Tree of the Week for September 22nd-September 29th, 2008: Acer rubrum - Part V
Part V: Physiology
A. rubrum is generally considered a shade intolerant species, preferring by far open skies and sun to the closed canopy of a mature forest. But there are exceptions to this; Red Maple seedlings are quite willing to germinate in deep shade. They seem ambivalent about the prospect, and first spend a year properly rooting themselves before ever sending any shoots above ground; but still, they will germinate. Nevertheless, if the canopy doesn't open up soon they probably won't last too long. Or, at least, that's true of the typical Red Maple. As I say, there are many exceptions to the species' general shade intolerance. Here in the Northeast, and, I'm told, in northern Michigan and southern Ontario, the species is reasonably able to withstand shade, and it is not uncommon to find it growing as an understory tree beneath even a reasonably dense pine/aspen overstory. The further south one goes, though, the less this is true, until at the southern edge of the species' range, along the Gulf coast and in Florida, it can be found exclusively in more open sites. As near as I can tell, from the sources I've been referencing, this is because of genetic variation rather than the direct influence of climate.
As mentioned in Part III, the Red Maple is curiously capable of growing in both extremely wet sites, such as bogs and fens, and on extremely dry sites, such as on rocky upland ridges. It accomplishes this feat rather ingeniously. Unlike many trees, who have a relatively fixed rooting pattern - such as pin oaks, who splay out dense mats of smallish roots near the soil's surface, or white pines, who invariably begin their life by sending a down a taproot as deep into the soil as it'll go - the red maple, according the ever-helpful Federal Silvics Manual, "shows an early tendency to develop root system characteristics according to soil conditions". As its young roots grow out from the fallen seed, they carefully determine what the subterranean environment of their new home is like. If it is exceedingly wet, they send down only a small taproot while reaching out with a multiplicity of thick lateral roots designed to help hold the tree firmly in place. Contrariwise, if the young rootlings sense that the soil they are tunneling through is particularly dry, they will tell the main taproot to grow long and deep, whilst the laterals remain much smaller. This taproot will, the young plant hopes, find and exploit what water has concentrated in the deeper reaches of the soil.
Finding and exploiting water since 1986,
--mark
A. rubrum is generally considered a shade intolerant species, preferring by far open skies and sun to the closed canopy of a mature forest. But there are exceptions to this; Red Maple seedlings are quite willing to germinate in deep shade. They seem ambivalent about the prospect, and first spend a year properly rooting themselves before ever sending any shoots above ground; but still, they will germinate. Nevertheless, if the canopy doesn't open up soon they probably won't last too long. Or, at least, that's true of the typical Red Maple. As I say, there are many exceptions to the species' general shade intolerance. Here in the Northeast, and, I'm told, in northern Michigan and southern Ontario, the species is reasonably able to withstand shade, and it is not uncommon to find it growing as an understory tree beneath even a reasonably dense pine/aspen overstory. The further south one goes, though, the less this is true, until at the southern edge of the species' range, along the Gulf coast and in Florida, it can be found exclusively in more open sites. As near as I can tell, from the sources I've been referencing, this is because of genetic variation rather than the direct influence of climate.
As mentioned in Part III, the Red Maple is curiously capable of growing in both extremely wet sites, such as bogs and fens, and on extremely dry sites, such as on rocky upland ridges. It accomplishes this feat rather ingeniously. Unlike many trees, who have a relatively fixed rooting pattern - such as pin oaks, who splay out dense mats of smallish roots near the soil's surface, or white pines, who invariably begin their life by sending a down a taproot as deep into the soil as it'll go - the red maple, according the ever-helpful Federal Silvics Manual, "shows an early tendency to develop root system characteristics according to soil conditions". As its young roots grow out from the fallen seed, they carefully determine what the subterranean environment of their new home is like. If it is exceedingly wet, they send down only a small taproot while reaching out with a multiplicity of thick lateral roots designed to help hold the tree firmly in place. Contrariwise, if the young rootlings sense that the soil they are tunneling through is particularly dry, they will tell the main taproot to grow long and deep, whilst the laterals remain much smaller. This taproot will, the young plant hopes, find and exploit what water has concentrated in the deeper reaches of the soil.
Finding and exploiting water since 1986,
--mark