Regeneration of Vegetation in the Brisbane Ranges After Fire and Infestation by Phytophthora cinnamomi

1985 ◽  
Vol 33 (1) ◽  
pp. 15 ◽  
Author(s):  
P Dawson ◽  
G Weste ◽  
D Ashton
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Phytophthora Cinnamomi ◽  
Basal Area ◽  
First Record ◽  
Inoculum Density ◽  
Crown Cover ◽  
Bush Fire ◽  
Crown Density ◽  
Sclerophyll Forest

The distribution, population density and regeneration of some prominent spp. of understorey and overstorey (dominant Eucalyptus spp.) were monitored over a period of 20 yr in seasonally well drained dry sclerophyll forest. Changes varied with susceptibility to the pathogen and to fire. Changes in spp. composition and crown density of the overstorey were attributed to fire. Population density, basal area and crown cover of the Eucalyptus spp. which were associated with the pathogen, also declined in 1962-82. Both distribution and population density of Xanthorrhoea australis and Isopogon ceratophyllus declined markedly following the spread of infestation, whereas those of Hakea sericea and Lepidosperma semiteres increased. Regeneration of X. australis but not of I. Ceratophyllus was observed in certain areas of the infested plots 12-20 years after infection. This is the first record of such regeneration. It is postulated that a bush fire in 1967 both stimulated X. australis seed production and reduced further an already declining pathogen inoculum density.

Rate of Disease Development in Eucalyptus sieberi Growing in Suppressive Soils Inoculated With Phytophthora cinnamomi

1985 ◽  
Vol 33 (2) ◽  
pp. 159 ◽  
Author(s):  
GC Marks ◽  
IW Smith
Keyword(s):  
Post Infection ◽  
Phytophthora Cinnamomi ◽  
Inoculum Density ◽  
Disease Development ◽  
The Core ◽  
Development Rates ◽  
Core Soil ◽  
Compound Interest ◽  
Root Collar

The rate at which root collar infection, caused by Phytophthora cinnamomi Rands, developed in Eucalyptus sieberi L. Johnson was tested by growing 40, 6-month-old seedlings in cores of disease- suppressive (DSS) krasnozem-type soil that had either been treated or not treated with steam. The core soil was inoculated by repotting the seedlings in a jacket of steamed or unsteamed sand or krasnozem that had been mixed with a mycelium-chlamydospore suspension. Disease development was of the compound interest type (sens. Van der Plank) and was slower in unsteamed DSS core soils. Inoculum density (ID) increased more than 10 times at the end of all tests, and the time taken for collar infection to appear was shortened when the inoculum was mixed with unsteamed DSS. The fungus was isolated more frequently from the collar of seedlings growing in steam-treated than in unsteamed DSS. The results showed that the soil used was only mildly disease-suppressive and suggest that post- infection antagonism may be the cause of slower disease development rates in DSS. Introduction

scholarly journals POPULATION DENSITY IN HYDROPONICS CULTURE FOR POTATO TUBER-SEED PRODUCTION (Solanum tuberosum L.)

2009 ◽  
Vol XV (3) ◽  
pp. 251-258 ◽  
Author(s):  
R. Flores-López ◽  
◽  
F. Sánchez-del Castillo ◽  
J. E. Rodríguez-Pérez ◽  
M. T. Colinas-León ◽  
...  
Keyword(s):  
Solanum Tuberosum ◽  
Population Density ◽  
Potato Tuber ◽  
Seed Production ◽  
Solanum Tuberosum L

Long-Term Development of Regeneration Under Longleaf Pine Seedtree and Shelterwood Stands

1993 ◽  
Vol 17 (1) ◽  
pp. 10-15 ◽  
Author(s):  
William D. Boyer
Keyword(s):  
Seed Production ◽  
Seedling Establishment ◽  
Longleaf Pine ◽  
Basal Area ◽  
Pinus Palustris ◽  
Stand Density ◽  
Distribution Characteristic ◽  
Volume Increment ◽  
Potential Impact

Abstract Well-stocked mature longleaf pine (Pinus palustris Mill.) stands were cut to five residual basal areas in 1957, namely 9, 18, 27, 36, and 45 ft² per ac, to observe the effect of stand density on seed production and seedling establishment. Seedlings, mainly from the 1955 or 1961seed crops, were established in treated stands. All pines on net 0.9 ac plots were remeasured in 1991 to determine the effect of residual pine density on development of the regeneration. Even the lightest residual overstory converted the structure of 29- to 35- yr-old ingrowth into the reverse-Jdiameter class distribution characteristic of uneven-aged stands. Four or six residual trees, now comprising 7 to 10 ft² basal area (ba)/ac, reduced ingrowth basal area to about half that of same-aged stands released from overstory competition. Merchantable volume of ingrowth under theselow residual densities averaged 40% of that in released stands. Mean annual per ac volume increment of ingrowth averaged 21 to 22 ft³ under the 9 ft² density but did not exceed 7 ft³ under any residual density above this. The potential impact of significant growth reductionsshould be taken into account when considering uneven-aged management methods for longleaf pine. South. J. Appl. For. 17(1):10-15.

scholarly journals Breeding value of Norway spruce (Picea abies [L.] Karst.)

2012 ◽  
Vol 50 (No. 1) ◽  
pp. 17-23
Author(s):  
Rożkowski KR
Keyword(s):  
Survival Rate ◽  
Norway Spruce ◽  
Growth Traits ◽  
Block Design ◽  
Basal Area ◽  
Tree Height ◽  
Breeding Value ◽  
Cross Sectional ◽  
Qualitative Traits ◽  
Crown Density

This is the first report on measurements and observations of an experimental plot of 35-year-old Norway spruce, established in 1970 by the Institute of Dendrology at K&oacute;rnik, where progenies of 22 plustrees from the Kłodzko Forest District were planted. The experiment was established in an incomplete block design of 20 families with 3 replications. Survival rate and growth traits determining productivity (plant height or basal area &ndash; stem cross-sectional area at breast height per 1&nbsp;ha) were assessed in several years, and qualitative traits (trunk straightness; degree of natural pruning; thickness, length and angle of branches; crown density; presence of galls caused by the aphids Adelges laricis Vall. and Sacchiphantes viridis Ratz.) were evaluated once in 2001. Analysis of variance revealed significant differences between the half-sib families in survival rate and productivity but no significant differences in qualitative traits. Statistically significant positive correlations were found between trunk straightness at the age of<br />&nbsp;36 years and height of 2-year-old seedlings in the nursery, and between the degree of natural pruning at the age of 36 years and both tree height at the age of 9 years and basal area at the age of 13 years.

scholarly journals Crop density and seed production of tall fescue (Festuca arundinacea Schreber). 1. Yield and plant development

1999 ◽  
Vol 79 (4) ◽  
pp. 535-541 ◽  
Author(s):  
N. A. Fairey ◽  
L. P. Lefkovitch
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Seed Yield ◽  
Tall Fescue ◽  
Festuca Arundinacea ◽  
Plant Density ◽  
Initial Density ◽  
Row Spacing ◽  
Initial Population ◽  
Crop Density

A field study was conducted with tall fescue (Festuca arundinacea Schreber) to determine the effect of the initial population density and spatial arrangement of plants on crop development and seed yield. Individual seedling plants were transplanted at seven densities (1.6, 3.1, 6.3, 12.5, 25, 50, and 100 plants m−2) and three row spacings (20, 40, and 80 cm), and characteristics of seed production were determined for 3 yr (1991–1993). Over the 3 yr, heading commenced at dates differing by 15 d and was delayed, as density increased, by 8, 6, and 2 d, respectively, in the first, second, and third production years. The time of seed maturity differed among years (21 July to 4 August) but was generally unaffected by density or row spacing. In the first production year, seed yield increased with density up to 25 plants m−2 for each row spacing, then remained constant to at least 50 plants m−2 with both 20- or 40-cm rows; it decreased slightly at 100 plants m−2 with 20 cm rows. In the second production year, seed yield was relatively independent of plant density except that it decreased when the initial density was less than 6 plants m−2 with a row spacing of 80 cm, and tended to be greatest with the 40-cm row spacing at 6–25 plants m−2. In the third production year, seed yield was much lower than in the previous 2 yr but the pattern of response to the density and row spacing treatments was similar to that in the second production year. The seed yield of tall fescue can be optimized for at least 3 consecutive years by establishing an initial density of 20–100 plants m−2 in rows spaced 20–60 cm apart. If the maximization of first-year seed yield is a priority, then the initial establishment should be at a density of 25–50 plants m−2 in rows spaced 20–40 cm apart. Key words: Tall fescue, Festuca arundinacea Schreber, population density, plant spacing, seed production

Vegetation Changes as a Result of Invasion of Forest on Krasnozem by Phytophthora cinnamomi

1980 ◽  
Vol 28 (2) ◽  
pp. 139 ◽  
Author(s):  
G Weste
Keyword(s):  
Pinus Radiata ◽  
Phytophthora Cinnamomi ◽  
First Year ◽  
Acacia Dealbata ◽  
Sclerophyll Forest ◽  
Lower Height ◽  
Leaf Spot Fungus ◽  
Future Status ◽  
Reduced Water ◽  
Increased Susceptibility

Disease caused by Phytophthora cinnamomi was studied for 5 years in native and planted forest growing on krasnozem in the northern foothills of the Great Dividing Range at Narbethong, 100 km northwest of Melbourne. Changes in species composition were recorded for three sites carrying mature dry sclerophyll forest of Eucalyptus obliqua and Eucalyptus radiata, young plantations of E. obliqua, and young plantations of Pinus radiata. The mature ecualypts were diseased in 1974 and now are gradually dying. The young E. obliqua showed greater resistance than the older trees to the pathogen but infected trees were characterized by lower height, small leaves with reduced water potential, and an increased susceptibility to the leaf spot fungus Aulographina eucalypti. Susceptible understorey species such as Tetratheca ciliata and Epacris impressa died, but seedling regeneration of these has since occurred on one site. No species has disappeared from all three sites but T. ciliata and Daviesia latifolia almost disappeared from site 2, and the total number of plants was reduced. Species such as Leptospermum juniperinum and Platylobium formosum developed fluctuating cycles of chlorosis and die-back followed by either recovery or death. Resistant plants such as sedges, grasses and Acacia dealbata invaded the diseased forest. During the first year of the investigation 13% of the 4-year-old Pinus radiata died, but this particular site was well drained, warmer and drier than the others and the surviving pines later grew vigorously and crowded out other species. Symptoms are no longer evident on this site. The future status of the mature forest and the probable effects of disease on the young E. obliqua plantation are discussed.

Effects of Sheep Grazing Astrebla Grasslands in Central Western Queensland. Iii. Dynamics of Astrebla Spp. Under Grazing and Exclosure Between 1975 and 1986.

1991 ◽  
Vol 13 (1) ◽  
pp. 36 ◽  
Author(s):  
DM Orr ◽  
CJ Evenson
Keyword(s):  
Population Dynamics ◽  
Seed Production ◽  
Basal Area ◽  
Summer Rainfall ◽  
High Variability ◽  
Plant Population ◽  
Sheep Grazing ◽  
Plant Population Dynamics ◽  
Winter Rainfall ◽  
Plant Populations

The basal area, yield and plant populations of Astrebla spp. were monitored under grazing and exclosure in Astrebla grasslands between 1975 and 1986. This study was undertaken to develop an understanding of how Astrebla spp. respond to grazing, particularly in relation to the high variability of rainfall. Basal area and yield of Astrebla spp. varied widely between years in response to summer rainfall, with few differences between exclosure and grazing. The failure of summer rainfall resulted in increased utilization of Astrebla spp. but this effect was partially offset in some years by the growth of forb species following winter rainfall. Grazing stimulated the recruitment of Astrebla spp. seedlings by increasing the density of inflorescences which, in turn, increased seed production. Survival of seedling cohorts depended on adequate summer rainfall and grazing tended to enhance cohort survival. There was a greater plant flux under grazing than under exclosure. It was concluded that rainfall is the major factor influencing the biomass and plant population dynamics of Astrebla spp. and that grazing up to about 30% utilization is not detrimental to Astrebla spp.

scholarly journals Seed Availability Does Not Ensure Regeneration in Northern Ecosystems of the Endangered Limber Pine

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 146 ◽  
Author(s):  
Vernon S. Peters ◽  
Darcy R. Visscher
Keyword(s):  
Seed Production ◽  
Abiotic Factors ◽  
A Priori ◽  
Production Capacity ◽  
Basal Area ◽  
Forest Composition ◽  
Theoretic Approach ◽  
Limber Pine ◽  
Seed Availability ◽  
Pine Regeneration

Research Highlights: When biotic interactions such as disease alter both the seed production capacity of stands, and seedling survivorship, the relative importance of seed availability versus substrate specificity may alter future regeneration opportunities for plant populations. Background and Objectives: We investigated the importance of disease severity, seed availability, and substrate limitation to the regeneration dynamics of the endangered limber pine, Pinus flexilis, in two ecosystems with varying forest composition, and different histories of white pine blister rust infection (WPBR; Cronartium ribicola). Materials and Methods: A total of 17 stands from the montane ecoregion (Alberta, Canada) were sampled for seed production between 2007–2010, seedling density, and age structure. Model selection using an information theoretic approach compared a series of a priori models and their combinations, based on our hypotheses on the role biotic variables play in the regeneration process. Results: Despite higher rates of WPBR infection, 2.3 times more seed was available for avian dispersers in the southern ecosystem. Recent seedling regeneration did not correspond to seed production (83 versus 251 seedlings/ha, in southern versus northern ecosystems, respectively), resulting in a seven-fold difference in seed to seedling ratios between ecosystems. Models suggest that disease and vegetation cover were important factors explaining the absence of regeneration in 79.4% of the plots sampled, while basal area (BA) of live limber pine, rocky substrates, ecosystem, South aspects, and slope enhanced limber pine regeneration. Seedling age structures suggest that recent regeneration is less likely in more diseased landscapes, than it was historically (40% versus 72.8% of seedlings < 20 years old, respectively, in southern versus northern ecosystems). Conclusions: At the northern limits of limber pine’s range, seed availability does not ensure regeneration, suggesting that other environmental or biotic factors hinder regeneration. Regeneration was consistently predicted to be lower in the southern ecosystem than in the northern ecosystem, suggesting that natural regeneration and the potential for population recovery are ecosystem dependent. We recommend that monitoring recent seedlings will aid the identification of biotic and abiotic factors affecting regeneration.

Sign in / Sign up

Export Citation Format

Share Document