The input of a proton load from the contaminated air has been followed in an immision area and in the control area of a beech ecological experimental stationary throughout a period of four years. It offers a picture of a different contamination degree of the atmosphere on the given sites. Mean values in the immission area were 18.3 mmol H+ day-1 m-2, and only 9.3 mmol H+ day-1 m-2 in the control, that means by 97% higher in the immission area. The comparison of values of the proton load on a bare spot and in the stand as well as the comparison of summer and winter seasons is given in Tables 1-4. The achieved results suggest that forest positively influences reduction of the proton load on the given sites.