Seasonal fluctuations of starch in wood and bark of trees from a tropical deciduous forest in México

Abstract

TWENTY FIVE TREE SPECIES FROM THE REGION OF CHAMELA, JALISCO, MEXICO, WERE STUDIED TO DETERMINE PRESENCE, ABUNDANCE, SHAPE AND SIZE OF STARCH GRANULES IN BOTH BARK AND WOOD. THE REGION HAS TWO WELL MARKED PERIODS: A VERY DRY ONE, LASTING CA. SEVEN MONTHS, AND A RAINY ONE; THE PREDOMINATE VEGETATION IS TROPICAL DECIDUOUS FOREST. A RELATIONSHIP BETWEEN THE ABUNDANCE OF STARCH GRANULES AND RAIN SEASONALITY AND THE PHEONOLOGY OF THE SPECIES STUDIED WAS OBSERVED. ALTHOUGH IN GENERAL THERE IS NO SINGLE BEHAVIORAL PATTERN IN REGARD TO STORAGE AND DEPLETION OF RESERVES, IN BOTH BARK AND WOOD, 61% OF THE SPECIES POSSESS THE LOWEST AMOUNT OF STARCH IN LATE SPRING AND SUMMER, AND THE GREATEST DURING AUTUMN AND WINTER. THE AMOUNT OF STARCH DECREASES AT THE BEGINNING OF THE RAINY SEASON, COINCIDING WITH THE DEVELOPMENT OF GROWTH SHOOTS. THE SHAPE OF THE STARCH GRANULES IS SPECIES-SPECIFIC AND CAN HELP IN THE IDENTIFICATION OF WOODS AND BARKS. THE MOST COMMON SHAPES OF THE STARCH GRANULES WERE SPHERICAL, ELLIPTIC, CLAVATE, TO SLIGHTLY IRREGULAR, VARYING IN SIZE FROM 5 TO 14 μM IN AXIAL CELLS, CONTRASTING WITH 2 TO 9 μM IN RADIAL CELLS, BEING SMALLER IN BARK.