| Popis: |
Mixed stands excel in their species richness and they theoretically have a better precondition for coping with disturbances than monocultures. On the other hand, there is interspecies competition, which may result in the oppression of individual species in the ecosystem. A total of 12 research plots in the province of North Karelia (Finland) were selected to approximate the effect of forest mixing on the growth of Scots pine (Pinus sylvestris L.). In growing season 2018, stem volume changes and drought stress responses were observed in monocultures and with the admixture of one or both of the species Norway spruce (Picea abies L.) and Silver birch (Betula pendula Roth.). The measurement of volume changes was performed using point dendrometers installed on individual pines, the temperature and soil moisture were monitored by a TMS-4 sensor located in the soil in the middle of each research area. It was found that in all cases, Scots pine grew only in dependence on rainwater, not groundwater. It was discovered that individuals in monoculture grew up to twice as much as in both types of mixed stands. They also showed a better ability to saturate the tissues with water after it had been spent for transpiration during the July drought. In August, however, the response to drought stress was comparable in monocultures and mixed stands. The measured results show that interspecific competition may have a negative effect on the growth and drought tolerance of Scots pine in the short term. However, at a time of escalating extreme climate events around the world, this issue needs to be further explored in order to create optimal conditions for the growth of future forests. |
