Seed banks of maritime chaparral and abandoned roads: potential for vegetation recovery

As humans increasingly disturb coastal ecosystems, there is a need to under stand the interaction between natural and human-caused disturbances in orde r to conserve these ecosystems. The goals of this study were: (1) to quanti fy the size and composition of seed banks in areas of intact maritime chapa rral and nearby abandoned roads; (2) to investigate whether a burning regim e is necessary to induce germination of the species present in the seed ban k; and (3) to compare the seed bank composition with the vegetation in mari time chaparral and abandoned roads. Soil samples for seed bank analysis wer e collected in October 1996 from seven paired areas of intact chaparral and abandoned roads near Monterey, California. Seed bank samples were subjecte d to a burn or a control (no burn) treatment, after which germination was m onitored in a greenhouse for five months. In spring 1997, vegetation at eac h area was surveyed. Results of the seed bank study indicated that greater numbers of native plant species and native seeds germinated in intact chapa rral compared to road areas, whereas numbers of exotic plant species and se eds germinating were similar in the two habitats. Burning reduced the numbe r of native species and seeds that germinated, and to a lesser extent the n umber of exotic species and seeds that germinated from the seed bank. In th e field survey, intact chaparral areas had greater numbers of native specie s and greater native cover than roads, whereas road areas had greater numbe rs and cover of exotic species. Several species were found only in field su rveys; in particular, few chaparral shrub seeds germinated from the seed ba nk. Similarity between the seed bank and vegetation was low in both chaparr al and road sites. The results suggest that although many native species of chaparral plants are present in the seed bank, planting of some species ma y help accelerate recovery in disturbed areas.