Average Tree Diameter Research Articles

Verification of a Forest Rating System to Predict Fisher, <em>Martes pennanti</em>, Winter Distribution in Sub-boreal Forests of British Columbia, Canada

This study verified the ability of a forest rating system to predict the winter distribution of Fisher (Martes pennanti) in the Sub-boreal Spruce Biogeoclimatic Zone of central interior British Columbia. Forest polygons (i.e., homogenous areas with similar forest stand characteristics) were classified according to their age and structural development, canopy closure, basal area in mature trees, average tree diameter at breast height, and percentage of shrub cover. Approximately 170 km of transects randomly distributed across polygons were inventoried (snowshoed) from December to February 2005-2008. A total of 278 Fisher tracks were recorded. The observed frequency of Fisher tracks per polygon type was significantly (P < 0.05) different from expected. The majority (245 or 88.1%) of tracks were recorded in excellent- and high-quality polygons corresponding mostly to mixed coniferous stands. On average, these stands were 138.2 years old, and had 54.4% canopy closure, 38.1 m2/ha basal area, 27.8 cm dbh, and 11.4% shrub cover. This study showed that the forest rating system was adequate to predict Fisher winter distribution, and could be used to develop forest management plans that are compatible with the species habitat requirements.

Microbats in a ‘leafy’ urban landscape: are they persisting, and what factors influence their presence?

AbstractUrbanization is an extreme form of habitat modification, but retention of native vegetation in bushland reserves may improve the ecological sustainability of cities. We focused on bats (Microchiroptera) and investigated the use of the urban matrix and surrounding bushland in a region of Sydney, Australia, where remnant bushland persists and gardens often support large trees. Ultrasonic surveys were conducted at 40 sites over one summer season in the backyard matrix, bushland remnants and surrounding National Parks to determine which species were present, and the influence of landscape elements and habitat characteristics on activity, species richness and presence of individual species. In total, 15 of the 17 microbat species known from the Sydney region were recorded in the study area. Yet only three of these species, Chalinolobus gouldii, Mormopterus species 2 and Miniopterus schreibersii were present in more than 40% of sites. Bat activity was significantly higher in remnant bushland on shale soils and in backyards, compared with sandstone gully and ridge remnants, or reference sites in nearby National Parks. Furthermore, species assemblages in urban areas were different from assemblages in reference sites. Of all the habitat characteristics examined, the amount of bushland within 0.5–3 km surrounding a site and tree density were the most common predictors of individual species presence, particularly rare species. Area of bushland, hollow abundance and average tree diameter were positively correlated with species richness, while tree diameter was the strongest predictor of total microbat activity. The proximity of large areas of bushland and the many trees remaining in residential areas of the northern ‘leafy’ suburbs of Sydney allowed the persistence of a range of bat species. The higher bat activity on fertile shale soils indicated that bushland remnants embedded within cities can have high conservation value for bats. Surveys in more urbanized areas of Sydney are needed to test predictions of the models derived in this study.

Effects of Planting Density and Seed Source on Loblolly Pine Stands in Southeastern Oklahoma

Abstract Since the early 1970s, loblolly pine (Pinus taeda L.) plantations have been established west of the native range of the species in the Ouachita Mountains of Oklahoma, using faster-growing seed sources from coastal North Carolina (NCC) rather than Oklahoma or Arkansas (O/A). Although the NCC sources outperform O/A sources early in stand development, it is not known how these provenances will perform later in stand development when density-dependent mortality is occurring. We tested the effects of planting density (1,075, 1,680, 2,990, and 6,725 trees ha−1) and seed source (NCC and O/A) on stand and tree attributes for 25-year-old plantations located on a droughty, mountain soil in southeastern Oklahoma. Survival decreased with increasing stand density but did not differ among sources. Average tree diameter also decreased with increasing planting density (25.5 to 15.8 cm), and, again, the pattern was consistent across provenances. Average tree heights decreased with stand density (18.6 to 16.8 m); however, the NCC seed source was taller than the O/A seed source (18.4 versus 17.0 m). This resulted in NCC stands maintaining greater stand volume than O/A stands (329 versus 301 m3 ha−1). Basal area was similar among seed sources and did not significantly differ among densities (average 49.0 m2 ha−1). These results indicate that over 25 years, the NCC seed source performed better than the regional seed source even when grown under extremely high densities and experiencing density-dependent mortality.

Landscape-scale variation in the structure and biomass of the hill dipterocarp forest of Sumatra: Implications for carbon stock assessments

One of the first steps in estimating the potential for reducing emissions from deforestation and forest degradation (REDD) initiatives is the proper estimation of the carbon components. There are still considerable uncertainties about carbon stocks in tropical rain forest, coming essentially from poor knowledge of the quantity and spatial distribution of forest biomass at the landscape level.We evaluate the influence of site and topography on forest structure, biomass and carbon stock over a forested landscape in Sumatra. Sixteen sites were selected across a landscape of ca. 1000km2, and within each site, a network of small 0.1ha plots was laid down perpendicular to the major topographical gradient. Structural parameters for trees with diameter bigger or equal to 10cm and major life forms were recorded for each plot. The total sampled area was 70.2ha.The above-ground biomass (AGBM) in the 16 sites ranged from 271±19 to 478±38Mgha−1, with a mean of 361±7Mgha−1. This value is similar to the global ‘tropical wet forest’ estimate of Keith et al. (2009), but 23% higher than the biome default value given in the IPCC (2006) guidelines. Plots on acid tuff were the most distinctive in having fewer and smaller trees, with a resulting low AGBM. The number of stems was low, but the average tree diameter was larger on the nutrient-rich young volcanic andesitic soils. Landscape-scale variability of forest structure and dynamics was considerable. Within sites, there was little variation of mean height or mean diameter of the trees, but significant differences in stem density, basal area and AGBM between land facets. Both topography and geology appeared to affect the dynamics and the biomass of the forest.At the same time, our findings confirm the need for caution in extrapolating data from small plots to larger spatial scales when estimating carbon stocks for a given forest type or a region. Our results for C stock values for Sumatra lowland and hill dipterocarp forests (135–240Mgha−1, with a mean of 180Mgha−1) showed higher variability in C stock values at landscape level than generally reported in the literature. Based on our results, stratified sampling is recommended for biomass and carbon estimation. Within an error range of 6–8% of the AGBM, a minimum area of 4–6ha should be sufficient to estimate biomass with satisfactory accuracy at the landscape scale. Networks of several small plots across landscape are preferable to fewer larger plots, providing that the sampling is representative of the land facets in the area.

Evaluation of Alternative Cut-to-Length Harvesting Technology for Native Forest Thinning in Australia

This research quantified the equipment productivity relationships between piece size and terrain conditions for mechanized harvesting operations in native forest re-growth thinning. In addition, the economic gains or losses of adding a feller buncher to a cut-to-length (CTL) harvesting system were quantified. Study results indicate that although the use of a feller buncher working in combination with two processors is more productive than the use of a harvester-processor (single-grip harvester) working alone the high cost per tonne of this harvesting system means that its use is not recommended in areas with moderately steep terrain and small tree diameter. The differential in costs obtained between the two harvesting systems (feller buncher and two processors vs. one harvester-processor) on moderately steep and gentle terrain was approximately AUD$5/tonne and AUD$2/tonne, respectively, for an average tree diameter of 19 cm. Regression models developed from the study showed that diameter at breast height accounted for more than 85 percent of the variance in productivity of the machines and, therefore, represented the main driver of productivity and cost per tonne of the harvesting systems in all of the scenarios studied.

Measuring heights to crown base and crown median with LiDAR in a mature, even-aged loblolly pine stand

This study evaluated the possibility of measuring the height to the base of the live crown and the height to the median of canopy elements with airborne scanning LiDAR (Light Detection And Ranging) in a simple, even-aged stand of loblolly pine. The first step in determining these heights was fitting truncated Weibull functions to the vertical distribution of elevations where discrete laser pulses were reflected from the dominant canopy strata. The height to the canopy median was defined as height at the median of the distribution. The height to the base of the live crown was defined as the height where the upper tail the distribution asymptotes to zero returns. Ground-based and LiDAR-based estimates of the canopy median differed by 0.3 m and were not significantly different ( P = 0.23). Ground- and LiDAR-based estimates of the base of the live crown differed by 0.6 m and were significantly different ( P = 0.03). LiDAR-based estimates of the canopy median exhibited positive bias over most of the range of field-measured values. Analyses of the LiDAR data resulted in overestimating the height to the canopy base over most of the range in field-measured values; however, the difference between ground and LiDAR-based estimates were negatively correlated with ground-based measurements. Average tree diameter was calculated with LiDAR-generated heights to the canopy median and to the base of the live crown. The overall average diameter was not statistically different from the overall quadratic mean diameter measured on the ground, demonstrating the possible utility of these canopy variables to forest managers working with simple stands such as plantations.

Recovery of Tawa‐dominated forest fragments in the Rotorua Basin, New Zealand, after cessation of livestock grazing

Summary Tawa (Beilschmiedia tawa)‐dominated forest fragments on farms within the Rotorua Basin were surveyed to quantify the likely recovery processes following exclusion of domestic livestock grazing, using a space‐for‐time substitution approach. Vegetation structure, plant diversity and soil fertility were measured at 24 sites within 15 forest fragments on six farms, covering a range in time since exclusion from grazing of 1–53 years. The forest fragments were compared with a large area of ungrazed forest in the nearby Lake Okataina Scenic Reserve. As time since exclusion from grazing increased, indigenous plant species diversity increased (up to 30–35 years); ground fern and epiphyte abundance increased (up to 30–35 years); tree seedling and sapling numbers, and litter cover also increased (up to 10–15 years); and overall tree numbers increased, while average tree diameter at breast height and overall tree basal area did not differ significantly. The soil fertility status was highly variable, obscuring clear patterns, although Olsen P status decreased with time since grazing exclusion. Once grazing of forest fragments ceases, significant changes in their diversity, structure and soil characteristics can be expected, which indicate recovery of these plant communities towards the conditions observed in ungrazed forest.

Nest Holes of Great Spotted WoodpeckersDendrocopos majorand Middle Spotted WoodpeckersD. medius: Do they Really Differ in Size?

Abstract. Great- and Middle Spotted Woodpecker nest-hole dimensions and tree diameters at hole-entrance height were analyzed in order to test the hypothesis that Middle Spotted Woodpeckers, by making use of a thinner substrate and excavating smaller nest-holes, may reduce interspecific competition for nest-sites with Great Spotted Woodpeckers. It was found that only the vertical diameter of Great Spotted Woodpecker nest-hole openings and the entrance-hole area (49.2 mm, 17.8 cm2 respectively) were significantly larger than the corresponding parameters in Middle Spotted Woodpeckers (44.9 mm, 16.2 cm2). The average tree diameter at nest-height was 42.7 cm in Great Spotted Woodpeckers and 38.2 cm in Middle Spotted Woodpeckers, and did not differ between the two species. There were no correlations between the tree diameter at nest height and nest height in either species. The small variation in hole-entrance diameters (CV ≤ 10%) and the distance that a predator had to reach to plunder the nest (≥ 19 cm) are m...

Using Instrumental Variables for Assessing the Overall Bias of Size-Number Relationships

Studies of relationships between number of trees (or other plants) per unit area and their average size have been haunted by doubts about their statistical validity. These doubts are based on the fact that both sides of the size-number equations share the same variable-number of trees. As a result, the error term may be correlated with the predicting variable which would bias the regression. Because of this bias, called artificial correlation, it has been recommended to avoid size-number relationships and use biomass-number relationships instead. This recommendation may work if the shared variable was the only source of bias. Actually, there are several other sources (error of independent variable and constrained variability), which affect both types of relationships. To estimate their overall influence, the variables (stand biomass, average diameter, and number of trees) were smoothed using age of the investigated stands. Using these smoothed variables, it was found that the overall bias of biomass-number relationships was about six times larger and of the opposite sign than that of size-number relationships. This application of the two-stage least squares (2SLS) suggests that we can relate size and number of trees without transgressing any statistical assumptions.

Modeling the effects of thinning on bark beetle impacts and wildfire potential in the Blue Mountains of eastern Oregon

We simulated management scenarios with and without thinning over 60 years, coupled with a mountain pine beetle outbreak (at 30 years) to examine how thinning might affect bark beetle impacts, potential fire behavior, and their interactions on a 16,000-ha landscape in northeastern Oregon. We employed the Forest Vegetation Simulator, along with sub-models including the Parallel Processing Extension, Fire and Fuels Extension, and Westwide Pine Beetle Model (WPBM). We also compared responses to treatment scenarios of two bark beetle-caused tree mortality susceptibility rating systems. As hypothesized, thinning treatments led to substantial reduction in potential wildfire severity over time. However, contrary to expectations, the WPBM predicted higher bark beetle-caused mortality from an outbreak in thinned versus unthinned scenarios. Likewise, susceptibility ratings were also higher for thinned stands. Thinning treatments favored retention of early seral species such as ponderosa pine, leading to increases in proportion and average diameter of host trees. Increased surface fuel loadings and incidence of potential crown fire behavior were predicted post-outbreak; however, these effects on potential wildfire behavior were minor relative to effects of thinning. We discuss apparent inconsistencies between simulation outputs and literature, and identify improvements needed in the modeling framework to better address bark beetle-wildfire interactions.

Nitrogen and phosphorus dynamics for 13-year-old loblolly pine stands receiving complete competition control and annual N fertilizer

Because stand growth and the uptake of nitrogen (N) and phosphorus (P) are proportional under most circumstances, a goal of silvicultural operations should be to increase uptake of nutrients by crop trees. The objectives of this study were to determine the effects of annual fertilization (average of 72 kg N ha −1 y −1 and total of 154 kg P ha −1) and complete elimination of interspecific competition on stand growth, N and P uptake, N and P budgets, and fertilizer retention in 13-year-old of loblolly pine ( Pinus taeda L.) stands growing in the Lower Coastal Plain of Georgia, USA. At age 13, fertilization increased average tree height from 14.8 to 19.3 m, average tree diameter from 14.5 to 19.3 cm, and stand basal area from 27.6 to 42.6 m 2 ha −1. Competition control increased average tree height from 16.5 to 17.5 m, average tree diameter from 16.3 to 17.6 cm, and stand basal area from 31.9 to 38.3 m 2 ha −1. The relative amount of biomass partitioned among the aboveground biomass components was not affected by treatments, but fertilization and complete competition control decreased the biomass of fine roots, a trend opposite that for aboveground biomass. In general, complete competition control had little effect on nutrient concentrations or contents. Annual N uptake at age 13 was approximately 100 and 60 kg ha −1 in the fertilized and nonfertilized stands, respectively. Annual uptake for P in nonfertilized stands averaged 7.5 kg ha −1 while that in fertilized stands averaged 10 kg ha −1. With the exception of stem bark N concentration and foliar P concentration, fertilization increased the N and P concentrations of the aboveground biomass components. Nitrogen contents in the aboveground biomass ranged from less than 160 kg ha −1 in the control stands to almost 410 kg ha −1 in the fertilized stands. Phosphorus contents ranged from approximately 12 kg ha −1 in the control stands to 27 kg ha −1. In contrast to the aboveground biomass, standing fine root N contents were 15.2, 16.4, 8.7, and 7.6 kg ha −1 while standing P contents were 2.22, 1.73, 1.09, and 0.95 kg ha −1 for the control, fertilize only, competition control only, fertilizer + competition control treatments, respectively. The large N and P uptake in these stands facilitated an estimated retention of 90% of N fertilizer and >100% of P fertilizer in the soils, O horizon, and living biomass of the fertilized stands. These results underscore the importance of nutrition to stand growth, raise the bar for the potential productivity of loblolly pine in the southeastern United States, and indicate that it is possible to aggressively fertilize these nutrient poor systems with potentially few offsite impacts.

Harvesting System Simulation Using a Systems Dynamic Model

Abstract To compete in the current work environment in the southeastern United States, forestry companies and logging contractors must manage their harvest systems to ensure efficient production. Efficiency in this case can be defined in terms of tons of wood produced per unit of system cost. Site and system factors affect the output from a stand and affect the efficiency of different harvesting systems. A model was developed that can simulate harvesting system production efficiency with changing stand and terrain parameters. Four common southeastern US harvesting systems were included in the model. The model includes functions, adjustable by the user, that quantify the efficiency of each harvest system is measured with respect to terrain parameters (slope and average extraction distance), as well as stand parameters (average tree diameter, stocking intensity, and harvest intensity). By adjusting any of these parameters, it is possible to compare the four harvest systems and to perform various sensitivity analyses. Result examples presented in the article include change in productivity with increasing tree size, productivity changes of a cut-to-length system in varied silvicultural conditions, as well as the associated evaluation of the cost of inefficiency of each system. South. J. Appl. For. 28(2):91–99.

To Thin or Not to Thin: Using the Forest Vegetation Simulator to Evaluate Thinning of Aspen

Abstract Thinning experiments are costly to install and take decades of monitoring. Computer simulation tools, however, allow for the creation of “virtual” thinning experiments that forest managers can use as a guide in prescribing thinnings. The Forest Vegetation Simulator (FVS) was used to conduct a “virtual” thinning experiment to a range of residual densities (8, 10, 12, 15, and 20 ft spacings) at a range of thinning ages (5, 10, 25, and 40 yr) over a 50 yr time period. Stand level volume production was not enhanced through precommercial thinning, but average tree diameter was increased. Stand level volume was less after commercial thinnings but total volume production was increased if volumes removed during thinnings were considered. Tree diameter growth was greater when thinnings were performed at a younger age at and at a wider spacing. The greatest total volume production (removed during thinning and standing at age 50) was found to be nearly equal at 8 ft and 10 ft spacing with thinnings occurring at ages 10 or 25 on a site index of 80. North. J. Appl. For. 20(1):14–18.

Carbon isotope discrimination and its relationship to drought resistance under field conditions in genotypes of Eucalyptus globulus Labill.

The aim of this study was to investigate the relationship between carbon isotope discrimination (Δ), survival and growth, to determine the value of Δ for screening for yield improvement under drought conditions. Intra-specific variation in carbon isotope discrimination (Δ) was examined in Eucalyptus globulus. Wood samples were collected from 3 to 7 year-old populations from three different field-sites at Huelva (south-western Spain). Differences between study sites were related to the availability of water resulting from soil physical properties. Average carbon isotope discrimination ranged from 16.7 to 18.1‰. There was a 2.2‰ maximum range in Δ values among different trees of the same age. A strong, positive correlation was observed between average carbon isotope discrimination and average tree diameter at breast height (DBH ob). Average carbon isotope discrimination was also strongly correlated with survival at the Valdeoscuro site ( r 2=0.95) and with the percentage of failures in neighbouring trees ( r 2=0.65) at the San Sebastián site. These results suggest a strong effect of availability of water on Δ values. Implications for the use of carbon isotope discrimination in selecting for better adapted genotypes are discussed.

Technical Note: Why Quadratic Mean Diameter?

Abstract Quadratic mean diameter is the measure of average tree diameter conventionally used in forestry, rather than arithmetic mean diameter. The historical and practical reasons for this convention are reviewed. West. J. Appl. For. 15(3):137-139.

The impact ofSirococcusshoot blight on radial and height growth of Norway spruce (Picea abies) in young plantations

The impact of Sirococcus shoot blight on the radial and height growth of Norway spruce in a young plantation (approximately 20 years old) was investigated by examining the increment losses for four infection intensities (classes). The average diameter at breast height of trees in the lightly damaged class was 72% when compared with the average diameter of the healthy trees, whereas moderately and severely damaged tree classes were 67 and 57%, respectively. Using tree ring analysis, the development of radial growth over time due to intensity of infection was studied. Height growth of affected trees was also significantly reduced (up to 43%) compared with the healthy trees, thus indicating a dramatic impact of Sirococcus conigenus on the growth of young Norway spruce.

Stream channel configuration, landform, and riparian forest structure in the Cascade Mountains, Washington

The hierarchical relationship of five key elements, valley constraint, riparian landform, riparian plant community, channel type, and channel configuration, are described for 21 sites in mature to old-growth riparian forests of the western Cascades Mountains, Washington, U.S.A. Channel type (bedrock, plane-bed, and forced pool-riffle) was closely related to channel configuration (especially large woody debris (LWD) volume, density, and LWD-formed pools) at the smallest spatial scale and valley constraint at the largest. Valley constraint significantly influenced off-channel habitat (r2 = 0.71) and LWD volume within forced pool-riffle channels (r2 = 0.58). Riparian plant community composition was differentiated by four landform classes: three alluvial landforms based on height above the channel and one based on hillslope. Just above the active channel, floodplain landforms contained more deciduous stems than conifer and greater conifer basal area than deciduous. Conifers dominated other landforms. The diameter of in-channel LWD increased with the age of the riparian forest (r2 = 0.34). In old-growth forests, LWD diameter was equivalent to or greater than the average riparian tree diameter for all sites. In younger forests, the mixed relationship between LWD and riparian tree diameter may reflect a combination of LWD input from the previous old-growth stand and LWD input from the existing stand.

CROP PRODUCTION AND ECONOMICS UNDERLITCHI CHINENSISSONN. PLANTATION ACROSS 1- TO 9-YEAR AGE SERIES IN NORTH BIHAR, INDIA

SUMMARY Litchi is a major commercial crop of north Bihar, India. Growing a number of other crops in association with litchi plantation is a widespread practice in all litchi growing areas. Yields of intercrops under two rotations, viz. paddy-wheat-green gram-ginger and maize-toria-green gram-pointed gourd were studied across an age series of litchi plantations during years 1–9 following planting. Average height and diameter of litchi trees under 1 to 9 year-old plantation varied between 1.0 ± 0.20 to 5.47 ± 0.33 m and 5.10 ± 1.30 to 36.3 ± 3.82 cm, respectively. Relative light intensity under tree plantations decreased with increasing canopy depth and tree height. There was a marked reduction in yield of all intercrops with increase in age of the plantations. The economics of intercrops and plantations each from 1 to 9 years of age were calculated at the end of year 9 of planting. The benefit: rcost ratio under paddy-wheat-green gram-ginger and fruit systems was 2.17 and under maize-toria-green gram-point...

Aboveground biomass and nitrogen nutrition in a chronosequence of pristine Dahurian Larix stands in eastern Siberia

Measurements of aboveground biomass and nitrogen (N) nutrition were made during July 1993 in 50-, 130-, and 380-year-old stands of Larixgmelinii (Rupr.) Rupr. in eastern Siberia. Constituting six forest types based on understorey plants, the stands were representative of vegetation throughout the Yakutsk region. Average tree height, diameter, and density ranged from 2 m, 23 mm, and 50 800 stems/ha in the 50-year-old stand to 11 m, 160 mm, and 600 stems/ha in the oldest stand. Aboveground biomass in the 50-year-old stand was 4.4 kg•m−2, and the aboveground N pool was 1.1 mol•m−2. This was slightly higher than the N pool in a 125-year-old stand with a Ledum understorey (1.0 mol•m−2), despite its higher biomass (7.2 kg•m−2). The highest observed aboveground biomass in a 125-year-old stand (characterized by the N2-fixing understorey plant Alnasterfruticosa) reached 12.0 kg•m−2, but the corresponding N pool was only 1.6 mol•m−2. In the oldest stand, aboveground biomass was 8.9 kg•m−2 and the N pool was 1.1 mol•m−2. There was thus a relatively constant quantity of N in the aboveground biomass of stands differing in age by almost 400 years. We postulate that N sets a limit on carbon accumulation in this boreal forest type. Trees were extremely slow growing, and there was essentially no aboveground biomass accumulation between the ages of 130 and 380 years because of a lack of available N. This conclusion was supported by graphical analysis indicating that the self-thinning process in our stands was not governed by the availability of radiation according to allometric theory. Much of the available N was used in the production of tree stems where 86% of the aboveground N (and 96% of aboveground biomass) was immobilized in the oldest stand. N in wood of the old stand exceeded the N pool in the litter layer and was 20% of the N pool in the Ah horizon. The processes of carbon and N partitioning were further explored by the estimation of carbon and N fluxes during three periods of forest development. We calculated a loss of ecosystem N during the period of self-thinning, while in the mature stands the N cycle appeared to be very tight. The immobilized N is returned from the wood into a plant-available form only by a recurrent fire cycle, which regenerates the N cycle. Thus fire is an essential component for the persistence of the L. gmelinii forest.

Apple, Evaluation on Ntn-33893 as a Trunk Application, 1993

Abstract Experimental sprays were applied to single-tree plots in a randomized block design consisting of 10 replicates. Test trees were 2 years old and spaced 3.7 × 5.5 m apart on M.26 EMLA rootstock. The average trunk diameter of trees 46 cm above the ground was 3 cm. Treatments for all plots were applied with a paint brush to the trunk in a 20-40 cm band beginning below the main scaffold limbs on 14 Apr. All plots received a regular fungicide maintenance schedule of captan 50WP and Nova 40WP, The effect of treatments on WALH was evaluated by counting nymphs/25 injured leaves/tree for the first generation and nymphs/50 randomly selected leaves for the second generation. Effectiveness on SA was evaluated by counting aphid-infested leaves/5 growing shoots, and aphids/most infested leaf. Effectiveness of the test chemicals on ERM, AF and ZM was evaluated by counting these mites during the season on samples of 25 random leaves/ tree, 250 leaves/treatment. STLM were counted at the end of both 1st and 2nd generation by examining 4 one year old shoots and determining the number of tissue feeding mines per leaf.