Communities and ecosystems: tropical forest ecology Flashcards
Why is there so much diversity in tropical rainforests?
- Higher speciation rates and lower extinction rates in the tropics
They can either be
- Cradle: Lots of diversity due high speciation rates
- Museums: Lots of diversity due to a long time since the origin (Example: tropical forest palms)
Threats to tropical forests
- Logging
- Fragmentation
- Fire
- Hunting
- Conversion to agriculture
- Climate change
- Mining
These threats are synergistic (e.g. risk of fire increased by climate change)
Consequences of the threats
- Biodiversity loss
- Loss of ecosystem services
o Carbon sequestration
o Erosion control
o Flooding control
o Climate regulation
Example of consequence: Trophic cascade in Venezuela due to fragmentation
The tropical forest was flooded to create a large resevoir leaving mountain tops as isolated islands
Impact:
- The lack if predaters and vertebrate lead to a top down trophic cascade altering the composition of ecological community
- Density of rodents and other common prey increased (herbivores) and seedling density reduced.
Hope for tropical rainforests: Regeneration
Tropical rainforests are good at regenerating to create secondary forests as long as the soil retians integrity and there is a source of seeds from nearby forests.
Increasing urbanisation in developing nations will allow for more secondary forest formation hopefully cusioning the effect of deforestation.
Solutions to TF threat: Protected areas
Protected areas: Areas can be protected from causes of biodiversity loss (e.g. ban hunting/ deforestation)
problems:
- Hard to monitor effectiveness
- Can provide no additional benefits in areas with low forest threats
- Threats outside the protected areas still have an effect
- Locals often do not like the idea of protected areas as they use these regions for their livlihoods
- Countries containing tropical rainforests are often poor and devloping rapidly and see TR as a natural resource to be exploited-> resources are over exploited
Ultimately, unless protecting forests makes economic sense for local stakeholders, reserves are unlikely to be the [only] solution
Solutions to TR threat: Agreements
Agreements: It is important to get public support and for powerful countries to make agreements. REgional initiatives follow
Example: 2011 Bonn agreement: world leaders agreed to restore 150 million Ha of degraded land by 2020 using Forest and Landscape Restoration (FLR)
prblems:
Challenging when areas are owned by many without effective governance.
Example of over exploitation: Brazil nut
- Populations are harvested intensly, removing all the seeds
- Young trees do not grow and populations are going to succumb to sensecence and demographic collapse
- Large bodied solitary bees are the pollinators and will no longer have this resource
Solution to TF threat: Land sharing vs land sparing
- Land sparing: intensify use of certain areas and protect other areas
- Land sharing: Wildlife friendly farming
Each strategy is more appropriate for a selection of species.
Example: land sparing> land sharing for logging.
Example: Land sharing > alnd sparing for palm oils
Solution to TF threat: Eco-tourism
- Tourism provides incomes to local people and justifies maintaining the forests.
Problems
* Benefits tend to accrue to a minority (often outsiders)
* Can have detrimental effects of tourism if numbers become too high
* Vulnerable to political and financial instability
Solution to TF threat: Bioprospecting
This is the process of getting useful chemicals and products from plants and animals.
This increases the incentive for forest protection.
Example: In 1991 Merck agreed to pay INBio (Costa Rica) $1 million for biodiversity samples plus a percentage of the royalties from any drugs that Merck developed
