Lack of Historical Data

One-time measures of soil or plant Ca concentrations can provide useful information of the current status of a site, particularly if Ca concentrations are clearly aberrant relative to limited established standards. However, short of this, they provide little insight into trends in Ca availability or potential disruptions in Ca cycling. In contrast, repeated measures (and the archiving of samples to allow for reanalysis should measurement protocols change over time) provide baseline data needed to make necessary trend assessments. To date, comparatively few such databases and archives have been established. Long-term research at the Hubbard Brook and other experimental forests, (e.g., Adams 1999, Likens and others 1996, Likens and others 1998), as well as a few recent studies (notably Bailey and others 2005, Lapenis and others 2004, Lawrence and others 2005) highlight the unique benefit of repeated measures for detecting meaningful changes in Ca nutrition. Recognition of the value of such data sets has bolstered efforts to compile broad nutritional data sets that encompass a variety of sites, tree species, and time periods, (e.g., see the foliar chemistry database compiled by the Northeastern Ecosystem Research Cooperative: http://www.folchem.sr.unh.edu/), and establish sample archives as described by Lapenis and others (2004) and Lawrence and others (2005). However, given practical (especially funding) limitations, even if such data sets and archives were dramatically expanded, appropriate historical data would exist for just a fraction of the land area impacted by pollution loading. Thus, alternatives for assessing the location and extent of Ca depletion across the landscape must be developed, tested, and employed.