FIGURE 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Ecological regions and subregions of the eastern United States included in analysis. Map based on McNab et al. (2007).
Source publication
There is a growing body of evidence that mesic tree species are increasing in importance across much of the eastern US. This increase is often observed in tandem with a decrease in the abundance and importance of species considered to be better adapted to disturbance and drier conditions (e.g., Quercus species). Concern over this transition is rela...
Contexts in source publication
Context 1
... resulted in a study area ranging from the U.S.-Canadian border in the north to the prairie-dominated ecological provinces in the west. This area encompasses 14 ecological provinces in the Central Hardwood Region, the Southern Pine Hardwood Region, the Forest-Prairie Transition Region, and the Northern Hardwood Region (Figure 1). ...
Context 2
... forests exhibited evidence of mesophication, but this forest type was more variable between ecological provinces ( Table 3). In several cases, we found differences in the degree and rate of mesophication in oak/pine forests compared to oak/hickory forests ( Table 3 and Supplementary Figure 1). Table 3 and Supplementary Figure 1). ...
Context 3
... several cases, we found differences in the degree and rate of mesophication in oak/pine forests compared to oak/hickory forests ( Table 3 and Supplementary Figure 1). Table 3 and Supplementary Figure 1). In a few cases, the degree of mesophication was greater in oak/pine than in oak/hickory forests. ...
Context 4
... a few cases, the degree of mesophication was greater in oak/pine than in oak/hickory forests. In the Southern Pine Hardwood and the Forest-Prairie region, the degree of mesophication was often greater in oak/pine forests when based on fire tolerance (Table 3 and Supplementary Figure 1). ...
Context 5
... general, mesophication was greater in areas that accumulate water ( Table 4). Mesophication either was similar or was greater in wetter areas based on soil available water holding capacity and terrain shape index (i.e., mesophication, based on drought and fire tolerance, increased as topography changed from convex/ridges to concave/coves, particularly in oak/pine forests; Table 4 and Supplementary Figures 9- 12). We found mixed evidence for the relationship between slope and mesophication, with evidence for mesophication not changing or increasing with slope in some cases (in oak/hickory forests) and decreasing in others (in oak/pine forests; Table 4). ...
Context 6
... found mixed evidence for the relationship between slope and mesophication, with evidence for mesophication not changing or increasing with slope in some cases (in oak/hickory forests) and decreasing in others (in oak/pine forests; Table 4). Mesophication was much more variable at steeper slopes and greater water supply in oak/pine forests ( Table 4 and Supplementary Figures 13, 14). ...
Context 7
... on the FIA categorial variable of physiographic condition (hydric, mesic, or xeric), the degree of mesophication was greater in mesic stands (compared to xeric stands) when evaluated based on shade, drought, or fire adaptations (Table 4 and Supplementary Figures 15, 16) in both oak/hickory and oak/pine forests. The rate of mesophication was also generally greater in mesic stands compared to xeric stands ( Table 4). ...
Context 8
... rate of mesophication was also generally greater in mesic stands compared to xeric stands ( Table 4). Similar to slope and AWS, the rate and degree of mesophication in hydric stands was much more variable regardless of metric ( Table 4 and Supplementary Figures 15, 16). ...
Context 9
... between mesophication metrics and elevation and soil pH were often highly variable or conflicting ( Table 4 and Supplementary Figures 17-19). In oak/hickory forests, fire tolerance and shade tolerance were greater in the overstory (compared to midstory) at higher elevations (suggesting a conflicting relationship between mesophication and elevation; Table 4 and Supplementary Figure 17). ...
Context 10
... between mesophication metrics and elevation and soil pH were often highly variable or conflicting ( Table 4 and Supplementary Figures 17-19). In oak/hickory forests, fire tolerance and shade tolerance were greater in the overstory (compared to midstory) at higher elevations (suggesting a conflicting relationship between mesophication and elevation; Table 4 and Supplementary Figure 17). Mesophication metrics in oak/pine forests were highly variable at high elevations (Supplementary Figures 17, 18). ...
Context 11
... oak/hickory forests, fire tolerance and shade tolerance were greater in the overstory (compared to midstory) at higher elevations (suggesting a conflicting relationship between mesophication and elevation; Table 4 and Supplementary Figure 17). Mesophication metrics in oak/pine forests were highly variable at high elevations (Supplementary Figures 17, 18). The relationship between mesophication and pH was generally negative (Table 4, Figure 5, and Supplementary Figure 19). ...
Context 12
... metrics in oak/pine forests were highly variable at high elevations (Supplementary Figures 17, 18). The relationship between mesophication and pH was generally negative (Table 4, Figure 5, and Supplementary Figure 19). When categorized based on shade tolerance, drought tolerance, or importance value, mesophication decreased with increasing pH (Figure 5 and Supplementary Figure 19). ...
Context 13
... relationship between mesophication and pH was generally negative (Table 4, Figure 5, and Supplementary Figure 19). When categorized based on shade tolerance, drought tolerance, or importance value, mesophication decreased with increasing pH (Figure 5 and Supplementary Figure 19). When categorized based on Model reference conditions were Forest Service owned, mesic, oak-hickory forests (see Table 4 for interactions with edaphic, topographic, and environmental predictors). ...
Similar publications
![Figure 1. Study area showing ten states of the eastern US [68].](publication/372631331/figure/fig1/AS:11431281177134255@1690373731064/Study-area-showing-ten-states-of-the-eastern-US-68_Q320.jpg)
White oak mortality is a significant concern in forest ecosystems due to its impact on biodiversity and ecosystem functions. Understanding the factors influencing white oak mortality, particularly the soil properties, is crucial for effective forest management and conservation efforts. In this study, we aimed to investigate the spatial pattern of w...
Citations
... If researchers can identify the drivers of mesophication, forest managers may be able to alter current management practices to slow or reduce the risk of mesophication (Woodbridge et al., 2022). Fire suppression (Hanberry et al., 2020) and climate change, i.e., cooler summer temperatures and increased precipitation (Goins et al., 2013;Larsen et al., 2023), have been identified as important drivers of mesophication. ...
The replacement of oaks (Quercus) with mesic tree species in the eastern deciduous forests of North America involves a positive feedback loop being driven by fire suppression and climate change. In this study, we explored the impact of timber harvesting as a potential facilitator of mesophication. Young stands resulting from shel-terwoods (on federal lands) and selective cutting (on private lands) were sampled to compare the composition and density of seedlings, saplings, and trees in western Virginia, USA. Oak overstory trees had lower importance values and densities at selective cutting sites compared to shelterwood sites. Among saplings, mesic species had higher importance values and densities than oaks at both selective cutting and shelterwood sites. Evidence of mesophication was found at both selective cutting and shelterwood sites; but a higher level of mesophication appeared to be occurring at the selective cutting sites than at shelterwood sites. At selective cutting sites scarlet oak (Quercus coccinea) was absent from all sampled plots and a dense midstory of subcanopy trees, especially eastern redbud (Cercis canadensis), appeared to be hindering successful oak regeneration. Our results indicate timber harvesting, without regard for the composition of the regeneration layer, may facilitate mesophication in the eastern deciduous forest, with selective cutting resulting in more successful establishment of mesic species compared to shelterwoods. These findings have implications for mesophication on private forest lands, where selective cutting is a very common method of timber harvesting.
... Information on the patterns of tree cover change associated with forest disturbances and interannual climate variability is essential for the effective management and conservation of tree-dominated ecosystems [1,2] and tracking carbon stock fluxes [3][4][5][6]. Historical land use knowledge can also often be important in understanding the above contemporary ecosystems [7,8]. ...
Variability in the effects of disturbances and extreme climate events can lead to changes in tree cover over time, including partial or complete loss, with diverse ecological consequences. It is therefore critical to identify in space and time the change processes that lead to tree cover change. Studies of change are often hampered by the lack of data capable of consistently detecting different types of change. Using the Landsat satellite record to create a long time-series of land cover and land cover change, the U.S. Geological Survey Land Change Monitoring Assessment and Projection (LCMAP) project has made an annual time series of land cover across the conterminous United States for the period 1985 to 2018. Multiple LCMAP products analyzed together with map validation reference plots provide a robust basis for understanding tree cover change. In LCMAP (Collection 1.2), annual change detection is based on harmonic model breaks calculated at each Landsat pixel from the Continuous Change Detection and Classification (CCDC) algorithm. The results showed that the majority of CCDC harmonic model breaks (signifying change) indicated partial tree cover loss (associated with management practices such as tree cover thinning) as compared to complete tree cover loss (associated with practices like clearcut harvest or fire disturbance). Substantially fewer occurrences of complete tree cover loss were associated with change in land cover state. The area of annual tree cover change increased after the late 1990s and stayed high for the rest of the study period. The reference data showed that tree harvest dominated across the conterminous United States. The majority of tree cover change occurred in evergreen forests. Large estimates of disturbance-related tree cover change indicated that tree cover loss may have previously been underreported due to omission of partial tree cover loss in prior studies. This has considerable implications for forest carbon accounting along with tracking ecosystem goods and services.
... becoming more mesophytic) and xerophying (i.e. becoming less mesophytic) is essential to manage changing forest conditions (Woodbridge et al., 2022). ...
... These include decreased drought (McEwan et al., 2011;Pederson et al., 2014); decreased Native American agroforestry ; increased anthropogenic nitrogen deposition and its influence on mycorrhizal associations (Alexander et al., 2021); and increased browsing pressure by larger white-tailed deer (Odocoileus virginianus; hereafter deer) populations (McEwan et al., 2011;Thomas-Van Gundy et al., 2014). Relatedly, although mesophication was initially identified as a response to historic reductions in fire and drought (Pederson et al., 2014), more recent research has found that mesophication is also occurring in response to recent changes in environmental drivers (Knott et al., 2019;Woodbridge et al., 2022). Although mesophication in the eastern US is often described as a large decline in abundance of oak (Quercus spp.; Nowacki and Abrams, 2008;Hanberry et al., 2020;Alexander et al., 2021), given that some non-oak tree species exhibit xerophytic traits, it would be useful to know if mesophication also occurs in forests that contain no oak. ...
... Environmental models and tree-ring records have been used to explore the drivers of mesophication at the scale of the eastern US (Nowacki and Abrams, 2015;Knott et al., 2019) and smaller areas (Rubio-Cuadrado et al., 2018;Vanhellemont et al., 2019). Others have noted that differences in species relative abundances between forest understory and forest canopy provide evidence of mesophication, with smaller trees established under a recent mesophying environment while canopy trees established under a past xerophying environment (Hart and Kupfer, 2011;Palus et al., 2018;Alexander et al., 2021;Woodbridge et al., 2022). ...
Forests of the eastern US have exhibited widespread taxonomic shifts involving decreasing abundances of many species of Quercus, Pinus and Carya and increasing abundances of many species of Acer, Fagus, Prunus as well as other genera. These taxonomic changes have been called mesophication and explained variously as decreased tolerance of fire, drought, and heat; decreased palatability for deer browsing; and increased tolerance of shade. The major driver of those shifts in taxonomy and ecological traits has been attributed to decreased surface burning due to Native American depopulation, cessation of settler-colonial land clearance, larger deer populations , and decreased drought, among other drivers. We endeavored to test which traits exhibited the most mesophication and which environmental factors best predicted that mesophication. We collected size-stratified taxonomic data for 2488 trees from 160 plots, converted that into measures of mesophyticness for each trait in each plot, and then inferred mesophication in each plot as the difference between the mesophyticness of small trees and large trees. Mesophyticness of each trait ranged from zero for a xerophytic trait to one for a mesophytic trait. We also collected site-specific data for 22 potential environmental predictors of trait changes (including abiotic, biotic, anthropogenic, and spatial predictors). All traits exhibited strong mesophication; these are, in descending order of percent of sites with strong mesophication: fire tolerance, white-tailed deer browse preference , Native American diet tree, cold tolerance, shade tolerance, drought tolerance, and general browse preference. For all traits, mesophication of small relative to large trees was greatest in plots where large trees were xerophytic, and least where large trees were mesophytic. We further found that mesophication was similar for plots regardless of the abundance or presence of Quercus, indicating that mesophication is not the same as oak decline. A diverse set of predictors best explained mesophication of taxonomic and ecological traits, but three were consistently chosen: cooler summer temperature, higher small tree density, and shorter distance to pre-1700 Native American towns. In addition to mesophication, there was also some evidence of xerophication, most strongly for an increase in heat tolerance as might be expected due to recent climate change. Our results show that forest mesophication is a complex syndrome involving changes in independent species traits that are driven by many environmental factors, creating a challenge for land managers.
The groundlayer flora has a disproportionate influence on ecosystem function and contributes to the biodiversity in temperate Quercus forests of eastern North America. Historically open understory conditions perpetuated, in part by fire, have become closed and homogenized by long‐term fire exclusion, likely impacting the groundlayer community. We explored the effects of burn season (unburned = CON, dormant season = DSB, growing season = GSB) on groundlayer (<1 m) vegetation attributes pre‐ and post‐burn. The difference (post‐burn – pre‐burn) in tree cover was greater in GSB (+8.22%) than DSB (+1.24%) and CON (+0.15%), while the change in forb cover was greater in GSB (+1.17%) than CON (−0.15%). Minor effects of burning were observed in diversity metrics, with the change in forb richness greater in GSB (+0.11 species/m ² ) than CON (−0.78 species/m ² ), while the change in tree richness was greater in GSB (+1.11 species/m ² ) than DSB (−1.11 species/m ² ) and CON (−1.67 species/m ² ). Nonmetric multi‐dimensional scaling provided evidence that between pre‐ and post‐burn, modest composition shifts in DSB and GSB were associated with more open conditions and lower litter depth. Understory composition did not vary among burn treatments pre‐burn, while post‐burn, composition differed significantly between CON and DSB and DSB and GSB. However, overall, a growing season burn had relatively minor effects on the groundlayer community compared to a dormant season burn. A better understanding of multiple factors affecting groundlayer response to burning is critical to the effective use of prescribed burning in attaining restoration goals.
