I hope to conduct a directed dispersal study of the remnant population of Chinese yew.
I am particularly focused on the habitat selection of frugivorous birds after they foraged seeds.
Is there anyone with experience for combining habitat selection by birds and directed dispersal?
There is abundant published research on that general topic, both empirical and theoretical. Just as some examples that could serve as introduction to previously used methods and theoretical frameworks:
Russo, Sabrina E., Stephen Portnoy, and Carol K. Augspurger. Incorporating animal behavior into seed dispersal models: implications for seed shadows. Ecology 87.12 (2006): 3160-3174.
Herrera, Jose M., Juan M. Morales, and Daniel García. Differential effects of fruit availability and habitat cover for frugivore‐mediated seed dispersal in a heterogeneous landscape. Journal of Ecology 99.5 (2011): 1100-1107.
Spiegel, O. and Nathan, R. (2012), Empirical evaluation of directed dispersal and density-dependent effects across successive recruitment phases. Journal of Ecology, 100: 392–404.
Aukema, Juliann E., and Carlos Martínez del Rio. "Where does a fruit-eating bird deposit mistletoe seeds? Seed deposition patterns and an experiment." Ecology 83.12 (2002): 3489-3496.
Santamaría L, Rodríguez-Pérez J, Larrinaga AR, Pias B: Predicting spatial
patterns of plant recruitment using animal-displacement kernels.
PLoS One 2007, 2:e1008.
Schupp, Eugene W., Pedro Jordano, and José María Gómez. Seed dispersal effectiveness revisited: a conceptual review. New Phytologist 188.2 (2010): 333-353.
Rodríguez-Pérez J, Wiegand T, Santamaría L: Frugivore behavior
determines plant distribution: a spatially explicit analysis of a
plant-disperser interaction. Ecography 2012, 35:113–123.
Morales JM, Carlo TA: The effects of plant distribution and frugivore
density on the scale and shape of dispersal kernels. Ecology 2006,
87:1489–1496.
Russo SE, Portnoy S, Augspurger CK: Incorporating animal behavior into
seed dispersal models: implications for seed shadows. Ecology 2006,
87:3160–3174.
Robledo-Arnuncio JJ, Klein EK, Muller-Landau HC, Santamaría L (2014) Space, time and complexity in plant dispersal ecology. Movement Ecology 2:16. (see section 2 in particular)
Dear Ning Li, notice that "directed dispersal" means that seeds are dispersed "mostly" to safe sites for plants to grow. To provide evidence for the mechanism, you may need to conduct both seed dispersal and seedling (saplings too?) survival/growth experiments. A nice example is given by Wenny & Levey (1998) PNAS.
Hi Ning
As mentioned in the previous answers, for establishing directed dispersal you need to identify two steps. first disproportionate arrival to certain habitat. this is probably true for most systems since the birds obviously prefer some habitat over the others. And therefore dispersal by animals is almost always non random. the second step is more tricky, here you need to show that the habitats the gets seeds favorable for establishment from the plants perspective (for instance when compared to the alternative habitats available at random).
there are two common issues with this second phase: first you want to account for density. a favorable habitat for establishment can become unfavorable if densities are very high locally. this is probably the case with many of the deposition sites since birds tend to revisits the same spot again and again and not to uniformly cover the habitat. the second issue is that density dependent mortality can become crucial at late life stages of the plant. so even if a habitat seems to be favorable for germination (or even for sapling early survival) the real question should be if it is better than the alternative habitats.
we have covered these issues in depth, both theoretically and empirically in these two publications (attached), including some reference to the possible caveats in the very elegant work by Wenny & Levey (1998) PNAS
Spiegel, O. & Nathan, R. (2012). Empirical evaluation of directed dispersal and density-dependent effects across successive recruitment phases. Journal of Ecology. 100, 392–404. PDF
Spiegel, O. & Nathan, R. (2010). Incorporating density dependence into the directed-dispersal hypothesis. Ecology. 91(5), 1538–1548. PDF
good luck
Orr
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