Diameter At Breast Height Increment Research Articles

DEJETO DE SUÍNO MELHORA O DESEMPENHO PRODUTIVO DO EUCALIPTO E SUPERA A ADUBAÇÃO MINERAL

ABSTRACT The nutrients contained in the liquid pig slurry (PS) make this residue a potential organic fertilizer for the cultivation of tree species for the production of wood, which can promote the circular economy. This research aimed to evaluate soil chemical parameters, nutritional status, and development of hybrid eucalyptus clone urograndis from PS application for three consecutive years. The treatments evaluated were without fertilization (C); mineral fertilization (NPK) – 300 kg ha-1 year1 of the 02-30-10 formulation; fertigation with PS of 200 m3 ha-1 year1 (FPS200); and fertigation with PS of 400 m3 ha-1 year1 (FPS400). Macronutrients and micronutrients from leaves and soil were evaluated. Tree development was analyzed using stem diameter at breast height (DBH) and total height (Ht). PS treatments resulted in leaves with higher accumulation of K and P and lower accumulation of N, Ca, M, S, Cu, and Fe. The treatments FPS200 and FPS400 presented DBH and Ht equal or superior to the mineral fertilization. Fertilizations with NPK, FPS200, and FPS400 resulted, respectively, in DBH increments 16, 27, and 30% higher than the control. Regarding the chemical attributes of the soil, the use of PS reduced the pH of the soil and increased the levels of P in comparison with the other treatments. The micronutrient values were adequate for fertility and no accumulation of potentially toxic elements at a level considered harmful was observed. The application of PS in eucalyptus hybrid urograndis proved to be an attractive alternative to increase wood production.

The C:N:P Stoichiometry of Planted and Natural Larix principis-rupprechtii Stands along Altitudinal Gradients on the Loess Plateau, China

Carbon:nitrogen:phosphorus (C:N:P) stoichiometry plays a critical role in nutrient cycling, biodiversity, and ecosystem functionality. However, our understanding of the responses of C:N:P stoichiometry to elevation and forest management remains elusive. Here we sampled 18 Larix principis-rupprechtii sites along altitudinal gradients (1700-2300 m) on Guandishan Mountain in the Loess Plateau, China. We determined the leaf, litter, and soil C N P contents and C:N:P stoichiometric ratios, as well as nutrient resorption efficiency (NuRE), and diameter at breast height (DBH) increments in both planted and natural stands, and then tested the impacts of elevation and stand origin on these parameters’ management. We found different C:N:P stoichiometry between natural and planted forests. The results revealed that: soil C, N, and N:P ratios, litter C:P and N:P ratios, leaf C:N and N:P ratios increased significantly; however, soil C:N ratios, litter P, leaf N and P, nitrogen resorption efficiency (NRE), and DBH increments decreased significantly with elevation in the planted forests. Soil C,N and N:P ratios, litter C, as well as C:N and C:P ratios increased significantly with elevation in natural forests. The soil N, P and N:P ratios, litter C:P and N:P ratios, leaf C, C:P and N:P ratios, nitrogen resorption efficiency (NRE), phosphorus resorption efficiency (PRE), and DBH increments were, on average, higher in the planted, rather than natural forests. Our results indicated that there was an enhancing P-limitation in both the planted and natural forests, and the plantations were more restricted by P. Moreover, compared to natural forests, plantations converged toward a higher conservative N- and P-use strategy by enhancing resorption efficiencies of internal nutrient cycling and a higher annual growth rate.

Productivity, Growth Patterns, and Cellulosic Pulp Properties of Hybrid Aspen Clones

Research Highlights: This research provides a firm basis for understanding the improved aspen hybrid performance that aims at facilitating optimal clone selection for industrial application. Background and Objectives: Rapid growth and wood properties make aspen (Populus tremula L.) suitable for the production of pulp and paper. We assessed the potential of tree improvement through hybridization to enhance aspen productivity in northern Poland, and investigated the effects of Populus tremula hybridization with Populus tremuloides Michaux and Populus alba L. on the growth and cellulosic pulp properties for papermaking purposes. Materials and Methods: A common garden trial was utilized that included 15 hybrid aspen clones of P. tremula × P. tremuloides, four of P. tremula × P. alba, and one, previously tested P. tremula clone. Clones of P. tremula, plus trees from wild populations, were used as a reference. Tree height and diameter at breast height (DBH) were measured after growing seasons four through seven. At seven years of age, the three clones representing all species combinations were harvested, and their cellulosic pulp properties and paper sheet characteristics were assessed. Results: The clones from wild populations exhibited the poorest growth. In contrast, the clone ‘Wä 13′ (P. tremula × P. tremuloides) demonstrated the highest DBH, height, volume production, and mean annual increment (MAI) (25.4 m3 ha−1 year−1). The MAI ratio calculated for interspecific crosses ranged from 1.35- to 1.42-fold, higher than that for the P. tremula. Chemical properties of pulp, fiber morphology, and the physical properties of paper sheets were more desirable for interspecific hybrid clones than those for the pure P. tremula clone. Conclusions: The results indicated that plantations of hybrid aspen may constitute an important additional source of wood for pulp and paper products in Poland. Our findings further suggested that the standard rotation of these trees may be reduced from 40 to 20 years, increasing overall biomass yield and enhancing atmospheric carbon sequestration.

Modelling the probability of microhabitat formation on trees using cross‐sectional data

Summary Context: Tree‐related microhabitats (TreMs), such as trunk cavities, peeled bark, cracks or sporophores of lignicolous fungi, are essential to support forest biodiversity because they are used as substrate, foraging, roosting or breeding places by bryophytes, fungi, invertebrates and vertebrates. Biodiversity conservation requires the continuous presence of TreMs in a forest. However, little is known about their dynamics. Moreover, we usually have only cross‐sectional TreM data (observations of many trees at a single time), making it difficult to estimate TreM formation rates. Method: This study adapted the methods of survival and reliability analysis to model the rate of TreM formation per unit of diameter increment as a function of tree diameter at breast height (DBH). We tested three variants of this model: the TreM formation rate independent of, proportional to or increasing nonlinearly with DBH. We calculated the likelihood of the models, considering cross‐sectional observations either of TreM presence/absence or TreM number on trees of different sizes. We calibrated the models in six subnatural montane forests dominated by European beech (Fagus sylvatica) and silver fir (Abies alba) – in the French Pyrenees. Assuming an annual DBH increment value, the annual formation rate of TreMs was predicted both at the level of the tree and at the level of the forest stand. Results: This method provides a coherent framework to model the probability that a TreM forms on a tree during a unit growth step and produces realistic predictions of TreM accumulation on trees. TreM formation accelerated as trees grew for A. alba but not for F. sylvatica. The TreM formation rate was twice as fast on F. sylvatica as on A. alba. We estimated a formation of 0·82–1·28 TreMs/ha per year and 0·5–0·9 TreM‐bearing trees/ha per year in the subnatural forests studied. Synthesis and applications: This method makes rigorous modelling of the formation of TreMs possible during the growth of trees and forest stands. The quantitative evaluation of TreM fluxes will help to design forest biodiversity conservation strategies favouring the development and temporal continuity of TreMs.

The diameter increment of selected tree species in a secondary tropical forest in Sarawak, Malaysia

Abstract. Karyati, Ipor IB, Jusoh I, Wasli ME. 2017. The diameter increment of selected tree species in a secondary tropical forest in Sarawak, Malaysia. Biodiversitas 18: 304-311. The diameter at breast height (DBH) increments of dominant tree species in a secondary forest can determine forest growth in the area. This study was conducted to investigate the DBH increments of the nine dominant tree species in a secondary tropical forest. A total number of 180 trees representing nine species, seven genera, and six families were selected for the assessment of DBH increments during two years of study. Those nine species, namely: Acacia mangium Willd. (2.33 cm year-1), Endospermum diadenum (Miq.) Airy Shaw (1.05 cm year-1), Cratoxylum arborescens Blume. (0.96 cm year-1), Vernonia arborea Buch. Ham. (0.96 cm year-1), and Cratoxylum glaucum Korth. (0.80 cm year-1) had shown a high growth rate during the assessment, while the other four species such as Macaranga gigantea Mull. Arg., Macaranga triloba Mull. Arg., Euodia glabra (Bl.) Bl., and Vitex pubescens Vahl. had 0.53, 0.48, 0.37, and 0.30 cm year-1 in DBH increments, respectively. The average DBH increments for the entire selected species was 0.86 cm year-1 for periodic measurement and 0.75 cm year-1 for monthly measurement. This information is needed in order to understand the succession process in the secondary forests. It is important for the selection of the suitable species in a reforestation and a rehabilitation projects.
 Keywords: Diameter increment, fast growing species, secondary forest, selected speciesÂ

Development of stem cracks in young hybrid aspen plantations

Abstract Cracks expose wood to fungal infections that significantly affects wood quality, while rapid wound occlusion decreases probability of infections. Assessment of scars was done at four grade scale in three adjacent hybrid aspen trials at the age of 8-10 years in central part of Latvia three years after bark crack occurrence. Occluded wounds were found for 95% of damaged trees, regardless of tree age. Among trees that had cracks wider than 1 cm, 42% had uniformly healed bark, but 7% still had open wounds. Wound development was significantly affected by crack width and length (both p < 0.001), but had no clear relation with tree DBH (diameter at breast height) and relative DBH increment (both p > 0.05). At clonal mean level, scar grade was significantly affected by grade of crack three years earlier and clone (both p < 0.001), but mean DBH of clone had no relation (p > 0.05) to proportion of trees evaluated by any of the scar grades. The results suggest that three years after the bark crack formation most of them had successfully occluded and selection of clones with better diameter growth has no influence on development of cracks.

Effects of size, neighbors, and site condition on tree growth in a subtropical evergreen and deciduous broad-leaved mixed forest, China.

Successful growth of a tree is the result of combined effects of biotic and abiotic factors. It is important to understand how biotic and abiotic factors affect changes in forest structure and dynamics under environmental fluctuations. In this study, we explored the effects of initial size [diameter at breast height (DBH)], neighborhood competition, and site condition on tree growth, based on a 3‐year monitoring of tree growth rate in a permanent plot (120 × 80 m) of montane Fagus engleriana–Cyclobalanopsis multiervis mixed forest on Mt. Shennongjia, China. We measured DBH increments every 6 months from October 2011 to October 2014 by field‐made dendrometers and calculated the mean annual growth rate over the 3 years for each individual tree. We also measured and calculated twelve soil properties and five topographic variables for 384 grids of 5 × 5 m. We defined two distance‐dependent neighborhood competition indices with and without considerations of phylogenetic relatedness between trees and tested for significant differences in growth rates among functional groups. On average, trees in this mixed montane forest grew 0.07 cm year−1 in DBH. Deciduous, canopy, and early‐successional species grew faster than evergreen, small‐statured, and late‐successional species, respectively. Growth rates increased with initial DBH, but were not significantly related to neighborhood competition and site condition for overall trees. Phylogenetic relatedness between trees did not influence the neighborhood competition. Different factors were found to influence tree growth rates of different functional groups: Initial DBH was the dominant factor for all tree groups; neighborhood competition within 5 m radius decreased growth rates of evergreen trees; and site condition tended to be more related to growth rates of fast‐growing trees (deciduous, canopy, pioneer, and early‐successional species) than the slow‐growing trees (evergreen, understory, and late‐successional species).

Growth rates of Eucalyptus and other Australian native tree species derived from seven decades of growth monitoring

There is widespread interest in estimating and forecasting individual tree and forest growth rates for restoration and carbon sequestration objectives. Outside intensively managed forests, past attempts have been limited by the lack of accurate long-term monitoring in multi-age mixed native forests to provide estimates of both expected mean diameter increments and the statistical variation in those estimates. A dataset from Eucalyptus-dominated native forests in subtropical Queensland, Australia offers an opportunity to provide accurate estimates of tree and forest growth rates. Over 86,400 trees from 155 native species were identified and remeasured between 1936 and 2011 in 641 permanent sample plots across a 500–2000 mm mean annual rainfall gradient. Individual tree diameter at breast height (DBH) increments observed for all species ranged mainly from 0.01 to 0.5 cm yr−1 (94 % of values), with consistent differences between rainfall zones (mean of 500–2000 mm yr−1), and varying differences between species (155) and stem diameter class (10–100 cm). For some species, diameter increment increased progressively with rainfall (e.g. Eucalyptus siderophloia, Eucalyptus propinqua, and Lophostemon confertus), but in others (e.g. Corymbia citriodora subsp. variegata, Corymbia intermedia, and Eucalyptus biturbinata) the greatest diameter increments were recorded between 1200 and 1600 mm yr−1. Where there were sufficient data, most species exhibited a quadratic relationship between DBH increment and DBH class, but two species (Callitris glaucophylla and Eucalyptus crebra) native to the 500–800 mm annual rainfall zone showed linear increases in DBH increment with increasing DBH. Continued monitoring of these plots would add to their already great value.

木兰围场典型落叶松-杨桦混交林生物量及固碳能力研究

A mixed Dahurian larch and polar birch forest,artificial Larix principis-rupprechtii forest,natural Betula platyphylla secondary forest,and natural Populus davidiana secondary forest,which are all part of the Bei-gou Forest Farm in Mulan Forestry Bureau were studied here. The layered cut method was used to measure aboveground biomass in all four forests. The layered mining method was used to measure underground biomass. The trunks were divided into segments 0. 5m in diameter and 5 cm thick. The north-south diameter of each disk was recorded. Tree roots were divided into 0. 5 cm layers,and the crown projection area was dug up. Fresh weights of the trunks( with bark),branches,leaves,and roots of model trees were recorded in the open air. Samples of each organ were dried to( 105℃) constant weight and weighed. To determine biomass,leaf and branch samples were collected from different parts of the crown cover. They were weighed and dried,and their moisture content was calculated. For trunks,disk sections were obtained and weighed before and after drying. Moisture content was calculated. The leaf,branch,and root biomass of each model tree was calculated. Incrementswere measured in analytic trees. Then models of biomass and increments were established. Carbon reserve and carbon sequestration were estimated. Significant power functions and logistic equations were chosen as biomass prediction models.DBH( diameter at breast height) served as an independent variable and the napierian logarithm of biomass and total biomass of organs as the dependent variable. Optimization was performed according to regression curve and residual sum of squares( SSE),discriminant coefficient( R2),total relative error( RS),average relative error( E1),absolute value of average relative error( E2),AIC( Akaike Information Criterion),and BIC( Bayesian Information Criterion). DBH increments were measured with analytic trees,wooden cores,and DBH increments of the past five years as a baseline. A power function regression model was established. Then the DBH increments of trees over the past five years were estimated.Then the fixed carbon content of each forest was calculated for that period using the carbon content of different tree species and organs. Results showed the Dahurian larch and polar birch mixed forest stored more carbon than other forests. The Dahurian larch,Betula platyphylla,and Populus davidiana in the mixed forest were all superior to their respective artificial and natural forests. The mean DBH( diameter at breast height) was higher by about 6. 7%,12. 8%,and 4. 1%. The mean was higher by about 12. 1%,1. 4%,and 11. 1%. The fixed carbon content growth rates of Dahurian larch,Betula platyphylla,and Populus davidiana in the mixed forest were 29. 74%,28. 36%,and 34. 52%,respectively. The rate of carbon fixation was 27. 09% in the artificial Larix principis-rupprechtii forest; 26. 34% in the natural Betula platyphylla secondary forest; and 26. 24% in the natural Populus davidiana secondary forest. The rates of carbon fixation of Dahurian larch,Betula platyphylla,and Populus davidiana in the Dahurian larch and polar-birch mixed forest were 2. 65%,2.02%,and 8. 28% higher,respectively,than in the corresponding monoculture forests.

Identifying the biological effects of pre-commercial thinning on diameter growth in young Scots pine stands

Data from seven Scots pine (Pinus sylvestris L.) stands in central Sweden that had undergone pre-commercial thinning (PCT) were used to investigate the biological effect of PCT on the diameter at breast height (DBH) growth of the remaining trees. Two treatments were considered: a PCT treatment and a control (C) with no PCT. The DBH of the trees in each stand was measured on up to four occasions over 15 years. We examined mean DBH and DBH growth of the largest 300, 600, 900 and 1200 trees ha−1. Two methods of selecting the trees used to calculate the mean DBH values for each measurement occasion were considered: the actual mean DBH (Dma), which is based on the DBH distribution of the trees on the measurement occasion in question, and the genuine mean DBH (Dmg), which is based on the DBH distribution of the trees on the final measurement occasion of the study and therefore focuses on the same set of trees for all measurement occasions. There was no clear difference between the Dma- and Dmg-based DBH increments, but the Dmg values tended to be somewhat larger both for the C and PCT treatments. Over a 15-year period, the relative mean yearly increments (Dma/Dmg) for different tree size classes ranged from 0.91 to 0.98, with lower values for the C treatment and larger DBH size classes. We found that PCT promotes DBH growth: over a 15-year period, the increased growth amounted to about 2.0 mm year−1 compared to the trees in unthinned plots.

Long-term effects of liming on health and growth of a Masson pine stand damaged by soil acidification in Chongqing, China.

In the last decades, the Masson pine (Pinus massoniana) forests in Chongqing, southwest China, have increasingly declined. Soil acidification was believed to be an important cause. Liming is widely used as a measure to alleviate soil acidification and its damage to trees, but little is known about long-term effects of liming on the health and growth of declining Masson pine forests. Soil chemical properties, health condition (defoliation and discoloration), and growth were evaluated following application of limestone powder (0 (unlimed control), 1, 2, 3, and 4 t ha−1) in an acidified and declining Masson pine stand at Tieshanping (TSP) of Chongqing. Eight years after liming, in the 0–20 cm and 20–40 cm mineral soil layers, soil pH values, exchangeable calcium (Ca) contents, and Ca/Al molar ratios increased, but exchangeable aluminum (Al) levels decreased, and as a result, length densities of living fine roots of Masson pine increased, with increasing dose. Mean crown defoliation of Masson pines (dominant, codominant and subdominant pines, according to Kraft classes 1–3) decreased with increasing dose, and it linearly decreased with length densities of living fine roots. However, Masson pines (Kraft classes 1–3) in all treatments showed no symptoms of discoloration. Mean current-year twig length, twig dry weight, needle number per twig, needle length per twig, and needle dry weight per twig increased with increasing dose. Over 8 years, mean height increment of Masson pines (Kraft classes 1–3) increased from 5.5 m in the control to 5.8, 6.9, 8.3, and 9.5 m in the 1, 2, 3, and 4 t ha−1 lime treatments, and their mean DBH (diameter at breast height) increment increased from 3.1 to 3.2, 3.8, 4.9, and 6.2 cm, respectively. The values of all aboveground growth parameters linearly increased with length densities of living fine roots. Our results show that liming improved tree health and growth, and these effects increased with increasing dose.

Effects of fertilization on the relations of diameter at breast height between different-aged ramets of Phyllostachys edulis population

Aims Clonal plants are physiologically integrated, allowing translocation of photosynthates, water, nutrients and other substances between connected ramets within a clone. This suggests that the sizes of ramets of different ages may be correlated. So far, however, little is known about the effects of fertilization on the size relationships between ramets of different ages. In this study, we aim to examine how fertilization affects the relations of diameter at breast height(DBH) between ramets of different ages in the giant clonal bamboo Phyllostachys edulis. Methods We established 112 20 m × 30 m plots of P. edulis in Longquan City, Zhejiang Province, China. Among them, 46 plots were fertilized only in 2008, 49 fertilized in five consecutive years from 2004 to 2008, and 17 unfertilized(the control). We measured DBH of ramets of one, three and five years old in each plot in 2009. The relations of DBH between ramets of different ages in different fertilization treatments were examined using allometric scaling by the standardized major axis(SMA) analysis, and that were also analyzed by multiple linear regression. Important findings The DBH of the 1-year-old ramets was significantly greater than that of the 5-year-old ones in the 5-year fertilization plots, while no significant difference was found in the 1-year fertilization plots. Under different fertilization treatments, the slopes of SMA(0.88–1.10) for the relations of DBH between ramets of one, three and five years old were not significantly different from 1.00(p 0.05), suggesting isomeric growth relationships. Compared to the control(unfertilization), fertilization in one or five years did not change the slope of SMA. However, fertilization in five years increased the intercept of SMA, indicating that continuous fertilization could result in greater DBH increment in the 1-year-old ramets. The multiple linear stepwise regression analysis indicated that 3-year-old ramets could greatly influence DBH of the newly produced ramets, and that the effect of DBH of the 5-year-old ramets on that of the 1-year-old ramets increased after five years of continuous fertilization.

Long-Term Trends in Tree-Ring Width and Isotope Signatures (δ13C, δ15N) of Fagus sylvatica L. on Soils with Contrasting Water Supply

We investigated long-term responses (since 1850) of Fagus sylvatica (Luxembourg; central Europe) to shifts in temperature, precipitation, and nitrogen deposition by analyzing diameter at breast height (DBH) increment, basal area increment (BAI), and tree-ring stable isotopes (δ13C, δ15N). We compared stands on soils with contrasting water supply (Regosols and Cambisols with an available water capacity of ca. 40 and 170 mm, respectively) and of two different age classes (ca. 60 vs. 200 years). All stands showed a peak in DBH increment in the decade 1978–1987, but a decline in increment growth in subsequent decades. In addition, BAI declined in mature stands in the last two decades. Decreasing increment rates were attributable to an increasing drought limitation of stands, mainly induced by increasing temperatures in the last two decades. Contrary to our expectations, stands on Cambisols showed a similar susceptibility to shifts in temperature and precipitation as stands on Regosols, suggesting a strong adaptation of the respective ecotypes grown at dryer sites. This result was in line with long-term trends for tree-ring δ13C signatures, which did not differ significantly between stands on Cambisols and Regosols. Climate impacts on tree-ring δ15N signatures were low. High spring precipitation and temperatures caused increasing and decreasing δ15N values, respectively, but only in mature stands on Cambisols. Stands on Regosols tended to have lower δ15N values than stands on Cambisols. Decreasing δ15N values in recent decades suggest an increasing impact of allochthonous N loads with isotopically lighter N.

Long-term black spruce plantation growth and structure after release and juvenile cleaning: A 24-year study

Vegetation management is crucial to meet growth and yield objectives in conifer plantations. But, the combined and longterm effects of mechanical release and juvenile cleaning on growth and stand structure have yet to be documented in black spruce plantations. A long-term study was carried out in Quebec (Canada) to evaluate the interactions between initial mechanical release at age 2 years and juvenile cleaning at age 14 years (i.e., a second release treatment) on planted black spruce survival and dimensions at age 24 years. Population structure and stand species composition were also assessed. Results showed that release and juvenile cleaning had an additive, positive effect on survival, diameter at breast height (DBH), height, crown width, crown length, and the last 5-year DBH and height increments. Juvenile cleaning effects were of higher magnitude than release effects, especially on 5-year DBH increment. Combination of both treatments reduced DBH and height variability of saplings, whereas juvenile cleaning alone resulted in a higher proportion of saplings occupying higher height classes. Total merchantable basal area was constant among treatments. But, without juvenile cleaning, hardwoods occupied a higher proportion of the basal area and were taller than spruces. In a context of sustainable forest management, in which conifer plantations are expected to offer high wood yield, our results demonstrate the importance of juvenile cleaning following initial mechanical release to promote crop tree growth and yield. Key words: plantation, vegetation management, black spruce, growth, stand development

Prediction of street tree morphological parameters using artificial neural networks

Street trees positively affect the everyday life of city inhabitants and therefore successful management of this resource is important. A tree inventory is an essential first step towards this end, but this activity can be complex, costly and must be optimized. In order to reduce time and effort required for data acquisition either when using traditional field work or airborne laser systems, a method is proposed to predict the value of essential tree morphological parameters with surrogate variables and artificial intelligence multilayer perceptron networks (MLPs). To evaluate MLPs, seven different models were tested on Acer platanoides L., Acer saccharinum L., Celtis occidentalis L., Fraxinus pennsylvanica Marsh., Gleditsia triacanthos L., Tilia cordata Mill., and Ulmus pumila L. data sets. Three models were intended to predict diameter at breast height (DBH), annual DBH increment and crown volume with a minimal number of input measurements to be extracted from aerial LIDAR (Light Detection and Ranging) data. The last four were associated with traditional ground inventory methods and aimed to predict height, crown volume and their respective annual increments using less labour-intensive variables. The prediction performance was assessed with the Pearson r correlation coefficient, computed between the measured and estimated output values for each of the cross-validation test files per tree species and model. By using carefully selected biotic and abiotic input parameters, the prediction performance of multilayer perceptron showed robustness and precision despite different age–class distribution per species, dissimilar species morphological characteristics, uneven distribution of species within defined urban ecological zones, and varied abiotic growth conditions. More precisely, prediction coefficients were greater than 70% for all models with very small probability levels except for two predictions were input data exhibited strongly non-Gaussian distributions. Overall, the average prediction for all scenarios was 91%. Considering these results, it was found that prediction of DBH, annual DBH increment and crown volume is possible with limited aerial LIDAR laser information. Moreover, it was established that traditional field work effort can be further reduced by predicting the value of unmeasured morphological parameters within acceptable levels of precision. These findings can have an impact on future urban tree inventories. Depending on the number of trees to be measured, municipal administrations have the choice to use either airborne or traditional data acquisition methods. In both cases, this research proposes optimized procedures that may reduce the overall inventory costs.

Soil nutrient availability, poplar growth and biomass production on degraded agricultural soil under fresh grass mulch

Poplar plantations have been recently established in southwestern upland areas of China as a source of future timber and to restore degraded lands. However, poor site conditions limit the growth and ecological function of poplar plantations. Soil resource availability is hypothesized to have a significant effect on growth performance of poplars when planted in the degraded upland areas. This study whether the application of fresh grass mulch improved the performance of poplar growth on degraded agricultural soils. Poplar plantations were established in 2004 by planting dormant, unrooted 1-year-old stem cuttings of the clone ‘Zhonglinmeihe’, a hybrid of Populus deltoides × P. nigra. Circular areas were mulched around each tree at four rates: 0.0 kg/m 2, 2.5 kg/m 2, 5.0 kg/m 2 and 7.5 kg/m 2 fresh grass ( Imperata cylindrical var. major). These equated to about 0 (M0, bare soil), 10,000 (M1), 20,000 (M2) and 30,000 (M3) kg/ha since only about 40% of the total plot area was mulched. The effect of grass mulch on soil nutrient availability, poplar growth and biomass production were monitored over 3 years. Application of fresh grass mulch markedly affected soil nutrient contents. As expected, both in the growing and non-growing seasons, plots with mulch had higher total N, available N, available P and available K concentrations than control plots, and the nutrient concentrations increased with mulching quantity. Grass mulch significantly affected tree height and diameter at breast height (DBH) growth of poplar plantations. At the end of third growing season, total tree height increment in M1, M2 and M3 treatments was 22.2%, 93.8% and 95.1% higher than that in M0 plots, whereas DBH increment in mulched plots was 24.3%, 91.0% and 102.7% greater than in bare soil plots, respectively. Productivity was enhanced by the addition of fresh grass mulch. Overall, the benefit of mulch on productivity was enhanced with greater fresh grass mulch. Compared to M0, the productivity in M1, M2 and M3 treatments was increased by 19.0%, 107.9% and 178.1% at the end of third growing season, respectively. The results of this experiment emphasized that mulching may therefore be an important technique for establishment and management of poplar plantation on degraded agricultural soils in the region. Annual application of 20,000 kg/ha fresh grass for soil improvement in young poplar plantations can be recommended from this study.

Growth response and sapwood hydraulic properties of young lodgepole pine following repeated fertilization.

We examined how tree growth and hydraulic properties of branches and boles are influenced by periodic (about 6 years) and annual fertilization in two juvenile lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) stands in the interior of British Columbia, Canada. Mean basal area (BA), diameter at breast height (DBH) and height increments and percent earlywood and sapwood hydraulic parameters of branches and boles were measured 7 or 8 years after the initial treatments at Sheridan Creek and Kenneth Creek. At Sheridan Creek, fertilization significantly increased BA and DBH increments, but had no effect on height increment. At Kenneth Creek, fertilization increased BA, but fertilized trees had significantly lower height increments than control trees. Sapwood permeability was greater in lower branches of repeatedly fertilized trees than in those of control trees. Sapwood permeabilities of the lower branches of trees in the control, periodic and annual treatments were 0.24 x 10(-12), 0.35 x 10(-12) and 0.45 x 10(-12) m2 at Kenneth Creek; and 0.41 x 10(-12), 0.54 x 10(-12) and 0.65 x 10(-12) m2 at Sheridan Creek, respectively. Annual fertilization tended to increase leaf specific conductivities and Huber values of the lower branches of trees at both study sites. We conclude that, in trees fertilized annually, the higher flow capacity of lower branches may reduce the availability of water to support annual growth of the leader and upper branches.