Changes in the balance between C3 and C4 plants expected in Poland with the global change

We can expect significant changes in the plant cover structure and crop structure due to the climate change, and the response of plants with different photosynthetic pathways to global change may be crucial for agriculture. The paper analyzes the impact of habitat factors connected with the climate change: temperature and concentration of CO2 in the atmosphere on the change of C3 and C4 plants primary production (NPP). The Ehleringer model describing the balance between C3 and C4 plants indicates that a shift in the balance in favor of C4 plants and the increase in CO2 levels, which has continued since the mid-nineteenth up to the present day, would require a temperature increase by 5-10°C. Nonetheless, this increase is much lower, while the review of previous studies and some phenomena observed in the Poland area: high level of NPP in maize crops and the increased in contribution of C4 species in the flora indicate the shift in the balance in favor of C4 plants. This fact can be explained by a factor not included to the Ehleringer model: the availability of water and nitrogen