Conservation Biology (book)

Conservation Biology (book)

1. The natural world

   • Life on Earth has existed for 4 billion years
     • has increased in diversity to the richness today
   • 1.5 million species have been described
     • vast majority are still unknown
   • Biodiversity is unevenly distributed amongst the taxonomic groups
     • class Insecta has a large number of species
   • Biodiversity increases from the poles to the tropics
     • suggestions
       • tropics are more climatically stable
       • tropics receive more energy input from the sun
   • Economic values have been placed on biodiversity to compare benefits of conservation vs development
     • spiritual value remains important to many people

2. Major world ecosystems

   • Terrestrial ecosystems can be categorised and described according to the prevailing plant species and physical structure
   • In terrestrial ecosystems, increasing biodiversity is associated with increasing structure of vegetation
   • Aquatic environments are classified by their water chemistry and the dynamics of the water body
   • In both cases abiotic factors have a primary role in shaping the community
     • predictable changes
       • from poles to tropics
       • from low to high altitude

3. The human impact

   • Recently human population size has had an exponential growth
   • Humans evolved as hunter-gatherers
     • similar to other large mammals in their role in the ecosystem
     • key advances like tool use and fire allowed humans to become a dominant influence over their environment
       • advances allowed humans to spread out over the earth changing ecosystems as they went
   • The industrial revolution and associated technological advances increased resource use per capita
     • enabled explosive population growth and brought with it new environment impact problems
   • influence of the developed world on the developing world has had an additional negative impact on the environment
     • quickening habitat destruction
   • good statistical evidence shows that humans are having a negative impact on biodiversity through habitat destruction, habitat disturbance and overexploitation of natural resources

4. Effects of habitat destruction

   • There is an intimate relationship between species and habitat
     • if habitat is destroyed species will go extinct
   • as a large patch of habitat is eroded from destruction the total area gets smaller, the proportion of the edge in relation to the total area is greater, any given point within the fragment is on average closer to the edge than before, and on average each fragment is more isolated from other fragments than before
     • they have profound effects on communities, species and their populations
   • as fragments get smaller the proportion of the habitat that is at the edge increases
     • edges contain different environments from the interior
       • altered climate
       • increased incidence of environmental catastrophes
       • increased incursion of predators and competitors
       • increased chance of passive emigration
   • theory of island biogeography predicts that as fragments become smaller and more isolated, species extinction will increase and colonisation will dcrease
     • loss of biodiversity and species richness
   • as populations get smaller the influence of demographic stochasiticity (random variation in birth and death), genetic stochasticity (random loss of genetic variation and inbreeding), environmental stochasticity (random variation in normal weather patterns) and enviornmental catastrophes beomes greater
     • increase extinction rate of small populations relative to large ones
   • metapopulation theory predicts species can persist as a number of populations connected by limited dispersal between habitat patches as long as the probality of extinction is balanced with the probability of colonisation in the complex of patches
     • many recent declines can be explained by the collapse of metapopulations

5. Effects of human disturbance

   • altered habitats natural dynamics
     • pollution
       • chemical pollution causes direct disturbance
         • aid pollution and acid rain
         • eutrophication
         • pesticide application
     • introduction of alien species
       • has been deliberate and accidental
       • greatest effects is on isolated islands as there is a lack of competitive ability, naviety of their native flora and fauna
       • larger land masses are vulnerable to generalist, competitve invasive species
     • introduction of alien diseases
       • have desvastated native populations due to no natural immunity
     • genes
       • GMOs (genetically modified organisms) pose a new potential threat to native biodiversity
         • their impact should be studied carefully following the precautionary principle before released into the wild

6. Non-sustainable use

   • many populations and species are being threatened
     • food
       • unregulated commercial hunting has caused serious depletion od whale and fish stocks throughout the world
     • materials
     • pet and ornamental trade
       • demand for exotic pets and ornamental plants has led to the illegal trade that has endangered particular taxa such as parrots, cacti and orchids
     • trade in animals parts
       • trade in animal parts for trophies, status symbols and alternative medicines haa lead to the endangerment of populations through poaching and illegal trade of species such as tigers, elephants and rhinos
     • overexploitation of oparticular keystone species can have a knock on effect on the whole ecosystem
     • overexploitation of natural resources like timber and freshwater leads to direct destruction or disturbance of habitats

7. The rise of conservation biology

   • early philosophies and religions contain some ideas on conservation but largely place humans at the top with the ability to control and right to exploit it
   • early conservation efforts were largely taken to secure natural rources not biodiversity
   • conservation ethics developed following the realisation that species and habitats as well as futile land where being lost through short-term exploitation
   • the science of conservation biology grew as an applied art of ecology during the 20th century, but has only been recognised in its own right during the last 30 years
   • Convention of Biodiversity has provided focus for consevation producing an even greater demand for the production of good science to underpin conservation action
     • agreed in 1992

8. Selecting protected species

   • protected areas vary greatly in their status
     • many different reasons for designating areas
     • different levels of protection
     • dependant on the country to which they belong
   • biodiversity is estimated and is subject to error
     • can be measured in sophisticated ways if the information is available
       • like species diversity index
     • species richness if there are constraints on resources
   • indicator taxa have been commonly used as surrogate measures of overall biodiversity in reserve selection
     • assumption that diversity of one taxon is an accurate indicator of diversity in others has been repeatly disproven by experiments
       • consequently more complex multi-taxa groups have been hosen
   • protected area selection must reflect both diversity and endemism
     • due to their history and biogeography some areas have a large number of endemic species whilst not being particularly diverse
       • tropical oceanic islands
   • there are key challenges for conservation of biodiversity in protected areas
     • most diverse areas are among the most weakly protected
       • Third World tropical countries
     • areas of high diversity are to some extent dependant on the taxonomic group measured
     • majority of diversity is composed of those groups least understood and least appreciated
     • centres of high diversity do not completely equate with centres of endemism
   • practical approaches to selection utilising data on both diversity, endemism and taxonomic distinctiveness can be used to select the most critical areas for protection
     • this may lead to the creation of isolated reserves and approaches needed to avoid diversity loss

9. Design and management of protected areas

   • protected areas should be as large as possible and circular in shape to provide as large a core area as posible in relation to edge habitat which is likely to be of lower value
   • several small reserves may be as important as a single large reserve in cases where habitats are patchy on an appropriate scale and movement between patches is feasible for species of concern
   • almost all protected areas are influenced or under threat from human activity
     • management is required to compensate for or counteract this activity in order to conserve biodivserity
       • level of management required is dependant on the nature of the ecosystem and past level of human involvement in its processes
   • semi-natural habitats often require intensive mnagement in order to retain the characteristics valuable to retention of the biodiversity
     • management activities may approximate to traditional management activites not originally undertaken with conservation aims
     • scientific research should seek to test and improve these techniques
   • monitoring the outcomes of management ativities is vital to good conservation practice
     • may involve the monitoring of species that act as surrogates for the community as a whole

10. Protecting species

    • In situ conservation
      • some species are naturally rare and are not necessarily threatened
        • prioritisation for conservation requires estimation of the level of threat and in terms of probability of extinction over a given time scale
          • this method was used in the construction of Red Data Books
      • populations are dynamic and have a finite probability of extiction
        • population vaiability analyses can be used to assess population vulnerability and set targets for management but their acuracy is limited by lack iof data in most cases
      • as populations become smaller and more isolated they become more prone to losing genetic diversity which underpins their adaptive ability and therefore their future survival prospects
        • recently developed molecular techniques can be used to measure genetic diversity within and among populations and constrcut genetic management strategies to counteract the loss of diversity
      • sustainable harvesting of wild populations has a well-developed theoretical basis but is much harder to achieve in practice because of the number of variables that can affect a population besides the impact of the harvest
    • Ex situ conservation and reintroduction
      • species are increasingly being taken into captivity to conserve them as they and their habitat become critically endangered
      • traditional and modern techniques are being employed to maintain both plant and animal species in ex situ facilities
      • although captive-breeding technology is becoming ever more successful, resource limitations preclude the vast majority of species from such protection
      • ex situ conservation is only appropriate in the context of eventual reintroduction and re-establishment of wild populations
        • many reintroduction programmes are under way but their success is not yet evaluated and future programmes need to be carefully planned to ensure wise use of scarce resources
      • species translocation are increasingly being used to find new populations or to reinforce existing ones
        • the effectiveness of these strategies has not been fully assessed and there are potential drawbacks to moving individuals around

11. Landscape-scale conservation

    • landscape can be viewed as a matrix of patches from micro to macro scale
      • species have to persist within the matrix despite the spatial and temporal dynamics
    • integration of landscape ecology and population dynamics has given rise to a greater appreciation of the importance of conservation at the landscape scale
    • emphasis in conservation has moved from conserving species in isolated reserves to enhancing movement between patches within the landscape matrix through use of wildlife corridors and stepping stone habitats, though the effectiveness of these concepts is yet to be adequately tested
    • conservation within the urban areas has progressed rapidly within the framework of a landscape-scale approach
      • properly managed urban green space can retain many species not associated with inner city areas
    • managing the landscape and its component ecosystems effectively may be partly a question of choosing the appropriate scale both from an ecological and socioeconomical view

12. Conserving the evolutionary process

    • conservation action to date has concentrated on dealing with short-term crisis situations by designating nature reserves and protecting species
      • result has been a culture of control of nature rather than facilitation of its dynamics
    • dynamic changes in distribution of species and communities can be tracked through time using phylogeographical analysis employing techniques in molecular genetics combined with traditional biogeographical studies
    • in order to recognise the dynamics of nature and formulate appropriate conservation strategies we need some new technology that does not recognise species as static units in time and space
      • evolutionary significant units, management units and operational conservation units have all been used but are not universally accepted
    • systematics can help us understand and identify transitional evolutionary events such as hybrid zones but we need to decide how we should respond to them in terms of conservation action
    • conservation priorities should move away from simply sepcies- and habitat-oriented goals toward the idea of conserving the evolutionary process on which all biodiversity depends

13. Ecological restoration

    • offers a positive action to turn back the tide of biodiversity loss and repair some of the damage done
    • can take place in many ways, from single species to whole ecosystems, and on many scales from local to regional
    • biggest challenge for restoration is understanding the complexity of systems and how to make them work again following disruption
      • ecological restoration projects are mostly employing the ability of the system to repair itself
      • practical attempts of restoration should be adequately montiored to assess reasons for success or failure
    • basic conservation principles laid out in earlier chapters can be used to decide whether restoration should take place to gain maximum benefit for the whole system
    • can be very beneficial to local communities but can also be misused by some interest groups to argue for habitat translocation and creation schemes that have little chance of success and are rarely monitored adequately to expose their inadequacy

14. Putting the science into practice

    • there is significant gap between the scientist and practitioner in conservation that is inhabiting progress in the discipline
    • in the past most conservation practises have been experience-based rather than evidence-based
    • advances in medice and public health practice provide a model of how to move from experience-based to evidence-based actions
    • current action plan formats used by conservation practitioners do not generally encourage the application of evidence in justification of actions
      • modifications of these formats can encourage evidence-based decision-making and identification of priority areas for research
    • conservation organisations will have to be the major drivers of this change by acting as users and commissioner of research, evaluators of action plans and grant awarding bodies