Response of rock-outcrop and fringing vegetation to disturbance by fire and drought

2007 ◽  
Vol 55 (7) ◽  
pp. 736 ◽  
Author(s):  
Andrew Benwell
Keyword(s):  
Shoot Growth ◽  
Growth Form ◽  
Habitat Type ◽  
Fire Frequency ◽  
Categorical Variables ◽  
Seedling Density ◽  
Rock Outcrop ◽  
Trophic Conditions ◽  
Density Response ◽  
Shoot Growth Rate

A comparative study of vegetation responses to fire and drought investigated whether species regeneration mode, seedling density response (SDR) and seedling shoot growth rate varied significantly in relation to disturbance agent (fire and drought), habitat type (rock-outcrop and fringing vegetation) and plant growth form. A three-way ANOVA showed that SDR varied significantly in relation to all three categorical variables and most strongly in relation to disturbance agent. Seeders comprised 87% of the post-fire flora and 99.3% of the peak seedling population in rock-outcrop habitat, while resprouters were much more prominent in fringing woodland. Species SDRs and seedling growth rates were generally much higher after fire. Fire produced a high SDR with high shrub, grass and ephemeral therophyte components, and drought produced a low SDR dominated by grasses and herbs and inhibited shrub and ephemeral recruitment. Post-fire obligate-seeder shrubs behaved as facultative resprouters after drought. Some species exhibited SDRs equivalent to fire and drought, others appeared to require fire for regeneration, while others recruited more successfully after drought. This spectrum of responses indicated a range of optimal disturbance environments, depending on species, which was only partly consistent with the hypothesis that species exhibit essentially the same life-history syndromes in response to fire and drought. The dominance of seeders in outcrop vegetation appeared to be related to skeletal soil, higher disturbance frequency and soil trophic conditions, rather than low fire frequency.

Life history and morphological variation in intraspecific seeder and resprouter populations of two species from rock outcrop vegetation in north-east New South Wales

2011 ◽  
Vol 59 (3) ◽  
pp. 197 ◽  
Author(s):  
Andrew Benwell ◽  
Bruce McCorkell
Keyword(s):  
Life History ◽  
Life Histories ◽  
Morphological Traits ◽  
Shoot Growth ◽  
Fire Regime ◽  
Habitat Type ◽  
Rock Outcrop ◽  
Experimental Conditions ◽  
North East ◽  
Shoot System

The processes underlying differentiation of seeder and resprouter life histories were explored by studying changes in life history and morphological traits in intraspecific seeder and resprouter populations of the grass Entolasia stricta and shrub Keraudrenia hillii var. hillii from adjoining rock pavement and fringing woodland habitats. Population traits were sampled in the field and studied under controlled conditions in a randomised experimental design with two levels of population/habitat (seeder/rock outcrop and resprouter/woodland) and two levels of fertiliser (low and high). Life history traits reflecting rate of growth, relative allocation of resources to reproductive and vegetative growth and timing of events, as well as a selection of simple morphological traits were recorded. Generalised linear model analysis showed that population had a strong, significant effect on the majority of traits examined, particularly those relating to reproductive output. Many traits were also significantly responsive to nutrient, or induced plasticity, and significant interaction terms were very few. The two species exhibited parallel intraspecific changes in life history between habitats and traits recorded under experimental conditions were similar to those observed in the field. The populations from pavement shrubland produced a more compact shoot system, faster early shoot growth (E. stricta), more numerous flowers and more numerous and lighter seeds. In fringing woodland, both species produced a larger shoot system, slower early shoot growth and fewer and larger seeds. Significant intraspecific differences in population traits and correlation of population with habitat type indicated that the intraspecific seeder-resprouter populations of both species were ecotypes selected by habitat factors, most likely associated with the edaphic environment rather than fire regime variables.

Post-fire Seedling Recruitment in Coastal Heathland in Relation to Regeneration Strategy and Habitat

1998 ◽  
Vol 46 (1) ◽  
pp. 75 ◽  
Author(s):  
Andrew S. Benwell
Keyword(s):  
Growth Rate ◽  
Shoot Growth ◽  
Seedling Recruitment ◽  
Seedling Survival ◽  
Regeneration Strategy ◽  
Seedling Density ◽  
Fire Response ◽  
Ecotypic Variation ◽  
North Eastern ◽  
Shoot Growth Rate

Post-fire seedling recruitment was studied at six heathland sites near Evans Head, north-eastern NSW, in a range of habitats from dry to wet sand-heath. Species fire responses were recorded and seedling density, seedling survival and seedling shoot-growth rate were monitored for 3 years. There were marked differences in total seedling density and survivorship in different habitats, caused by several possible factors. Obligate seeders and facultative resprouters were found to have overlapping yet broadly distinctive patterns of seedling recruitment behaviour. Facultative resprouters as a group had significantly lower levels of seedling density and survival than obligate seeders. Six species exhibited ecotypic variation in mode of regeneration, five accompanied by marked changes in seedling density. Patterns of seedling recruitment behaviour in relation to fire response and habitat were consistent with the theory that resprouting is a stress-tolerant regeneration strategy and that for a given species regeneration strategy is linked with habitat quality.

Shoot Growth Rate of Soybean as Affected by Drought Stress 1

1987 ◽  
Vol 79 (4) ◽  
pp. 598-607 ◽  
Author(s):  
Gerrit Hoogenboom ◽  
Curt M. Peterson ◽  
M. G. Huck
Keyword(s):  
Growth Rate ◽  
Drought Stress ◽  
Shoot Growth ◽  
Shoot Growth Rate

scholarly journals Analysis of Cold-Developed vs. Cold-Acclimated Leaves Reveals Various Strategies of Cold Acclimation of Field Pea Cultivars

2019 ◽  
Vol 11 (24) ◽  
pp. 2964 ◽  
Author(s):  
Alexandra Husičková ◽  
Jan F. Humplík ◽  
Miroslav Hýbl ◽  
Lukáš Spíchal ◽  
Dušan Lazár
Keyword(s):  
Cold Acclimation ◽  
Shoot Growth ◽  
Photosynthetic Performance ◽  
The Other ◽  
Remote Sensing Technology ◽  
Sensing Technology ◽  
Quenching Analysis ◽  
Shoot Growth Rate ◽  
Whole Plants

Peas (Pisum sativum L.) belong among the world’s oldest domesticated crops, serving as a source of proteins, complex carbohydrates, vitamins and minerals. Autumn sowing allows a higher biomass production as well as the avoidance of the drought and heat stresses of late spring. However, the character of European continental winters limits plant growth and development through cold stress. This work sought parameters that reflect the cold tolerance of pea plants and consequently to suggest an afila-type pea cultivar with resilience to European continental winters. For this purpose, we employed indoor remote sensing technology and compared the 22-day-long acclimation to 5 °C of four pea cultivars: Arkta, with normal leaves and the known highest cold resistance to European continental winters, and Enduro, Terno and CDC Le Roy, all of the afila type. Besides evaluation of shoot growth rate and quenching analysis of chlorophyll fluorescence (ChlF) by imaging methods, we measured the chlorophyll content and ChlF induction with a nonimaging fluorometer. Here we show that the acclimation to cold of the Arkta exhibits a different pattern than the other cultivars. Arkta showed the fastest retardation of photosynthesis and shoot growth, which might be part of its winter survival strategy. Terno, on the other hand, showed sustained photosynthetic performance and growth, which might be an advantageous strategy for spring. Surprisingly, Enduro showed sustained photosynthesis in the stipules, which transferred and acclimated to 5 °C (cold-acclimated). However, of all the cultivars, Enduro had the strongest inhibition of photosynthesis in new stipules that developed after the transition to cold (cold-developed). We conclude that the parameters of ChlF spatial imaging calculated as averages from whole plants are suboptimal for the characterization of various cold acclimation strategies. The most marked changes were obtained when the new cold-developed leaves were analyzed separately from the rest of the plant.

Growth and Development of Field Horsetail (Equisetum arvenseL.)

Weed Science ◽  
1986 ◽  
Vol 34 (2) ◽  
pp. 271-275 ◽  
Author(s):  
George Marshall
Keyword(s):  
Growth And Development ◽  
Dry Matter ◽  
Shoot Growth ◽  
Equisetum Arvense ◽  
Shoot Height ◽  
Potted Plants ◽  
Shoot Number ◽  
Herbicide Treatments ◽  
Shoot Growth Rate ◽  
Rhizome System

The growth and development of field horsetail (Equisetum arvenseL. # EQUAR) was measured outdoors using potted plants grown from one-node rhizome fragments. Shoot growth rate increased slowly after planting in March, accelerating to a maximum during July with maximas for shoot height during August and shoot number in September. Rhizome system growth rates initially followed a similar pattern to that of the shoots achieving a maximum during July. Dry matter accumulated in the rhizomes until October and declined thereafter throughout the winter. Tubers initiated during August grew in size and number until November, well beyond the period of active shoot growth and onset of senescence. The characteristics of the growth and development of field horsetail are discussed in relation to achieving weed control via cultural and herbicide treatments.

scholarly journals Periphyton Function in Lake Ecosystems

2002 ◽  
Vol 2 ◽  
pp. 1449-1468 ◽  
Author(s):  
Yvonne Vadeboncoeur ◽  
Alan D. Steinman
Keyword(s):  
Light Availability ◽  
Habitat Type ◽  
High Water ◽  
Nutrient Cycles ◽  
Lake Morphometry ◽  
Trophic Conditions ◽  
Lake Ecosystems ◽  
Food Web Interactions ◽  
Spatial Hierarchy

Periphyton communities have received relatively little attention in lake ecosystems. However, evidence is increasing that they play a key role in primary productivity, nutrient cycling, and food web interactions. This review summarizes those findings and places them in a conceptual framework to evaluate the functional importance of periphyton in lakes. The role of periphyton is conceptualized based on a spatial hierarchy. At the coarsest scale, landscape properties such as lake morphometry, influence the amount of available habitat for periphyton growth. Watershed-related properties, such as loading of dissolved organic matter, nutrients, and sediments influence light availability and hence periphyton productivity. At the finer scale of within the lake, both habitat availability and habitat type affect periphyton growth and abundance. In addition, periphyton and phytoplankton compete for available resources at the within-lake scale. Our review indicates that periphyton plays an important functional role in lake nutrient cycles and food webs, especially under such conditions as relatively shallow depths, nutrient-poor conditions, or high water-column transparency. We recommend more studies assessing periphyton function across a spectrum of lake morphometry and trophic conditions.

scholarly journals Shoot Growth Rate and Density Affect Bud Necrosis of `Riesling' Grapevines

1995 ◽  
Vol 120 (6) ◽  
pp. 989-996 ◽  
Author(s):  
Tony K. Wolf ◽  
M. Kay Warren
Keyword(s):  
Growth Rate ◽  
Positive Relationship ◽  
Shoot Growth ◽  
Growth Retardant ◽  
Photon Flux ◽  
Photosynthetic Photon Flux ◽  
Dormant Bud ◽  
High Incidence ◽  
Shoot Growth Rate ◽  
Growing Conditions

Examination of `Riesling' grape (Vitis vinifera L.) in Virginia suggested that a high incidence of bud necrosis (BN) in some vineyards was associated with canopy shade and rapid shoot growth. BN appeared to originate as an abortion and dehydration of the primary, and occasionally secondary, buds of the developing dormant bud. BN frequency was lowest among the basal four nodes of a given shoot or cane, and increased in frequency through node 20. Experiments were conducted in 1991 and 1992 to evaluate the specific involvement of shoot growth rate and canopy shade on `Riesling' BN. Shoot growth rate (SGR), measured in a 17-day period around bloom, had a significant, positive relationship with BN in one of two vineyards. BN was positively associated with cane diameter and average internode length. Applying the growth retardant paclobutrazol significantly reduced SGR and BN incidence up to 80% among nodes 6 to 15 in two separate vineyards. Artificial shade (64% or 92% reduction in photosynthetic photon flux), suspended over vine canopies in the 3-week period before véraison, did not affect BN. Shoots of canopies that had been thinned before bloom to 10 shoots/m of canopy expressed slightly lower BN levels than shoots sampled from canopies that had been thinned to 20 shoots per meter. `Riesling' BN appeared more influenced by shoot vigor than shade under Virginia growing conditions. Chemical name β-[(4-chlorophenyl)methyl]-α-(1,1-dimethyl-ethyl)-1H-1,2,4-triazole-1-ethanol (paclobutrazol).

scholarly journals ELEMENTAL CONTENT IN TOMATO SEEDLINGS AS INFLUENCED BY PRETRANSPLANT CONDITIONING

HortScience ◽  
1990 ◽  
Vol 25 (9) ◽  
pp. 1129a-1129 ◽  
Author(s):  
Ronald Garton ◽  
Irvin E. Widders
Keyword(s):  
Shoot Growth ◽  
Elemental Concentration ◽  
Elemental Content ◽  
Tissue Concentrations ◽  
Total N ◽  
Tomato Seedlings ◽  
Processing Tomato ◽  
Shoot Tissue ◽  
Shoot Growth Rate ◽  
Fertilizer Solutions

Processing tomato seedlings cultured in 288 cell plug trays were fertilized with solutions containing either 75-32-62 or 150-64-124 ppm N-P-K until the 4 to 5 true leaf stage (12 cm tall). At this developmental. stage, the seedlings were nutrient conditioned with 0-0-0, 75-32-62, 150-64-124, 300-128-248 or 450-194-374 ppm N-P-K for up to 12 days. Within 3 days of initiation of pretransplant fertilization treatments, both the contents and mean concentrations in shoot tissue of total N, P, K and soluble NO3- were significantly altered. The maximum effects on tissue concentrations were observed within 5 days. Shoot growth rate of seedlings was affected within 5 to 8 days by a modification of elemental concentration within fertilizer solutions. The benefits of nutrient conditioning on tomato seedlings will be discussed.

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