The University of West Florida Campus Ecosystem Study: age-diameter and growth relationships of longleaf pine using hurricane-induced windthrows

Abstract

The campus of the University of West Florida was constructed among second-growth longleaf pine (Pinus palustris) stands that survived extensive logging in the Florida Panhandle. Previous studies on longleaf pine on the main UWF campus have estimated that 65% of these pines are 75 to 125 years old, with estimates based on a model from old-growth longleaf in southern Georgia.To obtain more accurate age data, one can use an increment corer to collect samples from live trees on site; more accurately, disks can be collected from recently fallen trees. On 16 September 2020, Hurricane Sally impacted UWF as a Category 2 storm, with winds reaching 125 kph. Our study took advantage of longleaf pines blowdowns by Sally to obtain cross-sections for age determinations. Two on-campus natural areas were chosen for sampling: the Edward Ball Nature Trail and the Baars-Firestone Wildlife Sanctuary. For each sampled section, diameter at breast height (DBH) and number of annual rings were recorded. Based on a total of 50 sampled trees, linear regression revealed a highly significant (P<0.00001; r 2 =0.84) relationship between DBH and age. Applying this to DBH measures of 2,165 stems on the main campus indicates that the oldest longleaf pines are ~130 years old (mean age = 63.9±0.4 yr), consistent with cessation of historically wide-spread harvesting in the region. Mean age for the Trails site (55.7±1.6 yr) was significantly lower than that of the Sanctuary (66.7±2.0 yr), suggesting that they represented sites of contrasting land-use history. Direction of stem windthrows did not vary between natural areas and was consistent with characteristics of the eyewall of Hurricane Sally with strongest wind gusts moving from a southeast to northwest direction.

The University of West Florida Campus Ecosystem Study: Spatial and Temporal Variation in Water Quality at Thompson Bayou

“…Our study confirms the innate value of monitoring studies to understand the spatial and temporal dynamics of aquatic ecosystems [33]. Furthermore, because of the unique setting of Thompson Bayou as part of the greater UWF campus, this study also demonstrates the heuristic value of monitoring as a component of research by students which, in this case, adds to previous work on the ecology of the UWF campus [19][20][21]. Our results show that analytes that are quite common in assessing water quality-depth of photic zone, temperature, pH, DO, and SC [9,10,11]-exhibit distinct spatial and temporal patterns.…”

“…Prior to campus contruction, this region of northwest Florida was predominantly longleaf pine stands of varying age following cessation of widespread timber harvesting. To date, the UWF CES has comprised three connected studies: (1) assessing the longleaf pines of the main campus along with gopher tortoise populations in one of the natural areas [19], (2) determination of stand structure and composition of chronically-unburned longleaf stands of two natural areas [20], and (3) the creation of a stem age/diameter model for campus longleaf pines using windthrown stems that were blown down by Hurricane Sally in September 2020 [21].…”

The University of West Florida Campus Ecosystem Study: Spatial and Temporal Variation in Water Quality at Thompson Bayou

“…The initial strategy to sample for the duration of calendar year 2021 from early January to end of December was altered by Hurricane Sally, a Category 2 tropical cyclone with an eyewall that directly impacted the UWF campus on 16 September 2020 [22]. This caused extensive damage to forest stands of the natural areas around Thompson Bayou [21], resulting in unsafe conditions for navigation from numerous windthrown tree stems in the water until March 2021. Sampling commenced 5 March 2021 and was repeated as close to a weekly basis as possible, pending weather conditions and availability of personnel, until 24 February 2022.…”

“…Prior to campus construction, this region of northwest Florida was predominantly longleaf pine stands of varying ages following the cessation of widespread timber harvesting. To date, the UWF CES has comprised three connected studies: (1) assessing the longleaf pines of the main campus along with gopher tortoise populations in one of the natural areas [19], (2) determining of stand structure and composition of chronically-unburned longleaf stands of two natural areas [20], and (3) the creation of a stem age/diameter model for campus longleaf pines using windthrown stems that were blown down by Hurricane Sally in September 2020 [21].…”

Soil microbiomes of hardwood‐ versus pine‐dominated stands: Linkage with overstory species

“…Most forest stands along the UWF campus nature trails are typical of second‐growth longleaf pine forests experiencing chronic fire exclusion (Addington et al, 2015; Gilliam et al, 2021; Gilliam & Platt, 1999, 2006; Hiers et al, 2014; Provencher et al, 2003; Varner et al, 2005). These comprise stands of widely spaced longleaf stems primarily 50–100 years in age (Gilliam et al, 2022) with the otherwise fire‐maintained open matrix (Noel et al, 1998; Platt, 1999; Platt et al, 1988) filled with hardwood species, especially numerous southern oaks, for example, live oak ( Quercus virginiana ), laurel oak ( Q. laurifolia ), water oak ( Q. nigra ), and blackjack oak ( Q. marilandica ).…”