Comparison of winter-active phalaris with the Australian cultivar under rotational grazing. 1. Basal area and plant density

1996 ◽  
Vol 36 (3) ◽  
pp. 277 ◽  
Author(s):  
RA Culvenor ◽  
RN Oram
Keyword(s):  
Soil Fertility ◽  
Growth Rates ◽  
Plant Density ◽  
Basal Area ◽  
Breeding Population ◽  
Rotational Grazing ◽  
Deep Soil ◽  
Small Areas ◽  
Phalaris Aquatica ◽  
Significant Mortality

Basal area and plant density in fixed quadrats are presented from a grazing trial comparing the persistence of 2 'winter-active' cultivars (Sirosa, Holdfast) and a breeding population (Perla Retainer) of phalaris (Phalaris aquatica L.) possessing high seedling and winter growth rates with the original cultivar Australian. Four replicate pastures, 2 at each of 2 sites near Canberra, were grazed year-round at 15 wethers/ha for 3 years using a rotational system of management (2 weeks on, 4 weeks off,). The first site, The Elms, was located on a slope with shallow, coarse-textured soil; the second, Boundary Creek, was level with deep soil which was very acid in the upper 20 cm. Both sites were fertilised with superphosphate and, except for small areas, were limed before sowing. Significant mortality was observed only at The Elms during the summer-autumn drought after grazing commenced, when plant death was highest for Australian and lowest for Perla Retainer, an erect, summer-dormant population. Basal area of Australian and Sirosa, but not Holdfast and Perla Retainer, subsequently recovered. Australian established and maintained a 50-70% higher basal area due to a 30-40% higher area per plant and 15-25% more plants. The cultivars did not differ markedly in persistence measured as stability of basal area. However, Perla Retainer showed less vegetative expansion at the first site after grazing commenced and was considered less persistent than the cultivars there. Persistence was correlated with the productivity of individual plots, all cultivars being affected similarly. Regressions which varied with cultivar were derived in which basal area at establishment, but not subsequent changes in basal area under grazing, was positively related to soil fertility factors, mainly phosphorus, potassium and manganese. An association between the initial basal area of Sirosa and soil magnesium levels was also detected at 1 site. It was concluded from this study, which was conducted in the absence of major drought, that the winter-active cultivars of phalaris can be as persistent as Australian under rotational grazing and with adequate soil fertility, but that interactions with site will occur.

Comparison of winter-active phalaris with the Australian cultivar under rotational grazing. 2. Dry matter on offer, pasture composition and animal production

1996 ◽  
Vol 36 (3) ◽  
pp. 287 ◽  
Author(s):  
RA Culvenor ◽  
JT Wood ◽  
RN Oram
Keyword(s):  
Basal Area ◽  
Breeding Population ◽  
Animal Production ◽  
Rotational Grazing ◽  
Second Year ◽  
A Site ◽  
Tiller Density ◽  
Autumn And Winter ◽  
Made In

Composition and amount of pasture on offer and animal productivity are presented from an experiment in which 2 'winter-active' cultivars (Sirosa, Holdfast) and a breeding population (Perla Retainer) of phalaris (Phalaris aquatica L.) bred for rapid growth in autumn and winter were compared with the original cultivar, Australian, under rotational grazing at 15 wethersfha for 3 years at 2 sites near Canberra. A change of cultivar rank in phalaris herbage on offer occurred in winter of the second year, whereby Australian became the highest ranked cultivar, reflecting its 50-70% higher basal area and 70% higher tiller density. However, pastures of the winter-active lines had an average 30% more phalaris on offer per unit basal area and per tiller, and a larger component of other, mainly annual, grass. This resulted in total pasture on offer at least equivalent to that of Australian pastures, and possibly more herbage production in autumn and winter. Sheep on the winter-active phalaris pastures were slightly heavier on average due mainly to higher weight gains in the first half of the year. These sheep produced an average over both sites of 7% more wool than sheep on Australian pastures, the advantage being higher at a site with dense phalaris (10%, P<0.01) than at a site with shallow, coarse-textured soil and less phalaris (3.5%, P = 0.11). It was concluded that pastures of the winter-active phalaris lines can give higher wool production than pastures of Australian phalaris, but not necessarily because of higher amounts of phalaris in the pasture. Benefits in the long term would also depend on persistence. Breeders of phalaris should aim to increase yield per unit of basal area if animal production gains in the short term are to be made in this environment, but compromises may be necessary between productivity and long-term persistence.

Geostatistically modeling stem size and increment in an old-growth forest

1994 ◽  
Vol 24 (7) ◽  
pp. 1354-1368 ◽  
Author(s):  
Franco Biondi ◽  
Donald E. Myers ◽  
Charles C. Avery
Keyword(s):  
Spatial Patterns ◽  
Growth Rates ◽  
Spatial Dependence ◽  
Basal Area ◽  
Tree Density ◽  
Individual Growth ◽  
Old Growth ◽  
Model Estimate ◽  
Stem Size ◽  
Old Growth Forest

Geostatistics provides tools to model, estimate, map, and eventually predict spatial patterns of tree size and growth. Variogram models and kriged maps were used to study spatial dependence of stem diameter (DBH), basal area (BA), and 10-year periodic basal area increment (BAI) in an old-growth forest stand. Temporal variation of spatial patterns was evaluated by fitting spatial stochastic models at 10-year intervals, from 1920 to 1990. The study area was a naturally seeded stand of southwestern ponderosa pine (Pinusponderosa Dougl. ex Laws. var. scopulorum) where total BA and tree density have steadily increased over the last decades. Our objective was to determine if increased stand density simply reduced individual growth rates or if it also altered spatial interactions among trees. Despite increased crowding, stem size maintained the same type of spatial dependence from 1920 to 1990. An isotropic Gaussian variogram was the model of choice to represent spatial dependence at all times. Stem size was spatially autocorrelated over distances no greater than 30 m, a measure of average patch diameter in this forest ecosystem. Because patch diameter remained constant through time, tree density increased by increasing the number of pine groups, not their horizontal dimension. Spatial dependence of stem size (DBH and BA) was always much greater and decreased less through time than that of stem increment (BAI). Spatial dependence of BAI was close to zero in the most recent decade, indicating that growth rates in 1980–1990 varied regardless of mutual tree position. Increased tree crowding corresponded not only to lower average and variance of individual growth rates, but also to reduced spatial dependence of BAI. Because growth variation was less affected by intertree distance with greater local crowding, prediction of individual growth rates benefits from information on horizontal stand structure only if tree density does not exceed threshold values. Simulation models and area estimates of tree performance in old-growth forests may be improved by including geostatistical components to summarize ecological spatial dependence.

scholarly journals Pedology and plant physiognomies in the cerrado, Brazil

2013 ◽  
Vol 85 (1) ◽  
pp. 87-102 ◽  
Author(s):  
ANDREZA V. NERI ◽  
CARLOS E.G.R. SCHAEFER ◽  
AGOSTINHO L. SOUZA ◽  
WALNIR G. FERREIRA-JUNIOR ◽  
JOÃO A.A. MEIRA-NETO
Keyword(s):  
Soil Fertility ◽  
Principal Components ◽  
Environmental Gradient ◽  
Basal Area ◽  
Spearman Correlation ◽  
Area Density ◽  
Soil Attributes ◽  
Al Content ◽  
Soil Features

This study was carried out in Paraopeba National Reserve. It aims to classify and evaluate the soil of the studied area and to verify the influence of soil attributes on vegetation by testing the following hypotheses: 1) under woodland physiognomies (Cerradão) the soil fertility is higher and the Al content lower; 2) open savanna occurs only in areas with high Al contents. For this purpose, representative soils in the Paraopeba National Reserve were mapped, identified, and samples from five profiles were analyzed. The environmental gradient was easily observed by principal components analyses, where the differences between the sites were highlighted. The Spearman correlation was used to verify the hypothesis. The correlation between vegetation (basal area, density, and richness) and soil (K, Ca2+, and Al3+) was statistically significant. The hypotheses were accepted, but hypothesis 1 only partially. Soil features seem to have an influence on the Cerrado phytophysiognomies and structure. Available phosphorous was an important factor for the maintenance of woodland Cerrado. Also, exchangeable Al3+ plays a major role in the establishment of different Cerrado physiognomies in Paraopeba National Reserve.

scholarly journals Overstory Effects on the Understory of Aleppo Pine Plantations—Implications for Ecosystem Restoration

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 664 ◽  
Author(s):  
Patrizia Tartarino ◽  
Roberto Greco ◽  
Joaquim S. Silva
Keyword(s):  
Plant Density ◽  
Land Reclamation ◽  
Pinus Halepensis ◽  
Canopy Cover ◽  
Basal Area ◽  
Ecosystem Restoration ◽  
Wiener Index ◽  
Aleppo Pine ◽  
Pine Plantations ◽  
Mediterranean Countries

At the end of the 19th century and along the first half of the 20th century, public policies in Mediterranean countries and elsewhere in Europe strongly promoted pine afforestation for land reclamation and wood production. In many cases, the transition to native forests, more resilient and more diverse, was also foreseen. This study aims to find the overstory characteristics that are best related to the understory of Aleppo pine (Pinus halepensis) plantations, to assist ecosystem restoration goals. We installed 33 circular plots in mature Aleppo pine plantations located in the southeastern Salento peninsula, Apulia, Italy. We measured overstory characteristics and the corresponding understory on these plots. We assessed the effects of overstory variables on understory development (plant density, plant height, and the Magini regeneration index) and diversity (species richness and the Shannon–Wiener index) using linear mixed models (LMM). Understory development and diversity were positively correlated with the Hart–Becking spacing index and negatively correlated with basal area and canopy cover, the three overstory variables that best explained variance. We used polynomial fitting and the subsequent derivation of these functions to determine the values of the Hart–Becking index and of the canopy cover that corresponded to the maximum development (33.7% and 84.6%, respectively) and diversity (32.6% and 86.5%, respectively) of the understory. Redundancy analysis (RDA) showed that late-successional species, including Quercus coccifera, were associated with higher levels of understory development and stand spacing. These results may assist in the restoration of native ecosystems in Aleppo pine plantations installed in similar ecological conditions.

scholarly journals Reproduction, Prey, and Habitat of the Aplomado Falcon (Falco Femoralis) in Desert Grasslands of Chihuahua, Mexico

The Auk ◽  
2004 ◽  
Vol 121 (4) ◽  
pp. 1081-1093 ◽  
Author(s):  
Alberto Macías-Duarte ◽  
Angel B. Montoya ◽  
W. Grainger Hunt ◽  
Alberto Lafón-Terrazas ◽  
Robert Tafanelli
Keyword(s):  
Nest Site ◽  
Plant Density ◽  
Breeding Population ◽  
Prey Abundance ◽  
Severe Drought ◽  
Bird Abundance ◽  
Start Date ◽  
Important Prey ◽  
Occupied Territory ◽  
Summer Rain

Abstract A breeding population of Aplomado Falcons (Falco femoralis) remains in the desert grasslands of Chihuahua, Mexico, despite their extirpation in the nearby southwestern United States. We monitored falcon reproduction at 35 territories during 1996-2002, a period of severe drought in the region. To test the influence of prey abundance and vegetation on falcon reproduction, we surveyed avian prey abundance through plot counts in 1998-2002 and characterized vegetation at each plot. Aplomado Falcon productivity declined from 1.57 fledglings per occupied territory in 1997 to 0.63 in 2002 at the larger of two study areas, a trend consistent with cumulative effects of consecutive years of low rainfall. Reproduction in the smaller area remained low throughout the study. Both productivity and incubation start date were significantly associated with prey bird abundance. Summer rain most likely influenced falcon reproduction by affecting seed abundance and therefore abundance of granivorous prey birds the following winter and spring. Falcons nested in open grasslands with sparse woody vegetation, an adaptation likely related to higher prey vulnerability and fewer predators. However, important prey birds were positively correlated with woody-plant density, which suggests that proximity of shrublands increased nest-site suitability.

Growth and wood quality of young loblolly pine trees in relation to stand density and climatic factors

1988 ◽  
Vol 18 (7) ◽  
pp. 851-858 ◽  
Author(s):  
B. M. Cregg ◽  
P. M. Dougherty ◽  
T. C. Hennessey
Keyword(s):  
Specific Gravity ◽  
Loblolly Pine ◽  
Growth Rates ◽  
Basal Area ◽  
Summer Rainfall ◽  
Tree Size ◽  
Basal Area Growth ◽  
Area Growth ◽  
Summer Growth ◽  
Stand Basal Area

A 10-year-old stand of loblolly pine (Pinustaeda L.) in southeastern Oklahoma was thinned to three target basal-area levels: 5.8, 11.5, and 23 m2•ha−1 (control). Specific gravity, latewood percentage, date of transition from earlywood to latewood, growth, and climate variables were measured for 2 years after thinning. Variation in the measured wood properties was more influenced by climatic variation than by the thinning treatments. Diameter growth and per-tree basal-area growth were significantly greater on the thinned treatments both years after thinning. However, stand basal-area growth was greatest on the unthinned treatment. Basal-area growth rates were significantly related to stand basal area, tree size, soil water potential, and air temperature. Early in the summer, growth was positively related to mean daily temperature, while later in the summer, growth was negatively related to mean daily temperature, reflecting the influence of high-temperature stress on growth. A year with high summer rainfall (1984) resulted in wood with a higher percentage of latewood and higher specific gravity than wood produced in a year with low summer rainfall (1985). The date of latewood initiation was significantly related to tree size, soil moisture, and evaporative demand. The date of transition from earlywood to latewood occurred 10–14 days sooner on the unthinned plots in both years. However, annual ring latewood percentage and specific gravity were not significantly affected by thinning. Increased late-season growth rates compensated for the later transition date on the thinned treatments, resulting in no net change in ring latewood percentage due to thinning. The results indicate that individual tree basal-area growth can be increased by thinning without reducing wood density.

Agreement between floristic and soil organic carbon isotope (13C/12C, 14C) indicators of forest invasion of savannas during the last century in Cameroon

2001 ◽  
Vol 17 (6) ◽  
pp. 809-832 ◽  
Author(s):  
BERNARD GUILLET ◽  
GASTON ACHOUNDONG ◽  
JOSEPH YOUTA HAPPI ◽  
VÉRONIQUE KAMGANG KABEYENE BEYALA ◽  
JACQUES BONVALLOT ◽  
...  
Keyword(s):  
Organic Matter ◽  
Carbon Isotope ◽  
Large Diameter ◽  
Age Distribution ◽  
Basal Area ◽  
Floristic Composition ◽  
Linear Process ◽  
Deep Soil ◽  
Mature Forest ◽  
Large Tree

In an area of savanna-forest (S-F) mosaic of Cameroon, at Kandara near Bertoua, an enclosed savanna bordered by young semi-deciduous forests was selected for detailed studies of vegetation and soil carbon isotope compositions with a view to estimating the rate of forest advance into savannas. Forest floristic composition and structure were analysed in small plots along two S-F transects and within two large stands. Tree species counts and basal area (BA) measurements gave convergent results defining (1) an edge forest with low BA values that forms an irregular strip parallel to the S-F border, (2) a large colonization zone zone composed of pioneer species (Albizia species, with individuals of very large diameter) and (3) a mature forest composed of abundant Rinorea individuals and large individuals of Triplochiton scleroxylon and Piptadeniastrum africanum. Carbon stable isotopes were deter mined from organic matter of soil profiles sampled at various depths in savanna, colonization-zone and mature forest. In the deep soil horizons (40-50 cm) of the colonization-zone profiles, δ13C values similar to those of the present savanna reveal the past existence of a large-tree savanna. In subsurface horizons (15-20 cm), δ13C values intermediate between those of savanna and mature forest prove the encroachment of the forest ecosystem on savanna. Using 14C measurements, the mean residence time (MRT) of soil organic matter of these last horizons was determined with precision owing to the atmospheric 14C pulse from nuclear bomb tests prior to 1964. By assuming an exponential age distribution of organic compounds and by taking account of MRT and remaining carbon from the savanna, the coloniza tion zone was found to be 60-80 y old. The age of the colonization zone being the same near the present savanna and near the mature forest, it seems that the forest advance was probably not a linear process but would result from the coalescence of Albizia thickets born in savanna.

Stem borer damage in maize as affected by host plant density

1981 ◽  
Vol 96 (3) ◽  
pp. 695-697 ◽  
Author(s):  
E. O. Ogunwolu ◽  
K. Nwosu ◽  
S. O. Ogunyebi
Keyword(s):  
Host Plant ◽  
Plant Density ◽  
Stem Borer ◽  
Pest Population ◽  
Current Standard ◽  
Research Attention ◽  
Small Areas ◽  
Collective Effort ◽  
Host Plant Density ◽  
Maize Grain

Maize grain production in Nigeria is the collective effort of several growers individually cropping small areas. In these farms, maize stands are at suboptimal densities, soil fertility is low and crop loss from pests is high. Consequently, grain yields are characteristically low. By planting maize at closer spacing than the current standard, 90 x 25 cm, Fayemi (1963), Chinwuba (1967), and Okigbo (1972) were able to raise grain yield. However, the effect on pest population in Nigeria of increasing host plant density has received little research attention. Cromartie (1975) showed that host plant density and arrangement affect insect population dynamics. Other reports by Ficht (1932), Finch & Skinner (1976), Ralph (1977), Zepp & Keaster (1977), Adesiyun (1978) and Mayse (1978) indicate differential insect colonization, establishment and damage on host plants sown at different densities.

Bottom-up impact of soils on the network of soil, plants, and moths (Lepidoptera) in a South Korean temperate forest

2015 ◽  
Vol 147 (4) ◽  
pp. 405-418 ◽  
Author(s):  
Sei-Woong Choi
Keyword(s):  
Species Richness ◽  
Soil Fertility ◽  
Plant Diversity ◽  
Basal Area ◽  
Clay Content ◽  
Mountain Forest ◽  
Bottom Up ◽  
South Korean ◽  
Moth Species ◽  
Total Tree

AbstractThe influence of soil properties on the diversity of plants and moths (Lepidoptera) were examined in two South Korean high mountain forest localities (Mount Hallasan and Mount Jirisan) and one seashore mountain forest locality (Mount Seungdalsan). Six sites at each locality were included in the study. Soil physical and chemical properties and plant data were obtained from 20×20 m quadrats at every moth sampling site. Moth community data were obtained from the 18 sites. Stepwise regression analysis identified total tree basal area and tree species richness as significant determinants of moth species richness, and plant diversity index as a significant determinant of moth abundance. Total tree basal area was closely related to organic matter (OM), clay content, NaCl concentration, and pH, and plant diversity was closely related to clay content. Nonmetric multidimensional scaling ordination between plant and moth species across 18 sites and 17 soil variables showed that soil fertility factors (OM, total nitrogen content, and cation exchange capacity) were major variables. Our results indicate that soil, plants, and moths communities in temperate forests form a close, interacting network that is primarily affected by the bottom-up impact of soil fertility.

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