scholarly journals Influence of an Ice Storm on Aboveground Biomass of Subtropical Evergreen Broadleaf Forest in Lechang, Nanling Mountains of Southern China

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Fang Zhang ◽  
Guangyi Zhou ◽  
Motoshi Hiratsuka ◽  
Kazuo Tanaka ◽  
Yasushi Morikawa
Keyword(s):  
Aboveground Biomass ◽  
Southern China ◽  
Ice Storm ◽  
Dead Trees ◽  
Significant Damage ◽  
Short Period ◽  
Stem Bending ◽  
Biomass Loss ◽  
Extent Of Damage ◽  
Forest Rehabilitation

This study focuses on the influence of the 2008 ice storm in China and subsequent forest rehabilitation dynamics up until 2011. All seven plots studied exhibited significant damage, with the total number of damaged trees varying between 63 and 92%. In addition, most trees suffered stem bending in 2008 and the extent of damage varied with tree diameter at breast high (DBH). Relationships between loss of biomass as dead trees and stand characteristics were analyzed by multiple stepwise regression. The results showed that the decrease in biomass (Y) could be related to altitude (X1), slope (X2), and aboveground biomass (AGB) in 2008 (X5) according to the following formula:Y=−0.02456X1+0.2815X5−1.480X2+51.23. After 2 to 3 years, tree numbers had declined in all seven plots. The mean increase in AGB (4.9 t ha−1) for six of the plots was less than the biomass loss as dead trees (9.4 t ha−1) over the 3 year periods. This corresponds to a release of CO2to the atmosphere for each plot. Therefore, the forests of Lechang in the Nanling Montains have probably acted as a carbon source to the atmosphere for a short period after the 2008 ice storm.

scholarly journals Aboveground Biomass Allometric Models for Evergreen Broad-Leaved Forest Damaged by a Serious Ice Storm in Southern China

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 320
Author(s):  
Houben Zhao ◽  
Zhaojia Li ◽  
Guangyi Zhou ◽  
Zhijun Qiu ◽  
Zhongmin Wu
Keyword(s):  
Aboveground Biomass ◽  
Southern China ◽  
Management Strategies ◽  
Forest Damage ◽  
Diameter Distribution ◽  
Ice Storm ◽  
Allometric Models ◽  
Broad Leaved Forest ◽  
Biomass Loss ◽  
Leaved Forest

A catastrophic ice storm occurred in the spring of 2008, which severely destroyed nearly 13% of China’s forests; among them, the broad-leaved forest suffered the most extensive damage. In this study, allometric models of the evergreen broad-leaved forests damaged at different recovery stages after the disaster were established to estimate the aboveground biomass of damaged trees. Plant plots were established and surveyed in damaged forests to determine species composition and diameter distribution, and finally a sample scheme was formulated that contained 47 trees from 13 species. The destructive measurements of aboveground biomass of trees selected according to the scheme were conducted in 2008, 2010, 2012 and 2016, respectively. Undamaged trees in the same region were also selected to measure the biomass in 2010. Linear regression of logarithmic transformation of the power function form was performed using Diameter at Breast Height (DBH) as predictor to develop biomass allometric models. The results showed that the ice storm caused tree aboveground biomass loss, which caused different parameters of the tree biomass models at different recovery stages. The models have a high accuracy in predicting trunk and total aboveground biomass, with high determination coefficients (R2, 0.913~0.984, mean 0.957), and have a relatively low accuracy in predicting the biomass of branches and leaves (R2, 0.703~0.892, mean 0.784). The aboveground biomass reduced by 35.0% on average due to the ice storm, and recovered to the same level of undamaged trees in the same diameter 8 years after the disturbance. The branches and leaves recovered very fast, and the biomass of these parts exceeded that of the undamaged trees, reaching the same diameter 2 years after the disaster, indicating an over compensatory growth. The trees with a smaller diameter were mostly composed of middle and late succession species, and recovered faster than other species, indicating that the ice storm may alter the forest structure and accelerate community succession. The biomass allometric models built in this study, combined with forest inventory data, can estimate forest biomass loss and recovery after disturbance, and offer an important sense of the assessment of forest damage and the formulation of forest post-disaster management strategies.

scholarly journals Effects of large aboveground biomass loss events on the deadwood and litter mass dynamics of seasonal tropical forests in Cambodia

Tropics ◽  
2018 ◽  
Vol 27 (2) ◽  
pp. 33-48
Author(s):  
Yoshiyuki Kiyono ◽  
Eriko Ito ◽  
Yukako Monda ◽  
Jumpei Toriyama ◽  
Thy Sum
Keyword(s):  
Tropical Forests ◽  
Aboveground Biomass ◽  
Litter Mass ◽  
Biomass Loss

scholarly journals Estimating Aboveground Biomass Loss from Deforestation in the Savanna and Semi-arid Biomes of Brazil between 2007 and 2017

2020 ◽  
Author(s):  
Eduarda Martiniano de Oliveira Silveira ◽  
Marcela Castro Nunes Santos Terra ◽  
Fausto Weimar Acerbi-Júnior ◽  
José Roberto Soares Scolforo
Keyword(s):  
Aboveground Biomass ◽  
Biomass Loss ◽  
Semi Arid

Effect of stem bending on hydraulic conductivity and wood strength of loblolly pine

1994 ◽  
Vol 24 (3) ◽  
pp. 442-446 ◽  
Author(s):  
T.S. Fredericksen ◽  
R.L. Hedden ◽  
S.A. Williams
Keyword(s):  
Hydraulic Conductivity ◽  
Loblolly Pine ◽  
Modulus Of Rupture ◽  
Vertical Position ◽  
Sapwood Area ◽  
Significant Damage ◽  
Stem Bending ◽  
Average Loss ◽  
Wood Strength ◽  
Increased Susceptibility

Stems of 30-year-old loblolly pine (Pinustaeda L.) trees were bent with a winch to determine the effect of bending, which might occur from severe wind stress, on the hydraulic conductivity and wood strength of tree stems. Stems were bent to a point of imminent stem failure and then released. After release, stems leaned an average of 6.25° from their original vertical position. Measurements of sapwood permeability and viable conducting area were made on stem sections cut from bent trees and were compared with sections taken from unstressed (control) trees. Dye was used to determine the percentage of functional conducting elements. An average loss of approximately 30% in conducting sapwood area was attributed to the bending treatment. Loss of functional conducting area was greater along the axis of bending than on the lateral sides of the stem perpendicular to the direction of bending. Damage was greatest on the compression side of the stem. Despite this damage, no difference was observed in sapwood permeability due to treatment. Modulus of elasticity and modulus of rupture were reduced by 19% and 34%, respectively, on the compression side of bent stems compared with control stems. Loblolly pine appears to be capable of sustaining significant damage to its water conducting system without compromising its hydraulic conductivity. However, reduced wood strength due to bending may result in increased susceptibility to wind breakage and (or) decreased commercial value.

Finite Element Analysis of SiCp/Al Model of Unit Cell during Ultrasonic Vibration Scratching

2016 ◽  
Vol 693 ◽  
pp. 1022-1029
Author(s):  
G.Q. Liang ◽  
Ping Fa Feng ◽  
Jian Fu Zhang
Keyword(s):  
Finite Element ◽  
Maximum Amplitude ◽  
Element Model ◽  
Ultrasonic Frequency ◽  
Frequency Range ◽  
Element Analysis ◽  
Scale Modeling ◽  
Sic Particles ◽  
Significant Damage ◽  
Extent Of Damage

In this paper, finite element model of SiCp /Al single cell body and single diamond particles were established by cross-scale modeling method. The results shows that the extent of damage of SiC particles increased with the increase of amplitude and frequency; The integrity of SiC particles are still better under the ultrasonic frequency 20000 Hz and the maximum amplitude 5um,so the optimal frequency range of ultrasonic scratch is (20000-30000)Hz. As for 22000 Hz, the integrity of SiC particles was better under the amplitude 4um,while the SiC particles have a significant damage in the border area under the amplitude 5um,so the best frequency and amplitude for ultrasonic scratches are: 22000 Hz and 4 um.

scholarly journals CORROSION AND CAVITATION RESISTANCE IN SEAWATER OF CHROMIUM–NICKEL–MANGANESE HIGH-STRENGTH NITROGEN AUSTENITIC STEELS

2019 ◽  
Vol 62 (1) ◽  
pp. 49-56
Author(s):  
L. M. Kaputkina ◽  
A. G. Svyazhin ◽  
I. V. Smarygina ◽  
V. E. Kindop
Keyword(s):  
High Strength ◽  
Surface Damage ◽  
Ultrasonic Cavitation ◽  
Austenitic Steels ◽  
General Corrosion ◽  
Cavitation Resistance ◽  
Significant Damage ◽  
Stable Austenite ◽  
Extent Of Damage ◽  
Nickel Manganese

Corrosion and cavitation resistance in seawater of high-strength economically alloyed nitrogen chromium–nickel–manganese steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N is experimentally studied compared to chromium-nickel steels Cr18Ni9 and Cr18Ni9N. Tests for resistance to pitting corrosion were carried out according to the chemical method in the test solution 100 g/l FeCl3 ·6H2 O. Resistance to general corrosion was assessed by tests in synthetic seawater (3  %  NaCl). Test for cavitation resistance in seawater was performed using a research stand of high-intensity cavitation effects with the use of ultrasonic devices UIP 1000  hd Hielscher Ultrasonic in 3  %  NaCl solution in water at a frequency of 20 kHz, a power of 1000  W and amplitude of 25 microns for 8  –  36  hours. The extent of damage and change in the surface microhardness, change in the phase composition and mass of the samples were assessed after cavitation. It is shown that steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N are more susceptible to pitting in seawater and in solution of ferric chloride, and have the general corrosion rate lower than that of chromium-nickel steels type Cr18Ni9. It is shown that ultrasonic cavitation can not only lead to surface damage due to erosion, enhance local corrosion, but also to changes in their physico-mechanical properties by strain hardening and phase transformations. Steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N with thermally and mechanically stable austenite are more resistant to ultrasonic cavitation in the seawater in comparison with chromium-nickel steels, especially those with less strength and less resistant steel Cr18Ni9. So subjected to cavitation in the seawater for 36 hours, samples of chromium-nickel steels Cr18Ni9 and Cr18Ni9N had a significant change in their condition: significant damage (etching) and surface hardening, and there was formation of a small amount of martensite in steel Cr18Ni9. Samples of steels Cr19Mn10Ni6Mo2N and Cr19Mn10Ni6Mo2Cu2N had only minor changes in surface conditions and hardening of the surface layers.

scholarly journals Resprouting Responses Dynamics of Schima superba Following a Severe Ice Storm in Early 2008 in Southern China: A Six-Year Study

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 184
Author(s):  
Yonghui Cao ◽  
Benzhi Zhou ◽  
Xiaoming Wang ◽  
Lianhong Gu
Keyword(s):  
Secondary Forest ◽  
Southern China ◽  
Size Class ◽  
Ice Storm ◽  
Basal Diameter ◽  
Schima Superba ◽  
The Mean ◽  
The Difference ◽  
Set Up ◽  
Damage Types

In 2008, an unexpected and severe ice storm affected the forest of southern China. This storm caused damage in regeneration of an important dominant tree, Schima superba (Gugertree). To study this damage, we set up permanent monitoring plots in an ice-storm-damaged subtropical evergreen broad-leaved secondary forest dominated by S.superba in Jianglang Mountains, China. We surveyed the damage to all trees with a minimum basal diameter of 4 cm and monitored their growth for 6 consecutive years. We analyzed the degrees and types of damage for S.superba and their relationships with resprouting characteristics. The results revealed that the main damage types of S.superba were decapitation (45.45%) and uprooting (28.41%). The distribution percentage for both decapitated and uprooted trees were commonly highest in the range of 10–16 cm basal diameter (BD) size class. A great number of individuals sprouted vigorously after the storm. The mean total sprout number and sprout biomass per tree for S.superba varied by tree BD size class. During the first three years after the ice storm, decapitated trees of larger BD classes produced more sprouts per tree than trees of smaller BD classes. However, the opposite trend was seen in uprooted and leaning trees. There was a trade-off between the total number and length of the sprouts. The difference of mean sprouts number and biomass per tree with size class was mainly related to the damage types. As the recovery progressed since the ice storm, the number of sprouts and sprout biomass in uprooted trees was found mainly on the middle trunk sections of uprooted trees, but in the upper sections of decapitated trees. After six years, the mean number of sprouts per tree, on different parts of the tree and for the three types of damaged trees all declined; however, sprout biomass per tree all increased. The mean number of sprout and sprout biomass per tree on different sections for decapitated trees was always highest over time since the storm. Our study will help to provide data on resprouting ability to develop a predictive model for resprouting.

Fire history and forest age distribution of an unmanaged Picea abies dominated landscape

2005 ◽  
Vol 35 (7) ◽  
pp. 1540-1552 ◽  
Author(s):  
Tuomo H Wallenius ◽  
Aki Pitkänen ◽  
Timo Kuuluvainen ◽  
Juho Pennanen ◽  
Hanna Karttunen
Keyword(s):  
Fire History ◽  
Age Distribution ◽  
Tree Age ◽  
Natural State ◽  
Forest Age ◽  
Human Influence ◽  
Fire Scars ◽  
Southwestern Part ◽  
Dead Trees ◽  
Short Period

We examined fire history and forest age distribution in an unmanaged, Picea-dominated landscape in the Paanajärvi wilderness, located in northeastern Fennoscandia and northwest Russia. Maximum tree age was determined in 61 systematically located study plots in an area of about 6600 ha. Fire scars were examined in living and dead trees in the study plots and elsewhere in the study area. Charcoal and pollen analyses of peat were performed on samples from two locations. Fires had been rare in the landscape. Nearly half of the dendrochronologically dated fires occurred in a distinct and short period, from 1859 to 1889, in the northeastern part of the area. This nonrandom occurrence of fires, together with the observed signs of past human influence, suggests an anthropogenic origin for the majority of the fires. The fact that 95% of the study area consisted of forests older than 120 years reflects the end of the occurrence of fires in the 1880s. Pollen analysis from the southwestern part of the study area showed that the site had been dominated by Picea at least during the last millennium. Charcoal analysis from the same site indicated that likely more than 1000 years had elapsed since the last fire. In general, the results suggest that the abundance of old forests, with the oldest trees being approximately 300 years of age, belongs to the natural state of a Picea-dominated landscape.

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