Summary 1 Understanding seed dispersal by wind and, in particular, long‐distance dispersal (LDD) is needed for management of plant populations and communities, especially in response to changes in climate, land use and natural habitats. Numerical models designed to explore complex, nonlinear atmospheric processes are essential tools for understanding the fundamental mechanisms involved in seed dispersal. Yet, thus far, nearly all such models have not explicitly accounted for the spatial heterogeneity that is a typical feature of all ecosystems. 2 The recently developed Regional Atmospheric Modelling System (RAMS)‐based Forest Large Eddy Simulation (RAFLES) is used here to explore how within‐stand canopy heterogeneity impacts LDD. RAFLES resolves microscale canopy heterogeneity such as small gaps and variable tree heights, and it simulates their impacts on turbulence inside and above the canopy in the atmospheric boundary layer (ABL). For that purpose, an Eulerian–Lagrangian module of seed dispersal is added to RAFLES to simulate seed trajectories. 3 Particular attention is paid to the sensitivity of statistical attributes of the dispersal kernels (i.e. mean, mode, variance, tail) to key simplifications common to all seed dispersal models, such as horizontal homogeneity in the canopy and flow field, and the tight coupling between air parcel trajectories and seed trajectories (i.e. neglecting seed inertia). These attributes appear to be sensitive to various factors operating at scales ranging from the seed scale to the ABL scale. 4 Simulations with RAFLES show that LDD is characterized by a dispersal kernel with a ‘tail’, asymptotically approaching a power law decay of –3/2 (mainly occurring for lighter seeds at high wind speeds). This is consistent with asymptotic predictions from analytical models. The wind speed threshold at which seed abscission occurs, set‐up to be twice the standard deviation of the vertical wind speed, is shown to affect short‐distance dispersal, but has no significant impact on LDD. Ignoring the effects of seed inertia on the seed trajectory calculations has a minor effect on short‐distance dispersal and no effect on the probability of seed uplift. Thus, it has no significant impact on LDD. 5 Synthesis. Tree‐scale canopy heterogeneity affects the turbulence characteristics inside and above the canopy and, consequently, this affects dispersal kernel statistics. A key finding from this study is that ejection is enhanced above the shorter trees of the canopy. Seeds dispersed above shorter trees have a higher probability of experiencing LDD while their short‐distance dispersal remains practically the same. At inter‐annual time scales, such interactions could affect species composition.
Journal of Ecology – Wiley
Published: Jul 1, 2008
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.
Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.
All the latest content is available, no embargo periods.
“Hi guys, I cannot tell you how much I love this resource. Incredible. I really believe you've hit the nail on the head with this site in regards to solving the research-purchase issue.”Daniel C.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud
“I must say, @deepdyve is a fabulous solution to the independent researcher's problem of #access to #information.”@deepthiw
“My last article couldn't be possible without the platform @deepdyve that makes journal papers cheaper.”@JoseServera