RESULTS AND DISCUSSION 



Demographic monitoring 



Flowering of this monocarpic perennial is tentatively 

 characterized as a pattern of short-term oscillation conditioned 

 by climate. Flowering plant numbers increased at all sites in 

 1993 compared to the previous year, but have not returned to 

 numbers at the original time of plot establishment in 1990 (Table 

 1) . Both 1991 and 1992 were drought years . 



Table 1. Trends in cirsium lonqistylum flowering plant numbers 



*Note: Only the 15/37 ft circular plots identical to those 

 sampled in the original MTNHP study are used for basis of 

 comparison 



Overall plant numbers did not show parallel trends between sites. 

 It was difficult to determine with certainty whether any of the 

 flowering plants in 1993 belt transects corresponded with 

 rosettes or seedlings in the three previous years. Sample sizes 

 at Neihart and Russian Creek are low for stage-classified matrix 

 population analysis, and it is recommended that an additional 

 monitoring site be established at each of these sites for 

 producing sound demographic data. 



It is suggested that the size variation of the 3-leaflet stage 

 may depend on whether the seed germinates in fall or spring. 

 Flower heads are observed to release seeds throughout late summer 

 into winter. Investigations into seed germination requirements 

 and seedbank development have not been conducted. 



Juvenile stage numbers superficially appear to correlate with 

 rodent burrow density. This is supported by the escalation of 

 juvenile stage numbers with an episode of intense burrowing 

 activity which occurred at Kings Hill #1 in 1991 (Roe 1992) . If 

 this is the case, then relative groundcover within 1 x 1 m plots 

 should correlate with juvenile stage numbers over time, as will 

 be tested in future years. There is conspicuously less burrowing 

 activity at Neihart and Russian Creek sites, but it is unknown 

 whether this is due to intrinsic suitability differences for 

 rodent, or the vegetation change prompted by land use that has 

 favored sod-building exotic grasses. 



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