On Fri, 11 Nov 1994 keelandb@osprey.nwrc.gov wrote: > > On Tue, 1 Nov 1994, Mike Sonntag wrote: > > > How does a suppressed tree know that it is suppressed? > > Although the regional radiation, climate and soils may be very similar > (never identical), the local microclimate caused by differences in > vegetation (closed canopy forest versus open grassland [?]) will > result in the differences in growth form and amount. Under the canopy > a spruce clone will experience differences in light amount and > probably light quality. In addition the temperatures will be lower > and relative humidity will be higher under the canopy than compared > with the open area where wind is more free to blow and capture > moisture from the soil. Solar radiation at the level of the spruce > clone in the open will be more intense resulting in greater > evapotranspiration from that clone compared with the clone under a > canopy that only gets filtered sunlight and occasional sun specks. I agree with your answer to the original question. It leads to another question, however. Analyses of Nelder-design spacing experiments in New Zealand have indicated that in some cases height is correlated with spacing long before there is any measureable effect on diameter, and that between 500 and 2000 stems per hectare, height increases with increasing spacing. The effect has been observed in 3 and 4 year old experiments. The original question might be modified to read, "In stands where there do not appear to be any contacts between trees, why do trees grown at higher stockings grow taller? How do they detect their neighbours (if indeed this is what's going on)?" Regards, Euan ================================================================== Dr Euan G. Mason Silviculture, Modelling and Lecturer in Silviculture Decision-support systems School of Forestry University of Canterbury New Zealand's professional Christchurch, New Zealand Forestry School ================================================================== ------------------------------------------------------------------------- To find out more about the anon service, send mail to help@anon.penet.fi. Due to the double-blind, any mail replies to this message will be anonymized, and an anonymous id will be allocated automatically. You have been warned. Please report any problems, inappropriate use etc. to admin@anon.penet.fi.
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