The Experts below are selected from a list of 152121 Experts worldwide ranked by ideXlab platform
Melissa L Landeen - One of the best experts on this subject based on the ideXlab platform.
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Seed Production estimation for mountain big sagebrush artemisia tridentata ssp vaseyana
Rangeland Ecology & Management, 2017Co-Authors: Melissa L Landeen, Stanley G Kitchen, Loreen Allphin, Steven L PetersenAbstract:Seed Production is an essential component of postdisturbance recovery for mountain big sagebrush (Artemisia tridentata Nutt, ssp vaseyana [Rydb] Beetle; MBS). We tested a method for rapid estimation of MBS Seed Production using measurements of inflorescence morphology. We measured total stem length, stem length from first branchlet to stem tip, stem diameter, fresh weight, and number of stem branchlets for 750 inflorescences collected from five central and southern Utah sites. Florets per inflorescence were counted to provide an estimate of Seed Production potential. We used regression analysis to assess associations between morphological traits and potential Seed Production and evaluated the efficiency and scalability of each measure for field application. Site means for morphological measures varied ∼2 to 11-fold while mean number of florets per inflorescence varied ∼ 8-fold. Inflorescence weight was the best predictor of Seed Production potential (P < 0.0001, r2 = 0.897), although correlations for all tested variables were highly significant. Among-site differences in regression equations for this relationship were not significant (P = 0.226), suggesting that a single conversion factor may have broad application. However, validation will require additional testing across a broader range of sites and field conditions. Scalable methods for efficient estimation of sagebrush Seed Production potential, such as those evaluated in this study, could be useful for managers charged with assessing variability in sagebrush community stability.
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mountain big sagebrush artemisia tridentata ssp vaseyana Seed Production
Provo UT: Brigham Young University. 72 p. Thesis., 2015Co-Authors: Melissa L LandeenAbstract:Mountain Big Sagebrush (Artemisia tridentata ssp vaseyana) Seed Production Melissa L. Landeen Department of Plant and Wildlife Science, BYU Master of Science Big sagebrush (Artemisia tridentata Nutt.) is the most widespread and common shrub in the sagebrush biome of western North America. Of the three most common subspecies of big sagebrush (Artemisia tridentata), mountain big sagebrush (ssp. vaseyana; MBS) is the most resilient to disturbance, but still requires favorable climactic conditions and a viable post-fire Seedbank for successful unassisted recovery. This study was designed to assess MBS Seed Production throughout post-fire recovery. We performed 2 pilot studies to develop methods for estimating Seed Production and plant age. The results of the pilot studies and a space-for-time substitution strategy were used to measure Seed Production on 13 sites ranging from 10-33 years post-fire. We hypothesized that Seed rain (mean Seeds produced/ m2) would peak before stand density had maximized due to decreasing individual plant fecundity (mean Seeds produced/ plant) in high density stands. We measured population density and individual plant fecundity for three size classes of MBS and used forward stepwise regression analysis to identify environmental factors influencing Seed Production over time. Density for small (basal stem diameter 3 cm) plant density increased steadily with TSF (p=0.0002). Plant fecundity decreased with TSF for all three size classes (p range = 0.019 – 0.0506), with large plants dominating reproductive output. Small and medium-sized plant fecundity was negatively correlated with winter precipitation (p range = 0.0106-0.0174), while large plant fecundity was positively correlated with winter precipitation (p<0.0001) and negatively correlated with elevation (p=0.0001). Despite losses in plant fecundity over time for all size classes, steady recruitment in population density resulted in increased Seed rain (p=0.0039), suggesting that increases in stand density compensated for losses in individual plant fecundity. Results partially support our hypothesis that the time required for MBS Seed rain to be maximized was not tightly bound to indicators of stand maturation. Understanding the factors that influence post-fire Seed Production can help land managers better manage for successful recovery by providing them with tools for evaluating Seed Production capabilities of MBS communities.
Josep Maria Espelta - One of the best experts on this subject based on the ideXlab platform.
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the effects of local climate on the correlation between weather and Seed Production differ in two species with contrasting masting habit
Agricultural and Forest Meteorology, 2019Co-Authors: Michal Bogdziewicz, Jakub Szymkowiak, Marcos Fernandezmartinez, Josep Penuelas, Josep Maria EspeltaAbstract:Abstract Many plant species present inter-annual cycles of Seed Production (mast Seeding), with synchronized high Seed Production across populations in some years. Weather is believed to be centrally involved in triggering masting. The links between meteorological conditions and Seeding are well-recognized for some species, but in others consistent correlates have not been found. We used a spatially extensive data set of fruit Production to test the hypothesis that the influence of weather on Seed Production is conditioned by local climate and that this influence varies between species with different life history traits. We used two model species. European beech (Fagus sylvatica) that is a flowering masting species, i.e. Seed Production is determined by variable flower Production, and sessile oak (Quercus petraea) that is a fruit-maturation masting species, i.e. Seed Production is determined by variable ripening of more constant flower Production. We predicted that climate should strongly modulate the relationship between meteorological cue and fruit Production in Q. petraea, while the relationship should be uniform in F. sylvatica. The influence of meteorological cue on reProduction in fruiting masting species should be strongly conditioned by local climate because the strength of environmental constraint that modulates the success of flower-to-fruit transition is likely to vary with local climatic conditions. In accordance, the meteorological cuing was consistent in F. sylvatica. In contrast, in Q. petraea the relationship between spring temperature and Seed Production varied among sites and was stronger in populations at colder sites. The clear difference in meteorological conditioning of Seed Production between the two studied species suggests the responses of masting plants to weather can be potentially systematized according to their masting habit: i.e. fruiting or flowering.
Michal Bogdziewicz - One of the best experts on this subject based on the ideXlab platform.
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the effects of local climate on the correlation between weather and Seed Production differ in two species with contrasting masting habit
Agricultural and Forest Meteorology, 2019Co-Authors: Michal Bogdziewicz, Jakub Szymkowiak, Marcos Fernandezmartinez, Josep Penuelas, Josep Maria EspeltaAbstract:Abstract Many plant species present inter-annual cycles of Seed Production (mast Seeding), with synchronized high Seed Production across populations in some years. Weather is believed to be centrally involved in triggering masting. The links between meteorological conditions and Seeding are well-recognized for some species, but in others consistent correlates have not been found. We used a spatially extensive data set of fruit Production to test the hypothesis that the influence of weather on Seed Production is conditioned by local climate and that this influence varies between species with different life history traits. We used two model species. European beech (Fagus sylvatica) that is a flowering masting species, i.e. Seed Production is determined by variable flower Production, and sessile oak (Quercus petraea) that is a fruit-maturation masting species, i.e. Seed Production is determined by variable ripening of more constant flower Production. We predicted that climate should strongly modulate the relationship between meteorological cue and fruit Production in Q. petraea, while the relationship should be uniform in F. sylvatica. The influence of meteorological cue on reProduction in fruiting masting species should be strongly conditioned by local climate because the strength of environmental constraint that modulates the success of flower-to-fruit transition is likely to vary with local climatic conditions. In accordance, the meteorological cuing was consistent in F. sylvatica. In contrast, in Q. petraea the relationship between spring temperature and Seed Production varied among sites and was stronger in populations at colder sites. The clear difference in meteorological conditioning of Seed Production between the two studied species suggests the responses of masting plants to weather can be potentially systematized according to their masting habit: i.e. fruiting or flowering.
Steven L Petersen - One of the best experts on this subject based on the ideXlab platform.
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Seed Production estimation for mountain big sagebrush artemisia tridentata ssp vaseyana
Rangeland Ecology & Management, 2017Co-Authors: Melissa L Landeen, Stanley G Kitchen, Loreen Allphin, Steven L PetersenAbstract:Seed Production is an essential component of postdisturbance recovery for mountain big sagebrush (Artemisia tridentata Nutt, ssp vaseyana [Rydb] Beetle; MBS). We tested a method for rapid estimation of MBS Seed Production using measurements of inflorescence morphology. We measured total stem length, stem length from first branchlet to stem tip, stem diameter, fresh weight, and number of stem branchlets for 750 inflorescences collected from five central and southern Utah sites. Florets per inflorescence were counted to provide an estimate of Seed Production potential. We used regression analysis to assess associations between morphological traits and potential Seed Production and evaluated the efficiency and scalability of each measure for field application. Site means for morphological measures varied ∼2 to 11-fold while mean number of florets per inflorescence varied ∼ 8-fold. Inflorescence weight was the best predictor of Seed Production potential (P < 0.0001, r2 = 0.897), although correlations for all tested variables were highly significant. Among-site differences in regression equations for this relationship were not significant (P = 0.226), suggesting that a single conversion factor may have broad application. However, validation will require additional testing across a broader range of sites and field conditions. Scalable methods for efficient estimation of sagebrush Seed Production potential, such as those evaluated in this study, could be useful for managers charged with assessing variability in sagebrush community stability.
Walter D Koenig - One of the best experts on this subject based on the ideXlab platform.
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dissecting components of population level variation in Seed Production and the evolution of masting behavior
Oikos, 2003Co-Authors: Walter D Koenig, Dave Kelly, Victoria L Sork, Richard P Duncan, Joseph S Elkinton, Mikko Peltonen, Robert D WestfallAbstract:Koenig, W. D., Kelly, D., Sork, V. L., Duncan, R. P., Elkinton, J. S., Peltonen, M. S. and Westfall, R. D. 2003. Dissecting components of population-level variation in Seed Production and the evolution of masting behavior. – Oikos 102: 581–591. Mast-fruiting or masting behavior is the cumulative result of the reproductive patterns of individuals within a population and thus involves components of individual variability, between-individual synchrony, and endogenous cycles of temporal autocorrelation. Extending prior work by Herrera, we explore the interrelationships of these components using data on individual Seed Production in 59 populations of plants from 24 species spanning a large range of annual variability, from species exhibiting strong masting to others with little annual variability in Seed Production. Estimates of population and individual variability were not biased by sample size or average overall Seed Production when based on untransformed Seed Production values, but these values declined as log-transformed Seed Production increased. Population variability was more strongly correlated with individual variability (r= 0.86) than individual synchrony (r=0.73). These latter two components were also significantly correlated (r=0.45), but randomizations confirm that they need not covary closely. Thus, selection can act separately on inter-annual variability and between-individual synchrony. We illustrate the potential for such fine-tuned selection on Seed Production patterns by discussing several examples and by demonstrating significant differences in components of population-level variation in Seed Production among species related to their life-history.
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patterns of annual Seed Production by northern hemisphere trees a global perspective
The American Naturalist, 2000Co-Authors: Walter D Koenig, Johannes M H KnopsAbstract:We tested whether annual Seed Production (masting or mast fruiting) in Northern Hemisphere trees is an evolved strat- egy or a consequence of resource tracking by comparing masting patterns with those of annual rainfall and mean summer temper- atures, two environmental variables likely to correlate with available resources. There were generally significant negative autocorrela- tions between the Seed crop in year x and year (year x 1 1 x 1 2 in species of Quercus requiring 2 yr to mature acorns), as expected if resources are depleted in mast years in part by switching resources from growth to reProduction. Spatial autocorrelation in annual Seed Production generally declined with distance but was statisti- cally significant over large geographic areas. Variability in annual Seed Production was relatively high and inversely correlated with latitude and generally not bimodally distributed. Patterns of spatial autocorrelation in annual rainfall and summer temperatures are generally similar to those exhibited by annual Seed Production, and relative variability in annual rainfall is also inversely correlated with latitude. However, these environmental variables exhibit distinctly different patterns of temporal autocorrelation, are much less var- iable, and are more normally distributed than annual Seed pro- duction. Combined with the inverse relationship between growth and reProduction previously documented, these results support the hypothesis that variability in annual Seed Production is an evolved strategy and that annual Seed Production is more or less normally distributed rather than an all-or-none phenomenon.
