Invasion of Bassendean Dune Banksia Woodland by Phytophthora cinnamomi

1994 ◽  
Vol 42 (6) ◽  
pp. 725 ◽  
Author(s):  
TCJ Hill ◽  
JT Tippett ◽  
BL Shearer
Keyword(s):  
Infection Rate ◽  
Water Table ◽  
Phytophthora Cinnamomi ◽  
Root Systems ◽  
Aerial Photographs ◽  
Dune System ◽  
First Order ◽  
Top 40 ◽  
Banksia Attenuata ◽  
Upper Slope

The rate and mechanism of the spread of Phytophthora cinnamomi in Banksia woodland of the Bassendean Dune system north of Perth, Western Australia was studied. Aerial photographs were used to measure the spread of disease in fronts longer than 5 km over 35 years. Fronts in upper slope positions moved downhill and uphill at 1.01 and 1.13 m year-1, respectively, while fronts in low-lying positions moved downgrade and upgrade (with and against the direction of water table flow) at 1.30 and 1.20 m year-1, respectively. Fronts in low-lying areas spread significantly faster than those on upper slopes. Excavations to 2 m depth of the root systems of 21 dying plants of Banksia attenuata R.Br., an overstorey co-dominant, revealed that 28% (3.9 roots/tree) of all first-order roots were infected. Assessment of the proportion of roots infected revealed a significant (P < 0.01) departure from uniform distribution of disease down the profile in both upper slope and drained flat sites. In 14 trees on dune slopes, 6-40 m above the aquifer, infection rate was higher than expected in roots lying at 21-40 cm depth, but lower than expected in roots below 1 m. Seventy three percent of infected roots lay in the top 40 cm of soil. In seven trees on a drained flat, 2-3 m above the aquifer, infection rate was high in the 21-60 cm horizon and also in roots below 1 m. Even though Phytophthora cinnamomi was active in the vicinity of the water table in trees on drained flats, the slow, steady spread of the disease in all landscape positions suggested that the primary mode of fungal invasion was through roots of susceptible vegetation. No evidence was found of accelerated spread of disease caused by the dispersal of zoospores.

The structure of Eucalypt roots

1976 ◽  
Vol 24 (5) ◽  
pp. 619 ◽  
Author(s):  
JT Tippett ◽  
TP O'Brien
Keyword(s):  
Comparative Study ◽  
Growth Rates ◽  
Phytophthora Cinnamomi ◽  
Root Systems ◽  
Root Anatomy ◽  
Age And Growth ◽  
First Order ◽  
Root Zones ◽  
Eucalypt Species ◽  
Finest Roots

The two eucalypt species Eucalyptus obliqua and E. st johnii differ in their susceptibility to Phytophthora cinnamomi, which infects their roots. A comparative study of the anatomy of the root systems of 12-week-old intermediate seedlings was made, the material used ranging in size from the finest roots to first order laterals. The root anatomy of the two species was similar but the species could be distinguished by differences in cortex persistence and in the rate of polyphenol accumulation. However, it was recognized that such differences were dependent on the age and growth rates of the roots sampled and could not be correlated with the differing susceptibilities of the two eucalypt species to Phytophthora cinnamomi. The walls of the exodermis and endodermis in both species are suberized and the ultrastructure of these walls was examined. Broad bands of suberized lamellae completely lined the exodermal cells in the zone of differentiation. In mature root zones the external radial walls of the epidermis were thickened and contained polyphenols. The roots which had commenced secondary thickening developed a specialized periderm, a polyderm, which consisted of alternating layers of suberized and non-suberized cells.

Impact and Disease Centre Characteristics of Phytophthora cinnamomi Infestations of Banksia Woodlands on the Swan Coastal Plain, Western Australia

1996 ◽  
Vol 44 (1) ◽  
pp. 79 ◽  
Author(s):  
BL Shearer ◽  
M Dillon
Keyword(s):  
Plant Species ◽  
Water Table ◽  
National Parks ◽  
Coastal Plain ◽  
Phytophthora Cinnamomi ◽  
Soil Surface ◽  
High Impact ◽  
Species Number ◽  
Dune System ◽  
Swan Coastal Plain

Phytophthora cinnamomi Rands was isolated from either dead plants or soil at 46 disease centres in Banksia woodland at national parks and reserves on the Swan Coastal Plain. Phytophthora cryptogea Pethybridge & Lafferty was also isolated from roots of dead Acacia pulchella R.Br. in one disease centre infected with P. cinnamomi. Dead plants were infected with Armillaria luteobubalina Watling & Kile in four disease centres on the Spearwood Dune System, and these centres were excluded from further analysis. Phytophthora cinnamomi diseased areas ranged from 0.01 to 30 ha in size (mean 1.6 ± s.e. 0.7 ha). The total area infested for the 46 disease centres was 71.5 ha. Impact of P. cinnamomi was high in 17% of disease centres and low in 11% of disease centres. Age of plant death was a mixture of old and recent in 85% of disease centres. Mainly old deaths occurred in only 4% of disease centres. The proportion of species dying in infested areas varied between 10-64% (mean 28 ± s.e. 2%) and was positively correlated with impact type. It was found that infestation decreased species number; on average, there were seven fewer species in infested compared to non-infested areas. Four plant species associated with moist sandy sites tended to occur more frequently in centres of high impact than by chance alone. Occurrence of P. cinnamomi was related to soil association with soils of 60% of the disease centres belonging to the Bassendean or Southern River associations of the Bassendean Dune System. Sixteen percent of disease centres occurred in the Cannington, Guildford and Serpentine River associations of the Pinjarra Plain. No disease centres of P. cinnamomi were found on soils of the Speanvood and Quindalup Dune Systems. A water table was found within 3 m of the soil surface in 48% of the centres. Disturbance was associated with all disease centres. Firebreaks were associated with 72% of disease centres. Banksia woodland remnants on the Bassendean Dune System and the Pinjarra Plain are highly vulnerable to infection by P. cinnamomi and their conservation requires control of existing infestatinns and protection from introduction af the pathogen.

Effects of Temperature on Root Morphology and Ectendomycorrhizal Development in Pinusresinosa Ait.

1975 ◽  
Vol 5 (2) ◽  
pp. 171-175 ◽  
Author(s):  
Hugh E. Wilcox ◽  
Ruth Ganmore-Neumann
Keyword(s):  
Root Growth ◽  
Root System ◽  
Root Morphology ◽  
Root Systems ◽  
Second Order ◽  
Root Temperature ◽  
First Order ◽  
Effects Of Temperature

Seedlings of Pinusresinosa were grown at root temperatures of 16, 21 and 27 °C, both aseptically and after inoculation with the ectendomycorrhizal fungus BDG-58. Growth after 3 months was significantly influenced by the presence of the fungus at all 3 temperatures. The influence of the fungus on root growth was obscured by the effects of root temperature on morphology. The root system at 16 and at 21 °C possessed many first-order laterals with numerous, well developed second-order branches, but those at 27 °C had only a few, relatively long, unbranched first-order laterals. Although the root systems of infected seedlings were larger, the fungus increased root growth in the same pattern as determined by the temperature.

scholarly journals Hydro-ecological controls on dissolved carbon dynamics in groundwater and export to streams in a temperate pine forest

2018 ◽  
Vol 15 (2) ◽  
pp. 669-691 ◽  
Author(s):  
Loris Deirmendjian ◽  
Denis Loustau ◽  
Laurent Augusto ◽  
Sébastien Lafont ◽  
Christophe Chipeaux ◽  
...  
Keyword(s):  
Water Table ◽  
Hydrological Cycle ◽  
Dissolved Inorganic Carbon ◽  
Shallow Groundwater ◽  
Pine Forest ◽  
Heat Fluxes ◽  
Similar Proportion ◽  
Forest Plot ◽  
Dissolved Carbon ◽  
First Order

Abstract. We studied the export of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) from forested shallow groundwater to first-order streams, based on groundwater and surface water sampling and hydrological data. The selected watershed was particularly convenient for such study, with a very low slope, with pine forest growing on sandy permeable podzol and with hydrology occurring exclusively through drainage of shallow groundwater (no surface runoff). A forest plot was instrumented for continuous eddy covariance measurements of precipitation, evapotranspiration, and net ecosystem exchanges of sensible and latent heat fluxes as well as CO2 fluxes. Shallow groundwater was sampled with three piezometers located in different plots, and surface waters were sampled in six first-order streams; river discharge and drainage were modeled based on four gauging stations. On a monthly basis and on the plot scale, we found a good consistency between precipitation on the one hand and the sum of evapotranspiration, shallow groundwater storage and drainage on the other hand. DOC and DIC stocks in groundwater and exports to first-order streams varied drastically during the hydrological cycle, in relation with water table depth and amplitude. In the groundwater, DOC concentrations were maximal in winter when the water table reached the superficial organic-rich layer of the soil. In contrast, DIC (in majority excess CO2) in groundwater showed maximum concentrations at low water table during late summer, concomitant with heterotrophic conditions of the forest plot. Our data also suggest that a large part of the DOC mobilized at high water table was mineralized to DIC during the following months within the groundwater itself. In first-order streams, DOC and DIC followed an opposed seasonal trend similar to groundwater but with lower concentrations. On an annual basis, leaching of carbon to streams occurred as DIC and DOC in similar proportion, but DOC export occurred in majority during short periods of the highest water table, whereas DIC export was more constant throughout the year. Leaching of forest carbon to first-order streams represented a small portion (approximately 2 %) of the net land CO2 sink at the plot. In addition, approximately 75 % of the DIC exported from groundwater was not found in streams, as it returned very fast to the atmosphere through CO2 degassing.

Evolution of a beach–dune system following a catastrophic storm overwash event: Greenwich Dunes, Prince Edward Island, 1936–2005

2010 ◽  
Vol 47 (3) ◽  
pp. 273-290 ◽  
Author(s):  
Sojan Mathew ◽  
Robin G.D. Davidson-Arnott ◽  
Jeff Ollerhead
Keyword(s):  
Prince Edward Island ◽  
National Park ◽  
Aerial Photographs ◽  
Dune System ◽  
Aerial Photos ◽  
Sand Supply ◽  
Digital Elevation ◽  
Intense Storm ◽  
Geomorphic Units ◽  
Subsequent Stabilization

Greenwich Dunes, Prince Edward Island National Park, is a sandy mainland and barrier spit beach–dune complex stretching for about 10 km along the northeast shore of Prince Edward Island, Canada. In October 1923, surge associated with an intense storm produced catastrophic overwash along the whole length of the study area. Subsequent evolution of the system was quantified from historic aerial photographs taken in 1936, 1953, 1971, 1997, and 2005. Orthophoto mosaics were generated for each photo set using PCI Geomatica OrthoEngine, a digital photogrammetric software. Linear changes in shoreline position and areal changes in geomorphic units were evaluated for each photo set. In addition, digital elevation models (DEMs) were extracted from the 1953, 1971, and 1997 aerial photos, enabling analysis of topographic and volumetric changes. The 1936 photos show complete destruction of all foredunes, with overwash and transgressive dunes extending 300 to 600 m inland. A descriptive model of the stages of evolution of the system is proposed based on the processes controlling overwash healing and dune stabilization. Detailed topographic and volumetric changes associated with the development of an extensive transgressive dunefield and subsequent stabilization as a result of reduced sand supply due to the growth of a new vegetated foredune complex and vegetation colonization are doccumented for each stage. It was nearly 40 years before a continuous foredune system was re-established and a further 30 years before the inland transgressive dunes became completely stabilized.

Tomato root distribution under furrow irrigation

1951 ◽  
Vol 2 (2) ◽  
pp. 118 ◽  
Author(s):  
K Spencer
Keyword(s):  
Root Distribution ◽  
Sandy Loam ◽  
Root Systems ◽  
Furrow Irrigation ◽  
Local Concentration ◽  
Tomato Root ◽  
Tomato Plants ◽  
Loam Soil ◽  
Two Measures ◽  
Top 40

The root distribution of mature tomato plants in a sandy loam soil under furrow irrigation was studied by measuring the lengths of roots washed from soil samples. Nearly 76 per cent. of the roots measured were found in the top 40 cm. of soil, but appreciable amounts of roots were found in the deepest samples (90-100 cm.). There were more roots half-way between plants in the row than closer to the plant, which suggests that mature root systems overlap when plants are spaced 29 ft. apart in the row. Distribution was compared for plants which had received an application of superphosphate and those which had not. Added phosphorus greatly increased the total length of roots and slightly increased the median root depth without much change in the relative values for these two measures between different lateral positions. In addition, there was some evidence for a local concentration of roots around the band of superphosphate. The relevance of the findings to cultivation and fertilizer practices in tomato culture is briefly discussed.

scholarly journals A Method of Applying Nutrients Locally to Roots Under Controlled Conditions, and Some Morphological Effects of Locally Applied Nitrate on the Branching of Wheat Roots

1972 ◽  
Vol 25 (6) ◽  
pp. 1169 ◽  
Author(s):  
C Hackett
Keyword(s):  
Root Systems ◽  
Extension Growth ◽  
Wheat Roots ◽  
First Order ◽  
Controlled Conditions

A method has been developed for examining the effect of locally applied ions on the initiation and early extension growth of first-order laterals of wheat roots. Features of the method are the avoidance of sealing, flexibility in the positioning of treatments, and freedom to examine the root systems during growth.

A landslide in till near Warman, Saskatchewan, Canada

1985 ◽  
Vol 22 (2) ◽  
pp. 195-204 ◽  
Author(s):  
E. Karl Sauer ◽  
E. A. Christiansen
Keyword(s):  
Shear Strength ◽  
Water Table ◽  
Back Analysis ◽  
Clay Content ◽  
Aerial Photographs ◽  
Adjacent Area ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Residual Shear Strength ◽  
Insight Into

Little information is available about typical shear strength parameters of tills in southern Saskatchewan even though till is the most common earth material used for construction in this region. The Warman landslide in the South Saskatchewan River Valley provides some insight into the shear strength characteristics of a till, and the results are compared with laboratory tests. The till is from the Upper till of the Sutherland Group, which has a high clay content relative to the underlying and overlying tills. A back analysis of the landslide produced [Formula: see text]′ = 27° assuming c′ = 0. Comparison with laboratory test data and results from a similar landslide near Lebret, Saskatchewan, suggests that [Formula: see text]′ = 22.5° with c′ = 7 kPa may be appropriate "residual" shear strength parameters. A rising water table appears to have been the main contributing factor to instability between 1969 and 1984. There is a possibility, however, that at the 1:50 return interval for flood levels on the river, erosion at the toe of the landslide debris may be a significant factor. Numerous slump scars in the form of small amphitheatres, presently inactive, can be observed in the aerial photographs of the adjacent area. These failures likely occurred intermittently, depending on fluctuating water table and river flood levels. Key words: landslide, till, correlation, stratigraphy, back analysis, shear strength, residual, aerial photographs.

scholarly journals Evaluating the Pathogenicity of Pythium vexans Isolates from Fraser Fir in North Carolina

2008 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Kelly L. Ivors ◽  
Z. Gloria Abad ◽  
D. Michael Benson
Keyword(s):  
North Carolina ◽  
Root Rot ◽  
Phytophthora Cinnamomi ◽  
Root Systems ◽  
Abies Fraseri ◽  
Fraser Fir ◽  
Pythium Vexans

The pathogenicity of Pythium vexans isolates collected from fir samples with typical root rot symptoms in North Carolina was evaluated on Fraser fir seedlings (Abies fraseri). Two replicated pathogenicity trials involving seven treatments were conducted in the lath house and greenhouse. Although the P. vexans isolates examined in these trials were able to colonize Fraser fir root systems, they did not cause mortality or incite root rot symptoms. In comparison, Phytophthora cinnamomi, a known aggressive pathogen of Fraser fir, caused severe root rot symptoms in all plants. These experiments provided no evidence that P. vexans is a pathogen of Fraser fir. Accepted for publication 12 July 2008. Published 6 October 2008.

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