Mean Girth Research Articles

Decline of moorland plants following the establishment of a Scots pine plantation

Summary A tract of heather (Calluna vulgaris) moorland on a brown-earth soil in north-east Scotland was planted with Scots pine in 1974, and the subsequent changes in heather and botanical composition were monitored. The pines established well and attained a mean girth of 37 cm by 1995. Before planting the moorland was heavily grazed by sheep which kept the heather short (mean height 7 cm) but with high cover (71%). After planting there have been three phases in the development of the ground vegetation. In the first eight years the heather benefited from the cessation of grazing, reaching 17 cm height and 89% coverin 1982. The cover of pine remained less than 5%, but grasses declined significantly in cover and some forbs became extinct e.g. Lotus corniculatus. In the second 8-yr phase the pine canopy closed but heather retained its dominance still having 89% cover in 1990 and a mean height of 20 cm. The main change in composition was a decline in the subsidiary dwarf shrubs (Arctostaphylos uva-ursi, Erica...

Ken and Barbie at life size

There has been considerable discussion in both the scientific literature and general media concerning the appropriateness of the body shape and proportions of the Ken and Barbie dolls, the most popular dolls in modern history. The greatest concern has been of the possible influence that these, and other “cultural ideals” for body shape, may have on young children. However, these concerns have been based entirely on the subjective interpretation of how one perceives the body dimensions of the dolls relative to an adult size. We therefore used our skills in anthropometry and the rules of allometry to scale the dolls to an adult height to determine the dimensions that these dolls would assume at this adjusted size. These were compared to actual proportions of several representative adult groups of predominantly Anglo-Australian males and females. The critics have been justified in their opinions since both Barbie and Ken are thin relative to the reference samples. Barbie's mean girth z-score relative to a reference cross-section of the young adult population was −4.2. This indicates that the probability for such a body shape is less than 1 in 100,000. Ken is more realistic at about 1 in 50.

Growth of field-grown ash trees (Fraxinus excelsior) exposed to ozone episodes

Ash trees were exposed to ozone episodes (150 nl l−1, 8 h d−1, 24–27 d y−1) from May to October, 1992 to 1994, in open-top chambers designed to minimise microclimatic modification. Many aspects of growth were studied, including leaf abscission, leaf area, mean leaf size, tree height and girth, extension growth, cross sectional area of annual rings and above-ground dry weight. An overview of the results is presented. This shows that the duration of the leaf fall period was increased by exposure to ozone. However, three seasons of severe ozone exposure relative to UK conditions did not significantly alter other aspects of growth.

Agroforestry development in northeastern Nigeria

Some results of recent agroforestry development efforts in northeastern Nigeria are summarised, and briefly discussed. An initial diagnostic survey of farms and local markets identified local practices and selected indigenous species of Acacia albida, Ziziphus spp., Tamarindus indica, etc. as particularly important sources of food, feed and soil resuscitation. There were indications that seeds of promising tree species suffer heavy insect infestation (28%) and have poor germination as well as seedling survival. Plantations of seven tree species, raised through the taungya system recorded over 75% survival and 4.08 cm annual mean girth increment. Older plantations of Azadiracta indica, Eucalyptus camaldulensis and Prosopis juliflora also improved soil and increased the dry matter yield of Zea mays, Sorghum vulgaris and Arachis hypogea to about five times the yield obtained on soil from the surrounding field. Work in progress and plans to investigate the social and economic prospects of alternative agroforestry systems among farmers in the region are also indicated.

Relação entre diferentes caracteres de plantas jovens de seringueira

O presente trabalho foi realizado com o objetivo de determinar a existência e as magnitudes de correlações e regressões lineares simples em plântulas jovens de seringueira (Hevea spp.), para melhor condução de seleção nos futuros trabalhos de melhoramento. Foram utilizadas médias de produção de borracha seca por plântulas por corte, através do teste Hamaker-Morris-Mann (P); circunferência do caule (CC); espessura de casca (EC); número de anéis (NA); diâmetro dos vasos (DV); densidade dos vasos laticíleros (D) e distância média entre anéis de vasos consecutivos (DMEAVC) em um viveiro de cruzamento com três anos e meio de idade. Os resultados mostraram, entre outros fatores, que as correlações lineares simples de P com CC, EC, NA, D, DV e DMEAVC foram, respectivamente, r =t 0,61, 0,34, 0,28, 0,29, 0,43 e -0,13. As correlações de CC com EC, NA, D, DV e DMEAVC foram: 0,65, 0,22, 0,37, 0,33 e 0,096 respectivamente. Estudos de regressão linear simples de P com CC, EC, NA, DV, D e DMEAVC sugerem que CC foi o caráter independente mais significativo, contribuindo com 36% da variação em P. Em relação ao vigor, a regressão de CC com os respectivos caracteres sugere que EC foi o único caráter que contribuiu significativamente para a variação de CC com 42%. As altas correlações observadas da produção com circunferência do caule e com espessura de casca evidenciam a possibilidade de obter genótipos jovens de boa capacidade produtiva e grande vigor, através de seleção precoce dessas variáveis.

A re-assessment of effects of fire on miombo regeneration in the Zambian Copperbelt

ABSTRACTIn 1933/34 eight coppice plots were established in Brachystegia-Julbemardia (miombo) woodland at Ndola in the Copperbelt area of Zambia by the Forestry Department. These plots have been maintained under fire protection, annual early or late dry season burning since 1934/35. Before establishment stems over 20.3 cm girth at breast height were enumerated. Three of the eight plots (one fire protected and two annually early burnt) were enumerated in 1982, 48–49 years after establishment. In addition, a coppice plot at Chitwi, 16 km southwest of the Ndola plots, cleared in 1972 and left to regenerate naturally was enumerated in May 1982 and August 1986 to assess woody plant growth.The density of stems over 20.0 cm girth in the 13-year-old coppice at Chitwi was 2.5 times that in an adjacent shelterbelt woodland. The stem density in the fire protected plot at Ndola in 1982 was 86% of the pre-felling density while in one of the early burnt plots it was 95% of the pre-felling density. The protected plot had the lowest species diversity after 49 years, largely because of the loss of 11 understorey species that were present before felling.There were no significant differences in stem mean girth at breast height (gbh) of canopy species in the Ndola plots under fire protection and early burning regimes. Mean annual gbh increments of abundant species were estimated at 1.17–2.21 cm yr−1 and 0.59–1.42 cm yr−1 during 0–9 and 0–49 year age-periods, respectively. Estimated mean annual basal area increments for stems over 30 cm gbh were 0.35 m2 ha−1 for the 13-year-old coppice and 0.24–0.27 m2 ha−1 for the 49-year-old coppice. These results indicate a decrease in both gbh and basal area increment with increasing age of miombo coppice

The effect of crown gall on growth of cherry trees

Over 1000 cherry trees, as rootstocks, nursery sweet cherry or ornamental cultivars or orchard trees up to 7 years old, with or without galls, were examined to determine the effect, if any, of crown gall disease on tree growth. No clear, consistent differences between healthy and galled trees were found. Healthy 1‐year‐old F12/ 1 rootstocks were smaller than their galled counterparts but the reverse was true for 2‐year‐old sweet cherries and ornamental cultivars. The mean girth of non‐galled 6‐year‐old trees of cv Schrecken was greater than that of galled trees from the same orchard. Detailed records on two sweet cherry cultivars, Napoleon and Roundel, revealed some differences in growth rate in the early years between healthy trees and those with various levels of galling at planting, but these differences were not sustained. Irrespective of gall status at planting no correlation was detected between final gall status and ultimate tree size. The data support the view that there is no consistent effect of crown gall on cherry tree growth and that the adverse appearance of affected nursery material is the main problem with this disease.

Bark stripping damage by red deer in a Sitka spruce forest in Western Scotland. I. Incidence

Bark stripping was monitored over a seven-year period on 240 permanent plots in Glenbranter Forest, Argyll. Sharp seasonal variation in incidence was found, rates being greatest in winter (December–March) and least in summer. There was very little damage in high-canopy ** forest (>44 years of age) or at the establishment stage (0–8 years). although 0.6 per cent y −1 of these younger trees were frayed. Trees aged 9–14, 15–28 and 29–44 years had mean rates of damage of 0.6, 1.0 and 0.5 per cent y −1 respectively. Norway spruce, only present in the pole and high-canopy stages, was more severely damaged than Sitka spruce. The incidence of bark stripping was patchy, the trees found damaged in the 3-month observation periods often being near neighbours. Over 2-year periods 74 per cent of the plots received no damage, but on 2 per cent of the plots >10 per cent of the trees were bark stripped. At such ‘hot-spots’ the intensity of damage was usually much lower in the preceding and following periods. However, individual trees suffered repeated bark stripping more often than would be expected by chance although the likelihood of repeated damage declined as time after the initial wounding increased. The trees damaged were quite variable in girth; their size was average on plots with mean girth of 20–40 cm, significantly bigger than average when mean girth was < 20 cm, and smaller than average above 40 cm mean girth. Rates of damage were not related to the number of red deer pellet groups deposited on 15×5 m plots; most dung occurred on vegetated plots yet bark stripping was commonest on plots without vegetation. But when plots within each forest stage were classified according to their position, most damage was found in the spatial zone with most dung (edge in thicket and high-canopy forest, interior in pre-thicket and polestage forest).

678 THE VALUES OF ABDOMINAL GIRTH MEASUREMENT

The clinical value of measuring neonatal abdominal girth is not well established although it is frequently recorded. We studied 43 newborns with gestational ages ranging from 28-40 weeks. Measurements were obtained shortly after birth and before feeding by encircling the abdomen such that the lower border of the tape measure was directly above the umbilicus and the two iliac crests. The data were analyzed by standard regression analysis techniques. The relationship of abdominal girth was greater with weight (r=.90) than with age (r=.83) although both were significant (P<0.05). The regression line for mean abdominal girth as a straight line function of weight is given by: Abdominal girth (cm)=18.90 ± 3.5 (kg). The standard deviation of points around the line equals 1.54 cm. (i.e.standard error of estimate). The following chart shows, at four selected weights, the estimated mean girth as given by the above regression equation. Preliminary data show that abdominal measurements outside the 95% prediction limits indicate possible gastrointestinal and abdominal pathology. Frequent abdominal girth measurements may be a useful screening procedure for gastrointestinal and abdominal pathology in pre-term and full term newborns.

Mapping forest biomass in India through aerial photographs and nondestructive field sampling

A method for mapping of forest biomass using black-and-white aerial photographs and nondestructive field sampling is described through a case study of Ladhiya subcatchment in Kumaun Himalaya, India. Forest types were mapped using aerial photographs and field checks. Each forest type was divided into five crown cover classes. Mean crown cover for each class was determined in the field. Density and basal cover were measured on reference sites. Stand biomass was estimated by using biomass estimation equations, mean girth and mean density on the reference sites. Regression equations were developed between crown cover and basal cover, and between crown cover and stand biomass. Mean basal cover and mean stand biomass for each photo-interpreted crown cover class were estimated through these equations. Forest biomass values were substituted for crown cover classes on the interpreted map.