Two opposite forces operate in the growth and development of every population. One of them related to the ability to reproduce at a given rate. The force opposite to it is called 

Environmental resistance is a factor, that can limit the increase in a population. Common factors include predators, disease, competitors, and lack of food, water, and suitable habitat. Due to factors that contribute to environmental resistance, not all individuals that are born can survive to adulthood or reproductive age. As a result, the overall population of the species does not grow uncontrollably but instead is limited and controlled.
All limiting factors in the environment that act on a particular population is termed as environmental resistance.
Hence, the opposing force is environmental resistance.