|RUSSELL, SUSAN - PEACE CORP
|SCHUPP, EUGENE - UTAH STATE UNIVERSITY
Submitted to: Plant Species Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/30/1997
Publication Date: N/A
Interpretive Summary: Curlleaf mountain mahogany is small tree in the Intermountain region which is an important winter browse and summer shade plant for wildlife such as elk and deer. Population sizes of this species are declining throughout the region due to reduced recruitment of seedlings and young individuals. This research was begun to try to discover the causes of reduced recruitment and to make recommendations for improved management of mountain mahogany populations. In this paper we examined the success of sexual reproduction in this species, and followed the fate of seeds to determine when seed mortality occurs. we found that this species is both insect and wind pollinated, and that flowers generally received adequate amounts of pollen to produce seeds. There were insignificant losses of seeds to seed eaters before the seeds were dispersed. Reduced recruitment appears not to be due to reduced sexual reproduction or pollinator absence.
Technical Abstract: In this study we explore the reproductive biology of Cercocarpus ledifolius (Rosaceae), a species showing extremely limited recruitment throughout its range in the Intermountain West. We examined (1) self-compatibility, (2) the potential for wind pollination, (3) pollen limitation of seed production, and (4) loss of developing seeds from initiation to maturation. Through hand-pollination experiments, we determined that C. ledifolius flowers are highly self- compatible. Abundant seeds were produced form flowers pollinated with pollen from the same plant (geitonogamy); the level of seed production did not differ from control outcrossed treatments. Furthermore, we measured substantial airborne pollen loads within C. ledifolius stands, indicating transport of pollen via wind and a strong potential for wind pollination, despite its apparent adaptations for insect pollination. C. ledifolius likely experiences both anemophily and entomophily, although the relative importance of each is unknown. We also found that pollen did not limit seed production during the year studied. Branches on which all flowers were hand-pollinated with outcrossed pollen did not have greater seed production than control branches only open to natural pollination. Lastly, virtually all initiated seeds developed to maturity, indicating low seed abortion rates and minimal losses to pre-dispersal seed predators.