Threats to Biodiversitychap 3

“Extinction is the most irreversible and tragic of all environmental calamities.

With each plant and animal species that disappears, a precious part of creation is

callously erased”Michael Soule, 2004

Threats to Biodiversity

• As our numbers climb, we expand agricultural conversion, import invasive species, hunt more species, degradate habitat, fragment and lose habitat, pollute water and air, impact climate…

• In short, we are causing the 6th mass extinction, the only biological driven one

Threats to Biodiversity

• Major factors impacting biodiversity

Threats to Biodiversity

• Habitat Degradation• Includes conversion from suitable to

unsuitable, lowering quality, fragmentation that lower PVA

• Causes: many industries (e.g. forestry, agriculture, development, fishing, mining, chemical)

Threats to Biodiversity

• Overexploitation• Hunting, collecting, fishing (and

indirect by-catch), trade of animals (and parts)

Threats to Biodiversity

• Invasive Species• With our help, species have the ability

to get virtually anywhere in the world• Direct actions: predation, parasitism,

disease, competition or hybridization• Indirect paths: changing abundances,

disruption of mutualisms, modifying habitat, reducing habitat quality)

Threats to Biodiversity

• Anthropogenic Climate Change• Climate has been a cause of previous

mass extinctions• Couple this with lower abundance,

invasive species and other problems, a severe impact is likely from climate change

• Climate change will also trigger additional biological responses (e.g. malaria in temperate places)…Fig 3.3

Threats to Biodiversity

• “Snowballing” effect of the invasion of the alien root pathogen

Threats to Biodiversity

• “Snowballing” effect of the invasion of the alien root pathogen

• Indirect effects

Threats to Biodiversity

• Anthropogenic Pollution• There are direct discharges of

chemicals into the environment, there are also pollutants released into the atmosphere

• Toxic chemicals (e.g. mercury, lead) are found even in remote areas

• Also have the problem of bioaccumulation (or biomagnification)

Threats to Biodiversity

• Toxic chemicals (PCB’s and dioxins) accumulate in fatty tissues

Anthropogenic Extinctions… impact on communities and

ecosystems• Loss of species, populations and/or

habitat is dramatic and extreme• Extinction as a process…• Can be local or global (also,

ecological)

Anthropogenic Extinctions… impact on communities and

ecosystems• Early extinctions probably caused by

overexploitation • Now, habitat degradation and/or

invasive species major factors

Anthropogenic Extinctions… impact on communities and

ecosystems• No. of genera (megamammal) extinct

and cause• 72% Aust• 88% NAm

Anthropogenic Extinctions… impact on communities and

ecosystems• Consider Polynesian colonization of

Pacific Islands 1-3KYA• Over 2000 species of birds (flightless

rails) and 8000 populations driven to extinction

• Story is not so simple…• Where invasive sp and habitat

degradation combined, extinction followed

Anthropogenic Extinctions… impact on communities and

ecosystems

Anthropogenic Extinctions… impact on communities and

ecosystems• Since 1500, >129 sp extinct• Habitat loss major cause• Invasive sp contributed for many• Overexploitation for 1/5

Anthropogenic Extinctions… indirect impacts

• Species don’t exist in a vacuum and extinctions usually have a ripple effect

• ‘Cascade effects’ such as secondary extinctions may occur

• E.g. plants with a single sp pollinator or seed dispersers

• E.g. sea otters and sea urchins

Anthropogenic Extinctions… indirect impacts

• Tambalacoque & Dodo

Anthropogenic Extinctions… indirect impacts

• E.g. sea otters and sea urchins

Anthropogenic Extinctions… indirect impacts

Anthropogenic Extinctions… indirect impacts

• Another problem is the removal of top predators, which may cause the ‘ecological release’ of mesopredators

Anthropogenic Extinctions… indirect impacts

• So there are many important species in a given community and some are more important than others

• Dominant sp: common, but also have strong effects on other members

• Ecosystems engineers: those that modify the ecosystem (e.g. beaver, elephant)

• Keystone sp: sp that has more impact on community than numbers (biomass) would suggest (e.g. bat pollinator)

Anthropogenic Extinctions… indirect impacts

Current Patterns of Global Endangerment

• Best data on global endangerment are collated in the IUCN Red List of Threatened Species (www.redlist.org)

• All species placed into one of 9 categories (3 primary categories: Critically Endangered, Endangered, Vulnerable)

• To date, only 2.5% of species evaluated (and 41% considered endangered)

Current Pattern of Global Endangerment

Current Pattern of Global Endangerment

Current Pattern of Global Endangerment

• What groups are in endangered?

Turtles at 42%

Current Pattern of Global Endangerment

• Globally threatened processes• Some dramatic phenomenon may

disappear (e.g. large-scale migrations)

• Read Essay 3.3

Current Pattern of Global Endangerment

• Factors threatening biodiversity• Factors are listed in the Red List• Knowledge varies tremendously and

by taxonomic group and habitat• Most face multiple threats and

threats can act synergistically

Current Pattern of Global Endangerment

• Overexploitation is major cause for fish

Current Pattern of Global Endangerment

• Where are sp most at risk worldwide?• Not all biomes (and their inhabitants)

are equally at risk• Most tropical habitats and grasslands

have large substantial numbers of threatened vertebrates

Current Pattern of Global Endangerment

Current Pattern of Global Endangerment…the US

• Geographically, there are very high numbers in SAm, SE Asia, sub-Saharan AF, Oceania, and NAm (where?)

• The US is second (Ecuador) for the number of species though to be at risk of extinction globally (IUCN)

• Many are plants (>5000sp), freshwater species (e.g. mussels {70%},crayfish, stoneflies)

Current Pattern of Global Endangerment…the US

• Proportion of sp threatened in US

Current Pattern of Global Endangerment…the US

• Examining threats to US sp

A correlative cause of many of these factors is urbanization

Current Pattern of Global Endangerment

• Threatened species in other countries• Unfortunately, many countries lack

solid data on what and how many sp are actually in trouble

• Some countries have a high proportion of the flora and fauna at risk

• E.g. Madagascar 80% of plants and 30% of vertebrates (case study 3.2)

Current Pattern of Global Endangerment

Current Pattern of Global Endangerment

• What types of sp are most vulnerable?

• Through studies, we have determined there are ‘suites’ of characteristics that make some sp more vulnerable

• E.g. large range requirements, narrow habitat range, rarity, low reproductive rate, extreme specialization or co-evolutionary dependancies

Current Pattern of Global Endangerment

• Vulnerability due to Specialization• Many species (especially tropical)

have narrow environmental ranges and highly specialized diets or habitats

• Perturbations can easily disturb them• Specialization on other species can

be precarious as well

Current Pattern of Global Endangerment

• Top carnivores with low densities, large ranges, large body size, are often cited as being vulnerable to habitat degradation, as well as overexploitation

• For marine animals, body size itself does not appear to be a problem, but is associated with another…

low reproductive rate

Current Pattern of Global Endangerment

• Vulnerability of Rare species• Why might a species be rare?

– Consider 3 characteristics: geographic range, habitat breadth and abundance

• How might each influence vulnerability?

• How might they interact?

Current Pattern of Global Endangerment

vent sp

raptors seabirds

batsIsland sp

big cats

Current Pattern of Global Endangerment

• Let’s consider a case of extreme endemism: ‘Centinela Ridge’ in Ecuador

• During a RAP inventory, 90 endemic plant species were discovered

• Immediately following the inventory, entire ridge cleared for agriculture

Current Pattern of Global Endangerment

• Island communities have relatively high rates of endemism, although communities maybe less rich than comparable mainland sites

• However, many island biotas are frequently endangered; why?

Current Pattern of Global Endangerment

• Case Study: birds of Channel Islands• 80 year comparison of pop(s)

– 40% of small pop(s) went extinct (<10 bp)

– 10% of pop(s) with 10-100 breeding pairs

– 1 population of 100-1000 bp– No pop(s) if >1000 bp

Current Pattern of Global Endangerment

• “Bad luck” species do not have intrinsically vulnerable traits, just bad luck

• For example, many freshwater fish near large cities are vulnerable, whatever their LHC

• 50% of variation in extinction risk for primates and carnivores is strictly due to anthropogenic distrubances

Current Pattern of Global Endangerment

• Economic and Social Context• Economic growth and rising affluence

drive habitat conversion and overexploitation

• Unfortunately in the US, areas of high endemism and richness are areas of high human growth (e.g. s. CA, e-c TX, s FL)

Current Pattern of Global Endangerment

• At the other end of the economic spectrum, billions live in poverty– 1B < $1/day– 2.7B < $2/day

• As a result, unsustainable levels of burning, small-scale agriculture, grazing and bushmeat hunting occur wherever these practices help people survive

Current Pattern of Global Endangerment

• Responses to the Biodiversity Crisis• Conservationists and developers

agree where solutions need to come from:– 1) scientific analysis and promotion of

the causes of biodiversity change– 2) technological improvements– 3) legal and institutional instruments– 4) economic incentives and plans– 5) social interventions

Current Pattern of Global Endangerment

• Solutions will include: – Establishing protected areas– Targeted interventions at the genetic,

species, and ecosystems levels– Restoration of damaged ecosystems– Recovery of endangered species– Creation of sustainable forms of

development

Current Pattern of Global Endangerment

• Single-species approaches will not be enough to conserve ‘biodiversity’…larger spatial scales are going to be needed

• However, many conservation actions are achieved at smaller scales (i.e. local)

• Need to prioritize and plan at larger scales (consisting of local partners)

Conservationist’s are generally asking “where” questions to set geographicalpriorities and “how” questions about developing and implementing strategies to conserve conservation targets at priority places Redford 2003

Laws and International Agreements

• One major tool for conservationists are US laws and international agreements

• Please Review Case Study 3.3!!

Driving Factors and Trends in Species Endangerment

• The first step is identifying a trend• The second step is to determine what

factors most influence trends• Finally, establish a plan to remove or

eliminate the identified threats• As easy as they sound, none of these

steps are as easy as they appear and the further along, the more ‘external’ factors enter the process

Driving Factors and Trends in Species Endangerment

• Besides developing a plan for a single species, important to track ‘status’ trends to determine success

• The Red List Index tallies changes in status due to either a deterioration or improvement of all threatened species

Driving Factors and Trends in Species Endangerment

• Overall, birds down 7%

• Albatrosses and petrels down 25%

Driving Factors and Trends in Species Endangerment

• Unfortunately most species groups are too poorly known to adequately evaluate trends

• However there are a number of indicies attempting to bridge these gaps

• IBI (index of biotic integrity), LPI (living planet index; pop change of 1100 terrestrial, marine, and freshwater vertebrate sp)

Driving Factors and Trends in Species Endangerment

• Terrestrial sp (A) and broken down

Driving Factors and Trends in Species Endangerment

• It is not enough to determine where changes are occurring (reactive), but rather perhaps we can use information to generate predictive models of what species or systems may be more vulnerable than others (proactive)

Driving Factors and Trends in Species Endangerment

• Projected trends• Dark most impact

Driving Factors and Trends in Species Endangerment

• In the end, it is essential we better understand the factors that drive human behavior, which ultimately drive the causes of biodiversity loss

Current Pattern of Global Endangerment