Nature, Culture, and Conservation in the Anthropocene - Biodiversity Conservation and Environmental Change - page 158

looper caused a dramatic decline in hemlock and an increase in species immune to the pest;
sugar maple and beech in northern New England and oak in the south (Bhiry and Filion 1996,
Foster 2003). Though hemlock increased in abundance in most areas over the next 500 years,
complete recovery took almost a thousand years, which does not bode well for current popu-
lations of hemlock in New England, currently threatened by introduced woolly agdelid
(an insect pest), as well as a multitude of other climatic and environmental stresses (Ellison
et al. 2005).
Throughout the Holocene, disturbance would have maintained forest heterogeneity at a
range of spatial scales. Windthrow and surface fires would have been a normal part of forest
dynamics, helping to maintain heterogeneity and habitat for light and disturbance adapted
taxa at small spatial scales. Ice, snow, and thunder storms, north-westerly winds and frontal
systems would have created disturbance at stand-landscape scales, while tornadoes cause a
narrow discontinuous band of intense damage. Hurricanes would have occasionally caused
major forest reorganization at the landscape-regional scale. Fire regimes followed regional
climatic, edaphic, and topographic gradients. Fire frequency would have been c. 10-100 years
in the southern coastal sites, and as low as once every thousand years at higher elevations
inland. These interacting disturbances created a complex pattern of spatial and structural
heterogeneity, which forest clearing and subsequent abandonment over recent centuries has
largely obliterated (Foster 2003, North and Keeton 2008).
Climate cooled across north-eastern North America from about 2,000 years ago, leading to
an expansion of spruce forest, though chestnut (a southern species), also only appeared at
this time. Many of the common tree and herb species followed different migration routes at
different rates, highlighting the possibility for further species reshuffling in the future (Jack-
son 2006, Williams and Jackson 2007, Jackson and Hobbs 2009). Though we tend to associate
longevity with resilience, this may not always be the case and more recent assemblages could
be better suited to the climate and disturbance patterns of today and the coming decades
(Jackson 2006).
New England is a particular focus for multidisciplinary of studies of forest dynamics and
landscape history in the northern hardwood region. David Foster, Director of Harvard Forest,
leads a team of over 100 researchers, using palaeoecology, historical, and ecological data to
address questions of environmental change, past human impacts, and the implications for
current and future management (Foster 2002c, Foster 2003, Motzkin and Foster 2004, Foster
et al. 2008, Foster et al. 2010). This work has led to an excellent understanding of the interacting
effects of climate change and people on forest dynamics, providing information that helps in
developing visions for the New England landscape and informing forest management plans.
This work has shown that Native American populations probably had relatively little
impact on forest structure in this region, and mainly in low-lying and coastal regions,
whereas European arrival wrought massive environmental change that disrupted the natu-
ral patterns of forest heterogeneity, which had resulted from millennia of climate change
and disturbance (Parshall and Foster 2002). Native Americans did not keep livestock, but
used fire to improve habitat for game species, by burning leaf litter and understory shrubs,
usually in the spring or autumn. Cultivation of maize began in c. 1000 ce, alongside beans,