Fire tolerance of three tree species in pine - oak forests of Chignahuapan, Puebla, Mexico

2012 ◽  
Vol 21 (7) ◽  
pp. 873 ◽  
Author(s):  
Juana E. Juárez Bravo ◽  
Dante A. Rodríguez-Trejo ◽  
Ronald L. Myers
Keyword(s):  
Logistic Regression ◽  
Vegetation Dynamics ◽  
Inverse Relationship ◽  
Important Determinant ◽  
Oak Forests ◽  
Recovery Strategy ◽  
Shrub Species ◽  
Burned Site ◽  
Individual Trees ◽  
In Fire

Resprouting is a common recovery strategy of many tree and shrub species in fire-prone environments and is an important determinant of post-fire dominance and vegetation dynamics in many ecosystems. Top-kill, mortality and resprouting of the trees Quercus crassifolia, Arbutus xalapensis and Pinus teocote were studied on contiguous burned and unburned sites in the pine–oak forests of Chignahuapan, Puebla, Mexico. The study sample consisted of 375 individual trees, 199 on the burned site and 176 on the unburned site. T-tests and logistic regression were used in the statistical analysis. The number of resprouts per tree increased significantly (P < 0.001) in the broadleaved species, but not in the pine species. On the sites affected by fire, the smaller the diameter and higher the extent of top-kill in Q. crassifolia, the greater the probability of resprouting. None of the species exhibited differences in mortality (P > 0.05) regardless of fire or lack of fire. With Q. crassifolia, top-kill and tree death were greatest in the smaller-diameter individuals. Also, the probability of top-kill was much greater than the probability of mortality; however, this difference diminished at diameters greater than 16 cm. Similarly, with A. xalapensis, there was an inverse relationship between diameter and probability of tree death.

CAMBIAL BEHAVIOR WITH REFERENCE TO CELL LENGTH AND RING WIDTH IN PINUS STROBUS L.

1962 ◽  
Vol 40 (8) ◽  
pp. 1057-1062 ◽  
Author(s):  
M. W. Bannan
Keyword(s):  
Inverse Relationship ◽  
Ring Width ◽  
Pinus Strobus ◽  
Growth Patterns ◽  
Cell Length ◽  
Annual Rings ◽  
Forest Types ◽  
Thuja Occidentalis ◽  
Cambial Cells ◽  
Individual Trees

The relationships between width of annual rings, length of wood cells, and frequency of anticlinal (multiplicative) divisions in fusiform cambial cells were studied by reference to trees of various growth patterns. The trees selected ranged from 8 to 20 in. diameter and included both open-grown specimens with branches close to the ground and forest types with tall, slender shafts. Much fluctuation was noted among individual trees, but in general there was, in the peripheral growth, an inverse relationship between length of wood cells and width of annual rings. The frequency of anticlinal divisions in the cambium remained at a more or less uniform rate in trees with rings from 1.5 to 5 mm wide, but rose sharply when ring width fell below 1.3 mm. This was in contrast to the situation observed earlier in Thuja occidentalis where the rise in frequency of anticlinal divisions was slight and occurred only in trees with rings less than 0.3 mm wide.

Abstract 591: Can Waveform Characteristics Predict Defibrillation to a Perfusing Rhythm in Short Versus Prolonged Ventricular Fibrillation in a Swine Model?

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Julia H Indik ◽  
Mathias Zuercher ◽  
Karl B Kern ◽  
Ronald W Hilwig ◽  
Robert A Berg
Keyword(s):  
Logistic Regression ◽  
Ventricular Fibrillation ◽  
Short Duration ◽  
Important Determinant ◽  
Swine Model ◽  
Median Frequency ◽  
Chest Compressions ◽  
Long Duration ◽  
Spectral Area ◽  
Minute Duration

It is known that defibrillation of ventricular fibrillation (VF) to a perfusing rhythm (ROSC) is more likely to occur in VF of short duration. It is unknown whether ROSC can be predicted by waveform characteristics in VF of short compared to long duration, apart from a consideration of time alone. VF was untreated for 2 minutes (N=10) or 8 minutes (N=10) in normal swine, after which a defibrillation shock was applied. Chest compressions for two minutes were allowed following but not prior to the shock to achieve a perfusing rhythm (ROSC). VF was analyzed from needle electrodes prior to the shock for amplitude spectral area (AMSA), slope, median frequency and bandwidth. Predictors of ROSC were determined by logistic regression. In VF of 2 minute duration 7 out of 10 swine achieved ROSC compared to 2 out 10 swine with VF of 8 minutes (P=0.025) and time was a significant predictor of ROSC (P=0.033). AMSA was significantly higher at 2 minutes (75 ± 18 mV-Hz) compared to 8 minutes (56±11 mV-Hz, p=0.007) as was slope (3.5±1 vs 2.6±0.5 mV/s, p=0.015). Bandwidth was slightly increased from 2.2±0.6 Hz at 2 minutes to 2.8±0.8 Hz at 8 minutes,(p=0.048), while median frequency was similar. However, no waveform characteristic was a significant predictor of ROSC, with substantial overlap in distributions between animals with and without ROSC. Duration of VF is an important determinant of the likelihood of achieving ROSC with defibrillation. Particularly in VF of short duration, VF waveform characteristics do not add to the predictability of achieving ROSC even though they may demonstrate a significant time evolution.

Floral Phenology of a Stand of Mountain Ash (Eucalyptus regnans F. Muell.) In Gippsland, Victoria

1980 ◽  
Vol 28 (4) ◽  
pp. 393 ◽  
Author(s):  
AR Griffin
Keyword(s):  
Gene Flow ◽  
Important Determinant ◽  
Flowering Phenology ◽  
Structural Level ◽  
Relative Time ◽  
Eucalyptus Regnans ◽  
Floral Phenology ◽  
Mountain Ash ◽  
The Mean ◽  
Individual Trees

Flowering phenology was observed in a stand of Eucalyptus regnans F.Muell. at Narracan, Gippsland, Vic. during 1977 and again in 1979. The first tree flowered on 15 February in 1977 and on 30 January in 1979. Flowering of all trees was completed after 90 and 100 days respectively, and in both seasons the modal value for the number of trees concurrently in flower occurred 40 days after commencement. There was a highly significant association, between years, for the relative time and duration of flowering of individual trees. Tree size was not an important determinant of flowering attributes. Trees were not randomly distributed with respect to peak flowering time: thus flowering of adjacent trees tended to be synchronous. Detailed observation of flowering within the crowns of three trees showed that within inflorescences the mean period between anthesis of the earliest and latest flowers was 6 days, and within branches 14 days. The degree to which flowering was synchronous within the crown varied consistently between trees at each structural level assessed, which suggested genetic control of this trait. Implications of the floral phenology for the breeding system and gene flow of the species are discussed.

The structural characteristics and climatic and human impacts of deciduous oak forests in China

2021 ◽  
Author(s):  
Guoping Chen ◽  
Qiong Cai ◽  
Wenjing Fang ◽  
Yuhao Feng ◽  
Jiangling Zhu ◽  
...  
Keyword(s):  
Species Richness ◽  
Spatial Patterns ◽  
Tree Species ◽  
Structural Characteristics ◽  
Tree Height ◽  
Oak Forests ◽  
Oak Forest ◽  
Stem Density ◽  
Shrub Species ◽  
The Mean

Abstract Aims Deciduous oak forest is one of the typical vegetation types in temperate and subtropical mountain zones in China. However, the patterns and determinants of the structural characteristics of these forests remain poorly understood. Methods We investigated 682 oak forest plots across China to characterize the community structures of the oak forests and analyze the underlying factors controlling their spatial patterns. Important Findings Across all plots, the overall mean values were 13.7 cm, 10.0 m, 1468 stems/ha, and 24.3 m 2/ha for the diameter at breast height (DBH), height, stem density and total basal areas (TBA) of trees, respectively. The average species richness was 6 species/600 m 2, 10 species/100 m 2, and 4 species/1 m 2 for the tree, shrub and herb layers, respectively. As latitude increased, the mean tree height, stem density, TBA, tree species richness and shrub species richness decreased, and the mean DBH did not show a significant trend, while species richness of herbs increased significantly. Climatic and anthropogenic variables could explain more variations in mean DBH, mean tree height, TBA, tree species richness, shrub species richness than those in stem density and herb species richness. Further analysis showed that precipitation-related climatic factors were major factors shaping the spatial patterns of community structures. Our findings provide a basis for recognizing the biogeographic patterns of oak forest structures and their responses to global change in China.

scholarly journals Improving Estimates of Acceptable Growing Stock in Young Upland Oak Forests in the Missouri Ozarks

1998 ◽  
Vol 15 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Daniel C. Dey ◽  
Paul S. Johnson ◽  
H. E. Garrett
Keyword(s):  
Species Group ◽  
Slope Position ◽  
Oak Forests ◽  
Regression Analyses ◽  
Quadratic Mean ◽  
Growth And Survival ◽  
Growing Stock ◽  
Individual Trees ◽  
The Relationship ◽  
Future Growth

Abstract Estimates of regeneration or growing stock in young oak forests may be too high unless criteria are established that define explicitly acceptable growing stock. In young hardwood stands, crown class can be used to identify acceptable growing stock because it is related to the future growth and survival of reproduction. A method is presented for assigning crown class categories to hardwood stems based on their diameters (dbh). Young upland oak forests originating from clearcuts in the Missouri Ozarks were sampled to determine the relationship between dbh and crown class. Stands were 19 to 25 yr old. Threshold diameters (TD) separating one crown class category from another were determined using regression analyses. TD was not significantly affected by species group, and in some cases by aspect and slope position. Quadratic mean stand diameter (QMSD) was significantly related to TD. As QMSD increased so did TD. When QMSD equals 3 in., trees with dbh ≥ 3.9 in. are allocated to the codominant and dominant crown class category, and those ≥ 2.5 in. to the dominant, codominant, and intermediate category. TD can be used to assign a crown class category to individual trees, thereby improving estimations of acceptable growing stock. By this method, crown class can be used to define acceptable growing stock and evaluate stocking, yet it does not have to be measured in stand inventories. North. J. Appl. For. 15(1):28-32.

Biomass estimation of individual trees for coppice-originated oak forests

2019 ◽  
Vol 138 (4) ◽  
pp. 623-637 ◽  
Author(s):  
Emrah Ozdemir ◽  
Ender Makineci ◽  
Ersel Yilmaz ◽  
Meric Kumbasli ◽  
Servet Caliskan ◽  
...  
Keyword(s):  
Biomass Estimation ◽  
Oak Forests ◽  
Individual Trees

Simulating co-existence of functionally diverse trees in European natural forests with LPJmL-FIT

2020 ◽  
Author(s):  
Kirsten Thonicke ◽  
Maik Billing ◽  
Werner von Bloh ◽  
Boris Sakschewski ◽  
Ülo Niinemets ◽  
...  
Keyword(s):  
Vegetation Dynamics ◽  
Functional Divergence ◽  
Latitudinal Gradients ◽  
Natural Forests ◽  
Niche Space ◽  
Forest Patch ◽  
Dynamic Global Vegetation Model ◽  
Functional Richness ◽  
Individual Trees ◽  
Functionally Diverse

&lt;p&gt;We adopted the flexible trait Dynamic Global Vegetation Model LPJmL-FIT for European natural forests by eliminating bioclimatic limits of Plant Functional Types (PFTs) and replacing prescribed values of functional traits with flexible individual traits. Vegetation dynamics are simulated with permafrost and fire disturbance being considered in the simulation domain. Leaf and stem-economic traits are assigned to individual trees at establishment which then determine plant competition for light and water in a forest patch. We simulate vegetation dynamics in selected natural forests sites and at the Pan-European scale. We quantified functional richness (FR), functional divergence (FDv) and functional evenness (FE) from combinations of functional and structural traits of the simulated individual trees.&lt;/p&gt;&lt;p&gt;We find good agreement with observed productivity, biomass and tree height, and spatial PFT and local trait distributions. The latter is compared against TRY observations. We find site-specific trait distributions and spatial gradients of the simulated LES and SES traits to coincide with environmental and competitive filtering for light and water in environments with strong abiotic stress. Where deciduous and needle-leaved trees co-occur in a forest patch, functional richness (potential niche space) is high, and extreme ends of the niche space are occupied resulting in high FDv. Functional divergence declines where the performance of deciduous trees decreases due to increasing environmental stress as simulated along altitudinal and latitudinal gradients. When climate gets cooler, needle-leaved trees become dominant, occupying the extreme ends of the niche space. Under Mediterranean climate conditions, drought increasingly limits tree growth thus niche differentiation becomes more important.&lt;/p&gt;&lt;p&gt;Co-existence of functionally diverse trees within and across PFTs emerges from alternative life history strategies, disturbance and tree demography.&lt;/p&gt;

Relationship between CD33 Expression, P-Glycoprotein-Mediated Drug Efflux, and Clinical Outcome in Patients Treated in Phase II Trials with Gemtuzumab Ozogamicin Monotherapy.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2324-2324 ◽  
Author(s):  
Roland B. Walter ◽  
Ted A. Gooley ◽  
Vincent H.J. van der Velden ◽  
Michael R. Loken ◽  
Jacques J.M. van Dongen ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Clinical Outcome ◽  
Regression Model ◽  
Phase Ii ◽  
Inverse Relationship ◽  
Logistic Regression Model ◽  
Gemtuzumab Ozogamicin ◽  
Drug Efflux ◽  
Expression Levels ◽  
P Glycoprotein

Abstract Background: The anti-acute myeloid leukemia (AML) immunoconjugate, gemtuzumab ozogamicin (GO; Mylotarg™), contains a humanized anti-CD33 antibody (hP67.6) to facilitate uptake of the toxic calicheamicin-γ1 derivative in CD33-positive AML cells. This putative mechanism implies a critical role for the intracellular accumulation of the toxic moiety for GO-induced cytotoxicity. Indeed, drug efflux by P-glycoprotein (Pgp) mediates resistance to GO and correlates with clinical outcome after GO monotherapy. Furthermore, recent in vitro data obtained in human myeloid cell lines have unequivocally demonstrated a quantitative relationship between CD33 expression and GO-induced cytotoxicity. In light of these findings, we have now re-examined the significance of CD33 expression levels on AML blasts and relationship with Pgp activity for clinical outcome of patients treated with GO monotherapy. Methods: Pre-treatment bone marrow samples from patients enrolled in multicenter phase II protocols evaluating the safety and efficacy of GO monotherapy (generally 2 doses of 9 mg/m2 14 days apart) were used for analysis. Relative CD33 expression was quantified by flowcytometry immunophenotyping using the hP67.6 antibody, and linear fluorescence values used for calculations. Pgp function was cytofluorometrically determined by efflux of the fluorescent dye, DiOC2. Results are presented as mean values and 95% confidence intervals. Unpaired t-tests, Pearson correlations, and logistic regression models were used for statistical analysis. Results: Patients achieving a complete remission (CR) or CR with incomplete recovery of platelet counts (CRp) had statistically significantly higher mean CD33 expression levels (71.20 [57.20–85.19], n=69) compared to non-responders (54.44 [48.38–60.51], n=203; p=0.01). There was an inverse relationship between CD33 expression and Pgp efflux (r=−0.23) and this contributed to responders having a statistically significantly lower mean Pgp efflux (1.40 [1.28–1.52], n=57) compared to non-responders (1.83 [1.72–1.95], n=173; p<0.0001). The addition of Pgp statistically significantly improved a logistic regression model containing only CD33 (p<.0001), whereas the addition of CD33 did not lead to a statistically significantly improved logistic regression model containing only Pgp (p=0.14). Conclusion: These data indicate that CD33 expression levels as well as Pgp efflux are associated with clinical outcome of patients treated with GO monotherapy, and that knowledge of Pgp provides important information regarding the probability of achieving a response, even after consideration of CD33 expression level. The inverse relationship between CD33 abundance and Pgp efflux is consistent with the notion of maturation-stage dependent expression of these proteins, and offers the rationale for the use of cell-differentiation-promoting agents, for example cytokines, in combination with GO to enhance GO-induced cytotoxicity and possibly improve clinical outcome of patients undergoing GO-containing AML therapy.

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