Human occupation is usually associated with degraded landscapes. How has 13,000 years of repeated occupation by coastal indigenous peoples (British Columbia, Canada) influenced patterns of forest productivity in temperate rainforests? In particular, how have ecosystem processes changed over the past 6,000 years when intensified intertidal shellfish usage resulted in the accumulation of substantial shell middens? How do these ecological and cultural legacies compare to other patterns globally? Using a combination of airborne lidar and field-based ecological methods, we examine how the consequences of long-term site occupation, such as shell middens and fire, influence measures of forest productivity at our study site on the Central Coast of British Columbia, Canada. Forest productivity, expressed by forest canopy height, forest width, vegetation greenness and forest canopy cover at habitation sites was compared with forests along the entire coast contained within our study area using lidar extracted from the coastal forest boundary.
Results/Conclusions
We show that soils at habitation sites are higher in calcium, phosphorous and pH. All of which are limiting factors in coastal temperate rainforests. We also reveal a strong association between habitation sites and low-severity fire. In general, forests growing on sites with shell middens were significantly more productive than those growing on otherwise similar sites. Western redcedar (Thuja plicata) trees growing on shell middens were found to be taller, have higher wood calcium, greater radial growth and exhibit less top die-back. Coastal British Columbia is the first known example of long-term intertidal resource use enhancing forest productivity and we expect this pattern to occur at archaeological sites along coastlines globally.