3. LAW OF TOLERANCE 

A species is confined, ecologically and geographically, by the extremes of 
environmental adversities that it can withstand. 

The boundaries of a species realm --
Hill, valley, sea, dry land --
Are drawn when hardships overwhelm
Its power to withstand


4. LAW OF VALENCE 

In each part of its area, a given species shows a greater or lesser amplitude 
in ranging through various habitats (or communities); this is conditioned by 
its requirements and tolerances being satisfied or nearly overcome.
Where best its needs are met, a species grows,
But hindered or deprived, its ouput slows.