Nature and science
The tower measuring water on its way back to the sky
Documented history and research · Evidence reviewed
A forest tower measured an often-invisible part of the Pinelands water budget.
Above the wetland canopy
From November 2004 to February 2007, instruments on a 24.5-meter tower measured water-vapor exchange above a pitch-pine wetland. The 2012 USGS report paired those observations with weather, groundwater and soil-moisture records. Researchers were measuring evapotranspiration: water returning to the atmosphere through evaporation and plants, rather than flowing onward into streams or groundwater storage. Sumner, Nicholson and Clark, USGS SIR 2012–5118.
Even wetland water use could become constrained
Twelve-month totals ranged from 786 to 821 millimeters. Rates peaked in July and were lowest in winter. During extended dry periods, declining soil moisture reduced the fraction of available energy used to evaporate water; that fraction recovered after rain. Even here, available water could limit the process. Sumner, Nicholson and Clark, USGS SIR 2012–5118.
Disturbance changed the comparison
Wetland evapotranspiration averaged 32 percent above reported values from nearby upland sites. Restricting the comparison to undisturbed upland periods reduced the difference to 17 percent. Fire and insect defoliation therefore affected the apparent wetland-upland contrast. The percentages describe these stands and periods. Sumner, Nicholson and Clark, USGS SIR 2012–5118.
Sources and research limits
- Sumner, Nicholson and Clark, USGS SIR 2012–5118 — Indexed report abstract, tower methods, source-area discussion and wetland/upland comparison inspected; Forest Service institutional abstract cross-checked.
The tower sampled a changing upwind area. No raw flux data or model files were reanalyzed.