Changing tree composition by life history strategy in a grassland‐forest landscape

Abstract

Abstract. After rapid deforestation in the eastern United States, which generally occurred during the period of 1850-1920, forests did not return to historical composition and structure. We examined forest compositional change and then considered how historical land use and current land use may influence forests in a grassland-forest landscape, the Missouri Plains, where frequent surface fire was the historical land use and intensive agricultural is the current land use. We compared composition, distribution, and environmental relationships during historical (1813-1860) and current (2004)(2005)(2006)(2007)(2008) forest surveys. We also examined changing composition of life history strategies of (1) stress tolerators based on fire tolerance, (2) colonizers based on shade intolerance, and (3) competitors based on shade tolerance. Open forest ecosystems of fire-tolerant oaks have been replaced by forests of fire-sensitive species, such as ashes, hackberry, and maples that expanded from riparian firebreaks and osage-orange and eastern redcedar that expanded from planted windbreaks and rocky firebreaks. Colonizing species increased from 7% to 32% of total composition, with assisted tree migration from planting; we expect continued expansion particularly by eastern redcedar into areas unoccupied by trees. Competitive species have increased slightly to 38% of total composition although the trajectory of current forests suggested competitors may increase to 56% of total composition by replacing oaks in forest ecosystems. Changed success of life history strategies in an agricultural landscape without fire resulted in increased composition and extent of fire-sensitive colonizers compared to fire-tolerant oaks. We suggest that patterns of loss of fire-tolerant oaks and increased distribution of fire-sensitive species reflect suppression of fire, the historical land use. In addition, we suggest that subsequent land use dictates the success of either shade-intolerant colonizers or shade-tolerant competitors in current forests. Forests will be composed of shade-intolerant colonizers where land use disturbance is frequent, such as in agricultural landscapes, and forests will be composed of species with greater shade tolerance where land use disturbance is less frequent.

Disassociating tree species associations in the eastern United States

“…Currently, in areas where urbanization and forestry are major land uses, moderately shade-tolerant species such as red maple (see Tab. 1) are most abundant and in areas where intensive agriculture is the major land use, species that are tolerant to exposure are more abundant (Hanberry et al 2014b).…”

“…Rather, these forest types were open oak savannas and woodlands (Hanberry et al 2012b, Hanberry et al 2014b). In the stronghold of Braun's Oak-Hickory forest region in the Missouri Ozarks landscape ( Fig.…”

Restoring oak forests, woodlands and savannas using modern silvicultural analogs to historic cultural fire regimes

“…Forest structure occurs on portions of the landscape that burn infrequently enough to permit development of high stem density and multiple canopy layers. Landscapes that once were intricate mosaics of diverse natural communities that spanned the structural gradient from prairie to forest have become more homogeneous after decades of fire suppression in the eastern U.S. (Schulte et al, 2007;Hanberry et al, 2012Hanberry et al, , 2014a. The region is dominated by maturing forests where lands have escaped development (Shifley and Thompson, 2011;Shifley et al, 2012).…”

“…Restoration of oak savannahs or woodlands usually begins with a forest state because of the densification of these former natural communities in the absence of fire (Hanberry et al, 2012(Hanberry et al, , 2014a. The main objectives in savannah and woodland restoration are to reduce tree density and reintroduce fire.…”

Fire in the Northeast: Learning from the Past, Planning for the Future

“…Spruce-fir forests are distributed across northerly latitudes and high elevations of the northeastern United States (De Lafontaine & Payette, 2011;Kudish, 2013;Stehn, Webster, Jenkins, & Jose, 2011). Finally, grasslands are widely distributed due to their relationship with human landclearing, and they dominate flatter sites with fertile soils (Hanberry, Kabrick, & He, 2014;.…”