Exploitation and Sustainability in Ecosystems

This set of flashcards covers key concepts about overexploitation, sustainability, and ecological impacts on various species and ecosystems.

What is overexploitation?

The use of wild populations for food, medicine, materials, etc., considered the second most important threat to birds, plants, and mammals.

What historical evidence suggests about human impact on species?

Archaeological and paleontological evidence shows that premodern people have driven species to extinction for tens of thousands of years.

What has human colonization led to concerning wildlife?

Extinction of large-bodied vertebrates in regions such as Europe and parts of North America.

How significant is hunting and fishing to the U.S. economy?

Hunting generates 700K jobs and has an economic impact of $61 billion.

What is timber extraction's impact on tropical forests?

5.8 million hectares of tropical forests are logged each year, accounting for 25% of world wood production.

What are non-timber forest products (NTFP)?

Fruits, nuts, oil seeds, latexes, resins, gums, medicinal plants, spices, and fibers that are extremely important for indigenous peoples.

What is a major concern regarding NTFP?

The sustainability of NTFP is under question, as high harvesting intensity can lead to negative impacts.

What effects does subsistence hunting have in tropical forests?

It can affect forest structure through cascading effects originating in mammal assemblages.

What is referred to as ecological forestry?

An approach maintaining small clear-cut patches within a forested matrix to avoid habitat fragmentation.

What is the intrinsic growth rate (r) in population dynamics?

The potential growth rate of a population at low density, unique to the species and not involving density-dependent factors.

How does overharvest of seeds affect plant populations?

It can lead to low recruitment and demographic collapse, as seen in species like the Brazil nut.

What were the fishing trends since the 1990s?

Global catches have leveled off, with an increase in aquaculture.

What is bycatch and why is it significant?

Bycatch refers to non-target species caught unintentionally, resulting in significant ecological impacts on marine ecosystems.

What impact does hunting of large mammals have on ecosystems?

It can lead to overpopulation of certain species and depletion of resources, affecting entire ecosystems.

What does the logistic model provide in terms of population dynamics?

Estimates the number of individuals in a population over time based on carrying capacity and intrinsic growth rates.

What are the challenges of constant quota management in fisheries?

It often leads to population collapse, as the quotas do not adjust based on population size.

What is the proportional quota in sustainable exploitation?

Ties harvest rates to population size, allowing for sustainable practices as long as the exploitation rate is below the growth rate.

What is threshold exploitation?

A method that allows harvesting only above the carrying capacity, taking only the surplus.

What is the demographic rule of thumb for tropical mammals?

It estimates maximum potential production occurs at about 60% of carrying capacity.

How does aquaculture compare to wild fisheries?

Aquaculture is increasing in importance as wild stocks decline due to overexploitation.

What is a key benefit of managing small game hunting?

It generates income that protects habitats from other land uses while benefiting species of concern.

How are non-target species affected by overexploitation?

Indirectly through cascading effects when target species are overexploited.

What is a significant trend in recreational fishing statistics in the U.S.?

35 million people participate, contributing $38 billion annually.

How does logging affect fire frequency and intensity?

Increases desiccation and dry fuel loads, leading to more severe fire conditions.

What is the Allee effect observed in some mollusk populations?

Need for individuals to be at specific densities for effective reproduction and survival.

What are extractive reserves?

Protected areas in tropical forests aimed at promoting sustainability of resource use.

What role do keystone mammals play in ecosystem dynamics?

Their absence can lead to negative cascading effects on other species and habitats.

What is the significance of salmon in nutrient cycling?

Salmon contribute substantial nutrient loads to streams, which support plant and animal life.

What defines the term 'sustainable yield' in population dynamics?

Occurs at 50% or more of maximum population size, balancing harvesting and population growth.

What is the measurable carrying capacity (K) of a population?

The maximum number of individuals that an environment can sustain.

What threats are associated with marine fisheries management?

Poor management practices lead to the decline of 232 stocks by 83% over the past 25 years.

What is the significance of fecundity in assessing population health?

It reflects reproductive success and population viability, crucial for long-term species sustainability.

What is the importance of population sensitivity analysis?

It helps in assessing how changes in demographic parameters affect overall population growth and sustainability.

What are the economic implications of overfishing?

It can lead to decreased fish populations, reduced fishing jobs, and economic instability in communities relying on fisheries.

How does fishing impact biodiversity in aquatic systems?

Overfishing can lead to reduced biodiversity by depleting specific species and disrupting ecological balance.

What strategies can help prevent fishery collapses?

Implementing sustainable quotas, monitoring populations, and reducing bycatch through better fishing practices.