Diameter Growth Rate Research Articles

Seedling Survival and Growth of Tree Species: Site Condition and Seasonality in Tropical Dry Forest Restoration

Restoring seasonally dry tropical forest is a worldwide priority, since it is the most threatened of all major tropical forest types. In Veracruz, Mexico, the dry forest has been reduced to fragments and fallows representing 7% of the original cover. Our objective was to determine the effect of site condition and seasonality on seedling survival and relative growth rate in height and diameter of selected native tree species. We studied plant performance during two dry and two rainy seasons and the effect of existent woody vegetation > 1 m height. A total of 960 seedlings were transplanted: 40 individuals of six species (Cedrela odorata, Ceiba aesculifolia, Guazuma ulmifolia, Ipomoea wolcottiana, Luehea candida, Tabebuia rosea) in four fallows. Seedling survival and relative growth rate were monitored every four months during two years. Survival was higher in sites with more woody species richness, whereas relative growth rate in height was positively correlated with existent vegetation height. Relative growth rate was higher for all species and sites during the rainy season. In the site with less existent woody vegetation, seedling performance was poor and only Guazuma survived. Overall, Ceiba showed the highest survival rate (82-90%) and the lowest relative growth rate. Guazuma had a high survival (20-94%) and the highest relative growth rate; Cedrela showed the lowest survival (3-7%) and high relative growth rate. Our results suggest that site condition, seasonality, and tree species selection act together on seedling performance during early establishment. A vital implication in terms of ecological restoration is the importance of taking advantage of existent vegetation even if it is scarce.

Soil Quality Attributes as Indicators of Urban Tree Performance

Soil quality assessments are needed to improve a professional’s ability to manage urban soils and trees. This research was conducted to identify which soil properties are most useful for relating information on urban tree performance. In total, 48 soil properties were measured at 84 sites from five urban landscapes in the western suburbs of Chicago, Illinois, U.S. Key physical, chemical, and biological properties to be included in a minimum data set (MDS) for assessing urban soil quality were identified using statistical approaches and practical considerations. The MDS included: texture, bulk density, wet-aggregate stability, pH, electrical conductivity, soil organic matter (SOM), and particulate organic matter. The MDS was used to establish an urban soil quality index (USQI). The MDS and USQI were highly correlated with tree size attributes of height, trunk diameter, crown area, and age. Correlations between the MDS and USQI with trunk diameter growth rate, height growth rate, foliar N, and chlorophyll content were often significant, but less strong. Among the MDS parameters, SOM, pH, and texture appear to be the most informative measures for soil quality relating to urban tree performance. Soil quality and tree performance increased logarithmically following site disturbance, with a plateau after 50 years.

Measurement of growth in the lichenRhizocarpon geographicumusing a new photographic technique

AbstractAdobe® Photoshop® CS3 Extended software and a photographic time series were used to generate accurate and precise measures of change in the area, perimeter and diameter ofRhizocarponthalli at one, three and seven year intervals. Systematic measurements at a fixed grid of eight diameters per thallus showed a rapid and highly variable diametric growth phase in the smallest thalli (<5 mm2) and slower diametric growth (<0·01 mm2yr–1) in larger thalli (5–500 mm2). When standardized to an annual rate, the areal growth trend was similar, regardless of the number of years studied. This suggests that the areal and diametric growth of small and mid-sizedRhizocarponthalli may be insensitive to annual climatic variation and can be accurately characterized by repeat measurements taken over months rather than decades. Unlike diametric growth rate, change in thallus area and perimeter are statistically robust measures of growth inRhizocarponthalli. Our mean measurement accuracy was 99%. Measurement precision (reproducibility) was >95% (P>0·05) for thallus area and >96% for thallus perimeter. Our technique is tedious, but on flat rocks it can resolve and accurately measure change in thallus morphology at the sub-millimeter scale, and it can be used with recent and/or historical images.

Functional traits and their plasticity predict tropical trees regeneration niche even among species with intermediate light requirements

Summary Niche differentiation is a key issue in the current debate on community assembly mechanisms. In highly diverse moist tropical forests, tree species sensitivity to canopy openness is thought to be a major axis in niche differentiation. In the past, the syndrome of traits driving the demographic trade‐off involved in the niche‐based theory of coexistence has always been established among species situated at the two extremities of the shade‐tolerance gradient, even though most tropical tree species have intermediate light requirements. In addition, trait plasticity has seldom been linked to tropical tree species distribution along environmental gradients. This article examines covariations between leaf traits, whole‐plant traits and niche parameters among 14 tree species with intermediate light requirements in French Guiana and across a range of canopy openness. Each functional trait measured under field conditions was characterized by a median value and a degree of plasticity expressed under contrasting light regimes. Niche differentiation was characterized in terms of spatial light gradient. We first examined covariations between functional traits then explored to what degree the median value and plasticity in functional traits could predict light niche characteristics at the sapling stage and the ontogenetic change in light availability estimated by adult stature. Leaf mass per area (LMA) was positively correlated with leaf life span (LLS); species with higher LMA and higher LLS displayed lower diameter growth rates (GRs) and lower responsiveness to canopy gap at both whole‐plant and population levels. This proved that the relationships previously established over a broader range of species held true within the narrow range of the light requirements covered. Height GR plasticity accounted for 49% of the variation in light niche optimum. LMA plasticity, unlike LLS plasticity, was significantly correlated with light niche breadth and adult stature. Synthesis. This study demonstrates the relevance of considering the phenotypic plasticity in functional traits in community ecology, particularly for quantifying breadth of species distribution over environmental gradients. Our findings did not support Hubbell's hypothesis of functional equivalence and suggest that even a rather subtle variation in forest canopy disturbance promotes the coexistence of tropical tree species.

Canopy gaps affect long-term patterns of tree growth and mortality in mature and old-growth forests in the Pacific Northwest

Canopy gaps created by tree mortality can affect the speed and trajectory of vegetation growth, species’ population dynamics, and spatial heterogeneity in mature forests. Most studies focus on plant development within gaps, yet gaps also affect the mortality and growth of surrounding trees, which influence shading and root encroachment into gaps and determine whether, and how quickly, a gap becomes occupied by recovering vegetation. The objective of this study was to determine the effect of canopy gap size on mortality and growth of surrounding trees over a 16-year period in mature and old-growth Douglas-fir dominated forests in the coastal Pacific Northwest, USA. Replicates of four sizes of experimental gaps and controls were created in two mature stands (90 and 145-years old) and two old-growth stands (overstory trees 350–525-years old); mortality and diameter of surrounding trees were measured periodically over 16 years. A subset of trees was cored to compare growth increment before and after gap creation. There was no difference between mortality rates of trees within 8m of gaps and trees in closed-canopy controls, although mortality causes did differ for understory trees. Mortality of understory trees was higher at gap edges than in controls, but lower several meters into the forest, suggesting a shift from negative to positive effects with the gradient in exposure. Diameter growth rates of trees were greater next to gaps than in controls, with the greatest difference ranging from 39% for overstory trees to 111% for understory trees in mature stands. Growth rates of trees in old-growth stands differed by crown class and position around gap, suggesting an effect of direct solar radiation. Growth rates of trees in mature stands were relatively insensitive to gap size and position, suggesting that increased soil moisture drove responses in these stands. Somewhat unexpectedly, there were rapid increases in growth in some old-growth trees, but not in the largest gap sizes. Results suggest canopy gaps can create heterogeneity of ecosystem function through spatial variation in effects on growth and mortality across mature and old-growth stands.

Incidentally discovered benign pancreatic cystic neoplasms not communicating with the ductal system: MR/MRCP imaging appearance and evolution

The authors sought to determine magnetic resonance/magnetic resonance cholangiopancreatography (MR/MRCP) imaging features of incidentally discovered benign, noncommunicating cystic neoplasms (BNCNs) of the pancreas to assess their evolution over time and identify MR/MRCP imaging features predictive of tumour growth. This was a retrospective study, so informed consent was waived. Sixty-two patients with a diagnosis of BNCN were assessed. Inclusion criteria were incidentally discovered cystic neoplasm of the pancreas with nonmeasurable walls, no mural nodules and no communication with the pancreatic ductal system and who underwent ≥ 1 MR/MRCP examination. Image analysis, performed at diagnosis and during follow-up, included macroscopic pattern (microcystic/macrocystic/mixed), number of cysts (unicystic/oligocystic/multicystic), BNCN maximum diameter and tumour growth rates. A total of 64 BNCNs was detected. Macroscopic pattern was mixed in 31/64 (48%), microcystic in 28/64 (44%) and macrocystic in 5/64 (8%). BNCNs appeared multicystic in 38/64 (59%) cases, oligocystic in 22/64 (35%) and unicystic in 4/64(6%). All qualitative parameters remained unchanged during follow-up. At diagnosis, the median maximum BNCN diameter was 35.0 mm and 38.0 mm at the final examination (p<0.001). BNCNs showed a tumour growth rate of 2 mm/year. Mixed and microcystic patterns were the most common, accounting for 48% and 44% of cases, respectively, and showed no change over time. MR/MRCP features predictive of lesion enlargement were a mixed/ macrocystic pattern, and lesion size was >3 cm (both p<0.001).

Predicting fine root lifespan from plant functional traits in temperate trees

Although linkages of leaf and whole-plant traits to leaf lifespan have been rigorously investigated, there is a limited understanding of similar linkages of whole-plant and fine root traits to root lifespan. In comparisons across species, do suites of traits found in leaves also exist for roots, and can these traits be used to predict root lifespan? We observed the fine root lifespan of 12 temperate tree species using minirhizotrons in a common garden and compared their median lifespans with fine-root and whole-plant traits. We then determined which set of combined traits would be most useful in predicting patterns of root lifespan. Median root lifespan ranged widely among species (95-336 d). Root diameter, calcium content, and tree wood density were positively related to root lifespan, whereas specific root length, nitrogen (N) : carbon (C) ratio, and plant growth rate were negatively related to root lifespan. Root diameter and plant growth rate, together (R² = 0.62) or in combination with root N : C ratio (R² = 0.76), were useful predictors of root lifespan across the 12 species. Our results highlight linkages between fine root lifespan in temperate trees and plant functional traits that may reduce uncertainty in predictions of root lifespan or turnover across species at broader spatial scales.

Ganancia genética esperada en Acacia mangium en Los Chiles, zona norte de Costa Rica.

Ganancia genética esperada en Acacia mangium en Los Chiles, zona norte de Costa Rica. Con el objetivo de seleccionar los materiales de mayor crecimiento y calidad de fuste en Acacia mangium, se evaluó un ensayo de progenie de Acacia mangium Willd. conformado por veinticinco familias.El ensayo fue establecido en Los Chiles, zona norte de CostaRica, en 2006 con evaluaciones en el 2007 y en 2010. Se utilizó material genético seleccionado por la Cooperativa de Conservación y Mejoramiento Genético Forestal “GENFORES”,en Costa Rica y Colombia. Cada familia estuvo representada por 48 progenies, plantadas en cuatro parejas distribuidas enforma aleatoria dentro de cada uno de los seis bloques delensayo. Se evaluó el diámetro a la altura de pecho “DAP”,incremento en DAP, adaptabilidad al sitio, número de trozas comerciales, bifurcación, altura de bifurcación, calidad de las primeras cuatro trozas. Se determinó el volumen de maderacomercial por árbol y hectárea. Los datos fueron analizadospor medio del software SELEGEN de EMBRAPA para obtenerlos parámetros genéticos. Todos los caracteres registraron valores de heredabilidad media familiar superiores a 0,68.Si se seleccionaran los dos mejores individuos dentro de las mejores doce familias, se obtendría una ganancia genética del40,8% en volumen comercial/ha a los cuatro años de edad.Esta ganancia corresponde a un volumen comercial de 91,65m3/ha, a una tasa de 22,9 m3/ha/año. Las dos procedencias derivadas de Colombia son significativamente superiores a los demás materiales evaluados. El análisis de correlación genética entre caracteres muestra que la tasa de crecimiento diamétrico se expresa desde temprana edad en esta especie, lo que podría ser utilizado a futuro en una selección a menor edad.

Provenance variation in survival, growth and dry matter partitioning of Parkia biglobosa (Jacq.) R.Br. ex G.Don seedlings in response to water stress

The effects of drought stress on growth and dry matter partitioning of seven provenances of Parkia biglobosa were assessed in a nursery experiment. Three different water regimes were applied: soil high, medium and low water content (HWC, MWC and LWC) corresponding respectively to 100, 75 and 50 % of field capacity. A split-plot experimental design was applied with the provenance as main plot and the water regime as sub-plot, replicated three times. Each provenance was represented by 30 seedlings in each replication, corresponding to three test periods with ten seedlings each (6, 12 and 18 months after water stress started). There were significant interactions between provenance and water regime for survival rate and the relative growth rates of diameter and height. After 18 months, the dry matter mean was 20.00 ± 0.65 g for the HWC regime, 11.50 ± 2.90 g for the MWC regime while all plants in the LWC regime died. After 6 months, the accumulated water use efficiency (WUE) showed significant differences between water regimes, but not between provenances. Seedlings from the LWC regime showed higher WUE than those from the MWC regime. However, the HWC regime displayed the highest mean value of WUE. Despite differences between provenances, it was not possible to clearly separate them according to the geographical position or climatic parameters, based on the growth performance or both fresh to dry weight and shoot to root dry weight ratios.

Abstract 100: Periaortic Leptin Induces Local Medial Degeneration in ApoE -/- Mice Preceding Aneurysm Formation

Background: Leptin (Ob) is a proatherogenic hormone involved in vessel wall remodeling. We hypothesized that Ob locally synthesized in the abdominal aorta regulates vascular remodeling mediators (TGFβ, MMPs) thereby sensitizing the aorta to subsequent aneurysm formation. Methods: Human abdominal aortic aneurysm (AAA) wall (n=10), and non-dilated aortic (n=3) samples underwent real time qPCR mRNA analysis for Ob and Ob receptor (ObR), and immunohistochemical analysis (SM-αactin, CD68, Ob, and ObR). Plasma samples obtained prior to AAA surgery were analyzed for Ob and ObR antigen (n=20). A novel mouse model was utilized to elucidate the role of Ob in AAA formation. Local Ob synthesis was simulated by point application of 20μg Ob slow release (n=10), or placebo (n=10) compound at the peri-vascular space of the para-visceral aorta in ApoE -/- mice on a Western diet. Serial ultrasound examinations on days 0, 14, 28, 35, and 42 assessed aortic diameter at reference locations. A parallel group (n=10), randomized to Ob or placebo treatment was euthanized on day 5 for aortic mRNA analysis. Results: Increased Ob mRNA levels and immunoreactivity were evident in human AAA wall samples vs controls. Plasma Ob and ObR levels were within normal range. Ob treated mice demonstrated augmented growth rate of luminal aortic diameter in the para-visceral segment on day 28 (p=0.0001). Aortas analyzed 5 days after Ob deployment revealed suppressed TGFβ mRNA (p=0.002), while MMP-9 transcript was up-regulated (p=0.047). Ob treated mice euthanized on day 45 demonstrated localized aortic derangement of elastic fibers and loss of SM-αActin (p=0.07), alongside with increased MMP-9 (p=0.02), MMP-12 (p=0.001) antigen, and augmented adventitial macrophage infiltration. Conclusions: Ob is locally synthesized in human AAA wall. Peri-aortic Ob modulates the vessel wall in ApoE -/- mice, inducing medial degeneration at the para-visceral region. Mechanistically, the observed derangement of ECM components was associated with suppressed TGFβ mRNA, and up-regulated MMP-9 synthesis. These data suggest novel mechanistic links between Ob and human AAA formation.

Size and time-resolved growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei

Abstract. This study presents measurements of size and time-resolved particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Novel data analysis methods were developed, de-coupling for the first time the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated total aerosol (neutral and charged) were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the particle detector. One new particle formation (NPF) event from each campaign was analyzed in detail. At a given instant in time during the NPF event, size-resolved growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with particle size from ~1 to 3 nm geometric diameter, increasing from 5.5 ± 0.8 to 7.6 ± 0.6 nm h−1 in Atlanta (13:00) and from 5.6 ± 2 to 27 ± 5 nm h−1 in Boulder (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter. For the presented NPF events, values for Γ had lower limits that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and had upper limits that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Nucleated particle survival probability calculations comparing the effects of constant and size-dependent growth indicate that neglecting the strong dependence of growth rate on size from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival probability.

How the timberline formed: altitudinal changes in stand structure and dynamics around the timberline in central Japan

Altitudinal timberlines are thought to move upward by global warming, a crucial topic in ecology. Tall tree species (the conifer Abies mariesii and the deciduous broad-leaved Betula ermanii) dominate the sub-alpine zone between 1600 and 2500 m a.s.l., the timberline, on Mount Norikura in central Japan. Dwarf pine Pinus pumila dominates above the timberline to near the summit (3026 m a.s.l.). This study evaluated how the timberline formed on Mount Norikura by examining altitudinal changes in stand structure and dynamics around the timberline. One hundred and twenty-five plots of 10 m × 10 m were established around the timberline (2350-2600 m a.s.l.). Trunk diameter growth rate during 6 years was examined for A. mariesii, B. ermanii and P. pumila. Mortality during this period and mechanical damage scars on the trunks and branches due to strong wind and snow were examined for A. mariesii only. The density, maximum trunk height and diameter of A. mariesii in plots decreased with altitude. The maximum trunk height of B. ermanii decreased with altitude, but density and maximum trunk diameter did not decrease. In contrast, the density of P. pumila abruptly increased from around the timberline. A strong negative correlation was found between the densities of P. pumila and tall tree species, indicating their interspecific competition. Trunk diameter growth rates of A. mariesii and B. ermanii did not decrease with altitude, suggesting that these two tall tree species can grow at the timberline. The ratio of trees with mechanical damage scars increased with altitude for A. mariesii, a tendency more conspicuous for larger trees. The mortality of larger A. mariesii was also greater at higher altitude. Tall tree species may not increase their trunk height and survive around the timberline because of mechanical damage. This study suggests that the altitudinal location of the timberline is mainly affected by mechanical damage due to strong wind and snow rather than by growth limitation due to low temperature. Therefore, the timberline would not move upward even under global warming if these growth and mortality characteristics do not change for a long time.

Testing metabolic theory with models of tree growth that include light competition

Summary 1. Metabolic scaling theory predicts that diameter growth rates of tree species are related to tree diameter by a universal scaling law. This model has been criticised because it ignores the influence of competition for resources such as light on the scaling of demographic rates with size. 2. We here test whether scaling exponents of abundant tropical tree species comply with the prediction of metabolic scaling theory and evaluate whether the scaling of growth with size depends on light availability. Light reaching each individual tree was estimated from yearly vertical censuses of canopy density, and a hierarchical Bayesian approach allowed quantifying confidence intervals for scaling exponents and accounting for different sources of error. 3. We found no universal scaling relationship, and 50–70% of the species had scaling exponents that significantly differed from the predicted value of 1 ⁄ 3. As would be expected if competition for light were important, scaling exponents were >1 ⁄ 3 for the majority of species when all trees were combined. However, the community average of scaling exponents was not significantly different from the predicted value of 1 ⁄ 3 when only considering individuals that grew under highlight conditions. 4. These results support the hypothesis that the prediction of metabolic ecology for the scaling of tree growth with size is only valid when competition for light is unimportant.

봉산 생태·경관보전지역 팥배나무 군락 보전방안

This study was carried out for the purpose of presenting basic data bases for conservation and management measures of Ecological and Scenery Conservation Area in Bongsan. The analysis results of the actual vegetation showed that rate of vegetation cover were composed of 72.3% of Robinia pseudo-acacia Forest, 10.7% of Sorbus alnifoila Forest, and Sorbus alnifoila was founded as a dominant woody plant species in the Core Zone of Bongsan Ecological and Scenery Conservation Area. To investigate the vegetation structure of Sorbus alnifolia Community in Bongsan Ecological and Scenery Conservation Area, twelve <TEX>$100m^2$</TEX> sized plots were set up in Bongsan. According to the classification by TWINSPAN, the communities were divided into the three groups of Sorbus alnifolia Community, Pinus koraiensis Community and Robinia pseudo-acacia Community, To analyze annual diameter growth rate for major tree species, nine sample trees from research plots were measured. Expected ages of Sorbus alnifoila trees were 27~37years, Robinia pseudo-acacia trees were 17~26 years, Pinus koraiensis, Pinus rigida, Prunus sargentii, and Quercus mongolica trees were 27~38 years. As a result, annual diameter growth rates of Robinia pseudo-acacia and Pinus rigida tended to remarkably decreased, Sorbus alnifoila had the wood on inter-specific competition of the woody plant species. Importance values of Sorbus alnifoila in the three layers of Sorbus alnifoila communities were evenly high.

Size-dependent growth responses to competition and environment in Nothofagus menziesii

The increased availability of permanent-plot and environmental data allows examination of the relative influence of environment and competition as controls of individual tree growth at large spatial scales. To understand and predict stem diameter growth of a dominant tree, Nothofagus menziesii (Hook. F.) Oerst., within natural forest in the South Island of New Zealand we tested the relative importance of stem diameter, competition by neighbors, soil water balance and elevation as explanatory variables. The analysis was based on 482 permanent sample plots and GIS data. Because only relatively short trees are susceptible to shading, models were fitted independently for trees smaller and larger than 25cm in stem diameter at breast height, using multilevel log-linear models. N. menziesii exhibited slow diameter growth rates in natural forest, with a median 0.39mmyear−1 and 1.39mmyear−1 for small and large trees, respectively. Growth rates were broadly uniform across 11 sampled regions, but an important fraction of the explained variation was attributed to plot-level growth estimates. Stem diameter, elevation and cross-sectional area of neighbors at the tree top (a refinement of basal area of larger neighbors, a commonly used variable) were important explanatory variables for growth of small stems. The effect of elevation was important for large stems, but size and competition had much weaker effects; there was a clear negative effect of elevation on growth but only moderate statistical support for a humped effect of tree size and for a negative effect of stand density. Thus, our results indicate that whilst asymmetric competition for light controls diameter growth in small trees, the physical environment is relatively more important in large canopy trees.

Salinity constrains size inequality and allometry in two contrasting mangrove habitats in the Gulf of Mexico

Abstract:The competition for resources increases size inequality in trees, particularly under low abiotic stress. Because mangrove communities are subject to site-specific salinity (and therefore abiotic stress) gradients, these habitats should differ in height–diameter allometry and size inequality. The size inequality (by the Gini Coefficient, G) and maximum potential height (Hmax from a height–diameter asymptotic model) were determined within the mangrove forest of a coastal lagoon in Veracruz, Mexico in 20 0.25-ha plots, 10 in interdistributary basins (IBs, lower salinity) having Avicennia germinans, Laguncularia racemosa and Rhizophora mangle and 10 in mudflats (MFs, higher salinity) dominated by A. germinans. Size inequality was significantly higher in IBs (G = 0.59 ± 0.02 vs. 0.39 ± 0.03). Due to their significant intercorrelation G, total basal area and density were synthesized in one PCA axis accounting for 67% of total variance and inversely correlated with salinity (R = −0.65, P = 0.003). The height–diameter scaling model reached a stable asymptote (Hmax range: 16–21 m; coefficient of variation CV: 7.7) in IBs, suggesting that trees can still increase their diameter after achieving maximum height. In MFs, no stable asymptote was reached (Hmax range: 11–26 m; CV: 32.5), suggesting a lower growth rate of diameter in the MF trees when compared with IB trees.

Effects of soil nutritional status on seedling nursery performance of Arizona cypress (Cupressus arizonica var arizonica Greene) and Medite cypress (Cupressus sempervirens var. horizantalis (Mill.) Gord)

The present research was carried out to determine the influence of different combinations of organic matter as growing media on seed germination, survival, growth, biomass and performance of needle-leaved Arizona cypress (Cupressus arizonica var arizonica Greene) and Medite cypress (C. sempervirens var. horizantalis (Mill.) Gord) seedlings in Koloudeh nursery, located in Amol city (North of Iran). Seeds were sown in plastic pots as randomized completely block design (RCBD) with four replications atfour different soil treatments, including: T1) nursery common soil (control), T2) control soil: cattle manure (5:1), T3) control soil: decomposed litter (5:1), T4) control soil: cattle manure: decomposed litter (5:1:1). The results after one year showed that seedlings of both species grown on T4 obtained better germination percent, survival, shoot height, collar diameter, seedling vigor index and Quality Index (QI). Greatest relative growth rate (RGR) of height and diameter were achieved on organic matter treatments. In most of the studied attributes, response of C. arizonica was better than C. sempervirens, showing the different biological requirements of these species. From the study, it is concluded that the increased of soil nutrient can be useful in seedling production of both species. Key words: Biomass, Cupressus arizonica, Cupressus sempervirens, organic matter, quality index, vigor index.

Quantification of the effects of aboveground and belowground competition on growth of seedlings in a conifer–angiosperm forest

Differential shade-tolerance is thought one of the critical components of coexistence of conifer and angiosperm canopy tree species in temperate forests. However, belowground competition for nutrients may also change along light gradients, confounding apparent differences in shade tolerance. Despite this co-variation in light and nutrients, in situ manipulation of belowground competition along a light gradient has not been previously used to investigate conifer–angiosperm seedling performance. In this study we selected conifer–angiosperm seedlings along a light gradient and used trenching to reduce belowground competition for half of the seedlings. The forest is currently dominated by an angiosperm (Beilschmiedia tawa) that is more shade-tolerant than the co-occurring conifers Prumnopitys ferruginea and shade-intolerant Dacrydium cupressinum. Diameter and height growth rates of the fastest growing seedlings (top 25%) across all species were greater for seedlings with reduced belowground competition – increased light did not significantly alter growth rates. For these fast-growing seedlings the diameter growth rates of the coniferous P. ferruginea and D. cupressinum were superior to that of the angiosperm B. tawa. Of the fastest growing seedlings, height growth was also greatest for D. cupressinum across the gradient of light availability. This species was most responsive to light, shoot growth showing a positive interaction between increased light and trenching. Approximately 30% of its seedlings occurred at >10% full sun, and rates of both diameter and shoot growth were increased approximately threefold at the highest light levels, compared with the lowest (c. 2% full sun). Despite the angiosperm’s current dominance of the study forest, the superior performance of the fastest growing conifer seedlings, coupled with their longevity, suggests the conifer species will persist even under current conditions.

Magnetic resonance imaging surveillance following vestibular schwannoma resection

To describe the incidence, pattern, and course of postoperative enhancement within the operative bed using serial gadolinium-enhanced magnetic resonance imaging (MRI) following vestibular schwannoma (VS) resection and to identify clinical and radiologic variables associated with recurrence. Retrospective cohort study. All patients who underwent microsurgical resection of VS between January 2000 and January 2010 at a single tertiary referral center were reviewed. Postoperative enhancement patterns were characterized on serial MRI studies. Clinical follow-up and outcomes were recorded. During the last 10 years, 350 patients underwent microsurgical VS resection, and of these, 203 patients met study criteria (mean radiologic follow-up, 3.5 years). A total of 144 patients underwent gross total resection (GTR), 32 received near-total resection (NTR), and the remaining 27 underwent subtotal resection (STR); 98.5% of patients demonstrated enhancement within the operative bed following resection (58.5% linear, 41.5% nodular). Stable enhancement patterns were seen in 24.5% of patients, regression in 66.0%, and resolution in only 3.5% of patients on the most recent postoperative MRI. Twelve patients recurred a mean of 3.0 years following surgery. The average maximum linear diameter growth rate among recurrent tumors was 2.3 mm per year. Those receiving STR were more than nine times more likely to experience recurrence compared to those undergoing NTR or GTR (P < .001). Nodular enhancement on the initial postoperative MRI was associated with a 16-fold increased risk for future recurrence compared to those with linear patterns (P = .008). Among those with nodular enhancement on baseline postoperative MRI, a maximum linear diameter of ≥ 15 mm or volume of ≥ 0.4 cm(3) was associated with an approximate five-fold increased risk for future growth (P < .02). Persistent nonspecific radiologic enhancement within the postoperative field is common, making the diagnosis of tumor recurrence challenging. Factors including completeness of resection and baseline postoperative MRI findings provide valuable information regarding risk for recurrence, which may assist the clinician in determining an appropriate postoperative MRI surveillance schedule. Future studies using standardized terminology and consistent study metrics are needed to further refine surveillance recommendations.

Hydraulic conductivity traits predict growth rates and adult stature of 40 Asian tropical tree species better than wood density

Summary1. Stem xylem characteristics have a great impact on growth and adult stature of trees because of their role in mechanical support, long‐distance water transport and whole‐plant carbon allocation. Yet, despite the potential causal link between xylem traits and plant growth/adult stature, most studies have tried to link wood density, an indirect but easy to measure proxy for wood properties, to tree growth and size.2. To determine whether xylem traits outperform wood density as predictors of tree growth and stature, we evaluated the covariation among wood density, xylem anatomical traits, tree diameter growth rate and adult stature in 40 Asian tropical tree species through principal component analyses and through bivariate correlation, both across species and across phylogenetically independent contrasts.3. Vessel diameter exhibited a tight negative relationship with vessel frequency. Wood density showed a significant correlation with vessel diameter and density, but not with vessel fraction. Most correlations between functional traits indicate adaptive coordination, demonstrated by significant correlations between phylogenetically independent contrasts.4. Across species, diameter growth rate and adult stature were positively correlated with vessel lumen diameter and potential hydraulic conductivity, but not with wood density. Thus, our results suggest that xylem anatomical traits that are linked to hydraulic conductivity are better predictors of tree growth rate and adult stature than wood density.5. Synthesis. We found that xylem anatomical traits have a more significant influence on whole‐plant performance due to their direct association with stem hydraulic conductivity, whereas wood density is decoupled from hydraulic function due to complex variations in xylem components.