Reproductive costs are associated with both the male and female functions in Alnus viridis ssp crispa

An organism has a finite amount of resources which must be allocated to dif ficult functions such as maintenance, growth and reproduction. In cosexual plants, allocation to reproduction is in both male and female structures: t here is thus an opportunity for these two functions to compete for the limi ted resources available for reproduction. Male and female reproductive effo rt was experimentally manipulated over a three-year period on shoots of Aln us viridis ssp, crispa to detect the presence of trade-offs (i) between the male and female reproductive functions. and (ii) among reproduction. growt h and future reproduction. The results show that there is no detectable tra de-off between the male and female functions. In filer. the number of male and of female reproductive structures co-vary through time. However. combin ed male and female reproductive effort reduces current growth and future re production. There are thus costs to reproduction in this species, but these are associated with the combined effect of both the male and female functi ons. To my knowledge. this is the first experimental study on the cost of r eproduction in a long-lived woody species showing clear trade-offs.