The Benefit of Including Rarely-Used Species in Dendroclimatic Reconstructions: A Case Study Using Juglans nigra in South-Central Indiana, USA

Abstract

The benefit of using multiple species in dendroclimatic reconstructions in the eastern U.S. has been demonstrated. However, the benefit of including rarely-used species in multispecies reconstructions has been little explored. This paper shows the utility of using a rarely-used species in dendrochronology, Juglans nigra, in a multispecies Palmer Drought Severity Index (PDSI) reconstruction at a site in southern Indiana. First, the crossdating J. nigra is established, followed by determining the climate response. The standardized J. nigra chronology is then compared with co-occurring standardized species chronologies (Quercus alba, Quercus rubra, and Liriodendron tulipifera) reported in Maxwell et al. (2015). Using a principal component regression model, the bi-weights of each species were calculated to determine how much J. nigra contributed to the explanatory power of the model. J.nigra had a high interseries correlation (0.604) and mean sensitivity (0.304) and a strong correlation with summer PDSI, which was comparable in strength and more consistent through time than the cooccurring species. The inclusion of J. nigra in the composite reconstruction provided more consistency and better captured the observed PDSI variability. This is compelling evidence for why rarely-used species should be tested for inclusion in multispecies climate reconstructions. © 2016 by The Tree-Ring Society.