Microclimate in CRUI Land Use Project at Harvard Forest 1997

Understory microenvironmental patterns are strongly influenced by both the forest community and substrate, which are in turn affected by site factors, disturbance history and recovery processes. We measured ground-level microclimates across the growing season as part of a multi-faceted study of soil-plant-atmosphere interactions in sites with different agricultural land-use legacies (formerly plowed, formerly pastured, permanent woodlots) in Prospect Hill. A permanent 30 x 50 m plot was established in each of six sites (2 per land use category) and gridded into 5 x 5 m sub-plots. Fifteen microclimate stations were used to measure photosynthetic photon flux (PPF, umol m-2 s-1, LI-190 quantum sensor, Li-Cor, Inc), soil temperature (107B thermistor, Campbell Scientific, Logan, Utah), and air temperature (107 thermistor, Campbell Scientific, Logan, Utah) at 5 locations each in three sites simultaneously. PPF and air temperature were measured at 50 cm, while soil temperature was measured 5 cm. The central sample station was located in the center (sub-plot D6) of the 30 x 50 m grid and four additional stations were positioned 10 m from the central station in the cardinal directions. In addition to the variables described above, relative humidity (%, 207 air temperature/relative humidity probe, Campbell Scientific, Logan, Utah) was measured at 50 cm at the central station. All sensors were connected to a Campbell Scientific 23X datalogger and sampled continuously every 10 sec and averaged every 10 minutes for 5 days at a time. The stations were switched between two sets of sites (P1-S2-W2 followed by P2-S1-W1) at the end of every week, so the data record for any one site includes alternate weeks. Measurements were made during April through September, 1997. The data archived here are daily means per variable per station. Missing records are due to inclement weather, while blank fields represent occasional sensor or datalogger connection problems.