Ecological changes of many forms affect plant communities worldwide by modifying species’ ranges, increasing rates of species’ extinctions, and homogenizing biotas, all of which threaten biodiversity. However, environmental changes do not affect all species in similar ways. Some species decrease in abundance in response to modified environments (i.e. “losers”), while others actually benefit from these changes (i.e. “winners”). It is often assumed that these contrasting species’ responses reflect differences in plant life history traits. Here, we compare plant life history traits of species identified as winners and losers in upland Wisconsin forests. These classifications reflect changes between the 1950s and the 2000’s at >150 forest sites. We assessed how winners and losers differ in 14 life history traits using classic general linear models and phylogenetic general least square regression. We compared traits of winners and losers in southern and northern upland forests separately, as these forests differ greatly in composition and have experienced contrasting changes over time.
Results/Conclusions
In the more fragmented southern upland forests, winner species tended to have higher Specific Leaf Area (SLA), higher leaf nitrogen levels, lower Leaf Dry Matter Content (LDMC), and thinner leaves. Winners were also taller than losers. These traits are generally associated with higher relative growth rates. Together, these results are consistent with southern upland forests experiencing a “mesophication”, whereby fire-adapted species are replaced by shade-tolerant species with bigger and thinner leaves. These results may also suggest an “eutrophication” of southern upland forests, potentially reflecting the cumulative effects of aerial nitrogen deposition. In northern upland forests, we found fewer significant life history trait differences between winners and losers. Winners included grasses and sedges that were more likely to be wind pollinated, but no differences in leaf morphology were detected. These forests have experienced fewer changes over time, and we identified fewer winners and losers compared to southern upland forests.