A simple and effective sampler to collect undisturbed cores from tidal marshes
Core sampling is a common procedure in wetland ecology. PVC tubes are widely used to collect soil cores; however several studies fail to describe even the most typical characteristics of their sampling auger. This work aims to fill this gap and provide a simple and standardized core sampler design. A simple and inexpensive sampler is described for field use. Its main advantages are: 1) extraction of undisturbed cores; 7.6 cm diameter and up to 100 cm depth, 2) it is light-weight, sturdy and reliable, 3) it is made from widely available PVC items and 4) it requires minimal skills to assemble. The sampler is introduced in the wetland soil, by rotation, to the desired depth; the tooth-like edge can cut and penetrate through the dense root systems. The sampler is capped with an industrial-type stopper, and pulled up. The core is held in the sampler by suction - negative pressure. A plunger is then used to slowly remove the soil - core and sub - samples are collected. Alternatively, both ends of sampler could be sealed and taken to the lab. An 8 cm long sub-sample was adequate for soil physical, biogeochemical and molecular analysis. The sampler has been tested for 2 years with more than 200 cores taken from tidal wetlands in Chesapeake Bay, Virginia, USA. A negative correlation between salinity and organic matter content at 3 - 5 and 8 - 10 cm was found. For the deeper samples (48 - 50 cm), a positive correlation between salinity and organic matter was observed. The sampler worked satisfactory and it required no maintenance besides cleaning.