HYPOTHESES Madrone diseases are related to soil type –Soil structure and function (for instance, drainage) –Soil chemistry (for example, pH and nutrients) Madrone diseases are related to community physical structure Madrone diseases are related to disturbances (fire) Madrone fruits provide a scarce resource for migratory and resident birds during a critical time period (late fall) in Puget Sound
Pure Broadleaf Evergreen Forest of Pacific Madrone
SAND QUARRIES ALLOW FOR STUDY OF BASAL ROOTS IMPORTANT FOR WATER UPTAKE, SLOPE STABILITY AND ANCHORING PLANT
PIT SHOWING ESPERENT SAND WITH Bw/Bs? Hypothesis: natural soil series supports healthy madrones
Lower left - Nattrassia induced branch cankers produced black sunken centers with areas of active pathogen growth on the borders Upper right - Cankers may completely girdle branches Lower right - Competition for nutrients between the tree and fungus and girdling of vascular tissue ultimately may cause death in major branches or trunks of large trees. Here the two madrone trunks to the right (one dead with leaves, the other alive) are from the same tree; the dead trunk was girdled by Nattrassia.
A TYPE OF ROOT ROT (PHYTOPHTHORA) INFECTS POTTED AND FIELD PLANTS THAT ARE PERIODICALLY FLOODED. BELOW SHOWS THE PROGRESSION OF PHYTOPHTHORA SYMPTOMS IN OVERWATERED POTTED PLANTS. FLOODING IS COMMON IN URBIC (CONSTRUCTION FILL) SOILS Left most plant showed initial signs of infection, but the watering regime was made drier and it recovered Second from left - fungus spreads from root clogging vascular system killing plant from top down. Middle - the rapidity of death caused by root rot aids in identifying it because the leaves remain on the plant at the time of death. Far right - all leaves eventually abscise.
LAWTON CLAY FOUND BELOW LAWN AT LAURELHURST PARK, SEATTLE. IS THIS IMPERMEABLE STRATA RESPONSIBLE FOR DISEASED MADRONES GROWING HERE?
MAGNOLIA BLUFFS HAS A COMPACTED CAP OF GLACIAL TILL. MADRONES ARE BELIEVED TO PLAY A ROLE IN STABILIZING THESE SLOPES WITH THEIR ROOTS, BUT THE SHALLOW HARDPAN MAY CAUSE MADRONES TO BECOME SICK?
Undisturbed, natural soils with madrones are very uncommon in the urban areas. Compaction and erosion destroy upper soil surfaces crucial for ion exchange and plant nutrient uptake
SOME POSSIBLE PROJECT TOPICS Help in field work to determine the relationship of depth to hardpan to madrone health at Magnolia Bluffs Characterize construction fill material (urbic soil) at Warren Magnunson and NorthSeattle Community College wetland fill Characterize soil profiles beneath sick madrone trees at Laurelhurst Park. Take part in a soil and leaf sampling project at a natural, healthy madrone site. Conduct literature research on Phytophthora infestations at other places and on other plants (for instance, California oaks) and relate it to Pacific madrone problems. Conduct literature research on Nattrassia (stem cankers) infections at other places and on other plants and relate it to Pacific madrone problems Analyze results of studies on previous bird frugivore studies, develop hypothesis and design your on bird study. Plant/pathogen coevolution