It is from our terrestrial ecosystems that we receive the nourishment which allows us to  live on  a daily basis.   We harvest our food here,  we obtain our spices, we collect our water.   Yet,  so often we do not  give these things  a second thought.  They have always been, and we assume they will always be.  Such complacency is both sad and destructive.
 
 

Plants  and  animals also  have hidden benefits  to humankind.   Because they are always battling to see which will be the victor in keeping their species prpagating,  both  plants  and  animals produce  many  forms  of  self-defense.  Some of these are in genetic traits such as height,  climbing or  flying abilities, nocturnal vision, etc.   However, other defenses  are chemical;  and it  is these traits which are often beneficial to man.

MEDICINAL USES

Many  medicines  have been  discovered  through  research of  plant defense compounds.  Every day new medicines are being discovered.  Yet, there are a multitude of species which we have yet to identify; and along with this identification comes further potential for medicinal purposes we have yet to discover.  We do not know for sure how many useful traits our cohabitants of this planet possess.  Yet, we give little thought to this as we go about plundering our natural resources and destroying habitats, causing the extinction of numerous species along the way.  See Loss of Biodiversity for details.
 

MAN-INDUCED CATASTROPHES

Air pollution in Sao Paulo, Brazil, was so severe in the 1970s and 1980s that it killed most of the trees in the surrounding Atlantic forest.  Vegetative cover was significantly reduced, and landslides occured (Lovejoy 10).  See Air Pollution for more details about these types of problems.
 
 

Man is  incapable of  visiting  a place  and leaving it the way he found it. The mark of our presence is everywhere.  Sometimes it is simply the absence of other species which indicates our presence Sometimes it is what we leave behind by being irresponsible.

PLEASURE

One of the often overlooked aspects of destruction of our natural resources is the fact that once they are gone, we have nothing with which to replace them.  This is a sobering thought.   What would life be  like if we had no mountains to which to retreat to escape from our heavily populated cities?   What would we do if all our lakes  and streams  were so  polluted  that  we could not  use  them as  places of recreation any longer?  I cannot even imagine the strain this would place on the human population.  Without my moments of reflection in which I simply gaze in awe at our natural surroundings, I believe I would become a very dour, miserable person.   There must be  some relief  for us from  our concrete  and brick abodes teeming with countless other people.
 
 

UNEXPECTED RESULTS What about all those annoying insects with which we share our planet?  Surely they have no useful purpose,  and their loss would have no effect on our lives.

Yet,  it is these very  species which help us  propagate the plant species which we need to exist.  Without insects many species of plants would not be pollinated and thus would bear no fruit.  The soil, which contains all the vital nutrients for plants to thrive, would not be aerated and mixed.  It would become much less fertile, and we  would  lose many species of plants  –  not to mention  which we would have a much more difficult time cultivating crops for our own nutrition.  Many animals are dependent in  one respect or  another on  the work done  by insects or  on insects themselves as food.  Without the insects, these animals would die.  The connection between species on earth is a delicate one which we do not usually understand.  All species are woven together in an intricate pattern which we often disrupt just by going about our daily activities.
 
 

ALTERATION OF NATURAL RESOURCES Freshwater  areas are  probably being  degraded faster than tropical forests.  In the United States alone 75,000 dams have been built on our rivers, and 360,000 kilometers of fresh water have been channelled for “flood control”.  Currently only 2% of our rivers are free-flowing without our intrusion into their natural paths (Myers 126).

Yet,  our  alteration  of these  natural  resources  is  anything  but helpful.   By straightening our rivers and building flood retaining walls we have forced our rivers to run faster and run deeper when there is significant precipitation upstream.  This has many negative consequences.  The first and foremost which directly affects us is that flooding is much more severe when it occurs.  Because the current of the water is so much faster,  water reaches low-lying areas much more quickly than in the past.  As the water rushes in, it has nowhere to go but up.   It cannot  dissipate  into the earth because  we have built so many walls to contain it.  Therefore, it rises very quickly; and flooding occurs much sooner and more often than had the river been allowed to follow its natural course.

Another consequence is that in areas where there are no flood walls erosion of soil on the  banks  of the  river is  much  more severe.   The force  of the water  is much greater, thereby causing it to gouge deeper into the soil of the banks.  This causes instability  in the river  banks and  sedimentation of  the river water.   Still another consequence of altering the flow of rivers is that ecosystems which once existed due to  the river’s  presence are  often destroyed.   The animal and  plant species which depended on the river for their existence often cannot survive without it.

HOTSPOTS AND LOSS OF HABITAT

Hotspots are areas  of the globe where there  is a high concentration of species.  Habitat loss in these areas will almost certainly spell extinction of many species.  Examples of these types of areas include tropical rainforests, coral reefs, and some isolated inland lakes.  Lake Baikal in Russia has over 2000 species, 1500 of which are endemic (Myers 127).  The places near the equator where there is sufficient year-round moisture to sustain tropical forests are vitally important.  Though only covering about 7% of the earth’s dry surface, they contain almost 50% of all species (Lovejoy 8).

TRANSITION ZONES

There is  a significant  link between aquatic and terrestrial ecosystems.   The transition area where fresh water or  salt water meets the land is much more important than many people realize.  The shoreline is a boundary, crowded on
each side with life.   On the one side are terrestrial creatures and on the other aquatic organisms.  When we damage these environments, we usually damage at least two different ecosystems at once.

Coastal wetlands are important as habitats for valuable marine animals that utilize these areas at specific points in their lives.  These include shrimp, clams, crabs, and oysters, as well as many species of fish.  Yet, these areas are also important for the plants which they harbor.  These plants trap solid particles in the water and therefore reduce sedimentation in the water as it heads towards the ocean.

Mangrove areas are  especially important in this process.   Without mangroves to trap suspended  particles in  the water,  coral reefs  would be  smothered.   It is essential that the water for coral reefs be clean for the coral to survive.  Mangrove  roots are also nurseries for many types of coral reef fish.
 
 

Wetlands Wetlands are areas that contain enough water during some stage of the year to foster special ecosystems.  These areas include  marshes,  bogs,  floodplains, deltas, and estuaries.  Because of their location, these areas often have dense human habitation very near them.  This causes many problems because we,  as humans, often destroy or modify these wetlands for our own uses.  During the last century alone, we have destroyed more than 50% of these areas globally (Myers 129).

Wetlands  cover about 6%  of the earth’s  land surface and  can be found in most countries of the world.  Some of them are extensive and connect different countries (example:  the Pantanal Swamp in South America).  These areas are unusually rich in wildlife and therefore are particularly susceptible to disruption.