Historical Land Use Change in Grafton County, NH:
Impacts on the Present and Future Landscape

Steve Hamburg, Jack Mustard, Laura Schneider, and Matt Vadeboncoeur

 

The northern forest has a long history of strong anthropogenic influence, dating back more than three centuries.  We are studying an area in central Grafton County, NH, (Figure 1) with a mix of historical land use ranging from commercial clear-cutting to small-scale agriculture.  The influence of human management of these ecosystems can still be seen more than a century after abandonment, and has profound impacts on forest structure, species composition, soils, nutrient cycles, and carbon accumulation. It is therefore essential to examine the role of a forest’s history in determining its potential for future carbon uptake.  The few available measures of the effects of land use on carbon storage are based on the rates of land use change, usually obtained from aggregated data on agricultural and forestry activities. Spatially explicit data on historic (Figure 2) and current (Figure 3) land use linked to estimations of carbon storage are almost absent for this region.  We seek to increase our understanding of the effects of land use change trends on landscape-level carbon fluxes by estimating changes in carbon storage in the context of historical disturbance patterns. 

 

Project Objectives

• To document the pattern of land cover changes in our study area over the last 150 years.
• To link spatially explicit land cover change patterns to estimates of carbon stock changes over the past 150 years.
• To use remote sensing data (TM and ETM+) to estimate current carbon fluxes resulting from land use changes.
• To construct scenarios that illustrate the influence of different regional patterns of land use change on future carbon storage in forest ecosystems.

 

Figure 1.  Our study area is Grafton County, NH.  Data on the structure and composition of the forest is available from numerous studies at Hubbard Brook and Bartlett Experimental Forests, The Bowl Natural Area, and at abandoned farm sites studied by Rhoads and Hamburg.

 

Figure 2.  Detail of H.F. Walling’s 1860 map of Grafton County, which shows the location of each farm in the county at that date. These data can be combined with tabular data from agricultural census schedules to create a spatially-explicit land use database. The area shown is just south of Mount Moosilauke, in the northern part of the Town of Warren.

 

Figure 3.  Detail of a modern aerial photograph of the area mapped in figure 2.  Historic land use patterns are clearly visible in the forest structure and composition. Darker areas are dominated by conifers and indicate that an area was used as pasture before being abandoned. The straight lines transitions in forest type correspond to stone walls separating two distinct historic uses.

Updated 05/22/2008
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