Habitat Segregation by Serotinous Shrubs in Heaths: Post-fire Emergence and Seedling Survival

1997 ◽  
Vol 45 (1) ◽  
pp. 31 ◽  
Author(s):  
Paul R. Williams ◽  
Peter J. Clarke
Keyword(s):  
Soil Moisture ◽  
Field Experiments ◽  
Seedling Survival ◽  
Habitat Segregation ◽  
Differential Survival ◽  
Shrub Species ◽  
Edge Zone ◽  
Drainage Channels ◽  
Germination Trial ◽  
Adult Plants

Seeds of two serotinous shrub species generally restricted to the drier edges, and two serotinous shrub species commonly confined to the wetter drainage channels of upland sedge–heaths were assessed for germinability and used in manipulative field experiments. In post-fire field experiments the effects of habitat and manipulated soil moisture were examined to test if the distribution of adult plants was influenced by soil moisture at seed germination. The effects of habitat on seedling survival for 11 months were also assessed. One species from the edge zone, Banksia marginata Cav., and one from the channel zone, Hakea microcarpa R.Br., had germination preferences corresponding to the distribution of adult plants. The other edge species, Hakea dactyloides (Gaertner) Cav., did not show a significant preference for either zone. The second channel species, Callistemon pityoides F.Muell., did not germinate in the field or in a laboratory germination trial. Some evidence for soil-stored dormancy related to temperature and or waterlogging was found in both Hakea species. Overall the results suggest that for two species habitat segregation occurs when seeds are incorporated into the seed-bed and germination occurs. No differential survival effects across habitats were found in the first year of growth.

scholarly journals Climate Differently Impacts the Growth of Coexisting Trees and Shrubs under Semi-Arid Mediterranean Conditions

Forests ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 381
Author(s):  
J. Julio Camarero ◽  
Cristina Valeriano ◽  
Antonio Gazol ◽  
Michele Colangelo ◽  
Raúl Sánchez-Salguero
Keyword(s):  
Soil Moisture ◽  
Radial Growth ◽  
Pinus Halepensis ◽  
Growth Dynamics ◽  
Early Summer ◽  
Growth Responses ◽  
Shrub Species ◽  
High Soil Moisture ◽  
Semi Arid ◽  
Mediterranean Conditions

Background and Objectives—Coexisting tree and shrub species will have to withstand more arid conditions as temperatures keep rising in the Mediterranean Basin. However, we still lack reliable assessments on how climate and drought affect the radial growth of tree and shrub species at intra- and interannual time scales under semi-arid Mediterranean conditions. Materials and Methods—We investigated the growth responses to climate of four co-occurring gymnosperms inhabiting semi-arid Mediterranean sites in northeastern Spain: two tree species (Aleppo pine, Pinus halepensis Mill.; Spanish juniper, Juniperus thurifera L.) and two shrubs (Phoenicean juniper, Juniperus phoenicea L.; Ephedra nebrodensis Tineo ex Guss.). First, we quantified the intra-annual radial-growth rates of the four species by periodically sampling wood samples during one growing season. Second, we quantified the climate–growth relationships at an interannual scale at two sites with different soil water availability by using dendrochronology. Third, we simulated growth responses to temperature and soil moisture using the forward, process-based Vaganov‒Shashkin (VS-Lite) growth model to disentangle the main climatic drivers of growth. Results—The growth of all species peaked in spring to early summer (May–June). The pine and junipers grew after the dry summer, i.e., they showed a bimodal growth pattern. Prior wet winter conditions leading to high soil moisture before cambium reactivation in spring enhanced the growth of P. halepensis at dry sites, whereas the growth of both junipers and Ephedra depended more on high spring–summer soil moisture. The VS-Lite model identified these different influences of soil moisture on growth in tree and shrub species. Conclusions—Our approach (i) revealed contrasting growth dynamics of co-existing tree and shrub species under semi-arid Mediterranean conditions and (ii) provided novel insights on different responses as a function of growth habits in similar drought-prone regions.

scholarly journals Influence of Land Cover and Soil Moisture on the Horizontal Distribution of Sensible and Latent Heat Fluxes in Southeast Kansas during IHOP_2002 and CASES-97

2007 ◽  
Vol 8 (1) ◽  
pp. 68-87 ◽  
Author(s):  
Margaret A. LeMone ◽  
Fei Chen ◽  
Joseph G. Alfieri ◽  
Mukul Tewari ◽  
Bart Geerts ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Latent Heat ◽  
Land Surface ◽  
Field Experiments ◽  
Time Of Day ◽  
Horizontal Distribution ◽  
Heat Fluxes ◽  
Surface Model ◽  
Green Vegetation ◽  
The Impact

Abstract Analyses of daytime fair-weather aircraft and surface-flux tower data from the May–June 2002 International H2O Project (IHOP_2002) and the April–May 1997 Cooperative Atmosphere Surface Exchange Study (CASES-97) are used to document the role of vegetation, soil moisture, and terrain in determining the horizontal variability of latent heat LE and sensible heat H along a 46-km flight track in southeast Kansas. Combining the two field experiments clearly reveals the strong influence of vegetation cover, with H maxima over sparse/dormant vegetation, and H minima over green vegetation; and, to a lesser extent, LE maxima over green vegetation, and LE minima over sparse/dormant vegetation. If the small number of cases is producing the correct trend, other effects of vegetation and the impact of soil moisture emerge through examining the slope ΔxyLE/ΔxyH for the best-fit straight line for plots of time-averaged LE as a function of time-averaged H over the area. Based on the surface energy balance, H + LE = Rnet − Gsfc, where Rnet is the net radiation and Gsfc is the flux into the soil; Rnet − Gsfc ∼ constant over the area implies an approximately −1 slope. Right after rainfall, H and LE vary too little horizontally to define a slope. After sufficient drying to produce enough horizontal variation to define a slope, a steep (∼−2) slope emerges. The slope becomes shallower and better defined with time as H and LE horizontal variability increases. Similarly, the slope becomes more negative with moister soils. In addition, the slope can change with time of day due to phase differences in H and LE. These trends are based on land surface model (LSM) runs and observations collected under nearly clear skies; the vegetation is unstressed for the days examined. LSM runs suggest terrain may also play a role, but observational support is weak.

Effects of Soil Moisture on Shrub Seedling Survival in Semi-Arid Grassland

Ecology ◽  
1991 ◽  
Vol 72 (3) ◽  
pp. 1138-1149 ◽  
Author(s):  
Graham N. Harrington
Keyword(s):  
Soil Moisture ◽  
Seedling Survival ◽  
Semi Arid

scholarly journals Interspecific Hybridization in Hazelnut (Corylus)

2000 ◽  
Vol 125 (4) ◽  
pp. 489-497 ◽  
Author(s):  
Veli Erdogan ◽  
Shawn A. Mehlenbacher
Keyword(s):  
Seed Germination ◽  
Seedling Survival ◽  
Genetic Relationships ◽  
Female Parent ◽  
Interspecific Crosses ◽  
Shrub Species ◽  
Cluster Set ◽  
Reciprocal Differences ◽  
Hybrid Seedling ◽  
Bridge Species

Eight Corylus L. (hazelnut) species were intercrossed in all possible combinations to reveal genetic relationships. Pollinations were made on either individually bagged branches or trees covered entirely with polyethylene using mixtures of pollen of five genotypes to minimize low cluster set due to single incompatible combinations. Percent cluster set, seed germination, and hybrid seedling survival were determined. Hybridity of seedlings was verified by inspection of morphological traits. Based on percent cluster set, seed germination, and hybrid seedling survival along with observed morphological similarities, Corylus species were placed in three groups: 1) the tree hazels C. colurna L. (turkish tree hazel) and C. chinensis Franchet (chinese tree hazel), 2) the bristle-husked shrub species C. cornuta Marshall (beaked hazel), C. californica (A.DC.) Rose (california hazel), and C. sieboldiana Blume (manchurian hazel), and 3) the leafy-husked shrub species C. avellana L. (european hazel), C. americana Marshall (american hazel), C. heterophylla Fischer (siberian hazel), and C. heterophylla Fischer var. sutchuensis Franchet (sichuan hazel). The two tree hazel species crossed with each other readily, as did the three bristle-husked shrub species. The frequency of blanks was low (<20%) for crosses of the tree hazels, and <50% for interspecific crosses within the group of bristle-husked species. The leafy-husked shrub species could be crossed with each other in all directions, although cluster set on C. heterophylla was low. For crosses of species belonging to different groups, set was generally low and the frequency of blanks high. Nevertheless, a few hybrid seedlings were obtained from several combinations. When used as the female parent, C. californica set nuts when crossed with all other species, indicating possible value as a bridge species. Crosses involving C. avellana were more successful when it was the pollen parent. In crosses with C. avellana pollen, cluster set on C. chinensis was better than on C. colurna and the frequency of blanks was much lower, indicating that it might be easier to transfer nonsuckering growth habit from C. chinensis than from C. colurna. Reciprocal differences in the success of crosses was observed. The following crosses were successful C. californica × C. avellana, C. chinensis × C. avellana, C americana × C. heterophylla, C. cornuta × C heterophylla, C. californica × C. colurna, and C. americana × C. sieboldiana, but the reciprocals were not.

scholarly journals Optimisation of Irrigation Regime for Early Potatoes, Late Cauliflower, Early Cabbage and Celery

2013 ◽  
Vol 1 (No. 4) ◽  
pp. 139-152
Author(s):  
Zavadil Josef
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Field Experiments ◽  
Actual Evapotranspiration ◽  
Suction Pressure ◽  
Irrigation Regime ◽  
Marketable Yield ◽  
Moisture Balance ◽  
Seasonal Irrigation ◽  
Soil Moisture Balance

The paper deals with optimisation of threshold suction pressure of soil water on light soils for early potatoes, early cabbage, late cauliflower and celery on the basis of results of small-plot field experiments with differentiated irrigation regime. Experiments were conducted in 2003&ndash;2005. Threshold suction pressures of soil water were identical for all crops: 15 kPa in treatment I, 30 kPa in treatment II, 60 kPa in treatment III, and 120 kPa in treatment IV. Precipitation, air temperature and relative humidity, global solar radiation, wind speed and direction were measured by an automated meteorological station. Reference and actual evapotranspiration was determined for the experimental crops according to FAO Paper No. 56 and by means of a biological curve (BC) in 2003&ndash;2005. To compare these two methods of calculation of actual evapotranspiration the soil moisture balance was found out. Based on the influence on marketable yield and proportion of the crop quality grades it is possible to determine the optimum threshold suction pressure on light loamy-sand soils in early potatoes, late cauliflower and cabbage 30 kPa and in celery 15 kPa. 80% of available soil water capacity (ASWC) corresponds to the threshold suction pressure 30 kPa, and as much as 96% of ASWC corresponds to 15 kPa. The seasonal irrigation depths determined on the basis of soil moisture balance, in which the crop evapotranspiration (ETc) is calculated either according to FAO 56 or by the BC, are substantially different from the really achieved irriga&shy;tion depths in the treatments where optimal suction pressure is maintained. For potatoes, the really achieved values of seasonal irrigation depths are nearer to the depths calculated by the BC, while for the other vegetables (cauliflower, cabbage and celery) they are more similar to the depths calculated by FAO 56 methodology. The theoretical irrigation depths calculated by the BC method sometimes differ substantially from those based on FAO 56. These differences are at maximum for cauliflower and celery and at minimum for cabbage and decrease with the decreasing irrigation depths.

Competition betweenElymus elymoidesandTaeniatherum caput-medusae

Weed Science ◽  
1999 ◽  
Vol 47 (6) ◽  
pp. 720-728 ◽  
Author(s):  
David W. Clausnitzer ◽  
Michael M. Borman ◽  
Douglas E. Johnson
Keyword(s):  
Soil Moisture ◽  
Interspecific Competition ◽  
Seed Production ◽  
Intraspecific Competition ◽  
Field Experiments ◽  
Block Design ◽  
Low Oxygen ◽  
Competitive Effects ◽  
Growing Seasons ◽  
Randomized Block Design

Two field experiments were conducted from 1993–1994 through 1995–1996 growing seasons in Harney County, OR, to determine the relative competitive abilities ofElymus elymoides(squirreltail) a native perennial range grass, andTaeniatherum caput-medusae(medusahead), an exotic annual grass weed. The 1993–1994 growing season was very dry, 1994–1995 was dry, and 1995–1996 was wetter than average. One experiment tested seedlings vs. seedlings in each of three seasons. The second experiment tested seedlings plus second- and third-year establishedE. elymoidesplants vs. 77caput-medusaeover 2 yr. Biomass, seed production, and soil moisture utilization 15, 30, 45, and 60 cm deep by the two species were measured. A randomized block design with factorial arrangement was used, with 25 2.25-m2plots per block. Initial seeding densities of each species were 0, 10, 74, 550, and 4,074 seeds m−2in all combinations of density. In the seedling vs. seedling experiment, intraspecific competition by 77caput-medusaeon itself was always significant (P ≤ 0.10) for both biomass and seed production. Interspecific competition byE. elymoidesseedlings onT. caput-medusaebiomass and seed production was not significant (P ≥ 0.10) in 2 of 3 yr and was always less than intraspecific competition by 77caput-medusae. Only 0.4% ofE. elymoidesseed germinated, and no seed was produced in the very dry first year, but 84% of remaining seed was viable for the next year, which had better moisture conditions for germination and establishment. Interspecific competition affected (P ≤ 0.10)E. elymoidesseedling biomass and seed production throughout the study. Intraspecific competition affected (P ≤ 0.10) seedlingE. elymoidesseed production in the dry year but not in the wetter than average year. In the matureE. elymoidesexperiment, intraspecific competition byT. caput-medusaeon weight and seed production per plant was greater than interspecific competition fromE. elymoides. Seedling/matureE. elymoidesreducedT. caput-medusaeweight per plant in the dry year but the effect was not biologically significant. Larger, matureEelymoidesplants produced 600 to 3,000 seeds per plant during the wet year; neither intra- nor interspecific competition was a factor.Taeniatherum caput-medusaewas better able to access deeper soil moisture and was more aggressive at extracting soil moisture than wereE. elymoidesseedlings in the wet year. Cold soils and low oxygen due to wet soils may have restrictedE. elymoidesseedling root activity. MatureE. elymoidesplants did not appear restricted by cold soils or low oxygen. Established second- and third-yearE. elymoidesplants were able to compete for soil moisture down to 45 cm. The generally greater interspecific competitive effects ofT. caput-medusaeonE. elymoidesthan vice versa suggested that it will be difficult to establish anE. elymoidesstand in an existingT. caput-medusaecommunity without first suppressingT. caput-medusae. IndividualE. elymoidesplants did establish and were productive with and withoutT. caput-medusaecompetition.

Soybean (Glycine Max) Cultivar Tolerance to San 582H and Metolachlor As Influenced by Soil Moisture

Weed Science ◽  
1995 ◽  
Vol 43 (2) ◽  
pp. 288-292 ◽  
Author(s):  
Bradley T. Osborne ◽  
David R. Shaw ◽  
Randall L. Ratliff
Keyword(s):  
Soil Moisture ◽  
Glycine Max ◽  
Plant Height ◽  
Field Experiments ◽  
Soybean Cultivar ◽  
Plant Populations ◽  
Crop Height ◽  
Reduced Height ◽  
Leaf Drop

Field experiments were conducted in 1991 and 1992 to evaluate differential soybean cultivar tolerance to SAN 582H and metolachlor applied PRE, as influenced by soil moisture. Eighteen d after planting, a 3× rate of SAN 582H (3.0 kg ai ha−1) reduced plant populations of ‘Wright,’ ‘Bedford,’ and ‘Stonewall’ and metolachlor did not. At leaf drop, neither herbicide reduced crop height with optimum moisture. With excessive moisture, 3× rates of SAN 582H reduced plant height of Wright, Bedford, ‘Walters,’ ‘Young,’ ‘Brim,’ and ‘Bryan,’ and metolachlor reduced height of ‘Sharkey.’ The greatest yield reductions were due to excessive moisture, regardless of herbicide. Neither herbicide reduced yields with optimum moisture nor did a 1× rate with excessive moisture. However, with excessive moisture, a 3× rate of metolachlor (5.0 kg ai ha−1) reduced yield of Bedford by 470 kg ha−1, and the 3× rate of SAN 582H reduced yield of ‘Rhodes,’ Walters, and ‘Centennial’ more than 500 kg ha−1. Overall, soybean tolerance to both herbicides was good, but if used above recommended rates and with excessive moisture, injury can occur.

Studies on Transpiration Suppressants on Spring Sorghum in North-Western India in Relation to Soil Moisture Regimes. I. Effect on Yield and Water Use Efficiency

1984 ◽  
Vol 20 (2) ◽  
pp. 151-159
Author(s):  
D. Boobathi Babu ◽  
S. P. Singh
Keyword(s):  
Soil Moisture ◽  
Water Use Efficiency ◽  
Water Use ◽  
Irrigation Water ◽  
Field Experiments ◽  
Western India ◽  
Moisture Regimes ◽  
Use Efficiency ◽  
Effect On Yield ◽  
North Western

SUMMARYThe results of field experiments conducted in the spring seasons (February/March to June) of 1980 and 1981 indicate that grain yields of sorghum increased with increase in frequency of irrigation. Crops sprayed with atrazine or CCC yielded more than the unsprayed control; maximum yields were obtained by the application of atrazine at 200 g ha−1. Water use efficiency decreased with increase in irrigation but increased as a result of spraying crops with either chemical. Irrigation water can be saved by the spraying of atrazine or CCC onto spring-sown sorghum.

Rooting depth and plant water relations explain species distribution patterns within a sandplain landscape

2004 ◽  
Vol 31 (5) ◽  
pp. 423 ◽  
Author(s):  
Philip K. Groom
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Water Loss ◽  
Rooting Depth ◽  
Summer Drought ◽  
Tissue Water ◽  
Shrub Species ◽  
Water Deficits ◽  
Groundwater Levels ◽  
Water Potentials

Tree and shrub species of the Banksia woodlands on the sandplains of northern Swan Coastal Plain, Western Australia possess a range of strategies to avoid or tolerate soil water deficits during the annual summer drought. Shallow-rooted shrub species (< 1 m rooting depth) inhabit a range of locations in the landscape, from top of dune crests to wetland embankments. These are the most drought-tolerant of all sandplain species, surviving extremely low summer soil water potentials (< –7 MPa) and tissue water deficits by significantly reducing their transpirational water loss (< 0.2 mmol m–2 s–1). This is in contrast to the few shallow-rooted species restricted to low-lying or seasonally waterlogged areas which are reliant on subsurface soil moisture or groundwater to maintain their relatively high summer water use. Recent studies of water source usage of selected Banksia tree species have shown that these deep-rooted species access groundwater up to a maximum depth of 9 m depth during the summer months, or soil moisture at depth when groundwater was greater than maximum rooting depths, depending on the species. Medium- and deep-rooted (1–2 m and > 2 m, respectively) shrub species cope with the summer soil drying phase and related decrease in groundwater levels by conserving leaf water loss and incurring predawn water potentials between –1 and –4 MPa, enabling them to occur over a range of topographic positions within the sandplain landscape.

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