Overexploitation and Its Impacts

A series of flashcards related to the themes of overexploitation, its historical context, and its effects on ecosystems and species management.

What is the definition of overexploitation?

It is the unsustainable use of natural resources, such as using wild populations (plants, animals, algae) for food, medicine, materials, fiber, etc.

What is the second most important threat to birds, plants, and mammals?

Overexploitation.

What does historical evidence suggest about human interaction with species extinction?

Humans have been causing species extinctions for tens of thousands of years.

What consequences did human colonization have on large-bodied vertebrates?

Extinction of many large-bodied vertebrates.

What is the economic impact of hunting in the US?

Generates $61 billion and supports 700,000 jobs.

What is a major threat to tropical forests according to the lecture?

Timber extraction.

How much of the world's wood production comes from tropical forests?

25% or 5.8 million hectares logged each year.

What is the risk associated with selective logging?

Severe collateral damage and almost no investment in regeneration.

What has greatly increased the consumption of bushmeat in tropical forests?

Hunting, particularly in the Amazon and Central Africa.

What is the sustainable hunting rate for mammals according to the lecture?

20% of production.

What are non-timber forest products (NTFP)?

Fruits, nuts, oil seeds, resins, medicinal plants, and other products from forests.

Why is the sustainability of NTFP questioned?

It is not fully understood and varies with intensity and part exploited.

What species exemplifies low recruitment due to overharvesting?

Brazil nut.

Which forest type has the highest remaining area, temperate or boreal?

Boreal forests (48%) compared to temperate forests (3%).

What type of forestry maintains the forested matrix and reduces fragmentation?

Ecological forestry.

What is a significant concern regarding hunting in temperate regions?

Managing populations of game species to prevent overexploitation.

What proportion of North American freshwater species are endangered?

72% of freshwater mussel species.

How does logging impact fire frequency and intensity?

Increases desiccation and dry fuel loads.

What is endozoochorous dispersal?

Seed dispersal primarily by animals, affecting 90% of plant species in tropical forests.

What keystone species' loss can cause cascading ecological effects?

Top predators like grizzly bears and wolves.

What is a significant aspect of marine fisheries related to by-catch?

Estimated global bycatch of 27 million tons annually.

What factors contribute to the vulnerability of some aquatic species to overexploitation?

Ease of capture, shallow water habitat, and high commercial value.

What happens when the maximum population size (Nmax) is exceeded?

Overexploitation can lead to population collapse.

What is logistic population growth?

A model estimating population size over time considering carrying capacity.

At what population size does sustainable yield occur according to the lecture?

At 50% or more of the maximum population size.

What are the two types of exploitation quotas discussed?

Constant (fixed) quotas and proportional quotas.

What determines if proportional quotas are sustainable?

If the exploitation rate is below the intrinsic rate of natural increase.

What is the primary goal of harvest-per-effort production models in fisheries?

To maximize yield based on fishing effort.

What is a threshold exploitation approach?

Harvesting only above carrying capacity and only if a surplus exists.

What does the demographic rule of thumb suggest about tropical mammals?

Maximum potential production occurs at about 60% of carrying capacity.

What percentage of Pmax is typically used to set quotas?

20-40% of Pmax.

Why is estimating carrying capacity (K) challenging?

Accurate surveys may be difficult and collateral mortality can affect estimates.

What role does the economic value of size play in sustainable exploitation?

Older individuals often have increased value, thus low exploitation rates can benefit future generations.

What are the two approaches to assessing sustainable exploitation effectiveness?

Data from Marten harvests and full demography analysis.

Why is monitoring fish populations important when using proportional quotas?

To ensure exploitation rates remain below the intrinsic growth rate.