Value and Maintenance of Biodiversity Biology/Env S 204 Spring 2009
Value and Maintenance • Benefits to humans, direct or indirect • Intrinsic value • What kind of a world do we want to live in? • Redundancy in ecosystems (how much is enough?)
Benefits to humans • Direct use value = marketable commodities • Food • Medicine • Raw materials • Recreational harvesting • Ecotourism
Benefits to humans: food • About 3,000 species (ca. 1% of 300,000 total) of flowering plants have been used for food • About 200 species have been domesticated • Wild relatives source of genes for crop improvement in both plants and animals
Benefits to humans: medicine • Organisms as chemists • About 25% of all medical prescriptions in the U.S. are based on plant or microbial products or on derivatives or on synthetic versions • Some medicinal products from animals (e.g., anticoagulant from leeches)
Benefits to humans: raw materials • Industrial materials: • Timber • Fibers • Resins, gums • Perfumes • Adhesives • Dyes • Oils, waxes, rubber • Agricultural chemicals
Benefits to humans: recreational harvesting • Recreational harvesting: • Hunting • Fishing • Pets • Ornamental plants
Benefits to humans: ecotourism • By definition based on biodiversity • Growing portion of the tourism industry
Indirect Use Value • Indirect use value = services provided by biodiversity that are not normally given a market value (often regarded as free) • Include primarily ecosystem services: atmospheric, climatic and hydrological regulation; photosynthesis; nutrient cycling; pollination; pest control; soil formation and maintenance, etc.
Indirect Use Value • Biosphere 2 was an attempt to artificially create an ecosystem that would sustain human life • Ca. US$200 million invested in design and construction plus millions more in operating costs • Could not sustain 8 humans for two years
Intrinsic value • Simply because it exists • Moral imperative to be good stewards, the preservation of other life for its own sake • Supported in many different religious or cultural traditions • Recognized in the Convention on Biodiversity
Intrinsic Value • Biophilia = the connection that human beings subconsciously seek with the rest of life (nature) or the innate connection of humans to biodiversity
Intrinsic Value • Biophilia = the connection that human beings subconsciously seek with the rest of life (nature) or the innate connection of humans to biodiversity • Should we put a monetary value on everything?
Intrinsic Value • Biophilia = the connection that human beings subconsciously seek with the rest of life (nature) or the innate connection of humans to biodiversity • Should we put a monetary value on everything? • If something can be valued, it can be devalued.
What kind of a world do we want to live in? • Human co-opt about 40% of the net primary productivity on an annual basis • Human population at over 6 billion and growing at about 80 million per year • Loss of some biodiversity is inevitable
What kind of a world do we want to live in? • Current extinction rate much higher than background; also commitment to extinction • Extinction is forever; species may have unforeseen uses or values (e.g., keystone species, medicinal value, etc.) • Biodiversity has recovered after previous mass extinctions, but are we also eliminating that possibility by severely restricting conditions conducive to evolution?
What kind of a world do we want to live in? If 6 billion people consume 40% of the annual net primary productivity, what is the theoretical limit (= carrying capacity) for humans under current conditions? 2.5 x 6 billion = 15 billion
What kind of a world do we want to live in? But this number does not factor in the costs of dealing with wastes or non-renewable resources. Nor does it leave room for other biodiversity, upon which we depend for ecosystem services (such as waste removal/recycling). Human population is expected to reach ca. 12 billion by 2050.
What kind of a world do we want to live in? • This is why many now argue that we have to find a way to put biodiversity into the economic equation • Previously no monetary values were associated with natural resources except the actual ones generated by extraction (the world is there for us to use)
What kind of a world do we want to live in? • Extraction costs (e.g., labor, energy) usually computed • But cost of replacement not included, nor costs of the loss of the services provided by that resource or its ecosystem (e.g., cutting forest for timber) • Because costs are undervalued, benefits of extraction are overvalued
What kind of a world do we want to live in? • Green accounting proposed as part of the solution • But requires that environmental assets have proper prices (p. 171, Chichilnisky essay in text) • Tie in to property rights for natural resources
Redundancy in Ecosystems • Or, how much biodiversity is enough? • How much redundancy is built into ecological processes/communities? • To what extent do patterns of diversity determine the behavior of ecological systems?
Redundancy in Ecosystems Two opposing views: rivet hypothesis vs. redundancy hypothesis redundancy rivet
Redundancy in Ecosystems • Rivet hypothesis: most if not all species contribute to the integrity of the biosphere in some way • Analogy to rivets in an aircraft—there is a limit to how many can be removed before the structure collapses • Progressive loss of species steadily damages ecosystem function
Redundancy in Ecosystems • Redundancy hypothesis: species richness is irrelevant; only the biomass of primary producers, consumers and decomposers is important • Life support systems of the planet and ecological processes will generally work fine with relatively few species
Redundancy in Ecosystems • In the past (from fossils), most ecological systems have been conspicuously less species rich • But no evidence that they operated any differently
Redundancy in Ecosystems • Major patterns of energy flow and distribution of biomass in existing ecological systems may be broadly insensitive to species numbers • But systems with higher diversity and more kinds of interactions may be more buffered from fluctuations • Lack of data regarding the link between species-richness and ecosystem function
Redundancy in Ecosystems • Middle ground: ecosystem processes often but not always have considerable redundancy built into them • Not all species are equal (e.g., functional groups, keystone species) • The loss of some species is more important than the loss of others • Species loss may be tolerated up to some critical threshold