Transcript Why does it matter- what are the benefits of biodiversity?

Benefits of biodiversity
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Dr John A Finn, Dept of Agriculture.
Lecture outcomes
 What is biodiversity?
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How much of it is there?
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Why does it matter- what are the benefits
of biodiversity?
What is biodiversity?
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The variety and variability among living organisms and the
ecological complexes in which they occur. Diversity can be
defined as the number of different items and their relative
frequency. For biodiversity, these items are organised at
many levels, ranging from complete ecosystems to the
chemical structures that are the molecular basis of heredity.
Thus, the term encompasses different ecosystems, species,
genes and their relative abundance.
What is biodiversity?
Other definitions
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The genetic taxonomic and ecosystem variety in living
organisms of a given area, environment, ecosystem or the
whole planet
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the total diversity and variability of living things and of the
systems of which they are a part. This covers the total
range of variation in and variability among systems and
organisms, at the bioregional, landscape, ecosystem and
habitat levels, at the various organismal levels down to
species populations and individuals, and at the level of the
population and genes.
How much biodiversity is there?
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How does one measure the number of species on Earth?
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Only about 1 million species described, and only about
100,000 are well known.
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Erwin and Stork: fogging samples of Tropical insects:
– 163 species of canopy-dwelling beetles specific to one
tree species
– about 50,000 tree species
–  8 million species of canopy-dwelling beetles
– about 40% of insects are beetles  20 million
canopy insects
HOTSPOTS
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Biodiversity hotspots refer to regions of the world that are
high in endemic species (and are usually threatened)
Endemic species refers to a species native to a particular
place and only found there
see o/h on hotspots and human population
Biodiversity Decline
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Species extinction is currently greater than ever before:
– background rate: 100 sp. per year
– current rate: 1,800 to 30,000 species per year
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Causes
– Habitat destruction
– Hunting
– Accidental introductions
36%
23%
39%
Consequences ?
Why does biodiversity matter?
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Source of marketable commodities
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Provision of non-marketable services and goods
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It is of intrinsic value
[From ‘Does biodiversity matter?’, Book chapter by Kunin
and Lawton (1996), In: Biodiversity: a biology of numbers
and difference by Gaston, K.J.]
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Stabilises the provision of non-marketable
services and goods- ‘the insurance effect’
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It is threatened
Biodiversity as a source of marketable products
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food (wild and cultivated sources)
– Zea diploperennis;
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medicinal compounds
– Rosy periwinkle (flower) ; aspirin discovered in
meadowsweet; hirudin in leeches;
– in US, quarter of all prescriptions are substances derived
from plants
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biological control
source of materials of industrial value
harvesting (hunting/ fishing- recreational)
culturing (e.g. gardening)
Provision of non-marketable services and goods
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Earth's biota can affect our environment
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Ecosystems provide a variety of functions that in turn
provide, directly or indirectly, a range of benefits to
humans.
– the regulation of climatic processes
– regulation of population processes
– breakdown of wastes and recycling of nutrients
– maintenance of soil fertility
– the provision of natural resources
– production of food, timber and natural products
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Current estimates put the global worth of such ecosystem
services at 33 trillion US$ per year (Costanza et al, 1997).
see o/h and h/o on ecosystem services
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Hypotheses: Relationship between diversity and function
null
Ecosystem
function
rivet
idiosyncratic
low
high
redundant
low
Species richness
high
Hypotheses: Relationship between diversity and function
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Redundant: Species richness is largely irrelevant: what is
important is that the biomass of primary producers,
consumers, decomposers etc. is maintained, and
ecological processes will function normally with very few
species.
Rivet: all species contribute to the integrity of an
ecosystem in a small but significant way such that a
progressive loss of species steadily damages ecosystem
function.
Idiosyncratic hypothesis: ecosystem function changes as
species richness changes, but the magnitude and
direction of the change is unpredictable because the roles
of individual species are complex and varied
Null hypothesis: ecosystem function is insensitive to
species additions or deletions
The insurance hypothesis
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Many current experiments examine ecosystem processes
under average environmental conditions.
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The next step is to ask 'Can higher biodiversity help
ecosystems to withstand and recover from extreme
events?'.
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More diverse systems have a greater probability than less
diverse systems of containing species that are suited to
the changed prevailing conditions- the ‘insurance
hypothesis’
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By chance, more diverse biological systems should better
withstand changes in environmental conditions
The insurance hypothesis- contd.
Stable conditions
7 spp
1 spp
Environmental fluctuations
6 spp
1 spp
Biodiversity is of intrinsic value
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Because it is of intrinsic value, humankind has moral and
ethical responsibilities towards it.
References
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Sutherland W.J. 1998, Conservation science and action.
Chapters 1 and 2.
‘Does biodiversity matter?’, Book chapter by Kunin and
Lawton (1996), In: Biodiversity: a biology of numbers and
difference by Gaston, K.J.
The Diversity of Life by E.O. Wilson. See Chapters 11,
12, 13, 14. Excellent book and easy to read.