This is the 3327th most frequent Chinese word.
增多
"Increase" or "grow in number/amount."
增多 in this sentence means 'to increase in quantity', referring to the growing population amount.
随着人口的增多,城市的交通压力逐渐增加。
As the population increases, the traffic pressure in the city gradually grows.
增多 here is used to indicate 'an increment in presence or amount', in this case, more vegetation.
近几年,这里植被的增多使得气候变得更加湿润。
In recent years, the increase in vegetation here has made the climate more humid.
增多 depicts 'an enhancement in the number or variety', referring to the augmented learning resources available.