Average Tree Height Research Articles

Hurricane Gilbert and structural changes in a tropical forest in south‐eastern Mexico

SummaryThis paper describes structural change and damage to the natural tree vegetation in the Dr Alfredo Barrera Marín Botanical Garden, following Hurricane Gilbert in September, 1988. Post‐hurricane data were compared with pre‐hurricane data from the same plots, focusing mainly on composition and structure. Near complete defoliation of trees and plants of the understorey occurred and average foliage loss was estimated to be 4.5 t/ha. The density of trees decreased by 33%, and the basal area decreased by 12%. Small diameter trees accounted for the great majority of losses and trees in the largest diameter classes survived best. The average height of trees in the lower canopy decreased by 6% and for those in the upper canopy by 9%. The frequency of understorey plants decreased by 51% and their cover decreased by 70%. Floristic richness decreased only slightly after the hurricane.

Patterns of woody plant abundance, recruitment, mortality, and growth in a 65 year chronosequence of old-fields

We surveyed vegetation along forest margins in a 65-year chronosequence of old-fields at the Cedar Creek Natural History Area in east-central Minnesota, USA, to identify successional patterns of woody plants and to determine if these were correlated with soil nitrogen. We predicted that shrub and tree abundance, size, and distance of occurrence from the forest edge would be correlated with field age or soil nitrogen. Instead we did not find successional trends in the abundance or composition of woody species. Even in the oldest field the abundance of trees and shrubs was low and concentrated in areas close to the forest. Though trees were larger and present further from the forest edges in older fields, average tree height was less than 126 cm in all fields. Since we did not find successional trends we looked at various local factors (local seed sources, deer browsing, and forest edge aspect) and their relation to recruitment, mortality, or growth to explain variation among fields in abundance of trees or shrubs. The three most common tree species (Quercus rubra, Q. macrocarpa,and Populus tremuloides) all had a higher relative abundance of seedlings, and two (Q. rubra and Q. macrocarpa) had a higher relative abundance of large trees adjacent to forests with a high abundance of conspecific adults. Most trees taller than 20 cm were browsed by deer and were shorter in 1995 than they were in 1993. Mortality was higher for trees less than 30 cm indicating that mortality was size-dependent. Forest edge aspect did not significantly influence the abundance or demography of any species. Our results suggest that the patterns of seedling recruitment were largely determined by the proximity of seed sources and that these patterns may persist so that tree communities in old-fields resemble adjacent forests. Deer may be a significant factor in the suppression of tree populations in old-fields through repeated browsing which reduces tree growth and elevates tree mortality by prolonging the period of time trees remain susceptible to size-dependent mortality.

Bird Communities and Habitat Relationships in a Residential Area of Tokyo.

Conserving birds in urban environments requires ecological information that can be applied to city planning and designing, but few ecological studies on bird communities in residential area have so far been made. I conducted surveys of the terrestrial bird communities at 12 locations in a residential area of Tokyo, Japan in both the breeding and wintering seasons in 1990-91, and identified habitat features associated with bird communities. In both seasons, the residential areas with abundant vegetation supported more species and higher densities of birds. Number of trees (>8m in height) and average tree height were the most significant variables for explaining variances of diversity of bird species among study plots. Abundance and height of buildings were negative factors for diversity in the wintering season, conversely they were positive in the breeding season. Most bird species preferred to use land covered by vegetation. Land occupied by buildings and bare land tended to be avoided by birds and used by fewer species than expected. It was confirmed that vegetation, especially trees, was the key element for bird conservation in residential areas. I present environmental guidelines required for bird conservation in residential areas.

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...

Magnitudes and seasonal patterns of energy, water, and carbon exchanges at a boreal young jack pine forest in the BOREAS northern study area

Seasonal patterns of the energy balance of a young jack pine site near Thompson, Manitoba, in the summer of 1994 are reported. The experiment was part of the Boreal Ecosystem‐Atmosphere Study (BOREAS), and it ran from May 24 to September 19. The average tree density was 4.4 trees m−2, but there was substantial spatial variation associated with three primary vegetation patterns: dense cover of short trees, sparse cover of tall trees, and a mixture of short and tall trees. The frequency distribution of tree heights was bimodal with peaks at 1 and 2 m and a range from 0.3 to 5.7 m. The average tree height was 2.3 m. The daily average photosynthetically active radiation albedo was conservative, varying from 0.054 under clear‐sky conditions to 0.051 under cloudy skies. The shortwave albedo was 0.136 under clear‐sky conditions and decreased by 1% following rain; the presence of smoke over the site increased it by 1%. Heat storage in the soil, trees, and air was an important component of the energy balance throughout the season with soil heat flux comprising the bulk of the total storage. On the average, for the whole experimental period, the sensible heat flux was approximately twice the latent heat flux (Bowen ratio ≈2). The average daily energy balance closure varied from 85% before day‐of‐year (DOY) 200 to 95% after DOY 200. As a result of problems with the measurement of the net CO2 flux above the canopy under stable nighttime conditions, all nighttime values were modeled. The typical diurnal pattern of net CO2 flux shows maximum uptake by the surface in the morning and a gradual decrease through the afternoon. For the whole field season of 118 days, the site fixed 224 g m−2 of carbon.

Nutrient Dynamics of a Futian Mangrove Forest in Shenzhen, South China

An ecological study was carried out to determine nutrient levels of sediments, plant tissues and nutrient dynamics in anAegiceras corniculatum–Kandelia candeldominated forest in Futian Mangrove Nature Reserve, Shenzhen, the People's Republic of China. The average tree height of the mangrove is 4·5m with no vertical stratification. Allometric methodology was used to measure the biomass, and yield a figure of 108·26t ha−1. The annual growth of the forest (1992) 15·92t ha−1and the litterfall rate amounted to 11·49t ha−1. Nutrient stocks of N, P and K in this mangrove were 616·05, 128·63 and 801·17kg ha−1, with an annual accumulation of 91·34, 14·74 and 130·60kg ha−1, and with an annual return of 88·30, 12·85 and 29·32kg ha−1in the form of litter, respectively. The annual uptake (accumulation+return) for N, P and K was 179·64, 27·59 and 159·92kg ha−1, respectively, in 1992. It seems that this mangrove community is close to equilibrium in terms of import and export of N and P, but has an obvious conservation of K. Enrichment ratios of N, P and K were at 1·10, 0·81 and 0·76, respectively, lower than their counterparts in terrestrial forests. The turnover rate (the stock amount in the community/annual return) of N, P and K was estimated at 7, 10 and 27 years, respectively. Flow coefficients and translocation rates, which reveal the dynamic processes of nutrients between mangrove plants and sediments, are also discussed.

Estimating Crown Height for Unthinned Planted Pines in East Texas

Abstract Stand-level models were derived to predict crown height or the distance from ground to the first live branch of unthinned planted loblolly (Pinus taeda L.) and slash (Pinus elliottii Engelm.) pine trees in East Texas. Average height of the tallest trees was the principal predictor in the models. In addition, the influence of number of planted trees per acre, nonplanted basal area and fusiform rust (Cronartium quercuum [Berk.] Miyabe ex Shirai f. sp. fusiforme) was considered. The models quantify the plantation ages when the butt log and successive lower stem logs are clear of live branches. This information may assist with merchandising the planted pines. South. J. Appl. For. 21(3):130-133.

Evaluation of approaches to estimating aboveground biomass in Southern pine forests using SIR-C data

A study was performed to evaluate various techniques for estimating aboveground, woody plant biomass in pine stands found in the southeastern United States, using C- and L- band multiple polarization radar imagery collected by the Shuttle Imaging Radar-C (SIR-C) system. The biomass levels present in the test stands ranged between 0.0 and, 44.5 kg m −2. Two SIR-C data sets were used: one collected in April, 1994, when the soil conditions were very wet and the canopy was slightly wet from dew and a second collected in October, 1994, when the soils and canopy were dry. During the October mission, pine needles were completely flushed and the foliar biomass was twice as great in the forest stands as in April. Four methods were evaluated to estimate total biomass: one including a straight multiple linear correlation between total biomass and the various SIR-C channels; another including a ratio of the L-band HV/C-band HV channels; and two others requiring multiple steps, where linear regression equations for different stand components (height, basal area, and crown or branch biomass) were used as the basis for estimating total biomass. It was shown that the data collected in October (dry soil conditions) were better for estimation of biomass than the data collected in April (wet soil conditions). Overall, a multistep approach resulted in the lowest root mean square (RMS) errors (5.91 kg m −2) when biomass levels were <20 kg m −2. For all biomass levels, the simple regression technique resulted in the lowest RMS errors (8.1 kg m −2). The multiple-step approaches have the additional advantage of being able to provide estimates of different components of stand structure and biomass, such as average tree height, basal area, branch biomass, canopy biomass, trunk biomass, and foliage biomass. The LHV channel is the critical element in all the biomass equations, as would be expected from the body of literature. The addition of other channels—generally, CHV or CHH—significantly improves biomass estimates, whether as a ratio or as additional terms in a regression equation.

VALUE OF COMMERCIAL FORESTRY AS A POST-MINING LAND USE

Forestry is becoming the preferred post-mining land use in the Appalachian region for the landowner as the value of forests becomes recognized. During the summer of 1996, a study was conducted in a white pine (Pinus strobus L.) plantation that was established in 1978 on a pre-SMCRA bench located in Wise County, Virginia. The objectives of this study were to illustrate the feasibility of commercial forestry as a post-mining land use, and to identify relationships between tree productivity and mine soil physical properties. The spoil was a deep, non-compacted, slightly-acid. weathered sandstone that had no topsoil applied. A timber inventory of the plantation showed that it was overstocked, therefore the plantation was thinned down to 20 m{sup 2} ha{sup -1} (90 ft{sup 2} of basal area per acre). The average tree height was 14.3 in (47 ft), translating to a very high site index of 35 in (110 ft; base age 50), compared to site indices of 24 in (80 ft) and 18.3 in (60 ft) for adjacent undisturbed forest soils and post-SMCRA reclaimed mine soils, respectively. When these site indices were used to project tree growth for 30 years, the estimated timber per-acre value was $3,480, $1,755, and $122more » for the non-compacted mine soil, undisturbed forest soil, and typical post-SMCRA mine soil, respectively. The twenty-fold difference in the timber value between the non-compacted none soil and the typical post-SMCRA mine soil represents a tremendous lost opportunity. for most post-SMCRA sites that are not reclaimed for commercial forestry. The high productivity of the white pine plantation growing on the pre-SMCRA bench was attributed to low soil bulk density and a moderately-acid sandstone mine soil. Reclamation practices that result in these desirable soil properties need to be encouraged, so that restored forest land will be profitable for the landowner, meet society`s needs, and meet the spirit and letter of the SMCRA.« less

Plant biodiversity inventory and conservation of two tropical dry evergreen forests on the Coromandel coast, south India

Species diversity, population structure, abundance and dispersion patterns of all woody plants ≥10cm gbh were inventoried in two 1-ha plots of tropical dry evergreen (sacred grove or temple) forests at Kuzhanthaikuppam (KK) and Thirumanikkuzhi (TM) on the Coromandel coast of south India. Site KK is a stunted forest (average tree height ca 6 m) and TM a tall forest (average tree height ca 10 m). A total of 54 species (in 47 genera and 31 families) were recorded. Species richness and stand density were 42 and 38 species and 1367 and 974 individuals ha−1 respectively for the sites KK and TM. About 50% of the total species were common to both the sites. Site TM is twofold more voluminous (basal area 29.48 m2 ha−1) than KK (basal area 15.44 m2 ha−1). Nearly one third of the individuals are multi-stemmed in the low-statured site KK whereas one fourth of the tree density is multi-stemmed in TM. Species abundance pattern varied between the two sites. The abundance of three species in KK and two species in TM is pronounced. Memecylon umbellatum, the most abundant species contributing to one third of total stand density in KK, is least represented in TM. Species richness, density and diversity indices decreased with increasing girth threshold. Most species exhibited clumped dispersion of individuals both at 0.25 and 1-ha scales. Population structure for girth frequency is an expanding one for both the sites, except for basal area distribution in KK. Variations in plant diversity and abundance are related to site attributes and human impacts. In the light of habitat uniqueness, species richness and sacred grove status, the need for conservation is emphasized.

Colonization in an abandoned East‐Mediterranean vineyard

Abstract. Previous studies on secondary succession in abandoned agricultural land in the Mediterranean area were carried out by the chronosequence method, including data from different sites. A unique opportunity to study secondary succession arose from a situation in which different parts of one homogeneous East‐Mediterranean vineyard were abandoned for 5, 8, 15 and 35 yr, and did not suffer from any disturbance subsequently. Most of the perennial species that colonized the abandoned vineyard were fleshy fruited species, which apparently were dispersed by birds from the surrounding maquis into the vineyard. These bird‐dispersed species were the first to be established, and were the dominant plant group according to dispersal modes. The abandoned vine plants and their supporting columns provided the birds with perching and feeding sites, enhancing the arrival of bird‐dispersed species regardless of their life forms. Under these conditions the most important attribute that affected vegetation dynamics was seed dispersal mode. Trees were among the first to colonize in the vineyard, implying that no facilitation was needed for their establishment. Annual plant species were the only species to disappear during succession. Almost all perennial species which had arrived persisted in the vineyard, and no replacement of perennial species was found. The rate of succession was rapid, as expressed by the short time (8–15 yr) needed for the stabilization of species composition, for growth to average height of late succession trees, and for reaching high cover of the invading perennial species in the abandoned vineyard. The secondary succession described above differs from that in the western Mediterranean by the absence of perennial species replacement and its rapid rate. The possible causes are discussed.

Predicting Dominant Height from Plantation Age and the Diameter Distributions—Site-Prepared Loblolly Pine

Abstract With over 1,300 observations from plots in mechanically site-prepared loblolly pine plantations, regression equations are fitted that predict average height of dominant and codominant trees (i.e., site index trees)from stand age and diameter distribution characteristics. The equations can be used to avoid measuring heights and thus reduce costs of volume inventories in loblolly pine plantations. South. J. Appl. For. 20(3):148-150.

Coupling a spatially-explicit forest gap model with a 3-D solar routine to simulate latitudinal effects

A multi-scaled forest model (ZELIG) which spatially embeds patch-scale processes into a larger landscape was linked with a 3-D insolation routine to simulate the effects of latitudinal variation in solar radiation on the growth and spatial patterns of idealized early successional, shade-intolerant and late successional, shade-tolerant species. At the individual tree level, average tree height increased for the shade-intolerant species with decreasing latitude as steep angled direct-beam radiation more readily penetrated narrow canopy gaps. This yielded an increase in interspecific competition and intraspecific competition among shade-intolerant trees. Consequently, though stem density dropped, basal area of shade-intolerant species increased as growth increased with decreasing latitude. Conversely, basal area for the shade-tolerant species increased with increasing latitude as stem density increased as the proportion of diffuse radiation increased. In terms of spatial pattern, the combined models produced non-random, anisotropic patterns which changed over the course of succession and were different for the shade-intolerant and tolerant species. However, differences in spatial patterns for the tropical, temperate, and boreal solar regimes were inexplicable. Shade-tolerant species consistently exhibited negative autocorrelation on adjacent grid cells (10–20 m away) during early successional stages and later stages after species replacement. Auto-correlation of shade-intolerant species shifted from negative to positive at this scale as its role changed from canopy dominant to gap colonizer. At scales > 20 m, whether or not a specific direction/distance autocorrelation value was positive or negative and significant or not significant was highly variable for both species and was attributed to stochastic properties (i.e., birth and mortality) of the model.

Soil compaction and conifer growth after tractor yarding at three coastal Washington locations

We measured soil density and tree growth after wet-season, ground-based yarding on fine-textured soils at three clear-cut sites. Four treatment conditions were sampled on or near four skid trails (replicates): nontilled and tilled primary skid trails, and adjacent slash-treated areas; the fourth treatment was secondary skid trails at two locations and a logged-only control at the third location. The 16 treatment plots were split into 4 subplots, each randomly assigned to a species–stock type and planted with 30 seedlings. Tree data through year 8 after planting were analyzed as a randomized block, split-plot design. Compared with nontrail areas, bulk density in the 0- to 8-cm depth on primary skid trails after logging averaged 41–52% greater. Eight years later, bulk density in the 0- to 30-cm depth of primary skid trails still exceeded that outside trails by about 20%, yet tree survival was similar except for western hemlock (Tsugaheterophylla (Raf.) Sarg.) having poorer survival on nontilled trails at one location. Average tree height and volume of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco var. menziesii), Sitka spruce (Piceasitchensis (Bong.) Carr.), and hemlock (except height at one location) did not differ among treatments. Observed differences among treatment means were small. Power analyses indicated that 20% or larger differences in tree height or volume were detectable with 30–95% power.

Trends of tree growth in Swedish forests 1953–1992: An analysis based on sample trees from the national forest inventory

Average tree height and basal area growth for Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) in Sweden were studied as functions of species, age, stand density, location and year of inventory in the period 1953–1992, on the basis of sample tree data from the National Forest Inventory. A highly significant annual increase of both height and basal area growth was found, of the magnitude 0.5–0.8%, during the 40 yr period. Possible reasons for the trend are discussed. The altered way of cutting in the early 1950s, from selective cutting to clear felling and thinning from below, has had a large impact. Also, improved regeneration methods, nitrogen fertilization and ditching have increased growth. The increasing atmospheric deposition of nitrogen is another possible factor.

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.

Genetic variation in carbon isotope discrimination and its relationship to growth under field conditions in full-sib families of Piceamariana

Measurements of the stable carbon isotope composition of leaf tissue were made on Piceamariana (Mill.) B.S.P trees from four full-sib families grown on three different field sites at the Petawawa National Forestry Institute, Ontario, Canada. The four families chosen exhibited genetic variation for growth characteristics. Genetic variation was also observed for carbon isotopic discrimination (Δ) among the families of P. mariana. In addition, a strong correlation occurred between Δ values measured on trees in 1991 and 1992, two years that had very different precipitation and temperature conditions during the growing season, indicating that the ranking of individual trees remained almost constant between years. A strong, negative correlation was observed between average carbon isotope discrimination and average tree height for the four families on the driest, least productive site, as was expected based on leaf photosynthetic characteristics. There was no significant correlation, however, between Δ values and growth on the other two study sites, where productivity was higher.

Modeling crown rise in even-aged stands of Sitka spruce or loblolly pine

A ‘crown-rise’ model that estimates average height to the base of a crown in an even-aged, monospecific stand is derived and fitted to loblolly pine and Sitka spruce data. Estimated standard errors are less than 1 m. The driving variables are average tree height and either tree count per unit area or average inter-tree distance. Two potential uses of the crown-rise model are (1) a component of an empirical or mechanistic forest model, and (2) and alternative to stocking charts for stand density management.

Growth and oil production of argan in the Negev Desert of Israel

Argan ( Argania spinosa L.) is a wild tree native to southwestern Morocco. It bears a plum-sized fruit with one to three kernels rich in oil. The oil is highly prized as an edible and cooking oil by the local people. Our study was carried out to investigate the possibility of domesticating the species. Seedlings were planted in the Negev Desert of Israel at the location Qetura with a high summer temperature and brackish water and at the location Ramat Negev with a low winter temperature and good-quality water. Average tree height in the seventh year was 4.0±0.6 m at Qetura and 4.6±0.6 m at Ramat Negev. Best yielders produced dry fruits between 20 and 25 kg/tree at both sites in the sixth and seventh years, and average orchard yield was three-four-times lower as a result of high variation between the trees. Kernels comprised 6.5% of fruit weight and contained 55% of oil. In the seventh year, oil yield was 0.6 kg/tree at Qetura and 50% lower at Ramat Negev. The higher oil yield at Qetura is related to higher average fruit yields, higher kernel weights and higher oil content of the kernels than the values for Ramat Negev. Characteristics of the fruits and fatty acid composition of the argan oil and the chemical composition and quality characteristics of the defatted argan kernel meal are being presented. Fruit components, such as the pericarp (45% of fruit weight), and the defatted meal (3.5% of fruit weight) can be used as animal feeds. The meal is characterized by a high protein content (46%) and a high in vitro digestibility (96%).

Early Results from an Old-Field Loblolly Pine Spacing Study in the Georgia Piedmont with Competition Control

Abstract The study reported here provides information on the yield potential of improved loblolly pine seedlings planted on marginal agricultural cropland in the Georgia Piedmont with control of herbaceous competition. Early growth rates greatly exceed those in existing plantations established on cutover and mechanically site-prepared land in this region without additional control of competing vegetation. After 8 growing seasons, average tree height, average dbh, basal area per acre, and stem volume per acre were all influenced by planting density, but the mean annual increment of merchantable volume (trees 4.0 in. dbh and bigger to a 2.0 in. top diameter) at age 8 yr, for planting densities of 400 to 1000 trees/ac, was 230 ft³, or approximately 3 cords/ac/yr. This is more than twice the average growth rate in this region of cutover and mechanically site-prepared loblolly plantations without additional vegetation control. These results should be of particular interest to prospective participants in the Conservation Reserve Program (CRP). South. J. Appl. For. 17(4):193-196.