Lecture 25 Flashcards
Biodiversity
-the richness and variety of life forms in the environment
- high diversity makes communities more resilient, more able to adapt to change, and more likely to survive
- includes genetic diversity, habitat diversity and species diversity
Genetic diversity
- how variable or heterogenous the DNA among individuals in the population are
- when a large population is descended from only a few individuals, genetic diversity is extremely limited-called a genetic bottleneck
Habitat diversity
- how many different habitat types there are in the ecosystem
- best in an ecosystem with narrow niches and greater niche diversity
- preserving habitat diversity may be key to preserving biodiversity
Species diversity
- how many species live in the ecosystem
- species richness refers to the number of species in the ecosystem or community
- species evenness refers to the relative abundance of individuals of each species in the community
Threats to biodiversity
- Endangered Species
- an imminent danger of extinction - Threatened Species
- significant decrease in population and range, or shows signs of imminent local extinction
Drivers of endangerment/threat
- competition from invasive species
- habitat destruction or fragmentation
- over harvesting
Utilitarian (anthropogenic)
- direct economic value (food, lumber, etc)
- potential medical and pharmaceutical uses
- recreation and tourism
- aesthetic
Intrinsic value
- species have intrinsic value and right to exist
- humans have ethical obligation to protect other species
Natural resources from the environment
Human populations take materials from their environment
- from biosphere (hunting, gathering, logging, agriculture)
- from hydrosphere (water, fishing, salt)
- from geosphere (minerals, fuels, building materials)
- from atmosphere (oxygen)
Waste products are returned
- to lithosphere (solid waste)
- to hydrosphere (dissolved material)
- to atmosphere (aerosols, gases)
Renewable and non-renewable resources
Renewable resources
- those replenished by new growth each season
- food crops, wood, running water, fisheries
Non renewable resources
- those replenished only on longer time scales
- most minerals, fossil fuels
Both have environmental impacts
Impacts and resource cycles
Review cycles on slides 1.3 (two slides)
Managing non renewable resources
- finite amount, not replenished on human timescale
- extend resource availability through conservation, reuse, recycling, or substitution
Managing renewable resources
- resources like fish and trees are renewable if managed properly
- use too fast=deplete resource
- use at replenishment rate=have a steady state
- if severely depleted, may not be able to regenerate
Forest resources
- 95% natural forests, 5% plantations
- timber, fuel, latex, nuts, fruits, oils all forest products
- forests link biosphere to other spheres
Threats to forest resources
- type of harvesting (clear cutting versus selective or reduced impact, unsustainable)
- Deforestation (loss of biodiversity, habitat, soil loss especially in tropical rain forests)
