IMPACT OF HUMAN ACTIVITY ON REGIONAL FOREST COMPOSITION AND DYNAMICS IN CENTRAL NEW-ENGLAND

Historical and ecological data from north-central Massachusetts sugges t that widespread and intensive human disturbance after European settl ement led to a shift in forest composition and obscured regional patte rns of species abundance. A paleoecological approach was required to p lace recent forest dynamics in a long-term context. Pollen and charcoa l data from 11 small lakes in north-central Massachusetts were used to reconstruct local vegetation dynamics and fire histories across the r egion over the past 1000 years. The sites are located across an enviro nmental gradient. Paleoecological data indicate that prior to European settlement, there was regional variation in forest composition corres ponding to differences in climate, substrate, and fire regime. Oak, ch estnut, and hickory were abundant at low elevations, whereas hemlock, beech, sugar maple, and yellow birch were common at high elevations. F ire appears to have been more frequent and/or intense at lower elevati ons, maintaining high abundances of oak, and archaeological data sugge st Native American populations were greater in these areas. A change i n forest composition at higher elevations, around 550 years before pre sent, may be related to the Little Ice Age (a period of variable clima te), fire, and/or activity by Native Americans, and led to regional co nvergence in forest composition. After European settlement, forest com position changed markedly in response to human disturbance and there w as a sharp increase in rates of vegetation change. Regional patterns w ere obscured further, leading to homogenization of broad-scale forest composition. There is no indication from the pollen data that forests are returning to pre-European settlement forest composition, and rates of vegetation change remain high, reflecting continuing disturbance o n the landscape, despite regional reforestation.