Mechanistic modeling of seed dispersal by wind over hilly terrain

Trakhtenbrot, Ana; Katul, Gabriel G.; Nathan, Ran

doi:10.1016/j.ecolmodel.2013.11.029

Cited by 45 publications

(30 citation statements)

References 58 publications

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“…This scale separation framework was already employed to model seed dispersal kernels over complex terrain covered by uniform canopies (Trakhtenbrot et al . ).…”

Section: Discussionmentioning

confidence: 98%

Effects of topography on in‐canopy transport of gases emitted within dense forests

Chen

Chamecki

Katul

2019

Quart J Royal Meteoro Soc

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The significance of air flow within dense canopies situated on hilly terrain is not in dispute given its relevance to a plethora of applications in meteorology, wind energy, air pollution, atmospheric chemistry and ecology. While the mathematical description of such flows is complex, progress has proceeded through an interplay between experiments, mathematical modelling, and more recently large‐eddy simulations (LESs). In this contribution, LES is used to investigate the topography‐induced changes in the flow field and how these changes propagate to scalar transport within the canopy. The LES runs are conducted for a neutral atmospheric boundary layer above a tall dense forested canopy situated on a train of two‐dimensional sinusoidal hills. The foliage distribution is specified using leaf area density measurements collected in an Amazon rain forest. A series of LES runs with increasing hill amplitude are conducted to disturb the flow from its flat‐terrain state. The LES runs successfully reproduce the recirculation region and the flow separation on the lee‐side of the hill within the canopy region in agreement with prior laboratory and LES studies. Simulation results show that air parcels released inside the canopy have two preferential pathways to escape the canopy region: a “local” pathway similar to that encountered in flat terrain and an “advective” pathway near the flow‐separation region. Further analysis shows that the preferential escape location over the flow‐separation region leads to a “chimney”‐like effect that becomes amplified for air parcel releases near the forest floor. The work here demonstrates that shear‐layer turbulence is the main mechanism exporting air parcels out the canopy for both pathways. However, compared to flat terrain, the mean updraught at the flow separation induced by topography significantly shortens the in‐canopy residence time for air parcels released in the lower canopy, thus enhancing the export fraction of reactive gases.

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“…This scale separation framework was already employed to model seed dispersal kernels over complex terrain covered by uniform canopies (Trakhtenbrot et al . ).…”

Section: Discussionmentioning

confidence: 98%

Effects of topography on in‐canopy transport of gases emitted within dense forests

Chen

Chamecki

Katul

2019

Quart J Royal Meteoro Soc

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“…), topography (Trakhtenbrot et al . ) and reproductive asynchrony (Varis et al . ), can generate large differences in pollen‐mediated gene flow independently of spatial isolation.…”

Section: Discussionmentioning

confidence: 99%

Estimating exotic gene flow into native pine stands: zygotic vs. gametic components

Unger¹,

Vendramin

Robledo‐Arnuncio³

2014

Molecular Ecology

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Monitoring contemporary gene flow from widespread exotic plantations is becoming an important problem in forest conservation genetics. In plants, where both seed and pollen disperse, three components of exotic gene flow with potentially unequal consequences should be, but have not been, explicitly distinguished: zygotic, male gametic and female gametic. Building on a previous model for estimating contemporary rates of zygotic and male gametic gene flow among plant populations, we present here an approach that additionally estimates the third (female gametic) gene flow component, based on a combination of uni- and biparentally inherited markers. Using this method and a combined set of chloroplast and nuclear microsatellites, we estimate gene flow rates from exotic plantations into two Iberian relict stands of maritime pine (Pinus pinaster) and Scots pine (Pinus sylvestris). Results show neither zygotic nor female gametic gene flow but moderate (6-8%) male gametic introgression for both species, implying significant dispersal of pollen, but not of seeds, from exotic plantations into native stands shortly after introduced trees reached reproductive maturity. Numerical simulation results suggest that the model yields reasonably accurate estimates for our empirical data sets, especially for larger samples. We discuss conservation management implications of observed levels of exposure to nonlocal genes and identify research needs to determine potentially associated hazards. Our approach should be useful for plant ecologists and ecosystem managers interested in the vectors of contemporary genetic connectivity among discrete plant populations.

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“…The study methods and habitat contrasts were too inconsistent to allow patterns to be discerned. It is likely that habitat type and structure will affect the dispersal process (Westcott et al 2005;Trakhtenbrot, Katul & Nathan 2014) and so more formal contrasts of kernels among habitat types would allow characterization of intraspecific variation in dispersal. Furthermore, synthesis of such data would be aided by more complete presentation of the gathered data in papers.…”

Section: E a S U R I N G S E E D D I S P E R S A Lmentioning

confidence: 99%

A synthesis of empirical plant dispersal kernels

et al. 2016

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Summary 1.Dispersal is fundamental to ecological processes at all scales and levels of organization, but progress is limited by a lack of information about the general shape and form of plant dispersal kernels. We addressed this gap by synthesizing empirical data describing seed dispersal and fitting general dispersal kernels representing major plant types and dispersal modes. 2. A comprehensive literature search resulted in 107 papers describing 168 dispersal kernels for 144 vascular plant species. The data covered 63 families, all the continents except Antarctica, and the broad vegetation types of forest, grassland, shrubland and more open habitats (e.g. deserts). We classified kernels in terms of dispersal mode (ant, ballistic, rodent, vertebrates other than rodents, vehicle or wind), plant growth form (climber, graminoid, herb, shrub or tree), seed mass and plant height. 3. We fitted 11 widely used probability density functions to each of the 168 data sets to provide a statistical description of the dispersal kernel. The exponential power (ExP) and log-sech (LogS) functions performed best. Other 2-parameter functions varied in performance. For example, the lognormal and Weibull performed poorly, while the 2Dt and power law performed moderately well. Of the single-parameter functions, the Gaussian performed very poorly, while the exponential performed better. No function was among the best-fitting for all data sets. 4. For 10 plant growth form/dispersal mode combinations for which we had >3 data sets, we fitted ExP and LogS functions across multiple data sets to provide generalized dispersal kernels. We also fitted these functions to subdivisions of these growth form/dispersal mode combinations in terms of seed mass (for animal-dispersed seeds) or plant height (wind-dispersed) classes. These functions provided generally good fits to the grouped data sets, despite variation in empirical methods, local conditions, vegetation type and the exact dispersal process. 5. Synthesis. We synthesize the rich empirical information on seed dispersal distances to provide standardized dispersal kernels for 168 case studies and generalized kernels for plant growth form/ dispersal mode combinations. Potential uses include the following: (i) choosing appropriate dispersal functions in mathematical models; (ii) selecting informative dispersal kernels for one's empirical study system; and (iii) using representative dispersal kernels in cross-taxon comparative studies.

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Mechanistic modeling of seed dispersal by wind over hilly terrain

Cited by 45 publications

References 58 publications

Effects of topography on in‐canopy transport of gases emitted within dense forests

Effects of topography on in‐canopy transport of gases emitted within dense forests

Estimating exotic gene flow into native pine stands: zygotic vs. gametic components

A synthesis of empirical plant dispersal kernels

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