Sycamore is in some ways similar to the well-known masting species such as oak and beech in that it is (jargon coming up) heterodichogamous. that aphid numbers affected flowering and seed set. Unlike the rest of my sycamore data set, the flowering data collection was actually set up to test a hypothesis i.e. The effects of bird cherry aphid infestation on reproductive success of the bird cherry, Prunus padus (Leather, 1988)
Sycamore seeds come equipped with two little wings (they are wing dispersed) and occur in little bunches (infructescences) so are quite noticeable. I realised that not all of the trees flowered and that there seemed to be a lot fewer seeds that year than I remembered there being the year before. People tend to associate masting with trees that produce heavy fruit, acorns, hazel nuts and beech nuts for example, and I was no exception, so it wasn’t until a couple of years (1995) after I started my mega-sycamore study at Silwood Park that I had a bit of a revelation. a mast year, then the chances of being pollinated are greatly increased (Moreira et al., 2014). A more recent, and less exciting suggestion (to me anyway), is that if the trees have a mass synchronised flowering effort, i.e. In the mast years, there are enough seeds to feed the surviving predators and produce another crop of trees. This basically says that the trees, by having on and off years, starve their specialist seed predators in the off years, thus reducing predator pressure by killing lots of them off.
One, which I find fairly convincing, is the “ predator satiation” hypothesis (Janzen, 1971). There are two schools of thought regarding this. You might wonder why, if reproduction is costly, that some trees are ‘willing’ to expend so much energy in one go. Beech ( Fagus sylvatica) mast production over a sixteen year period in England.
0 kommentar(er)
