Relative Effects of Light, Soil Moisture Availability and Vegetative Size on Sex Ratio of Two Monoecious Woodland Annual Herbs: Acalypha rhomboidea (Euphorbiaceae) and Pilea pumila (Urticaceae)

1987 ◽  
Vol 114 (3) ◽  
pp. 293 ◽  
Author(s):  
Carmen R. Cid-Benevento
Keyword(s):  
Soil Moisture ◽  
Sex Ratio ◽  
Light Soil ◽  
Moisture Availability ◽  
Soil Moisture Availability ◽  
Pilea Pumila

Seasonal variation in competitive effect on water stress and pine responses

1994 ◽  
Vol 24 (7) ◽  
pp. 1440-1449 ◽  
Author(s):  
M.A. Perry ◽  
R.J. Mitchell ◽  
B.R. Zutter ◽  
G.R. Glover ◽  
D.H. Gjerstad
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Volume Index ◽  
Integral Approach ◽  
Stem Volume ◽  
Competitive Effects ◽  
Moisture Availability ◽  
Soil Moisture Availability

Plant mixtures were established that differed in both proportion and density of loblolly pine (Pinustaeda L.), sweetgum (Liquidambarstyraciflua L.), and broomsedge (Andropogonvirginicus L.). Soil moisture availability to the pine seedlings was quantified every 2 weeks by measuring predawn xylem pressure potentials. Temporal variation in pine water potential was accounted for by a water stress integral approach. Cumulative water stress integral values were calculated over four overlapping periods, from May to June, May to July, May to August, and May to September and compared with the mean seedling stem volume index at each period to determine competitive responses at the whole plant scale. Diurnal measures of stomatal conductance were taken each month to compare competitive responses at the leaf scale. In addition, environmental and plant responses that may control stomatal behavior were quantified. The pine water stress integral was strongly influenced by competing vegetation after the onset of a period of drought in early summer. The correlation between the water stress integral and pine growth increased after a significant drying period, accounting for more than half of the variation in stem volume index at the end of the first growing season. Stomatal conductance was also influenced by competition, with competitive effects more evident during times of drought. Conductance was most often related to bulk leaf water potential, which in turn was related to competitive effects on soil moisture availability. Vapor pressure deficit also influenced stomatal conductance, but this was largely unrelated to competitive effects.

Carbon accumulation in loblolly pine plantations is increased by fertilization across a soil moisture availability gradient

2018 ◽  
Vol 424 ◽  
pp. 39-52 ◽  
Author(s):  
Rosvel Bracho ◽  
Jason G. Vogel ◽  
Rodney E. Will ◽  
Asko Noormets ◽  
Lisa J. Samuelson ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Loblolly Pine ◽  
Carbon Accumulation ◽  
Pine Plantations ◽  
Moisture Availability ◽  
Soil Moisture Availability

scholarly journals Splitting the Difference: Heterogeneous Soil Moisture Availability Affects Aboveground and Belowground Reserve and Mass Allocation in Trembling Aspen

2021 ◽  
Vol 12 ◽  
Author(s):  
Ashley T. Hart ◽  
Morgane Merlin ◽  
Erin Wiley ◽  
Simon M. Landhäusser
Keyword(s):  
Soil Moisture ◽  
Root System ◽  
Resource Availability ◽  
Moisture Regime ◽  
Trembling Aspen ◽  
Moisture Availability ◽  
Resource Limited ◽  
Heterogeneous Soil ◽  
Soil Moisture Availability ◽  
The Impact

When exploring the impact of resource availability on perennial plants, artificial treatments often apply conditions homogeneously across space and time, even though this rarely reflects conditions in natural systems. To investigate the effects of spatially heterogeneous soil moisture on morphological and physiological responses, trembling aspen (Populus tremuloides) saplings were used in a split-pot experiment. Following the division of the root systems, saplings were established for a full year and then subjected to either heterogeneous (portion of the root system exposed to non-lethal drought) or homogeneous (whole root system exposed to non-lethal drought or well-watered) treatments. Above- and belowground growth and non-structural carbohydrate (NSC) reserves (soluble sugars and starch) were measured to determine how allocation of reserves and mass between and within organs changed in response to variation in soil moisture availability. In contrast to saplings in the homogeneous drought treatment, which experienced reduced shoot growth, leaf abscission and fine root loss, saplings exposed to the heterogeneous conditions maintained similar aboveground growth and increased root system allocation compared to well-watered saplings. Interestingly under heterogeneous soil moisture conditions, the portion of the root system that was resource limited had no root dieback and increased carbon reserve concentrations, while the portion of the root system that was not resource limited added new roots (30% increase). Overall, saplings subjected to the heterogeneous soil moisture regime over-compensated belowground, both in mass and NSC reserves. These results indicate that the differential allocation of mass or reserves between above- and belowground organs, but also within the root system can occur. While the mechanisms and processes involved in these patterns are not clear, these responses could be interpreted as adaptations and acclimations to preserve the integrity of the entire sapling and suggests that different portions of plant organs might respond autonomously to local conditions. This study provides further appreciation of the complexity of the mechanisms by which plants manage heterogeneous conditions and offers evidence that spatial and temporal variability of resource availability, particularly belowground, needs to be accounted for when extrapolating and modeling stress responses at larger temporal and spatial scales.

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