Flashcards in F215: Ecosystems And Sustainability. Deck (18)
What is coppicing?
Cutting a tree trunk close to the ground to encourage new growth.
Several new shoots grow from the cut surface, and mature in stems of narrow diameter.
Harvesting wood whilst keeping the tree alive.
What is pollarding?
It involves cutting the trunk higher up, to prevent animals such as deer eating the emerging shoots from a coppiced stem, as they cannot reach.
What is rotational coppicing?
Dividing the woodland into sections and cutting one section each year until they have all been cut.
When they come back to the first section again it has matured and is ready to be cut again.
What are standards?
Larger trees that are left to grow without being coppiced to provide larger pieces of timber.
How does rotational coppicing effect biodiversity?
Different areas of woodland provide different types of habitat, letting more light in and increasing the number and diversity of species.
What is clear felling and it's effects?
Removal of all the trees in an area.
Reduces soil mineral levels and leaves the soil susceptible to erosion.
Destroys habitats on a large scale.
What is selective cutting?
Removing only the largest most valuable trees, leaving the habitat mostly unaffected.
What is conservation?
The maintenance of biodiversity of a variety of habitats and ecosystems.
What are ethical arguments for conservation?
Every species has value in it's own right, regardless of economical value. They have a right to live, and we have a responsibility to look after them.
This a subjective argument however.
What are economic and social reasons for conservation?
Many species provide a food source, and generic diversity in wild strains may be needed in future to breed for disease resistance, drought tolerance or improved yield.
Pharmaceutical uses, many drugs are discovered in wild plant species.
Indirect benefits, such as insects pollinating crops.
Ecotourism and recreation in the countryside has financial and social value.
What is the difference between observation and preservation?
Conservation involves management and reclamation.
Preservation involves protecting areas of land in their natural untouched form.
Describe habitat disturbance i the Galápagos Islands.
The dramatic increase in population size & tourism means that the authorities cannot meet demands for water, energy, sanitary etc.
Waste and pollution have thus increased, as has oil demands.
All of this has affected the local habitats.
Forests of scalesia trees, which are unique to the islands, and plants have been destroyed to make room for agricultural land.
Describe the over exploitation if resources in the Galapagos Islands.
Whale boats and fur traders harvested whales and seals faster than they could replenish the population.
Giant tortoises were taken from the islands, as they could survive on little food, to be killed and eaten.
There was an increase in fishing for exotic species depleted their population.
Shark fin hunting led to 150000 deaths per year.
Describe introduced species in the Galápagos Islands.
Fruit and veg plants and animals like goats and cats were introduced, bringing insects and influencing the food chains and habitats.
The red quinine tree is aggressively invasive. It occupies highlands and spreads rapidly, it shifted the habitat from grassland to forest, so now the cacaotillo shrub is endangered. It also out competes the scalesia trees.
Goats were introduced, eating unique purslane. It out competes the giant tortoise for grazing and steals their food.
They also have transformed the habitat from forest into grassland in some areas, leading to soil erosion.
Cats hunt species such as the lava lizard and young iguanas.
What did Charles Darwin introduce in 1999 to treat problems at the Galápagos Islands?
A quarantine system, where any boats of tourists arriving are searched.
Natural predators have been exploited to reduce the damage caused by pest populations, eg ladybird wiped out insects that damaged plants.
Culling against feral goats and pigs.
Describe nitrogen fixing.
Lives in legumes, eg beans/clover.
Mutualistic, supply nitrogen get carbon compounds back.
Convert nitrogen gas into ammonium compounds.
Describe the bacteria present in nitrofication.
Nitrosomonas: ammonium ions ---> nitrites.
Nitrobacter: nitrites ---> nitrates.