habitat change

frontier forest

intact blocks of undisturbed forest large enough to support all aspects of biodiversity

rain forests account for % of the Earths surface, but houses _% of the worlds species.

7% , 50%

What are some deforestation drivers in the Tropical rain forest.

1. Commodity-driven

2. Forestry

3. Shifting cultivation

4. Wildfire

5. Urbanization

what are the majority of tropical rainforests lost to?

logging, cattle, ranching, crops, palm oil

Shifting cultivation

slash and burn agriculture

what are some deforestation drivers in the tropical rain forest

demand for cheap agricultural products such as palm oil, rubber, cocoa, etc.

Tropical Deciduous forest habitat destruction example

Madagascar - 44% lost in this country because it is better for agriculture, therefore the human population is 5x more dense

Habitat destruction in grasslands

• easy to convert grassland into farmland

• 98% tall grass praire converted to farmland in the US

Habitat destruction in freshwater habitats

• filling/draining for development

• altered by dams, pollution, etc

habitat destruction in marine coastal areas

• 20% coastal agrees are degraded, filled in, and highly modified by humans

• pollution, dredging, sedimentation, overfishing, invasives, rising temperatures

habitat destruction in mangrove forests

• most important wetland community in tropical areas

• 50% have been lost

• 40% of mangrove dependent species are at high risk for extinction

• important for carbon sequencing

• sea levels rising is a major threat

how does the increase in CO2 effect coral reefs

causes coral bleaching and ocean acidification

desertification

converts dry communities (grasslands, scrub, savanna) to desert-like conditions

how can desertification cause habitat destruction

• increase in fire frequency

• productive capacity decreases

• soil erosion and loss of water-holding capacity

• not a functional ecosystem

habitat fragmentation

large continuous area of habitat is both reduced in area and divided into two or more fragments via roads, fields, towns, etc.

how do habitat fragments differ from original habitat

1. fragments have a greater amount of edge per area of habitat

2. the center of the habitat is closer to the edge

3. when a formerly large habitat with a large population is fragmented, each fragment now hosts a small population

t/f: fragmentation often correlates with habitat destruction

true

meta-analysis

statistical tool to combine results from multiple different research projects

effect size

magnitude of impact of interest

what did the meta-analysis of long-term fragmentation experiments find

• fragmentation reduced species diversity by 13-75%

• negative impacts on community composition

• negatie impacts on ecosystem processes

• species loss increased over time

edge effects

a result of the altered habitat at the edge of habitat fragments

how does the edge effect change the environment

causes increased wind, fire, species invasion, and predation

edge speices

species that thrive in transitional zones between habitat types

examples of edge species

Northern mockingbird and Northern Cardinal

Interior species

species that require large tracts of continuous habitat to survive

examples of interior species

Scarlet Tanager and Ovenbird

example of predation increase due to the edge effect

Bobcat predation on green heron nests

how does habitat fragmentation limit dispersal and colonization

limits the potential for a species to disperse and colonize a new area by creating barriers to normal movement

T/F: dispersal limitation can increase probabilty of inbreeding

true

ex of dispersal limitation

Freshwater turtles - females are disproportionally killed on roads due to having to travel to nest

Wildlife crossings

bridges and tunnels specifically designed for animals to reduce the impact of highways

how does habitat fragmentation restrict access to food and mates

• fences prevent natural migration of large grazing animals like bison

• dams fragment rivers affecting species that swim up river to spawn

how does habitat fragmentation create smaller populations

• division of widespread populations into smaller subpopulations

• increases vulnerability for inbreeding depression, genetic drift, etc.

how does habitat fragmentation increase interspecies interactions

• increases vulnerability to invasion by nonnative and native pest species

• road edges can be dispersal routes for invasive specoes

• disease risk

ex of interspecies interactions b/c of habitat fragmentation

Brown-headed cowbird (brood parasite) has had an increase in range across north america due to an increase in agricultural land and habitat adges

habitat degradation

decrease in habitat quality (ability to support species or communities)

examples of habitat degradation

• overgrazing in grasslands → desertification, loss of minerals, soil, water

• trawling

bioaccumulation of toxins

accumulationof toxic material inside the body of a single organism

Sentinel species

first obviously affected by pollution danger

water pollution

• diffuses over a wide area

• low concentration can be lethal due to bioaccumulation

• adaptations of animals and plants to low levels of nitrates, phosphates, and other minerals in water

Pollution

large amounts of these chemicals that can poison them or lead to overgrowth

what percent of endangered freshwater fish/mussels are threatened by water pollution

90%

Wastewater runoff

excess bacteria, viruses, parasites, and other chemicals such as medicines used in humans

agricultural runoff

pesticides - some acting as endocrine disruptors

examples of water pollution

• wastewater runoff

• agricultural runoff

• microplastics

air pollution examples

• acid rain

• ozone

• toxic metal

acid rain

nitrogen oxides and sulfur in the air combine with moisture to produce nitric and sulfuric acids

what does acid rain do

• lowers pH of rain

• acidity weakens/kills trees over wide areas

• increases concentration of toxic metals such as aluminum in the soil and water

what act helped decrease acid rain in the USA

clean air act