Seed and seedling performance detritus of with Microstigeum vimineum (Trin.) Camus

Background/Question/Methods

The objective of this study is to test the inhibitory effect of Microstigeum vimineum (Trin.) Camus detritus on seedling establishment and growth.  Seedlings and seeds of twelve native species were grown under 2 cm detrital material produced by M. vimineum in the previous growing season and compared to control conditions.  The twelve species, including one sedge, four grasses, and seven forbs, are tested.  In the first study, seeds were covered with detritus and, in the second, seedlings were covered with detritus.  In each study, there was an uncovered control.  Number of seedlings, height, and weight were measured after ten weeks in growth chambers set with 12 hours of light/day and 26^oC.  No attempt was made to reduce seed germination from the M. vimineum detritus.  Additional field testing is in place during spring/summer 2013.

Results/Conclusions

In most cases (8 out of 10), both the number of seeds germinated and the size of seedlings were depressed by the presence of the M. vimineum detritus.  In two cases, in both of the annual species, seed germination was similar but height and weight were significantly enhanced (by 15 to 50%).  When seedling of similar size were covered with detritus, seedling survival was 100% for both the control and detritus treatment.  The final seedling weights did not show any statistical differences after 10 weeks.

These results contrast with field observations which show little to no growth of other species under M. vimineum detritus.  Field studies will be conducted to test whether the results are similar.  If they are, it indicates that a lack of a robust native species seed bank may be an important factor in the invasive success of M. vimineum.