Existing comment:
William F. Laurance (Smithsonian Tropical Research Institute)
Much of his presentation was based on a survey of 80-some tropical reserves around the world. The researchers in each reserve if a variety of observed conditions (drivers) had increased or decreased over time. Just about every criteria showed, en masse, decreases for each of the categories:
- Apex predators (lions)
- Large, non-predatory species
- Primates
- Opportunistic omnivores (who they thought would be doing better)
- Stream fish
- Migratory species
Some exceptions:
- Understory birds (mostly no change, secondarily decreasing)
- Game birds (no change and decreasing are tied)
- Large frugivorous birds (mostly no change, secondarily increasing)
- Stream-dwelling amphibians (mostly no change, secondarily increasing, not a single one saying things are better)
- Disturbance- and Light-loving trees (mostly better)
- Lianas and wines (mostly better -- thank you kudzu!)
- Invasive plants (mostly increasing)
- Invasive animals (mostly no change, secondarily increasing)
- Human diseases (mostly increasing)
- Natural forest cover (mostly no change, secondarily decreasing)
- Hunting (mostly increasing)
- Fires (mostly no change)
- Selective logging (mostly no change, secondarily decreasing)
- Air pollution (mostly no change, secondarily increasing)
- River and stream sedimentation (mostly no change, secondarily increasing)
- Rising temperatures (mostly no change, secondarily increasing, not a single one decreasing)
- Droughts (increasing and no change tied)
- Automobile traffic (mostly no change, secondarily increasing)
- Nearby human populations (mostly no change, secondarily increasing)
Other drivers showing little net change:
- Illegal mining
- Pastoralism/grazing
- Rainfall
- River/stream flows
- Seed predation
Far more reserves are getting worse than are getting better
Some drivers are stable (or even improving), but many are worsening
Reserves with worsening drivers are declining ecologically
Smaller reserves are generally more vulnerable
Conclusions:
- Most tropical reserves are being altered, often seriously
--- Many guilds declining
--- Other guilds poorly studied
- Threats are eclectic, but some perils are common
--- Climate change
--- Air & water pollution
--- Declining freshwater ecosystems
--- Growing populations
--- Increasing isolation
--- Expanding roads
- Many reserves too small and poorly protected to buffer external threats and climate change |