Structure of Isolated Acer grandidentatum (Bigtooth Maple) Communities and Potential Population Changes

摘要: Isolated, relic populations of Acer grandidentatum (bigtooth maple, Sapindaceae) were found in deep canyons central Texas. Associated with them on hilltops communities Juniperus ashei (ash juniper). We determined the structure A. and compared to adjacent J. populations. The overstory understory density was counted basal area was for all woody species both communities using quadrat procedure. highest density (788 ± 964 or 52%) (29 35 or 52%) canyon while had (1589 146 92%) and basal (51 13 88%) hilltop communities. In of the communities, there five juvenile tree including which fourth (13% 176 110 plants/ha). the hilltop high (52% or 994 400 There no Grandidentatum plants an inverse quadratic size distribution few juveniles. Although we a number seedlings, little recruitment over last 16 years very potential previous 20 years. exponential with many considerable recruitment. Weibull age/size distributions showed one established 1670’s 2 1760’s, peak establishment in the 1970’s. Causes lack recent are uncertain, but it could be episodic due changes herbivory, management other environmental conditions.