An article has just been published in the “Agricultural and Forest Meteorology” journal presenting the influence of Scots pine on sessile oak spring phenology. The authors showed that budburst date of Quercus petraea is delayed in mixed stands with Pinus sylvestris.
The article is available until March 16, 2021 here:
Climate change is impacting temperate tree species phenology, especially the timing of budburst, which is mainly driven by air temperature. However, interactions with biotic or other environmental factors also influence the timing of budburst and are usually overlooked. We studied the influence of forest stand composition on the budburst date of adult trees belonging to two species: sessile oak (Quercus petraea, Matt. (Liebl.)) and Scots pine (Pinus sylvestris, L.). We monitored their budburst dates for seven consecutive years at 18 experimental plots located in central France. We compared the budburst dates of oaks and pines growing in monospecific stands with those of their counterparts in an oak-pine mixture. Our results show that sessile oak budburst date in mixed stands with Scots pine was delayed by 2.2 days on average (SE = 0.6) compared to its budburst date in monospecific stands. In years with early budburst, the delay was more pronounced – up to four days. For Scots pine, our results showed no difference between budburst dates in monospecific and mixed stands. We hypothesize that the persistent foliage of the Scots pine in the mixed stand intercepted a part of the solar radiation, which affected the temperature perceived by the oak buds, thereby delaying the heat accumulation needed for sessile oak budburst. This effect may be of interest for the management of sessile oak in the context of global warming. In the future, sessile oak may experience more frequent frost damage due to an earlier budburst. Managing sessile oak with an evergreen species could limit late frost damage to some extent by delaying budburst. Stand composition must obviously be taken into account when monitoring the phenology of temperate tree species and to enable robust comparisons of phenological events for a given tree species at different sites.