Effects of elevated CO2, water stress, and nitrogen level on competitive interactions of simulated loblolly pine and sweetgum stands

1995 ◽  
Vol 25 (7) ◽  
pp. 1077-1083 ◽  
Author(s):  
J.W. Groninger ◽  
J.R. Seiler ◽  
S.M. Zedaker ◽  
P.C. Berrang
Keyword(s):  
Loblolly Pine ◽  
Water Availability ◽  
Nitrogen Availability ◽  
Competitive Interactions ◽  
Total Biomass ◽  
Mixed Stands ◽  
Multiple Resources ◽  
Species Response ◽  
Application Rates ◽  
Stand Type

Loblolly pine (Pinustaeda L.) and sweetgum (Liquidambarstyraciflua L.) were grown in mixed stands and in monocultures at 2.54 × 2.54 cm spacing in controlled-environment chambers. Treatments consisted of present (ambient) and projected future (ambient + 400 ppm) carbon dioxide (CO2) concentrations, drought-stressed, and well-watered conditions, and low (20 kg N/ha) and high (474 kg N/ha) nitrogen application rates. After two accelerated growing cycles, total biomass of both species was significantly greater under elevated CO2. No significant interactions between CO2 concentration and water availability, nitrogen availability, or stand type were observed. Competitive interactions between loblolly pine and sweetgum were strongly influenced by water availability, but not CO2 concentration. Assessment of species response to CO2 was dependent upon growth in monoculture or mixture. Under low water availability, data from monocultures suggested that sweetgum had a stronger growth response to elevated CO2 concentrations than loblolly pine. In contrast, results from mixed-species stands showed that the competitive status of loblolly pine and sweetgum did not change under the high CO2 concentration. These results underscore the value of growing co-occurring species in mixed stands under varying levels of multiple resources for the determination of relative performance under future environments.

Photosynthetic response of loblolly pine and sweetgum seedling stands to elevated carbon dioxide, water stress, and nitrogen level

1996 ◽  
Vol 26 (1) ◽  
pp. 95-102 ◽  
Author(s):  
J.W. Groninger ◽  
J.R. Seiler ◽  
S.M. Zedaker ◽  
P.C. Berrang
Keyword(s):  
Loblolly Pine ◽  
Light Extinction ◽  
Photosynthetic Response ◽  
Mixed Stands ◽  
Photosynthetic Rates ◽  
Leaf Mass ◽  
Unit Leaf ◽  
Application Rates ◽  
Species Specific ◽  
Individual Seedling

Seedling stands of loblolly pine (Pinustaeda L.) and sweetgum (Liquidambarstyraciflua L.) were grown in monoculture or mixed stands for two growing cycles in controlled-environment chambers. Treatments consisted of ambient (408 ppm) and elevated (806 ppm) CO2, concentrations, water-stressed and well-watered conditions, and low (20 kg N/ha) and high (215 kg N/ha) nitrogen application rates. Photosynthesis rates were measured under ambient and elevated cuvette CO2 concentrations for both whole stands and individual seedlings from these stands. Significant interactions between CO2 and water suggested that elevated CO2 concentration compensated for low water availability in individually measured loblolly pine and in whole seedling stands regardless of stand type. Expressing photosynthesis on a soil area versus a leaf-mass basis influenced the photosynthetic rankings of the three stand types relative to one another. Net photosynthetic rates per unit leaf mass were 390 and 880% higher in individually measured seedlings than in whole monoculture stands for loblolly pine and sweetgum, respectively. Lower photosynthetic contributions from lower canopy leaves in whole seedling stands compared with the upper canopy leaves used in individual-seedling measurements were thought to be responsible for lower photosynthetic rates in seedling stands. These results suggest that photosynthetic response is influenced by canopy dynamics that are unaccounted for by individual-seedling measurements of photosynthesis. Differences in photosynthetic response between loblolly pine and sweetgum stands and individuals are thought to be largely due to species-specific differences in canopy light extinction characteristics.

Competition theory — science and application in mixed forest stands: review of experimental and modelling methods and suggestions for future research

2013 ◽  
Vol 21 (2) ◽  
pp. 71-84 ◽  
Author(s):  
Guy R. Larocque ◽  
Nancy Luckai ◽  
Shailendra N. Adhikary ◽  
Arthur Groot ◽  
F. Wayne Bell ◽  
...  
Keyword(s):  
Mixed Forest ◽  
Single Species ◽  
Experimental Designs ◽  
Competitive Interactions ◽  
Future Research ◽  
Relative Importance ◽  
Forest Stands ◽  
Management Scenarios ◽  
Mixed Stands ◽  
Individual Tree

Competition in forest stands has long been of interest to researchers. However, much of the knowledge originates from empirical studies that examined the effects of competition. For instance, many studies were focused on the effects of the presence of herbaceous species on the development of tree seedlings or the decrease in individual tree growth with increases in stand density. Several models that incorporate competitive effects have been developed to predict tree and stand growth, but with simplified representations of competitive interactions. While these studies provided guidance useful for forest management, they contributed only partially to furthering our understanding of competitive mechanisms. Also, most competition studies were conducted in single-species stands. As competitive interactions occurring in mixed stands are characterized by a higher degree of complexity than those in single-species stands, a better understanding of these mechanisms can contribute to developing optimal management scenarios. The dynamics of forest stands with at least two species may be affected not only by competition, but also by facilitation or complementarity mechanisms. Thus, knowledge of the mechanisms may provide insight into the relative importance of intra- versus inter-specific competition and whether competition is symmetric or asymmetric. Special attention to the implementation of field experimental designs is warranted for mixed stands. While traditional spacing trials are appropriate for single-species stands, the examination of competitive interactions in mixed stands requires more complex experimental designs to examine the relative importance of species combinations. Forest productivity models allow resource managers to test different management scenarios, but again most of these models were developed for single-species stands. As competitive interactions are more complex in mixed stands, models developed to predict their dynamics will need to include more mechanistic representations of competition.

Influence of Herbaceous Interference on Growth and Biomass Partitioning in Planted Loblolly Pine (Pinus taeda)

Weed Science ◽  
1990 ◽  
Vol 38 (6) ◽  
pp. 497-503 ◽  
Author(s):  
John R. Britt ◽  
Bruce R. Zutter ◽  
Robert J. Mitchell ◽  
Dean H. Gjerstad ◽  
John F. Dickson
Keyword(s):  
Leaf Area ◽  
Pinus Taeda ◽  
Loblolly Pine ◽  
Growth Efficiency ◽  
Biomass Partitioning ◽  
Lower Percentage ◽  
Total Biomass ◽  
Growth Responses ◽  
Area Index ◽  
Weed Interference

Three herbaceous regimes were established, using herbicides, to examine the effects of interference on growth and biomass partitioning in loblolly pine (Pinus taedaL.). Trees were sampled near Auburn and Tallassee, AL. Trees at the Auburn site grown with low weed interference (LWI) had 4, 10, 10, 8, and 4 times greater total aboveground biomass than did trees with high weed interference (HWI) for ages one through five, respectively. Medium weed interference (MWI, Auburn site only) resulted in three times greater biomass the first 4 yr and two times greater total biomass by the fifth year compared to trees grown with HWI. Trees growing with LWI were 5, 8, 10, and 6 times larger than those with HWI for ages one through four, respectively, at the Tallassee site. At all levels of interference, the percentage of total biomass in foliage decreased, and stem and branch components increased, with increasing tree size at both sites. Trees growing with HWI had a lower percentage of total biomass in foliage and a greater percentage of total biomass in stem than those growing with LWI when compared over a common size. Growth efficiency per tree, expressed as annual increase in stem biomass per unit leaf area (g m−2), was slightly greater for trees growing with LWI compared to HWI when leaf area index (LAI3, total surface) was less than 0.2. For LAI values greater than 0.2 the relationship was reversed. The latter contradicts the idea that growth efficiency can be used as a measure of vigor for young loblolly pine. Changes in carbon partitioning to the development of leaf area are suggested to be driving the accelerated growth responses associated with a reduction of weed interference.

A Population Level Temperature-Dependent Model of Seedling Johnsongrass (Sorghum halepense) Flowering

Weed Science ◽  
1989 ◽  
Vol 37 (3) ◽  
pp. 471-477 ◽  
Author(s):  
David C. Bridges ◽  
James M. Chandler
Keyword(s):  
Water Availability ◽  
Nitrogen Availability ◽  
Nitrogen Concentration ◽  
Population Level ◽  
Effect Of Temperature ◽  
Weibull Function ◽  
Data Sets ◽  
Data Set ◽  
Independent Field ◽  
Temperature Dependent Model

A population level, two-compartment, temperaturedependent model that predicts date of seedling johnsongrass flowering was formulated. The model consisted of a fourparameter poikilotherm rate equation to describe development rate as a function of temperature and a temperature-independent Weibull function to distribute flowering times for the population. Experiments were conducted to determine the effect of temperature, nitrogen availability, and water availability on development of seedling johnsongrass. Development was most sensitive to temperature while the effect of nitrogen concentration and water availability was minimum and inconsistent. The model was tested against three independent field data sets and provided accurate prediction of flowering dates for each data set.

Defining phreatophyte response to reduced water availability: preliminary investigations on the use of xylem cavitation vulnerability in Banksia woodland species

2006 ◽  
Vol 54 (2) ◽  
pp. 173 ◽  
Author(s):  
R. H. Froend ◽  
P. L. Drake
Keyword(s):  
Water Availability ◽  
Tree Mortality ◽  
Water Source ◽  
Resource Planning ◽  
Xylem Cavitation ◽  
Xylem Water Potential ◽  
Critical Thresholds ◽  
Species Response ◽  
Critical Range ◽  
Reduced Water

The consideration of phreatophyte response to changes in water availability is important in identifying ecological water requirements in water-resource planning. Although much is known about water-source partitioning and intra- and interspecific variability in groundwater use by Banksia woodland species, little is known about the response of these species to groundwater draw-down. This paper describes a preliminary study into the use of xylem cavitation vulnerability as a measure of species response to reduced water availability. A response function and critical range in percentage loss of conductance is identified for four Banksia woodland overstorey species. Similarity in the vulnerability curves of B. attenuata R.Br. and B. menziesii R.Br. at low tensions supports the notion that they occupy a similar ecohydrological niche, as defined by their broad distributions relative to depth to groundwater. B. ilicifolia R.Br., however, as an obligate phreatophyte, has a range restricted to environments of higher water availability and shallower depth to groundwater and this is reflected in greater vulnerability to cavitation (relative to other Banksia) at lower tensions. The wetland tree Melaleuca preissiana Schauer generally expressed a greater vulnerability at any given xylem water potential (Ψx). This paper identifies the range in Ψx within which there is an elevated risk of tree mortality, and represents a first step towards quantifying the critical thresholds in the response of Banksia woodland species to reduced water availability.

Larch litter and nitrogen availability in mixed larch–spruce stands. I. Nutrient withdrawal, redistribution, and leaching loss from larch foliage at senescence

1986 ◽  
Vol 16 (2) ◽  
pp. 321-326 ◽  
Author(s):  
J. C. Carlyle ◽  
D. C. Malcolm
Keyword(s):  
Nitrogen Availability ◽  
Field Measurements ◽  
N Availability ◽  
Mixed Stands ◽  
Available N ◽  
Low Field ◽  
Large N ◽  
Spruce Stands ◽  
And Storage ◽  
N Status

The growth and N status of Sitka spruce on deep peat sites low in available N is improved in the presence of larch. It has been suggested that larch stimulates N mineralization because of high N concentrations in its litter and the large N input resulting from its annual litter fall. However, while larch foliar N concentrations were shown to be high, marked withdrawal and storage in other tree components resulted in a relative and absolute impoverishment of the litter. P and K could be leached from senescing foliage in relatively large amounts, but the potential loss of N was low. Field measurements of throughfall substantiated this finding. Larch seemed extremely conservative in its use of N, suggesting that larch litter does not directly enhance N availability in mixed stands.

Size of subsoil clods affects soil-water availability in sand–clay mixtures

Soil Research ◽  
2016 ◽  
Vol 54 (3) ◽  
pp. 276 ◽  
Author(s):  
Giacomo Betti ◽  
Cameron D. Grant ◽  
Robert S. Murray ◽  
G. Jock Churchman
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Water ◽  
Best Management Practices ◽  
Water Availability ◽  
Water Retention ◽  
Management Practices ◽  
Crop Yields ◽  
Root Zone ◽  
Soil Water Availability ◽  
Application Rates

Clay delving in strongly texture-contrast soils brings up subsoil clay in clumps ranging from large clods to tiny aggregates depending on the equipment used and the extent of secondary cultivation. Clay delving usually increases crop yields but not universally; this has generated questions about best management practices. It was postulated that the size distribution of the subsoil clumps created by delving might influence soil-water availability (and hence crop yield) because, although the clay increases water retention in the root-zone, it can also cause poor soil aeration, high soil strength and greatly reduced hydraulic conductivity. We prepared laboratory mixtures of sand and clay-rich subsoil in amounts considered practical (10% and 20% by weight) and excessive (40% and 60% by weight) with different subsoil clod sizes (<2, 6, 20 and 45 mm), for which we measured water retention, soil resistance, and saturated hydraulic conductivity. We calculated soil water availability by traditional means (plant-available water, PAW) and by the integral water capacity (IWC). We found that PAW increased with subsoil clay, particularly when smaller aggregates were used (≤6 mm). However, when the potential restrictions on PAW were taken into account, the benefits of adding clay reached a peak at ~40%, beyond which IWC declined towards that of pure subsoil clay. Furthermore, the smaller the aggregates the less effective they were at increasing IWC, particularly in the practical range of application rates (<20% by weight). We conclude that excessive post-delving cultivation may not be warranted and may explain some of the variability found in crop yields after delving.

scholarly journals Nitrogen availability alters macrofungal basidiomycete community structure in optimally fertilized loblolly pine forests

2004 ◽  
Vol 162 (3) ◽  
pp. 755-770 ◽  
Author(s):  
Ivan P. Edwards ◽  
Jennifer L. Cripliver ◽  
Andrew R. Gillespie ◽  
Kurt H. Johnsen ◽  
M. Scholler ◽  
...  
Keyword(s):  
Community Structure ◽  
Loblolly Pine ◽  
Nitrogen Availability ◽  
Pine Forests

The influence of nutrient and water availability on carbohydrate storage in loblolly pine

2002 ◽  
Vol 159 (3) ◽  
pp. 261-270 ◽  
Author(s):  
K.H. Ludovici ◽  
H.L. Allen ◽  
T.J. Albaugh ◽  
P.M. Dougherty
Keyword(s):  
Loblolly Pine ◽  
Water Availability ◽  
Carbohydrate Storage
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