Canopy Projection Area Research Articles

Investigation of canopy interception characteristics in slope protection grasses: A laboratory experiment

Canopy interception significantly affects hydrological processes such as infiltration, runoff and evapotranspiration. Research on grass canopy interception remains limited, and the experimental methods employed differ substantially. To thoroughly investigate the canopy interception characteristics of grass and clarify the methodological differences, five commonly utilized slope protection grass species in temperate regions were cultivated in a laboratory setting, and their canopy interception characteristics were experimentally investigated using the water-balance method (WBM), the water-wiping method (WWM) and the water-immersion method (WIM), respectively. The results showed that the WBM is more accurate for measuring canopy interception in grass, whereas both the WWM and the WIM underestimate grass canopy interception capacity. The canopy interception capacity measured by the WBM was 1.61–2.09 times higher than that of the WWM and 1.93–3.47 times higher than that of the WIM. Grey correlation analysis of the eight evaluated factors indicated that leaf area is the most influential factor affecting canopy interception in grass, followed by rainfall amount, dry mass, rainfall intensity, canopy projection area, leaf contact angle, fresh weight, and average height. There is a negative power function relationship between the interception ratio and the rainfall amount. With increasing rainfall intensity, the canopy interception capacity initially increases and then decreases, peaking at rainfall intensities of 15 to 20 mm/h. Leaf contact angle is a key quantifiable parameter that explains the differences in canopy interception among different grass species, and the canopy interception per unit leaf area decreases as the leaf contact angle increases. This study demonstrates that the WBM provides the most accurate measurements of grass canopy interception compared to the WWM and WIM, and highlights the leaf contact angle as a key factor in explaining interspecies differences. These findings could enhance the understanding of grass canopy interception and guide the selection of experimental methods.

Allometric relationships between stem diameter, height and crown area of associated trees of cocoa agroforests of Ghana

Allometric models which are used to describe the structure of trees in agroforestry systems are usually extrapolated from models developed for trees in forest ecosystems. This makes quantitative assessment of the functions of shade trees in agroforestry systems challenging since increased availability of light and space in these systems may induce structural differences from those growing under forest conditions. We addressed this issue by providing species-specific allometric information on the structural characteristics of associated shade trees on cocoa agroforestry systems and assessed if allometries conformed to theoretical predictions. At the plot level, stand and soil characteristics affecting tree structural characteristics were assessed. The study was conducted in cocoa agroforestry systems at Suhum, Ghana. The height-diameter at breast height (H-DBH) allometry had the best fits (R2 = 53–89%), followed by the crown area (CA)-DBH allometry (R2 = 27–87%) and then the CA-H allometry (R2 = 22–73%). In general, the scaling exponents of the CA-DBH, H-CA and H-DBH allometries conformed to the metabolic scaling theory (MST). However, both the CA-DBH and H-DBH allometries diverged from the geometric similarity model. Though forest tree species had similar crown areas as fruit trees, they were slenderer than fruit trees. Tree slenderness coefficients were positively correlated with soil P, Ca, Cu and the ratios (Ca + Mg):K, (Ca + Mg):(K + Na) and Ca:Mg, but not C:N while DBH and H were correlated with soil P and C:N ratio. Our results show that critical soil nutrients and their ratios affects shade tree structural attributes (e.g. slenderness and CA), which possibly restrict variations in species-specific allometries to a narrow range on cocoa systems. Furthermore, shade tree species richness and density are better predictors of relative canopy projection area (a proxy for shade intensity) than tree species diversity. In conclusion, the results have implications for shade tree species selection, monitoring of woody biomass and maintenance of biodiversity.

Effect of gap size on the regeneration in Larix principis-rupprechtii plantation.

We conducted a survey on seedlings (height <1 m) and saplings (height ≥1 m, diameter at breast height <5 cm) in 20 gaps of Larix principis-rupprechtii plantations on Guandi Mountains, Shanxi to analyze regene-ration density, growth indicators, and spatial distribution of L. principis-rupprechtii seedlings and saplings under four gap sizes (<60 m2, 60-120 m2, 120-180 m2, and ≥180 m2). The results showed that growth indicators (ground diameter, height) of seedlings and saplings and regeneration density of seedlings were highest in small gaps (14-60 m2). The sapling regeneration density was highest in medium gaps (60-120 m2), and sapling density exceeded seedling density in each size category. L. principis-rupprechtii seedlings and saplings exhibited favorable regeneration in small and medium gaps, while large gaps (120-180 m2) and extra-large gaps (≥180 m2) were unfavorable for L. principis-rupprechtii regeneration. L. principis-rupprechtii seedlings and saplings were mainly distributed within the canopy projection area and along the edge of canopy gap area. Controlling gap size within the range of 14-120 m2 through artificial interventions, such as planting and thinning, could promote the regeneration of L. principis-rupprechtii.

Simulated annealing in feature selection approach for modeling aboveground carbon stock at the transition between Brazilian Savanna and Atlantic Forest biomes

Forest ecosystems are important in the carbon storage process. Thus, the objective was to investigate the effectiveness of the Simulated Annealing meta-heuristic analysis for selecting variables to maximize the accuracy of the aboveground carbon prediction at the tree level. We used data from uneven-aged forests located in the Rio Grande Basin - Minas Gerais, Brazil, where 227 trees had their carbon stock measured. The classic Spurr linear model, stepwise linear regression and pan-tropical coverage, Random Forest (RF), and the hybrid SARF method (Simulated Annealing and Random Forest) were used to estimate the carbon stock from the selection of variables for the different compartments of the tree (total, stem, branch, and leaf). The SARF consisted of the metaheuristic to select the variables to be used in the RF. These methods were evaluated by the root mean square error (RMSE), coefficient of determination (R²), and residual graph. As a result, the pan-tropical equation demonstrated superior performance than the Spurr model due to its greater homogeneity of residues. The stepwise technique reduced the number of variables and the error of the estimates, mainly for the validation set. SARF showed better adjustments than RF, as it reduced in on average 99.2% of the number of variables and 9% of the error of estimates considering all compartments. In general, variables such as volume, basic wood density, canopy projection area, diameter at 0%, diameter at breast height, height, and latitude contributed strongly to the carbon independent of the tree compartment. Among the methods, SARF is an alternative to the traditional method, as it can extract accurate information from a large data set.

Canopy interception and water harvesting function of shrubs in urban green spaces of semi-humid region and their influencing factors

In the semi-humid region, developing innovative water conservation urban green space design and facilitating urban greening projects from high water consumption to water conservation are hot topics in research and practice. Using the simulated rainfall method, we explored the water interception and collection functions and their influencing factors of six shrub species (Ligustrum ×vicaryi, Euonymus japonicas, Buxus sinica var. parvifolia, Photinia ×fraseri, Juniperus chinensis and Platycladus orientalis) in urban green space in the semi-humid region. The results showed that canopy interception and water harvesting were two stages in hydrological processes. The canopy interception of coniferous shrubs was high, while their stemflow was low. When the rainfall intensity increased, throughfall rates and stem-flow rates of all shrub species increased significantly, while the interception rate relatively decreased. The throughfall and stem-flow rates of broad-leaved shrubs were significantly higher than those of coniferous shrubs. The canopy interception was significantly lower in broad-leaved shrub species than in coniferous ones. At the center of canopy projection, the throughfall rate was the lowest. The leaf area index (LAI) and throughfall rate decreased gradually from the center of the canopy projection area. When the rainfall intensity was small, the throughfall rate at the center of canopy projection area was low, and thus the interception rate and the stem-flow rate were higher. When the rainfall intensity was more elevated, throughfall at the center of canopy projection area was large, and thus the interception rate and the stem-flow rate were low. With increasing rainfall intensity, the funnel-shaped water collection system tended to shrink due to the increases of throughfall rate at the edge of canopy. Rainfall intensity and LAI were the most critical factors affecting water harvesting function. Planting broad-leaved shrubs under the forest may be more effective in water harvesting than planting coniferous shrubs.

Effect of seventeen rootstocks on young ‘Valência’ sweet orange performance in western Santa Catarina, Brazil

Recommendations of rootstocks for ‘Valência’ sweet orange in southern Brazil have been partially based on empirical observations or information. Therefore, this study compared young ‘Valência’ trees budded on different rootstocks in western Santa Catarina, Brazil. Seventeen rootstocks were tested for growth (tree height and canopy projection area and volume) and fruit production (per tree, hectare, m² and m³ of canopy). The experiment comprised four replicates of three trees and was carried during six years under standard management, in a Cfa (humid subtropical) climate. In general, larger trees produced more fruit. However, ‘San Diego’ citrandarin, ‘Swingle’ citrumelo, ‘Cravo’ rangpur lime (among vigorous rootstocks), ‘Cravo’ x ‘Sunki’ EEI hybrid, ‘Fepagro C37 Dorneles’ citrange, ‘Rubidoux’ trifoliate orange (among medium vigorous rootstocks), ‘HFD25 EEI’ hybrid and ‘Flying Dragon’ trifoliate orange (among less vigorous rootstocks) stood out in cumulated production by area or volume of the canopy. ‘San Diego’ also stood out in production per tree. Cultivars ‘Cravo’ x ‘Sunki’ EEI, ‘San Diego’, and ‘HFD25 EEI’ should be further evaluated regarding disease susceptibility and fruit quality for possible release.

Spatial Modeling of Maximum Capacity Values of Irrecoverable Rainfall Retention by Forests in a Small Watershed

When performing hydrologic calculations, the actual amount of rain precipitation falling under the tree canopies of the taiga zone is one of the most important factors in forming and estimating rainfall runoff. This is due to the fact that only a portion of rainfall reaching the soil through the forest canopy takes part in forming river runoff. At present, there is no unanimity on methods of estimating rainfall retention by the canopies of different tree species in various natural geographical zones. The existing estimation methods rely on empirical observations of net and gross rainfall rather than on the results of physical modeling of moisture on leaf surfaces in droplet form. The disadvantages of the existing methods mean that it is not possible to make a spatial estimation of rainfall captured by canopies. The purpose of this study was to map the maximum rainfall interception capacity for a small forest watershed. The authors were able to solve the following problems: (1) In situ modeling of specific water retention in droplet form on leaf surfaces of tree species of the experimental watershed in the middle taiga subzone was carried out and the specific water retention per unit leaf area was determined. Such experiments have never been conducted previously. (2) Indirect methods of estimating the leaf surface area of tree plants depending on the amount of phytomass, age and height of tree stands were developed. (3) Mapping of tree stand characteristics (such as species composition, height, canopy cover) were performed, and together with the specific rainfall interception capacity, which was determined during experiments, provided the basis for a map of maximum rainfall retention capacity by canopies, i.e., a spatial image of irrecoverable rainfall losses was obtained. Rainfall is retained on a canopy in droplet form (droplet size varies from 10.6 to 18.6 mg). Specific water retention (mass per unit leaf surface area) is determined by the leaf (needle) roughness. The overall droplet retention on canopies is determined by leaf surface area and precipitation intensity. The maximum mass of the rainfall retained on the canopies of individual deciduous trees reaches 77 kg, (3.0–4.0 mm per canopy projection area) and that of coniferous trees ranges from 24.8 to 58.0 kg (1.9 to 5.9 mm). Understanding rainfall loss values in hydrology is of key importance in distributed models of rainfall flooding. Taking into account rainfall losses due to canopy interception makes it possible to reduce the margin of error in calculations of maximum rainfall flood loss from 126% to 25%.

Scaling Up Sap Flow Measurements from the Stem Scale to the Individual Scale for Multibranched Caragana Korshinskii on the Chinese Loess Plateau

The traditional heat balance method for measuring plant sap flow (SF) becomes troublesome and uneconomic for multibranched shrub species if all their stems are used for the measurement. The objectives of this study were to explore specific relationships between stem-scale SF and plant morphological traits and then to scale up SF measurements from the stem scale to the individual scale for Caragana korshinskii Kom., a dominant shrub species on the Chinese Loess Plateau. Sap flow was measured for twenty-one stems from three representative individuals from July to September 2018 during the rainy season. The results indicated that the stem-scale SF in C. korshinskii presented a positive linear correlation with the stem base diameter (SBD), stem length (SL), primary branch numbers in the stem (PBN), and estimated stem biomass (W). The SBD-based statistical models performed well in estimating the stem-scale SF, with an R2 value of 0.9726 and root mean squared error (RMSE) of 2.5389 g h−1. Over the canopy projection area, the individual-scale transpiration flows for the three selected C. korshinskii were 1.91, 1.10, and 1.59 mm·d−1. In addition, stem-scale SF was positively and linearly correlated with air temperature, photosynthetically active radiation, vapor pressure deficit, reference crop evapotranspiration, and variable transpiration. This study sheds light on morphological and meteorological influences on stem-scale SF and has made contributes to the accurate and rapid estimation of the plant sap flow from easily available morphological traits for multibranched shrub species in semiarid regions. Limitations, however, may exist for the established model when it is used to estimate SF of C. korshinskii during the water-limited dry season. Our study deserves further exploration of a more general model to have a better estimation of SF for C. korshinskii in both dry and rainy seasons.

Airborne LIDAR-Derived Aboveground Biomass Estimates Using a Hierarchical Bayesian Approach

Conventional ground survey data are very accurate, but expensive. Airborne lidar data can reduce the costs and effort required to conduct large-scale forest surveys. It is critical to improve biomass estimation and evaluate carbon stock when we use lidar data. Bayesian methods integrate prior information about unknown parameters, reduce the parameter estimation uncertainty, and improve model performance. This study focused on predicting the independent tree aboveground biomass (AGB) with a hierarchical Bayesian model using airborne LIDAR data and comparing the hierarchical Bayesian model with classical methods (nonlinear mixed effect model, NLME). Firstly, we chose the best diameter at breast height (DBH) model from several widely used models through a hierarchical Bayesian method. Secondly, we used the DBH predictions together with the tree height (LH) and canopy projection area (CPA) derived by airborne lidar as independent variables to develop the AGB model through a hierarchical Bayesian method with parameter priors from the NLME method. We then compared the hierarchical Bayesian method with the NLME method. The results showed that the two methods performed similarly when pooling the data, while for small sample sizes, the Bayesian method was much better than the classical method. The results of this study imply that the Bayesian method has the potential to improve the estimations of both DBH and AGB using LIDAR data, which reduces costs compared with conventional measurements.

Soil attributes in coal mining areas under recovery with bracatinga (Mimosa scabrella).

The coal reserves in the south of Brazil were intensely exploited at the time of great demand for such fuel. This resulted in changes in the environment, mainly in the chemical, physical and biological characteristics of the soil. Due to the potential to control erosive processes, increase soil quality and restore biological diversity, revegetation is a promising alternative to recover those impacted areas. In that respect, bracatinga is a pioneering tree species that easily grow in different environments and has being planted as vegetation cover in areas under recovery. Therefore, the objective of this work was to characterize the chemical features and to evaluate the soil microbiological attributes in areas degraded by coal mining and under recovery using bracatinga as cover plant. In the bracatinga canopy projection area, soil samples were collected in the environmental restoration areas that have been, at the time of collecting, under a regime of 2, 4, 6 and 12years of restoration. In addition an area with natural occurrence of bracatinga was used as control. Microbial biomass nitrogen, microbial biomass carbon and microbial biomass respiration increase in average 281, 230 and 157% respectively, when the 12-year-old areas were compared to the 2-year-old-areas. Likewise, a decrease in qCO2 in the order of 60% was observed for that same comparison. The 12-year-old areas reached the same values of qCO2 found in the reference area. The data suggest an improvement in the microbiological attributes of the soil with the increase in recovery time for the studied areas. SIGNIFICANCE AND IMPACT OF THE STUDY: In coal mining areas under recovery with typically acid soils, the use of the current recovery strategies (revegetation mainly) has been efficient to increase the quality of soils, especially in the environmental restoration areas. Soil microbiological attributes such as microbial biomass nitrogen, microbial biomass carbon, microbial basal respiration and metabolic quotient (qCO2 ) are dynamic and highly sensitive. These parameters have the potential to be adopted together with conventional attributes, such as floristic composition indices and species diversity indices, to evaluate the degree of any particular environmental recovery process being conducted at previously explored mining areas.

Stemflow-induced spatial heterogeneity of radiocesium concentrations and stocks in the soil of a broadleaved deciduous forest

The transport of radiocesium from the canopy and quantification of the spatial distribution of radiocesium in the soil of konara oak forests are important to better understand the variability of 137Cs stocks in the soil between proximal and distal stem areas as well as fine-scale variations around the tree trunk. Moreover, a better understanding of fine-scale spatial variabilities of 137Cs concentrations and stocks will provide insights for optimizing soil sampling strategies to provide a more robust estimation of contamination at the stand scale. This study aims to elucidate the transport of 137Cs by stemflow in a radioactively contaminated konara oak forest in Tsukuba, Japan by describing and quantifying the fine-scale spatial distribution of 137Cs in the soil and preferential flowpaths of stemflow on the tree stem by a dye tracing experiment. 137Cs concentrations and stocks were higher in the soils of the proximal stem area than distal stem area when they corresponded with the preferential flowpaths of stemflow. There was a significant relationship between canopy projection area of individual trees and average soil 137Cs concentrations and stocks, even though canopies of the trees overlapped. Our results demonstrate that the spatiality of 137Cs concentrations and stocks in the soil of the proximal stem area are governed (at least partially) by the preferential flowpaths of stemflow along the tree trunk. In addition, higher 137Cs concentrations and stocks in the near-trunk soils of trees with larger crown areas might be caused by an enhanced ability to capture dry deposition.

Modelling the relationship between canopy projection area and above-ground carbon stock of intermingled canopy trees using high-resolution satellite imagery

This study was aimed to establish regression models for the relationship of Canopy Projection Area (CPA) with carbon stock of intermingled canopy trees of dominant species for the prediction of above-ground carbon stock. Manual delineation of CPA of intermingled canopy trees of the dominant species was carried out using GeoEye Satellite Image. Diameter at breast height of trees were measured in 56 sample plots. The above-ground dry biomass of trees was calculated from the field measured DBHs using allometric equation while the above-ground carbon stock of the trees were obtained by multiplying their dry biomass with the factor 0.47. Individual basal area of intermingled canopy trees was calculated separately and was summed up (ΣBA) along with the summation of their carbon stock (Σcarbon). Correlation analysis was carried out to assess the linear relationship between CPA, DBH, BA, biomass, and carbon stock. Four types of functions, viz., simple linear, quadratic, logarithmic and power were used to fit the data using least square regression method. Shorea robusta, Schima wallichii and Terminalia alata were found dominant tree species in the study area. The relationship of CPA with ΣBA and Σcarbon of intermingled canopy trees of Shorea robusta was found to be linear with R2 of 0.29 and 0.25 respectively. Simple linear regression model resulted in the least error for the prediction of carbon stock of intermingled canopy trees. The identified simple linear regression models having the least error are not applicable for the prediction of above-ground tree carbon stock of broadleaf forest in hilly terrain.Banko Janakari, Vol. 23, No. 2

Integration of WorldView-2 and airborne LiDAR data for tree species level carbon stock mapping in Kayar Khola watershed, Nepal

Integration of WorldView-2 satellite image with small footprint airborne LiDAR data for estimation of tree carbon at species level has been investigated in tropical forests of Nepal. This research aims to quantify and map carbon stock for dominant tree species in Chitwan district of central Nepal. Object based image analysis and supervised nearest neighbor classification methods were deployed for tree canopy retrieval and species level classification respectively. Initially, six dominant tree species (Shorea robusta, Schima wallichii, Lagerstroemia parviflora, Terminalia tomentosa, Mallotus philippinensis and Semecarpus anacardium) were able to be identified and mapped through image classification. The result showed a 76% accuracy of segmentation and 1970.99 as best average separability. Tree canopy height model (CHM) was extracted based on LiDAR’s first and last return from an entire study area. On average, a significant correlation coefficient (r) between canopy projection area (CPA) and carbon; height and carbon; and CPA and height were obtained as 0.73, 0.76 and 0.63, respectively for correctly detected trees. Carbon stock model validation results showed regression models being able to explain up to 94%, 78%, 76%, 84% and 78% of variations in carbon estimation for the following tree species: S. robusta, L. parviflora, T. tomentosa, S. wallichii and others (combination of rest tree species).

Influence of shrub canopy morphology and rainfall characteristics on stemflow within a revegetated sand dune in the Tengger Desert, NW China

AbstractStemflow of xerophytic shrubs was monitored on event basis within a revegetated sand dune. Quantity of stemflow showed a clear species‐specific dependence in combination with the rainfall characteristics. Results obtained revealed that for ovate‐leaved C. korshinskii with an inverted cone‐shaped canopy and smooth bark, the quantity of stemflow in depth accounted for 7.2% of the individual gross rainfall, while it was 2.0% for needle‐leaved A. ordosica with a cone‐shaped canopy and coarse bark. There were significant positive linear relationships between stemflow and individual gross rainfall and rainfall intensity for the two shrubs. An individual gross rainfall of 1.4 and 1.8 mm was necessary for stemflow generation for C. korshinskii and A. ordosica, respectively. Multiple regression analysis showed that the abiotic and biotic variables including the individual gross rainfall, mean windspeed (WS), canopy height, branch length, and canopy volume have significant influence on stemflow for C. korshinskii, whereas for A. ordosica, the notable influencing variables were individual gross rainfall, stem diameter, and leaf area index. Generally, WS has less effect on stemflow than that of rainfall for A. ordosica. The correlation relationship between individual gross rainfall and funneling ratio showed that the funneling ratio attains its peak when the gross rainfall is 13 and 16 mm for C. korshinskii and A. ordosica, respectively, implying that the canopy morphology emerged as determining factors on funneling ratio decrease when the individual gross rainfall exceeds these values. In comparison, higher WS increased the funneling ratio remarkably for C. korshinskii than A. ordosica due partly to the greater branch length and canopy projection area in C. korshinskii. Funneling ratio can be used as an integrated variable for the effects of canopy morphology and rainfall characteristics on stemflow. The implication of stemflow on water balance and its contribution to sustain the shrubs and the revegetation efforts was discussed. Copyright © 2013 John Wiley &amp; Sons, Ltd.

CROWN DELINEATION INFLUENCE ON STANDING VOLUME CALCULATIONS IN PROTECTED AREA

Abstract. The aim of this study was to evaluate the automatically determined parameters of tree crowns, which are then used in two-phase inventory method of growing stock. Research was performed in forest stands of different age, located in the Stolowe Mountains National Park (south-western Poland) where the dominant species was Norway spruce (Picea abies L.). On the test area of approximately 500 hectares, 35 sample plots were measured. On LIDAR-based Crow Height Model (CHM), in the places corresponding to the position of 500 m2 circular ground samples, automatic segmentation was carried out. The extent of the crown was associated with the height of the tree. Two variants of the assigning separate crowns in the sample were used: (1) according to the centroid position, (2) according to the location of any fragment of the crown inside the sample plot boundary. In each of the variants five series of measurements with different relative height of the range 0.65–0.8 (with a gap of 0.05) were carried out. Relationship between the volume of living trees measured on the ground and LIDAR parameters (average height of trees and tree canopy projection area) automatically measured based on CHM was determined. Multiple correlation coefficient differed depending on the location to extract coverage crowns and ranged from 0.687 to 0.788. The variant of counting of all trees with crowns or pieces inside the sample appeared to perform better. The relationship between the above-indicated characteristics was stronger after elimination of dead trees (about 0.1 for each of cases). This means that for measurements of the growing stock in forests under protection, it is necessary to improve the process of automatic segmentation of the crown, by identification and elimination of dead trees – usually present at sample plot.

Canopy storage capacity of xerophytic shrubs in Northwestern China

► Canopy storage capacity of shrubs increased with increase of rainfall intensities. ► There were linearity correlations between storage and biometric characters. ► Needle-leaved species had higher water storage capacity than ovate-leaved species. ► Leaf area and dry biomass were better predictors for storage capacity estimation. The capacity of shrub canopy water storage is a key factor in controlling the rainfall interception. Thus, it affects a variety of hydrological processes in water-limited arid desert ecosystems. Vast areas of revegetated desert ecosystems in Northwestern China are occupied by shrub and dwarf shrub communities. Yet, data are still scarce regarding their rainwater storage capacity. In this study, simulated rainfall tests were conducted in controlled conditions for three dominant xerophytic shrub types in the arid Tengger Desert. Eight rainfall intensities varying from 1.15 to 11.53 mm h −1 were used to determine the canopy water storage capacity. The simulated rainfall intensities were selected according to the long-term rainfall records in the study area. The results indicate that canopy storage capacity (expressed in water storage per leaf area, canopy projection area, biomass, and volume of shrub respectively) increased exponentially with increase in rainfall intensity for the selected shrubs. Linear relationships were found between canopy storage capacity and leaf area (LA) or leaf area index (LAI), although there was a striking difference in correlation between storage capacity and LA or LAI of Artemisia ordosica compared to Caragana korshinskii and Hedysarum scoparium . This is a result of differences in biometric characteristics, especially canopy morphology between the shrub species. Pearson correlation coefficient indicated that LA and dry biomass are better predictors as compared to canopy projection area and volume of samples for precise estimation of canopy water storage capacity. In terms of unit leaf area, mean storage capacity was 0.39 mm (range of 0.24–0.53 mm), 0.43 mm (range of 0.28–0.60 mm), and 0.61 mm (range of 0.29–0.89 mm) for C. korshinskii , H. scoparium , and A. ordosica , respectively. Correspondingly, divided per unit dry biomass, mean storage capacity was 0.51 g g −1 (range of 0.30–0.70 g g −1 ), 0.41 g g −1 (range of 0.26–0.57 g g −1 ), and 0.73 g g −1 (range of 0.38–1.05 g g −1 ) for C. korshinskii , H. scoparium , and A. ordosica , respectively, when the rainfall intensities ranged from 1.15, 2.31, 3.46, 4.61, 6.92, 9.23 to 11.53 mm h −1 . The needle-leaved species A. ordosica had a higher canopy water storage capacity than the ovate-leaved species C. korshinskii and H. scoparium at the same magnitude of rainfall intensity, except for C. korshinskii when it was expressed in unit of canopy projection area. Consequently, A. ordosica will generate higher interception losses as compared to C. korshinskii and H. scoparium . This is especially the case as it often forms dense dwarf shrub communities despite its small size.

The variation of resource availability within canopy gaps and adjacent understories across elevational gradients of a Sri Lankan rainforest

Among factors that might help to explain coexistence of tree species is environmental heterogeneity created by physical and biological processes of the forest environment. The differences in resource availability across rainforest landscapes were investigated by measuring the abiotic resources of light, soil nutrients and soil water availability in relation to forest structure. This study was conducted in canopy gaps and adjacent understories across an elevational gradient from lowland mixed dipterocarp forest (100 m amsl) to submontane mixed dipterocarp forest (1200 m amsl) in southwest Sri Lanka. Middle elevation gap sites (300-700 m amsl) were sub divided into valley, midslope and ridge topographic positions. Eighteen canopy openings caused by tree falls were randomly selected across the elevation gradient. Plots were demarcated in gap centers and in adjacent understories and measurements were taken of forest structure (basal area, canopy height, tree canopy projection area), shade (light sensors- photosynthetic photon flux density or PPFD), and soil nutrients (pH, Al, K, N, P, Mg and Ca) across all sites. Surface soil moisture was measured at bi- weekly intervals for five years across the middle elevation site only. Stand basal area, mean canopy height, gap size and canopy area index (a surrogate for leaf area index) all declined with increase in elevation. As expected, understory PPFD decreased with increases in canopy height, basal area and canopy area index. The size of canopy opening decreased with increase in elevation. Valley sites had significantly greater levels of mean soil water contents compared to midslope and ridge sites. K and Ca in gap and adjacent forest understories increased with increase in elevation. pH increased and Al decreased with elevation but only for forest understory conditions. Results suggest strong differentiation in soil and light resources with elevation that appear to relate to size of disturbance, stature of the forest, and underlying geology and soil weathering environment. This implies that silvicultural practices need to develop and tailor techniques and treatments that can be applied to the forest that emulate and/or account for change in elevation and topographic position. Keywords: Dipterocarpus , gap dynamics, PPFD, Shorea , Sri Lanka. DOI: http://dx.doi.org/10.4038/jnsfsr.v39i4.3881 J.Natn.Sci.Foundation Sri Lanka 2011 39 (4):321-331

Solo, dimensão dos traqueídeos e densidade da madeira em Pinus caribaea var. hondurensis

The understanding of wood quality in relation to different forest sites is of fundamental relevance in current timber market. There are only few studies available concerning soil and wood quality of tropical pinots. So, the goal of this work was to characterize tracheid dimensions and wood density of Pinus caribaea var. hondurensis , correlating these variables with soil properties at different sites. Discs were taken at 1.3 m height and comprised two radial samples in each of the four dominant trees removed at four different sites. Measurements for wood density were made from the third to the eleventh year old rings, and the measurement of tracheid dimensions were made in the fourth, eighth and eleventh year sold rings. The soil, collected in the canopy projection area of each tree was analyzed chemically and physically in different layers. The tracheid dimensions and wood density showed stabilization between the eighth and the eleventh years old rings. Moreover, the tracheid dimensions varied between sites and did not present a pattern of variation in relation to soil properties at the different sites.

Predicting canopy and trunk cross-sectional area of silver linden ( Tilia tomentosa) in confined planting cutouts

Urbanized land is characterized by the dominance of paved surfaces. Increasing tree canopy in urbanized areas has been identified as an effective way to reduce stormwater runoff, sequester carbon, improve air and water quality, and otherwise mitigate the environmental impacts and increase the livability of cities. However, attaining sufficient tree canopy in urban areas remains an elusive goal. Site design characteristics such as cutout size may limit urban tree growth and complicate efforts to predict future canopy, especially in highly paved systems such as parking lots. We studied 25 silver lindens ( Tilia tomentosa Moench) grown for 14 years at one site, in pavement cutouts of various sizes. Regression analysis, even on these limited data, indicated a strong relationship between tree size and canopy projection area and unpaved soil surface area, but not soil depth. Cutout size explained 70% of the variability in tree canopy projection area and 77% of the variability in trunk cross-sectional area. The addition of other variables, such as soil bulk density, did not improve the model. Trees growing in parking lot cutouts <5.3 m 2 attained only limited size, regardless of the level of soil compaction. In larger cutouts, however, increases in soil bulk density from 1.1 to 1.5 Mg/m 3 were associated with a 70% reduction in trunk cross-sectional area. In order to create urban sites with a sustainable tree canopy, site design must provide large areas of uncompacted soil for trees and protect this soil from compaction during use. Urban tree growth models that incorporate cutout characteristics are needed to predict future canopy area with confidence.

Porta-enxertos para a tangerineira 'Michal' no Rio Grande do Sul

A tangerineira 'Michal' (Citrus clementina x C. tangerina) poderá ser uma boa alternativa ao Rio Grande do Sul como cultivar copa para produção de frutos em época precoce. No entanto, há falta de informações sobre seu comportamento em cultivo nas condições ambientais desse Estado. O objetivo deste trabalho foi avaliar o desenvolvimento das plantas, a produção e a qualidade dos frutos da tangerineira 'Michal' enxertada sobre cinco porta-enxertos: citrangeiro 'Troyer', citrumeleiro 'Swingle', limoeiro 'Cravo', tangerineira 'Sunki' e trifoliata 'Flying Dragon', na Depressão Central do Rio Grande do Sul. Foram avaliados os seguintes parâmetros: a altura das plantas, a circunferência do tronco, a área de projeção da copa (APC), o número e a massa (MF) de frutos produzidos, a relação MF/APC (IP), o teor de sólidos solúveis totais (SST), a acidez total titulável (ATT) e a relação SST/ATT do suco, além do tamanho dos frutos e do rendimento de suco. O citrumeleiro 'Swingle' promoveu bom vigor, boa produção, bom IP, bons níveis de SST e de ATT da 'Michal', enquanto o limoeiro 'Cravo' conferiu bom vigor, boa produção, bom IP e bom tamanho dos frutos, ambos podendo ser indicados como porta-enxertos em pomares de tangerineira 'Michal'.