect of thinning slash, Yang-yang, In-je, and Ga-pyeong-gun were selected as thinning-areas and non-thinning areas. The research was carried out with the variations of tree's types, area's characteristics, thinning strength, thinning types, and pile types of thinned tree. The survey areas of 14 areas were selected at Yangyang-gun (5 areas), Gapyeong-gun (4 areas), and Injegun (5 areas), and on-the-spot investigations were carried out at the thinning areas of 9 and the nonthinning areas of 5, respectively. Non-thinning areas of 5, which are adjacent to thinning areas, were selected for the comparison with thinning areas and for the analysis of risk of forest fire. It is considered that forest fire have no chance to diffuse to a tree trunk because the height of thinned trees was lower than 1 m. However, it is considered that forest fire may affect directly to a tree trunk if it spread to piled thinned tree because there was no space between thinned trees and trees. Furthermore, it was found that re-ignition had a chance to occur due to lots of piled thinning trees. 본 논문은 숲가꾸기 산물인 간벌목이 산불에 미치는 영향에 대하여 연구하였다. 즉, 간벌목이 산불에 미치는 영향을 조사하고자 강원도 양양군과 인제군, 경기도 가평군의 숲가꾸기 실행지와 미실행 지역을 선정하였다. 이 조사대상지에 대하여 수종, 입지특성, 간벌강도, 숲가꾸기 종류, 간벌재의 적재행태 및 산불 위험도에 대한 조사를 수행하였다. 조사대상지인 양양군 5개소, 가평군 4개소, 인제군 5개소 총 14개 조사구에 대하여 숲가꾸기 실행지 9개소, 미실행지 5개소에 대한 현장조사를 실시하였다. 숲가꾸기 미실행지 5개소는 숲가꾸기 실행지와 인접한 조사지역을 선정하였고, 숲가꾸기 실행지와의 산불위험도에 대해 비교 분석을 수행하였다. 본 연구의 조사결과 숲가꾸기 실행지의 산물인 간벌목의 적재높이는 1m 미만으 로 적재되어 있어 산불연소시 수관부로 전파될 위험성은 거의 없는 것으로 판단되었다. 그러나 적재된 간벌목과 임목간의 거리가 거의 붙어 있어 적재된 간벌목에 산불이 붙을 경우 임목 줄기부(수간)에 직접영향을 줄 것으로 판단된다. 그리고 적재된 간벌목이 많이 쌓여 있을 경우 이로 인하여 재발화의 가능성이 있을 것으로 판단되었다.

A multi-site approach toward assessing the effect of thinning on soil carbon contents across temperate pine, oak, and larch forests

Kim, Seongjun,Kim, Choonsig,Han, Seung Hyun,Lee, Sang-Tae,Son, Yowhan Elsevier 2018 Forest ecology and management Vol.424 No.-

<P><B>Abstract</B></P> <P>Large divergence of the post-thinning change in soil carbon contents has impaired the evaluation of the thinning effect on forest carbon storage reported in previous case studies. In this context, the present study used a multi-site approach to assess the effect of thinning on forest floor and mineral soil carbon contents. The sites included four pine (<I>Pinus densiflora</I> Sieb. et Zucc.), five oak (<I>Quercus</I> spp.), and four larch (<I>Larix kaempferi</I> (Lamb.) Carr.) forests under the temperate climate, each of which included un-thinned control, intermediate thinning (15–30% basal area reduction), and heavy thinning (30–50% basal area reduction) treatments. Forest floor and mineral soil (0–10, 10–20, and 20–30 cm depths) carbon contents were determined 0–1, 3–4, and 6–7 years after thinning. The average forest floor and mineral soil (0–30 cm) carbon contents (Mg C ha<SUP>−1</SUP>) were 6.7 and 54.1 under the control, 6.6 and 60.7 under the intermediate thinning treatment, and 6.0 and 64.7 under the heavy thinning treatment, respectively. There was a slight decrease in forest floor carbon contents but an increase in mineral soil carbon contents under the thinning treatments, although the magnitude and direction of the thinning effect were site-specific. The magnitude of the thinning effects was stronger under the heavy thinning treatment than under the intermediate thinning treatment. However, the effect of thinning was unrelated to time after thinning and forest type. Topography (altitude and slope), soil properties (soil water content, pH, and total nitrogen concentration), diameter at breast height and height of remaining trees, and the percentage of removed basal area explained approximately 45% of variance in the thinning effect, indicating that differences in the environment are important in the divergence of the thinning effect on soil carbon contents across multiple sites. Our results suggest that designing thinning practices to foster forest carbon sequestration should consider the contribution of thinning intensity and environmental conditions to variation in the thinning effect on soil carbon contents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The thinning effect on soil carbon contents differed in magnitude and direction among sites. </LI> <LI> Changes in soil carbon contents were larger under relatively heavy thinning intensity. </LI> <LI> Time after thinning and forest type did not affect the thinning effect on soil carbon contents. </LI> <LI> Topography and soil property contributed to variation in the thinning effect over sites. </LI> </UL> </P>

DBH growth for three years after thinning on even-aged Pinus koraiensis and Larix kaempferi plantations in South Korea

서영완,Somsanouk Pathammavongsa,Vireak Chhorn,이대성,최정기,차두송 한국산림과학회 2019 Forest Science And Technology Vol.15 No.1

This study was conducted to determine the effects of different thinning intensities on the DBH growth of Pinus koraiensis and Larix kaempferi trees. Permanent monitoring plots were installed in 26 P. koraiensis plantations and 36 L. kaempferi plantations in 2012 and 2014, respectively. To evaluate the effect of thinning intensity, each plot consisted of three square or rectangular plots; control or non-thinned, light thinning, in which 20% of the total basal area was removed, and heavy thinning, in which 40% of the total basal area was removed. The mean DBH increments for 3 years were computed and compared across thinning intensities. Other factors, such as slope, altitude, or stand density, were compared across thinning treatments to understand why DBH increment did not follow thinning intensity. Overall mean DBH increment for 3 years after thinning was affected by different thinning intensities: heavy thinning>light thinning>control. ANOVA showed that there was a significant difference in DBH increment among thinning intensities in both species. Also, Duncan’s multiple range test showed that all thinning treatments were significantly different from each other. Other factors that affect DBH besides thinning intensity were identified, such as residual basal area, slope gradient, and aspect.

유전간벌 방법에 따른 굴참나무 육종채종원의 개량효과 추정

나성준,우관수,강규석,박지민,한상억 경상대학교 농업생명과학연구원 2015 농업생명과학연구 Vol.49 No.6

굴참나무 육종채종원에서 유전간벌 모형 및 다양한 간벌 강도에 따른 재적생장에 대한 개량효과 및 유전다양성을 추정하였다. 유전간벌 모형은 개체간벌, 가계간벌 및 가계 내 개체간벌이었으며, 간벌강 도는 개체목 기준으로 10% 단위로 적용하였다. 유효집단크기는 채종목 가계 간 유전적 유연관계를 나 타내는 공동조상도를 이용하여 추정하였다. 유전간벌 모형에 있어 개체간벌이 가계간벌 및 가계 내 개 체간벌 보다 모든 간벌강도에서 높은 개량효과가 추정되었다. 가계간벌은 모든 간벌강도에서 매우 낮은 개량효과가 추정되어 본 굴참나무 채종원의 유전간벌 방법으로 적용하기에는 부적절한 것으로 판단되었 다. 각 유전간벌 모형에 대한 유효집단크기를 추정한 결과, 가계간벌이 다른 간벌모형 보다 높은 유효 집단크기가 추정되었다. 개체간벌은 약도의 강도에서는 일정하게 유지되었으나 강도의 간벌에서는 낮게 추정되었으며, 가계 내 개체간벌은 중도의 간벌강도까지는 감소하는 경향을 나타내다가 강도의 간벌강 도에서 다시 증가하였다. 이상의 결과를 종합하며, 50% 이하의 간벌강도를 적용할 경우에는 개체간벌 이 효과적인 반면, 50% 이상의 간벌강도를 적용할 시에는 가계 내 개체간벌 방법이 효과적일 것으로 판단된다. Genetic gain and gene diversity were estimated by genetic thinning methods under various thinning intensities in a breeding seedling seed orchard of Quercus variabilis. The genetic thinning methods included individual thinning, family thinning and family+within family thinning. The thinning intensity was imposed by 10% intervals in the thinning methods. The gene diversity was estimated by the concept of effective population size, which considered the genetic relatedness(coancestry) among individuals. As the results, individual thinning showed higher genetic gain compared to the other methods. The family thinning gave the lowest genetic gain, so it could not be applied in this seed orchard. On the other hand, the family thinning was more effective to maintain gene diversity than the other methods. Individual thinning and family+within family thinning showed consistent gene diversity under week thinning intensities, but decreased under moderate intensities. In conclusion, individual thinning method could be effective under 50% thinning intensities and family+within family thinning method would be applicable above 50% intensities for maximizing genetic gain and maintaining gene diversity in the breeding seedling seed orchard of Quercus variabilis.

잣나무 인공림의 1차 및 2차 간벌에 따른 입목생장 특성 분석

이대성,정성훈,최정기,Lee, Daesung,Jung, Sunghoon,Choi, Jungkee 한국산림과학회 2022 한국산림과학회지 Vol.111 No.1

본 연구는 잣나무(Pinus koraiensis Siebold & Zucc.) 인공림을 대상으로 1차 및 2차 간벌에 따른 입목의 생장특성을 규명하여 산림시업지침 및 매뉴얼 개발을 위한 기초자료를 제공하고자 수행되었다. 사용된 연구자료는 간벌강도에 따라 설치된 잣나무 인공림 영구고정표준지로부터 수집되었으며, 각 간벌시험림별 4~5회 반복조사된 자료를 토대로 임령 19~43년생 시기의 흉고직경, 재적, 고사목 등 주요 입목 및 임분 현황을 분석하였다. 간벌강도에 따른 일원분산분석에서 개체목의 흉고직경 및 재적 변화는 유의적인 차이를 보였으며(p<0.05), 특히 간벌강도가 클수록 시간이 경과함에 따라 경급분포는 더 오른쪽에 위치하여 입목의 경급이 더 큰 것으로 관측되었다. 흉고직경 정기평균생장량의 경우, 간벌강도가 강하고 간벌 후 경과기간이 짧을수록 생장량이 높았는데, 구체적으로 임령 19~24년생 때 간벌강도별 생장량 범위는 0.48~0.95 cm/year이었다. 이후 2차 간벌에 따른 정기평균생장량도 강도간벌구에서 더 큰 것으로 분석되었으며, 임령 37~42년생 때 간벌강도별 생장량 범위는 0.29~0.67 cm/year이었다. 개체목 재적의 정기평균생장량은 간벌강도에 따라 차이가 있었으며, 흉고직경과 달리 시간이 지나도 크게 줄어들지 않는 경향이 나타났다. 임분 재적은 전반적으로 임분밀도가 밀한 표준지에서 높은 경향이었으나, 임분재적 정기평균생장량은 시기에 따라 무간벌뿐만 아니라 약도간벌이 이루어진 임분에서 더 높은 것으로도 분석되었다. 고사목은 무간벌구에서 가장 많이 발생하였으며, 반복조사가 진행될수록 임분밀도에 따른 고사목 본수 차이는 더욱 증가하였다. 종합적으로 임분밀도가 밀할수록 개체목의 흉고직경과 재적 생장량은 낮아지는 경향이었으나, 적절한 1차 및 2차 간벌이 시행되면 생장량은 다시 촉진되었다. This study was conducted to provide basic information for the development of silvicultural guidelines and manuals. This was achieved through analysis of tree and stand characteristics according to the first and second thinning in Korean white pine plantations. Data were collected from permanent plots installed at Korean white pine plantations according to thinning intensity, and residual tree and stand variables, including diameter at breast height (DBH), volume, and mortality at age 19-43, were analyzed using data repeatedly collected in 4-5 measurements by experiments. According to one-way variance of analysis, tree DBH and volume were significantly different according to thinning intensity (p<0.05). DBH distribution was skewed to the left side over time as thinning intensity was heavier. Thus, tree DBH values were larger in heavy thinning plots with increased age. The periodic annual increment (PAI) of DBH was higher with heavier thinning intensity and fewer years after thinning. The PAI range by thinning intensity was 0.48-0.95 cm/year at age 19-24. In addition, the PAI increased in heavy thinning plots after the second thinning; The PAI range by thinning intensity was 0.29-0.67 cm/year after the second thinning at age 37-42. The PAI of tree volume differed according to thinning intensity, and the PAI value did not decrease obviously, in contrast to the pattern of the DBH PAI. Stand volume was generally higher in high-density stands, and the PAI of stand volume was high in unthinned and light thinning plots. Mortality was highest in unthinned plots, and the differences in mortality according to thinning intensity increased over time. Consequently, the growth of DBH and tree volume was lower as stand density increased, but this growth was facilitated with appropriate first and second thinning operations.

잣나무림에서 간벌 이후 지표 절지동물 군집의 변화 특성 분석

이대성,권태성,김성수,박영규,양희문,최원일,박영석 한국하천호수학회 2020 생태와 환경 Vol.53 No.2

Forest thinning brought the large variation to forest ecosystem including environment and animal. Our study was result of long-term monitoring for ground-dwelling arthropod communities after thinning in forest ecosystem. In this study, we conducted field study on plantation forest in Chuncheon, Korea in 2018, and compared with previous study data (2006 and 2008). We found that the effect of thinning was still existent 10 years later from thinning with difference of habitat environment (depth of ground organic matter, coverage rate of ground vegetation and canopy). And ground-dwelling arthropod communities showed changes of abundance and taxa at the study area and thinning conditions. Ground-dwelling arthropod communities in 2018 were dominant in the order of Diptera, Hymenoptera, Coleoptera (Insecta), Araneae (Arachnida) and Collembola (Collembola). Among the conditions of thinning, Araneae (Arachnida), Coleoptera and Hymenoptera (Insecta) showed amount of abundance in heavy thinning. And Collembola (Collembola) and Diptera (Insecta) were most common in area of light thinning. In 2018 ground-dwelling arthropod communities, abundance of Diptera and Coleoptera (Insecta) and Isopoda (Crustacea) were decreased although Hemiptera and Orthoptera (Insecta) were increased than 2008 arthropod communities. Arthropod communities in 2018 were more similar with those in 2008 (after thinning) than with those in 2006 (before thinning).

침식-부식에 의해 감육된 배관의 파손거동에 미치는 감육위치의 영향

안석환,석금철,남기우 한국해양공학회 2007 韓國海洋工學會誌 Vol.21 No.1

This study on the effects of local wall-thinned location on the fracture behavior of pipes was carried out, and the results were compared with the analytical results. Local wall-thinning for the bending test was machined with various sizes on the outside of pipes, in order to simulate the metal loss,due to erosion/corrosion. In addition, we had carried out FE analysis for the pipes with local wall thinning on the inside, and its results were comparatively studied with that of the outside. Three-dimensional elasto-plastic analyses were able to accurately simulate fracture behaviors of inner or outer wall thinning. Fracture types, obtained from the experiments and analyses, could be classified into ovalization, local buckling and crack initiation,depending on the thinned length and thinned ratio. Based onthe results, the fracture behaviors of pipes with the outer wall thinning can be applied to estimate the fracture behaviors of pipes with the inner wall thinning.1. 서 론현대 산업사회의 에너지 수요는 나날이 가일층 증가하고 있는 경향이다. 특히, 우리나라는 에너지의 수급을 원자력발전에 크게 의지하고 있는 실정이다. 원자력 플랜트의 건설비용에 막대한 재원이 필요하기 때문에, 이에 원자력 플랜트에 사용되는 기기들의 경년열화에 대해 대체방안을 수립함으로 서 사용 기기들의 수명연장을 가져 올 필요성이 있다. 여러 가지 기기들 중 배관은 상당부분을 차지하고 있다. 따라서 배관에 대한 건전성평가를 통하여 플랜트의 안전성을 확보해야만 한다. 그러나 원자력발전 플랜트 배관은 고온고압수나 증기가 고속으로 흐르기 때문에 Erosion/Corrosion 현상에 의한 국소 감육이 발생할 가능성이 많다. 이러한 국소 감육의 발생으로 인하여 배관시스템의 전체의 신뢰성이 떨어질 가능성이 농후하다. 감육에 의해 발생한 대표적인 원전사고로는 1986년에 발생한 미국의 Surry 원자력발전소 사고를 비롯하여 가장 최근에 발생한 일본 Mihama 원자력발전소 사고 등이 보고되고 있다(CNN. com, 2004; Virginia Electric and

IV분과 : 간벌강도에 따른 잣나무 인공림의 생장변화 모니터링

최정기 ( Jung Kee Choi ),이병기 ( Byung Ki Lee ),이대성 ( Dae Sung Lee ),최인화 ( In Hwa Choi ) 한국임학회 2014 한국산림과학회지 Vol.103 No.3

본 연구는 잣나무 인공림을 대상으로 간벌강도를 다양하게 실시한 후 흉고직경, 수고, 수관폭, 수간재적, 수간바이오매스, 고사목의 생장변화를 파악하고자 실시하였다. 1차 간벌은 19년생 때 입목본수의 29~69% 강도로 실시되었으며, 간벌 직후(19년생), 5년 후(24년생), 12년 후(31년생)에 3차에 걸쳐 입목조사가 수행되었다. 흉고직경생장의경우 대조구에 비해 강도간벌구의 평균생장량이 간벌 5년 후 19.6~19.9%, 12년 후 13.3~24.7% 높았으며 유의적인 생장차이가 나타났다. 또한 간벌 후 초기생장량이 후기생장량보다 좋은 것으로 나타났다. 대경목 후보(DBH ≥ 25 cm)본수를 비교한 결과, 강도간벌구에서 약 31%가 나타난 반면, 대조구에서는 단지 2%에 불과했다. 수고생장은 간벌강도에 따라 생장의 차이가 나타나지 않았으며, 평균수관폭 생장량은 강도간벌구가 대조구에 비해 5년 후 30.6~33.3%,12년 후 35.0~40.0% 높았다. 단목재적의 평균 생장량은 강도간벌구가 대조구에 비해 간벌 5년 후 39.8~46.8%, 12년후 23.0~52.0% 높았다. 단위면적당 최대 임분재적 및 바이오매스량은 무간벌표준지에서 간벌 후 12년 동안 133 m3/ha(51 kg/ha)에서 344 m3/ha(132 kg/ha)로 증가하였다. 수관폭, 재적, 바이오매스는 간벌강도에 따라 모두 유의적인 생장차이가 있는 것으로 나타났다. 고사목은 간벌 후 12년 동안 강도간벌구에서 전혀 발생하지 않은 반면 대조구에서는27.9~37.8% 발생하였다. 2차 간벌시기를 결정하기 위하여 목편을 통해 연륜생장을 분석한 결과, 1차 간벌 후 10년전후가 적합한 것으로 나타났다. This study was conducted to investigate growth changes of DBH, height, crown width, volume, stembiomass, and dead trees after thinning treatments with different thinning intensity for Korean white pine (Pinuskoraiensis) plantation. First thinning was applied with 29~69% intensity based on number of trees in 19-yearoldplantation, and trees were measured three times: right after thinning (19-year-old), 5 years later (24-yearold),12 years later (29-year-old). In the case of DBH growth, average DBH growth of heavily thinned plotswas 19.6~19.9% higher 5 years later, and 13.3~24.7% higher 12 years later, compared to that of unthinned plots.Initial diameter growth rate was higher than late growth rate. The proportion of large pole candidates (DBH ≥ 25 cm)was 31% in heavily thinned plot while only 2% was shown in unthinned plot. No difference was shown inheight growth depending on plots, and average crown width growth in heavily thinned plots was 30.6~33.3%higher, 5 years later, and 35.0~40.0% higher, 12 years later, compared to that of unthinned plots. Averagevolume growth of individual trees in heavily thinned plots was 39.8~46.8% higher, 5 years later, and23.0~52.0% higher, 12 years later, compared to unthinned plots. The maximum volume and biomass per unitarea were shown in unthinned plot; the volume and biomass 5 and 12 years later after thinning were 133 m3/ha (51 kg/ha) and 344 m3/ha (132 kg/ha), respectivily. The significant difference appeared in crown width,volume, and biomass depending on thinning intensity. No dead trees occurred in heavily thinned plots for 12years after thinning, while mortality rate in unthinned plots was 27.9~37.8%. As a result of analyzing annualincrement using cores to determine the timing of second thinning, it suggested that second thinning be suitablearound 10 years after first thinning.