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 BOIDI VERSITY  is the variation of  life forms within a given ecosystem,  biome, or on the entire Earth. Biodiversity is often used as a measure ofthe health of  biological systems. The biodiversity found on Earth todayconsists of many millions of distinct biological species. The year  2010

has been declared as the International Year of Biodiversity. 

Biodiversity is not distributed evenly on Earth, but is consistently richerin the tropics and in specific localized regions such as the Cape FloristicProvince; it is less rich in polar regions where fewer species are found.

Rapid environmental changes typically cause extinctions. Of all speciesthat have existed on Earth, 99.9 percent are now extinct Since life beganon Earth, five major mass extinctions have led to large and sudden dropsin the biodiversity of species. The Phanerozoic eon (the last 540 million

years) marked a rapid growth in biodiversity in the Cambrian explosion — a period during which nearly every phylum of  multicellular organismsfirst appeared. The next 400 million years was distinguished by periodic,massive losses of biodiversity classified as mass extinction events. Themost recent, the Cretaceous – Tertiary extinction event, occurred65 million years ago, and has attracted more attention than all others

 because it killed the dinosaurs. 

Today there is concern that the period since the emergence of  humans is

 part of a mass reduction in biodiversity, the Holocene extinction, caused primarily by the impact humans are having on the environment, particularly the destruction of plant and animal habitats. In addition,human practices have caused a loss of  genetic biodiversity. The relevanceof biodiversity to human health is becoming a major international issue,as scientific evidence is gathered on the global health implications of

 biodiversity loss>

A complex relationship exists among the different types of diversity.

Identifying one type of diversity in a group of organisms does notnecessarily indicate its relationship with other types of diversity.However all types of diversity are broadly linked and a numerical studyinvestigating the link between tetrapod taxonomic and ecologicaldiversity of tetrapods (terrestrial vertebrates) shows a very closecorrelation between the two.

The term was used first by wildlife scientist and conservationist RaymondF. Dasmann in a lay book 

[4] advocating nature conservation. The term

was not widely adopted for more than a decade, when in the 1980s it and

"biodiversity" came into common usage in science and environmental policy. Use of the term by Thomas Lovejoy in the Foreword to the

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 bookcredited with launching the field of  conservation biology introducedthe term along with "conservation biology" to the scientific community.Until then the term "natural diversity" was used in conservation sciencecircles, including by The Science Division of  The Nature Conservancy in

an important 1975 study, "The Preservation of Natural Diversity." By theearly 1980s TNC's Science program and its head Robert E. Jenkins, Lovejoy, and other leading conservation scientists at the time in Americaadvocated the use of "biological diversity" to embrace the object of

 biological conservation.

The term's contracted form biodiversity  may have been coined by W.G.Rosen in 1985 while planning the National Forum on Biological

 Diversity organized by the National Research Council (NRC) which wasto be held in 1986, and first appeared in a publication in 1988 whenentomologist E. O. Wilson used it as the title of the proceedings

 

of thatforum.

Since this period both terms and the concept have achieved widespreaduse among biologists, environmentalists, political leaders, and concernedcitizens worldwide. The term is sometimes used to equate to a concernfor the natural environment and nature conservation. This use hascoincided with the expansion of concern over  extinction observed in thelast decades of the 20th century.

A similar concept in use in the United States, besides natural diversity, isthe term "natural heritage." It pre-dates both terms though it is a lessscientific term and more easily comprehended in some ways by the wideraudience interested in conservation. Furthermore it may be misleading ifused to refer only to biodiversity, as natural heritage also includesgeology and landforms (geodiversity). The term "Natural Heritage" wasused when Jimmy Carter set up the Georgia Heritage Trust while he wasgovernor of Georgia; Carter's trust dealt with both natural and cultural

heritage. It would appear that Carter picked the term up from LyndonJohnson, who used it in a 1966 Message to Congress. "Natural Heritage"was picked up by the Science Division of the US Nature Conservancywhen, under Jenkins, it launched in 1974 the network of State NaturalHeritage Programs. This network took on a life of its own in the 1990swhen it became an independent non-profit organization named

 NatureServe. When NatureServe was extended outside the USA, the term"Conservation Data Center" was suggested by Guillermo Mann is nowalso used by several programs, for example those that operate as part of

 NatureServe Canada

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Evolution

Biodiversity found on Earth today is the result of 3.5 billion years ofevolution. The origin of life has not been definitely established by

science, however some evidence suggests that life may already have beenwell-established a few hundred million years after the formation of theEarth. Until approximately 600 million years ago, all life consisted ofarchaea, bacteria, protozoans and similar single-celled organisms.

The history of biodiversity during the Phanerozoic (the last 540 millionyears), starts with rapid growth during the Cambrian explosion — a periodduring which nearly every phylum of  multicellular organisms firstappeared. Over the next 400 million years or so, global diversity showed

little overall trend, but was marked by periodic, massive losses ofdiversity classified as mass extinction events.

The apparent biodiversity shown in the fossil record suggests that the lastfew million years include the period of greatest biodiversity in the Earth'shistory. However, not all scientists support this view, since there isconsiderable uncertainty as to how strongly the fossil record is biased bythe greater availability and preservation of recent geologic sections. Some(e.g. Alroy et al. 2001) argue that, corrected for sampling artifacts,modern biodiversity is not much different from biodiversity 300 million

years ago.[16] Estimates of the present global macroscopic speciesdiversity vary from 2 million to 100 million species, with a best estimateof somewhere near 13 – 14 million, the vast majority of them arthropods

The existence of a global carrying capacity has been debated, that is tosay that there is a limit to the number of species that can live on this

 planet. While records of life in the sea shows a logistic pattern of growth,life on land (insects, plants and tetrapods)shows an exponential rise indiversity. As one author states, "Tetrapods have not yet invaded 64 per

cent of potentially habitable modes, and it could be that without humaninfluence the ecological and taxonomic diversity of tetrapods wouldcontinue to increase in an exponential fashion until most or all of theavailable ecospace is filled.

Most biologists agree however that the period since the emergence ofhumans is part of a new mass extinction, the Holocene extinction event, caused primarily by the impact humans are having on the environment.

[19] 

It has been argued that the present rate of extinction is sufficient to

eliminate most species on the planet Earth within 100 years.

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with wildlife into agricultural, mining, lumbering, and urban areas forhumans.

 Non-material benefits that are obtained from ecosystems include spiritual

and aesthetic values, knowledge systems and the value of education.

Agriculture

The economic value of the reservoir of genetic traits present in wild Newspecies are regularly discovered (on average between 5 – 10,000 newspecies each year, most of them insects) and many, though discovered,are not yet classified (estimates are that nearly 90% of all arthropods arenot yet classified).  Most of the terrestrial diversity is found in tropicalforests. 

Human benef its

iodiversity also supports a number of natural ecosystem processes andservices.  Some ecosystem services that benefit society are air quality, climate (both global CO2 sequestration and local), water purification,

 pollination, and prevention of erosion.

Since the stone age, species loss has been accelerated above the

geological rate by human activity. The rate of species extinction isdifficult to estimate, but it has been estimated that species are now beinglost at a rate approximately 100 times as fast as is typical in thegeological record, or perhaps as high as 10 000 times as fast.  To feedsuch a large population, more land is being transformed from wildernessvarieties and traditionally grown landraces is extremely important inimproving crop performance Important crops, such as the potato andcoffee, are often derived from only a few genetic strains Improvements incrop plants over the last 250 years have been largely due to harnessing

the genetic diversity present in wild and domestic crop plants 

Interbreeding crops strains with different beneficial traits has resulted inmore than doubling crop production in the last 50 years as a result of theGreen Revolution. 

Crop diversity is also necessary to help the system recover when thedominant crop type is attacked by a disease:

  The Irish potato blight of 1846, which was a major factor in the

deaths of a million people and migration of another million, was

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the result of planting only two potato varieties, both of which werevulnerable.

  When rice grassy stunt virus struck rice fields from Indonesia to

India in the 1970s, 6273 varieties were tested for resistance.  One

was found to be resistant, an Indian variety, known to science onlysince 1966 This variety formed a hybrid with other varieties and isnow widely grown.

  Coffee rust attacked coffee plantations in Sri Lanka, Brazil, and

Central America in 1970. A resistant variety was found in Ethiopia.Although the diseases are themselves a form of biodiversity.

Monoculture, the lack of biodiversity, was a contributing factor to severalagricultural disasters in history, the European wine industry collapse inthe late 1800s, and the US Southern Corn Leaf Blight epidemic of1970.[26] Higher biodiversity also controls the spread of certain diseasesas pathogens will need to adapt to infect different species.

Biodiversity provides food for humans ..Although about 80 percent of

our food supply comes from just 20 kinds of plants humans use at least

40,000 species of plants and animals a day Many people around the

world depend on these species for their food, shelter, and clothing]. There

is untapped potential for increasing the range of food products suitablefor human consumption, provided that the high present extinction rate can

 be stopped.

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Loss of  old growth forest in the United States; 1620, 1850, 1920, and

1992 maps: 

 From William B. Greeley's, The Relation of Geography to Timber Supply,

 Economic Geography, 1925, vol. 1, p. 1 – 11. Source of "Today" map:

compiled by George Draffan from roadless area map in The Big Outside:

 A Descriptive Inventory of the Big Wilderness Areas of the United States,

by Dave Foreman and Howie Wolke (Harmony Books, 1992). These

maps represent only virgin forest lost. Some regrowth has occurred but

not to the age, size or extent of 1620 due to population increases and food

cultivation.

During the last century, decreases in biodiversity have been increasingly

observed. Studie ow that 30% of all natural species will be extinct by2050.  Of these, about one eighth of the known plant species arethreatened with extinction.  Some estimates put the loss at up to 140,000species per year (based on Species-area theory) and subject to discussion. This figure indicates unsustainable ecological practices, because only asmall number of species come into being each year. Almost all scientistsacknowledge .. that the rate of species loss is greater now than at anytime in human history, with extinctions occurring at rates hundreds oftimes higher than background extinction rates.

The factors that threaten biodiversity have been variously categorized.Jared Diamond describes an "Evil Quartet" of habitat destruction,overkill, introduced species, and secondary extensions. Edward O.Wilson prefers the acronym HIPPO, standing for Habitat destruction,Invasive species, Pollution, Human Over Population, andOverharvesting.

[56][57] The most authoritative classification in use today is

that of  IUCN’s Classification of Direct Threats[58]

 adopted by most majorinternational conservation organizations such as the US NatureConservancy, the World Wildlife Fund, , and Birdlife International.

Conservation of biodiversity

matured in the mid- 20th century as ecologists, naturalists, and otherscientists began to collectively research and address issues pertaining toglobal declines in biodiversity. The conservation ethic differs from the

 preservationist ethic, historically lead by John Muir, who advocate forThe conservation ethic advocates for wise stewardship and managementof  natural resource production for the purpose of protecting and

sustaining biodiversity in species, ecosystems, the evolutionary process, and human culture and society. Conservation biologists are concerned

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with the trends in biodiversity being reported in this era, which has beenlabeled by science as the Holocene extinction period, also known as thesixth mass extinction.  Rates of decline in biodiversity in this sixth massextinction match or exceed rates of loss in the five previous mass

extinction events recorded in the fossil record Loss of biodiversity resultsin the loss of  natural capital that supplies ecosystem goods and services. The economic value of 17 ecosystem services for the entire biosphere(calculated in 1997) has an estimated average value of US$ 33 trillion(10

12) per year!

 

One of the strategies involves placing a monetary value on biodiversitythrough biodiversity banking, of which one example is the Australian

 Native Vegetation Management Framework. Other approaches are thecreation of  gene banks, as well as the creation of  gene banks that have theintention of growing the indigenous species for reintroduction to theecosystem (eg via tree nurseries, ...) The eradication of exotic species isalso an important method to preserve the local biodiversity. Exoticspecies that have become a pest can be identified using taxonomy .Thismethod however can only be used against a large group of a certainexotic organism due to the econimic cost. Other measures contributing tothe preservation of biodiversity include: the reduction of pesticide useand/or a switching to organic pesticides, ... These measures however, areof less importance than the preserving of rural lands, reintroduction of

indigenous species and the removal of exotic species. Finally, if thecontinued preservation of native organisms in an area can be guaranteed,efforts can be made in trying to reintroduce eliminated native species

 back into the environment. This can be done by first determining whichspecies were indigenous to the area, and then reintroducing them. Thisdetermination can be done using databases as the Encyclopedia_of_life, Global Biodiversity Information Facility, ... Extermination is usuallydone with either (ecological) pesticides, or natural predators.

Strategies

As noted above (Distribution), biodiversity is not as rich everywhere onthe planet. Regions as the tropics and subtropics are considerably muchricher in biodiversity than regions in temperate climates. In addition, intemperate climates, a lot of countries are located which are already vastlyurbanised, and require -in addition- great amounts of space for thegrowing of crops. As rehabilitating the biodiversity within these countrieswould again require the clearing and redeveloping of spaces, it has been

 proposed of some that efforts are best instead directed unto the tropics.Arguments include economics, it would be far less costly and more

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efficient to preserve the biodiversity in the tropics, especially as manycountries in these areas are only now beginning to urbanise.

However, only directing the efforts into these areas would not be enough,

as many species still need to migrate at certain times of the year,requiring a connection to other regions/countries. In the more urbanisedcountries in temperate climates, this would mean that wildlife corridorsneed to be made. However, making wildlife corridors would still beconsiderably cheaper and easier than clearing/preserving entirely newareas.

A great deal of work is occurring to preserve the natural characteristics of

Hopetoun Falls, Australia while continuing to allow visitor access.

Biodiversity is beginning to be evaluated and its evolution analysed(through observations, inventories, conservation...) as well as being takeninto account in political and judicial decisions:

  The relationship between law and ecosystems is very ancient andhas consequences for biodiversity. It is related to property rights,

 both private and public. It can define protection for threatenedecosystems, but also some rights and duties (for example, fishingrights, hunting rights).

  Law regarding species is a more recent issue. It defines species that

must be protected because they may be threatened by extinction.The U.S. Endangered Species Act is an example of an attempt toaddress the "law and species" issue.

  Laws regarding gene pools are only about a century old[While the

genetic approach is not new (domestication, plant traditionalselection methods), progress made in the genetic field in the past20 years have led to a tightening of laws in this field. With the newtechnologies of genetic analysis and genetic engineering, people

are going through gene patenting, processes patenting, and a totallynew concept of genetic resources.  A very hot debate today seeks todefine whether the resource is the gene, the organism itself, or itsDNA.

The 1972 UNESCO World Heritage convention established that biological resources, such as plants, were the common heritage ofmankind. These rules probably inspired the creation of great public banksof genetic resources, located outside the source-countries.

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 New global agreements (e.g.Convention on Biological Diversity), nowgive sovereign national rights over biological resources (not property).The idea of static conservation of biodiversity is disappearing and beingreplaced by the idea of dynamic conservation, through the notion of

resource and innovation.

The new agreements commit countries to conserve biodiversity, developresources for sustainability and share the benefits resulting from their use.Under new rules, it is expected that bioprospecting or collection ofnatural products has to be allowed by the biodiversity-rich country, inexchange for a share of the benefits.

Sovereignty principles can rely upon what is better known as Access andBenefit Sharing Agreements (ABAs). The Convention on Biodiversity

spirit implies a prior  informed consent between the source country andthe collector, to establish which resource will be used and for what, andto settle on a fair agreement on benefit sharing. Bioprospecting can

 become a type of  biopiracy when those principles are not respected.

Measurment of biodiversity

 Alpha diversity

Alpha diversity (α-diversity) is the biodiversity within a particular area,community or  ecosystem, and is usually expressed as the Species richnessof the area. This can be measured by counting the number of  taxa(distinct groups of organisms) within the ecosystem (eg. families, genera, species). However, such estimates of species richness are strongl samplesize, so a number of statistical techniques can be used to correct forsample size to get comparable values by influenced.

: Simpson index

Where:

 

S  is the number of species   N  is the total percentage cover or total number of organisms  ni is the percentage cover of a species or number of organisms of

species i 

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Shannon index: 

Where

  S  is the number of species. Also called species richness   pi is the relative abundance of each species, calculated as the

 proportion of individuals of a given species to the total number of

individuals in the community: 

ni is the number of individuals in each species; the abundance ofeach species

 

 N  is the total number of all individuals

 Beta diversity

Beta diversity (β-diversity) is a measure of  biodiversity which works bycomparing the species diversity between ecosystems or alongenvironmental gradients. This involves comparing the number of taxa thatare unique to each of the ecosystems.

It is the rate of change in species composition across habitats or amongcommunities. It gives a quantitative measure of diversity of communitiesthat experience changing environments

At its simplest, beta diversity is the total number of species that areunique between communities . This can be represented by the followingequation:

β = (S 1 − c) + (S 2 − c)

where, S1= the total number of species recorded in the first community,S2= the total number of species recorded in the second community, andc= the number of species common to both communities.

Sørensen's similarity index

where, S1= the total number of species recorded in the first community,S2= the total number of species recorded in the second community, and

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c= the number of species common to both communities. The Sørensenindex is a very simple measure of beta diversity, ranging from a value of0 where there is no species overlap between the communities, to a valueof 1 when exactly the same species are found in both communities.

 

wittaker measure 

where, S= the total number of species recorded in both communities,=average number of species found within the communities.

 

Gamma diversity

Gamma diversity (γ-diversity) is a measure of  biodiversity. It refers tothe total species richness over a large area or region. It is the product ofthe α diversity of component ecosystems and the β diversity between

component ecosystems.

According to Whittaker (1972), gamma diversity is the richness inspecies of a range of habitats in a geographic area (e.g.,a landscape, anisland) and it is consequent on the alpha diversity of the individual

communities and the range of differentiation or beta diversity amongthem. Like alpha diversity, it is a quality which simply has magnitude,not direction and can be represented by a single number (a scalar).

Gamma diversity can be expressed in terms of the species richness ofcomponent communities as follows:

γ = S 1 + S 2 − c 

where, S1= the total number of species recorded in the first community,S2= the total number of species recorded in the second community, andc= the number of species common to both communities.

The internal relationship between alpha, beta and gamma diversity can berepresented as

β =γ / α 

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The most common formula for working out Species Diversity is theSimpson's diversity index, which uses the following formula:

Where:

  D = diversity index   N = Total number of organisms of all species found  n = number of individuals of a particular species

A high D value suggests a stable and ancient site, while a low D valuecould suggest a polluted site, recent colonisation or agricultural

management.

Usually used in studies of vegetation but can also be applied to animals.

In order to account for the probability of missing some of the actual totalnumber of species present in any count based on a sample population, theJackknife estimate may be employed:

where

  S = species richness  n = total number of species present in sample population  k = number of "unique" species (of which only one organism was

found in sample population)

Similarly the equation may also be noted as:

where

  E = the summation of number of species in each sample  k = number of rare/unique species  n = number of sample

As well, when looking at local diversity the appropriate formula to use is:

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where

  c = a specific number for each taxa  A = the area of study

t regulatory measures intended to test the effects of chemicals for biodiversity cannot appropriately address the complexity and dynamics ofinteractions between living systems, and with their abioticenvironment.[1], this question has not been adequately addressed.

Chemicals can originate from millions of consumer, agricultural andindustrial products and processes. In certain instances, the release of achemical is accidental, while in others it is a side effect of other

 processes, or due to their intended form of use. Once in the environment,some chemicals can persist for long periods of time and/or be brokendown into chemicals with further risk properties.

Chemicals may also produce unforeseen health and environmentalimpacts when interacting with other natural or manufactured chemicals.For a variety of chemicals, ―the dose makes the poison‖. On the contrary,

for many others, very low doses are enough for impacts to appear (e.g.,

disturbances to wildlife and ecosystems from low-level exposures tochemicals such as endocrine disruptors).

These and other physical and chemical transformations and the resultinghuman and environmental health impacts can go far beyond what existingregulations regarding the release of many chemicals (from zero emissionsafety provisions to standards of good practice) can adequately address.Emission patterns vary from point sources (where most data areavailable) to diffuse emissions from current and past activities: there are

at least two million contaminated sites in the EU (European Commission,2003).

Aquatic sediments can store certain chemicals and, with changingenvironmental conditions, release them either suddenly or over anextended period of time. Substances used in longlife products may be amajor source of chemicals emissions both during their use and once theyhave been dumped in the environment (e.g. CFCs from isolation foam).In order to understand the (potential) effects of chemicals on living

 beings, risk assessments are based on laboratory studies, via testing

organisms. Under the current risk estimation approaches in eco-

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In recognition of increasing pressure ont he planet's natural capital,representatives of governments around the world met in 1992 at theinternational Earth Summit in Rio de Janeiro, Brazil, to explore ways toconserve biodiversity. The Earth Summit in Rio produced the United

 Nations Convention on Biological Diversity. Canada was one of the firstof 182 countries to sign the Convention, which recognizes theresponsibility of individual countries to conserve biodiversity, to use

 biological resources sustainably, and to share related benefits equitably.To help fulfill that commitment, the federal, territorial and provincialgovernments formally endorsed a Canadian Biodiversity Strategy in1995.

Between 2001 and 2005, more than a thousand scientists from all over theworld took part in the UN Millennium Ecosystem Assessment. Theyconcluded that more than 60 per cent of the planet's ecosystems aredegraded or unsustainably managed. They noted that species aredisappearing at an alarming rate. They agreed that the negative impact onhumans would become more severe if we do not act to conserve

 biodiversity and use natural resources in a sustainable manner.

The National Sciences and Engineering Research Council of Canadareaffirmed this conclusion, stating in January 2004, that 'the biodiversityof earth is being reduced faster than at any time in history since the mass

extinction some 60 million years ago'

In this analysis, we set out to answer three questions. The first questiondealt with the pattern of species richness for rare and vulnerableterrestrial vertebrates. By extracting the species from the TNC databasethat were ranked as G1-G3 and tallying the number of species in eachhexagon, we observed a distinct geographic pattern in richness. Thehexagons with the greatest number of species (9-14) occurred along theCalifornia coastal zone, with a narrow band in the north and a wider band

in the south. Richness of rare species generally declined with distancefrom the coastline. Desert regions in California generally had 1-3 rarespecies, while the interior hexagons of Oregon and Washingtonfrequently had none.

Regression tree modeling was applied to answer the second questionabout the relationship of this pattern of richness to biophysical andanthropogenic stressors. Data were compiled for 13 stressors. Two datasets represented natural stressors, 8 were anthropogenic stressors, and 3were derived from satellite data and represented a combination of both

types of stressors. Some of the data sets correspond to actual stressors

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(e.g., roads), while others are surrogate measures of environmentalconditions (e.g., an index of habitat condition or percentage of area

 protected). For simplicity, we refer to all factors as "stressors" throughoutthe text. By far the most important predictors of rare species richness

were two natural stressors, seasonal temperature difference and degree-day cool sum. These two variables represent the extremes of hot and coldto which rare species must adapt and to the severity of the winter inwhich body temperature must be preserved and food must be available.Rare species richness was highest in hexagons with the lowest values ofthese stressors, that is, where the climate is relatively mild year-roundsuch as with a marine influence. The only anthropogenic stressorsselected in the regression tree model were the number of exotic species(both total and terrestrial vertebrates alone). Rare species and exoticspecies tended to have similar distribution patterns. It is unclear from ouranalysis whether exotic species have caused more vertebrates to becomerare and vulnerable or simply that, in the West Coast Transect study area,

 both are influenced by the same, undetermined ecological processes. Themore direct measures of stress such as population density, roadedness, orhabitat loss were not used by the regression tree model.

Our third question, about the value of satellite data in estimatingenvironmental stress and the number of vulnerable species, produced anegative result. None of the three measures of environmental stress from

 NDVI were selected by the regression tree. The most significantdifferences between potential and actual NDVI were in urban andagricultural areas, which were not generally associated with largenumbers of rare species. It may be that the vulnerable species havealready be extirpated from these hexagons and were thus not in TNCsdatabase.

Our study was hindered by a lack of stressor data at the requiredresolution. A great deal of data, however, exist at the county scale or

similar geographic units. It may still be

 possible to use these data to estimate stressors are the finer, hexagon scalethrough development of smart interpolation methods. For instance,grazing density could be inferred based on a model that uses commonlyavailable spatial data such as topography. This kind of GIS model canexplicitly limit predicted land uses to appropriate environmental settingsand land stewards while disaggregating county level statistics. Other landuses such as logging might be modeled in a similar manner, as might theagricultural census data on chemical applications.

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We mentioned at the beginning of this chapter how human activity hasappropriated a large proportion of NPP and energy. Estimates of thismonumental alteration of ecosystem function has only been estimated atnational or global levels. We were disappointed in our attempts to apply

this approach at the hexagon level. Data inputs were often too coarse, asdiscussed above. It may yet be possible to implement this approach, but itwill require greater use of the coarse-scale data and smart interpolationtechniques. One intriguing possibility of relating energy usage to

 biodiversity loss is to estimate energy usage from the nighttime lightsdata from DMSP satellite data.

There is an alternative approach that could be taken in using the stressordata sets. Rather than using them to predict richness of vulnerable speciesin a modeling context, they could be used to identify potential "trainwrecks" in hexagons where both stresses and biodiversity are high. Thiswould require the development either of thresholds for levels of stressorsthat correspond to threat to biodiversity or of a new index that synthesizesthe effects of stresses into an overall metric of threat.