Sprouting ability of diverse tropical tree species depends on environmental conditions

Damaged trees' resprouting probability is a critical component of their response to disturbances. Because global change will affect both climate and disturbance patterns, it is important to understand how species' resprouting rates are affected by different environmental conditions. We measured the ability of trees to grow new shoots from cut stumps in two distinct environments in central Panama. Trees of 33 species were planted at three meter spacing by the PRORENA project of the Smithsonian Tropical Research Institute in 2003 and 2004 in two sites. The first site, Soberania National Park, has relatively fertile soil and receives about 2100 mm of rain per year. The second site, Rio Hato, has less fertile soil and only 1100 mm of rain in an average year. About two years after planting, plantations were thinned by half by cutting trunks near the ground. In the early dry season of 2007, we counted the number of sprouting stumps in each thinned block. Species' sprouting rates ranged from 0.5% to 91%. Twenty-three of the 33 species had higher sprouting rates in the wetter, more fertile site. Among all species, the drier, less fertile site had a sprouting rate 12.9% lower than the more favorable site. When species were grouped by light requirements, light demanding species showed only a 2% decrease in sprouting from the wetter to drier site, while shade tolerant species showed a 21% decrease between the same sites. The decreased ability of many of the species in this study to sprout in the drier, less fertile site could adversely impact the resilience of forests in the face of disturbance in the hotter, drier climate predicted for the future of central Panama.