Greetings, I would posit that the mass growth & bloom was a result of the reduced competition for sunlight and moisture but I would further posit that seed-setting is comparatively more limited by trace elements than by sunlight/moisture. It would be interesting to test this by comparing the seed-set (rather than merely the vegetative growth or flowers) of two populations that experience manual vs. fire-induced clearing (assuming there is some truth to the idea that fire returns nutrients to the soil!). -|<ipp > Date: Mon, 21 May 2012 14:45:44 -0700 > From: rarebulbs@suddenlink.net > To: pbs@lists.ibiblio.org > Subject: [pbs] Mass blooming Calochortus > > I was in the Sierra foothills about a month ago for my usual trip to see > the wildflowers. Last year I was very dismayed to see that virtually > all vegetation in one area had been cleared in on both sides of the road > to a depth of about 20 feet. This went on for some miles, and was > probably for fire control. In a completely different area, similar > clearing of manzanita had taken place. This spring there was a mass > blooming of Calochortus tolmiei in one place and C. monophyllus in > another. In both areas (which I know very well) I have never seen > blooming like this, and in some places I have never seen them blooming > at all. This was not a good year for bulb flowers due to the two month > dry spell we had, so these two areas really stood out. It has been > postulated that mass blooming of bulbs after fire could be due to smoke > penetrating the ground, or to nutrients from the ash, but there were > neither, just the removal of dense shrubby vegetation, so maybe it isn't > anything mysterious at all, just the removal of competition, thereby > making available to the existing bulbs more moisture and nutrients in > the soil. I went back this weekend for seed, and another thing struck > me was that the percentage of plants that set seed in colonies like this > is very small. The flowering was amazing, but seed was fairly sparse, > not even 10% of the individuals producing seed. the C. monophyllus (it > is not spotted) literally covers square miles in this area, and the C. > tolmiei is almost as abundant. > > Diana > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/