The Ecology of Hydric Hammocks - USGS National Wetlands ...

Figure 38. Tree blowdowns due to hurricanes are a common sight in gulf coastal hammocks. Thissouthern red-cedar was located in a patch of hammock surrounded by salt marsh.stand (especially ages and species oftrees), and seed sources. If the disturbance(fire, hurricane, 1 oggi ng,etc. ) is re1 atively moderate, removingmainly canopy trees, then the new forestwill be dominated by the growth ofremai ninq seed1 i nqs and sap1 ings andsprouts from vigorous sprouters suchas sweetgum and persimmon. More severedisturbances favor sprouting ornew regeneration; the outcome probablydepends on the original composition ofthe stand. Virtually all hardwoodscommon to hydric hammock are capableof sprouting, but in many species thisability is inversely related to thesize of the tree. Therefore, if younghardwoods are present in the pre-di s-turbance stand and the disturbance isnot so intense as to destroy theirroots, they may then sprout vigorouslyto produce a new canopy. The new forestis likely to contain sweetgum andhornbeam, but a1 so oaks, sugarberry,and other hardwoods. On the otherhand, if the canopy contained mostlyolder hardwoods and little understorywas present prior to the disturbance,then severe disturbance will initiatenew regeneration in which 1 oblol lypine and sweetgum are dominantspecies. Sweetgum is the major colonizerfollowing most disturbances inhydri c hammock because usually it isan abundant member of the forest, itis a pro1 ific producer of seeds, andit vigorously sprouts from roots andstumps. However, loblolly pine ismore favored by severe, 1 arge-scal edisturbances, such as clearcuts withthe slash removed. Loblolly pine requiresmineral soil and the absence ofcompeting vegetation for good seedgermination and growth, and it regeneratesand grows very rapidly whenthese conditions are present in hydrichammock. The development of "mature"hydric hammock, with its abundance of