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Individual Highlight

Long-term Fragmentation Reduces Ecosystem Carbon Storage and Productivity

Photo of Airborne Carnegie Airborne Observatory-LiDAR image from a January 2008 flight showing vegetation height for more than 100 kipuka on the Island of Hawaii. Inset shows one example kipuka of roughly 25 hectares. Greg Asner, Carnegie Institution of ScienceAirborne Carnegie Airborne Observatory-LiDAR image from a January 2008 flight showing vegetation height for more than 100 kipuka on the Island of Hawaii. Inset shows one example kipuka of roughly 25 hectares. Greg Asner, Carnegie Institution of ScienceSnapshot : In the naturally fragmented tropical montane landscape in Hawaii, Forest Service researchers used a highly replicated (more than 600) set of fragments ranging in size from less than 0.1 hectares to more than 100 hectares (1 hectare = 2.47 acres) to examine long-term fragmentation effects on above-ground carbon density, coarse woody debris, and stand productivity. Their analyses showed that all three ecosystem measures declined as fragments get smaller, with canopy and nutrient return through litterfall indicating that long-term nutrient loss from fragments increases as fragments get smaller.

Principal Investigators(s) :
Giardina, Christian P. 
Research Location : Upper Waiakea Forest Reserve, Hawaii Island, Hawaii, USA
Research Station : Pacific Southwest Research Station (PSW)
Year : 2015
Highlight ID : 901

Summary

Fragmentation poses one of the greatest threats to tropical forests, with short-term changes to the structure of forest canopies affecting microclimate, tree mortality, and growth. The long-term effects of fragmentation are poorly understood because: (1) most effects require many decades to materialize, but long-term studies are very rare; (2) the effects of edges on forest canopy structure as a function of fragment size are unknown; and (3) fragmentation studies are often confounded by various factors that are difficult to control. Forest Service scientistsquantified the long-term (centennial) effects of fragmentation on forest carbon storage, productivity, and canopy structure using ground-based sampling and airborne light detection and ranging (LiDAR) of Hawaiian montane forest fragments. The fragments, which ranged in size from 0.02 to 1,000 hectares (1 hectare = 2.47 acres), were created more than 130 years ago by flowing lava. The scientists found that carbon storage in above ground living biomass and in coarse woody debris declined dramatically with decreasing fragment size, as did stand productivity. Forest canopy structure varied strongly between forest fragment center and edge, and between large and small fragments, becoming gappier in edges and in small fragments. Finally, nutrient return through litterfall declines as fragment size declines, indicating stronger nutrient losses from small versus large fragments. These changes caused by long-term fragmentation highlight the ecosystem benefits of maintaining large versus small fragments, and complement conservation biology findings from this system and elsewhere that large fragments more effectively support native biodiversity compared with small fragments.?

Forest Service Partners

External Partners

 
  • Carnegie Institution for Science, Stanford University, Michigan Technological University, ??Hawaii Division of Forestry and Wildlife