He shows the extent of game harvesting in Amazonia. The pattern of harvest varies with village size (rodents and possums in depleted state). The vulnerable, low fecundity species start dropping out at a human density of 1 person per km2 (Peres 2011 Conservation Biology)
They have censused vertebrate populations throughout the Amazon. Map hunting pressure throughout the Amazon (all sites are structurally intact). Did lots of paired comparisons.
The harvest-sensitive species are largely frugivores. Frugivory is the unifying guild. In non-hunted areas large bodied primates dominate community animal biomass. In hunted areas they are largely gone. The build a demographic model of source-sink dynamics.
Over 3-5 years the community skews towards the smaller bodied species. There is density compensation and a lot of the smaller-bodied species come back.
Cascade; hunting pressure increases -> frugivore populations decline -> dispersal imitation -> plant fitness reduced of large seeded species -> some density compensation -> shifts in community structure and biomass.
Janzen-Connell effects inhibit recruitment and survival of sapling near the mother trees (pathogen load).
Woolly monkeys alone are responsible for scattering a million seeds km2
One fruit syndrome common in Amazonia: large seeded, indehiscent (don’t break open, need a passage through a gut) fruits are particularly vulnerable to frugivore loss.
They do a model simulation where they replace random trees by non fruit-dispersed trees. Many frugivore trees tend to be heavy wooded. This suggests that forest biomass will reduce over time as frugivore-dispersed trees drop out and are replaced by lower wood density species.
Adam Wolf:: at what time scale do you imagine this loss of biomass to take place
Carlos Peres: one tree generation time.
They have censused vertebrate populations throughout the Amazon. Map hunting pressure throughout the Amazon (all sites are structurally intact). Did lots of paired comparisons.
The harvest-sensitive species are largely frugivores. Frugivory is the unifying guild. In non-hunted areas large bodied primates dominate community animal biomass. In hunted areas they are largely gone. The build a demographic model of source-sink dynamics.
Over 3-5 years the community skews towards the smaller bodied species. There is density compensation and a lot of the smaller-bodied species come back.
Cascade; hunting pressure increases -> frugivore populations decline -> dispersal imitation -> plant fitness reduced of large seeded species -> some density compensation -> shifts in community structure and biomass.
Janzen-Connell effects inhibit recruitment and survival of sapling near the mother trees (pathogen load).
Woolly monkeys alone are responsible for scattering a million seeds km2
One fruit syndrome common in Amazonia: large seeded, indehiscent (don’t break open, need a passage through a gut) fruits are particularly vulnerable to frugivore loss.
They do a model simulation where they replace random trees by non fruit-dispersed trees. Many frugivore trees tend to be heavy wooded. This suggests that forest biomass will reduce over time as frugivore-dispersed trees drop out and are replaced by lower wood density species.
Adam Wolf:: at what time scale do you imagine this loss of biomass to take place
Carlos Peres: one tree generation time.