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8. Humans can have a


                                      positive effect on the environment:


                                                   Conservation of Species



      OBJECTIVES
      > To understand that humans may have a beneficial effect on the environment
      > To realise that conservation often involves compromise To understand a conservation strategy
      > To know some examples of successful conservation



     Humans do not always damage the environment -            The  reasons  for  this  are  not  always  understood,
     growing  numbers  of  conservationists  try  to          but the following may be to blame:
     balance the human demands on the environment                 Pest  control  -  the  term  pest  includes  any
     with the need to maintain wildlife habitat. They will        species that causes inconvenience to humans.
     try  to  assess  the  likely  effects  of  any  human        Many  species  have  been  hunted  ruthlessly,
     activity  by  producing  an  Environmental  Impact           such  as  red  deer  (which  damage  trees),  and
     Statement.                                                   also  predators  such  as  cheetahs,  and

     Forest management                                            scavengers such as vultures.
     Humans  have  been  responsible  for  deforestation          Commercial exploitation - species of value to
     of much of the Earth's surface. Humans have also             humans have been exploited, such as the tiger
     set  up  schemes  for  the  large-scale  planting  of        which has been hunted and trapped for fur and
     trees  -  in  areas  that  have  been  cleared               medicinal compounds.
     (reforestation)  or  in  a  new  site  (afforestation).      Loss of habitat - more land is being used for
     There are a number of reasons for planting trees:            agriculture, including previously unusable land
         as  a  cash  crop,  providing  timber  for  building     that has been drained. This removes habitats

         (coniferous  plantations  in  the  UK)  or  for  fuel    for  many  species,  such  as  wading  birds  and
         (fast-growing  eucalyptus  trees  are  widely            amphibians.
         planted in central Africa)                               Climate  change  -  loss  of  ice  from  the  Arctic
         to reverse soil erosion, particularly valuable in        reduces hunting sites for polar bears.
         areas that have become deserts                           Pollution - ponds and rivers may be polluted
         to  provide  valuable  wildlife  habitats  -  for        by  fertilisers  and  sewage.  Many  oxygen-
         example, Scots pine plantations are important            requiring species can be lost.
         habitats for red squirrels                               Introduced  species  -  predators  such  as
         as  recreational  areas,  providing  leisure             stoats  and  weasels  introduced  to  offshore
         activities  such  as  camping  and  mountain-            islands can eliminate ground-nesting birds.
         biking.                                              Conservationists  work  to  slow  down  or  stop  the
     A  well-managed  forest  can  combine  all  of  these    decline  in  biodiversity  (the  number  of  different
     functions and maintain this valuable resource.           species), and also to raise public awareness of the
     Endangered species                                       need  to  maintain  species  and  their  habitats.  The
                                                              number  of  different  species  in  a  community  of
     Competition  between  humans  and  other  living
                                                              living  organisms  can  be  described  by  a  formula
     organisms  means  that  many  species  have
                                                              called the Species Diversity Index.
     disappeared or declined in number.



          29         Learning Module Organisms and Their Environment | Class 11
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