scholarly journals Physiological Mechanisms of Foliage Recovery after Spring or Fall Crown Scorch in Young Longleaf Pine (Pinus palustris Mill.)

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 208
Author(s):  
Mary Anne S. Sayer ◽  
Michael C. Tyree ◽  
Eric A. Kuehler ◽  
John K. Jackson ◽  
Dylan N. Dillaway

We hypothesized that physiological and morphological responses to prescribed fire support the post-scorch foliage recovery and growth of young longleaf pine. Two studies conducted in central Louisiana identified three means of foliage regrowth after fire that included an increase in the gas exchange rate of surviving foliage for 3 to 4 months after fire. Saplings also exhibited crown developmental responses to repeated fire that reduced the risk of future crown scorch. Starch reserves were a source of carbon for post-scorch foliage regrowth when fire was applied in the early growing season. However, the annual dynamics of starch accumulation and mobilization restricted its effectiveness for foliage regrowth when fire was applied late in the growing season. As such, post-scorch foliage regrowth became increasingly dependent on photosynthesis as the growing season progressed. Additionally, the loss of foliage by fire late in the growing season interrupted annual starch dynamics and created a starch void between the time of late growing season fire and mid-summer of the next year. The occurrence of drought during both studies revealed barriers to foliage reestablishment and normal stem growth among large saplings. In study 1, spring water deficit at the time of May fire was associated with high crown scorch and poor foliage and stem growth among large saplings. We attribute this lag in stem growth to three factors: little surviving foliage mass, low fascicle gas exchange rates, and poor post-scorch foliage recovery. In study 2, May fire during a short window of favorable burning conditions in the tenth month of a 20-month drought also reduced stem growth among large saplings but this growth loss was not due to poor post-scorch foliage recovery. Application of this information to prescribed fire guidelines will benefit young longleaf pine responses to fire and advance efforts to restore longleaf pine ecosystems.

Forests ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 95
Author(s):  
Yuan Gong ◽  
Christina L. Staudhammer ◽  
Susanne Wiesner ◽  
Gregory Starr ◽  
Yinlong Zhang

Understanding plant phenological change is of great concern in the context of global climate change. Phenological models can aid in understanding and predicting growing season changes and can be parameterized with gross primary production (GPP) estimated using the eddy covariance (EC) technique. This study used nine years of EC-derived GPP data from three mature subtropical longleaf pine forests in the southeastern United States with differing soil water holding capacity in combination with site-specific micrometeorological data to parameterize a photosynthesis-based phenological model. We evaluated how weather conditions and prescribed fire led to variation in the ecosystem phenological processes. The results suggest that soil water availability had an effect on phenology, and greater soil water availability was associated with a longer growing season (LOS). We also observed that prescribed fire, a common forest management activity in the region, had a limited impact on phenological processes. Dormant season fire had no significant effect on phenological processes by site, but we observed differences in the start of the growing season (SOS) between fire and non-fire years. Fire delayed SOS by 10 d ± 5 d (SE), and this effect was greater with higher soil water availability, extending SOS by 18 d on average. Fire was also associated with increased sensitivity of spring phenology to radiation and air temperature. We found that interannual climate change and periodic weather anomalies (flood, short-term drought, and long-term drought), controlled annual ecosystem phenological processes more than prescribed fire. When water availability increased following short-term summer drought, the growing season was extended. With future climate change, subtropical areas of the Southeastern US are expected to experience more frequent short-term droughts, which could shorten the region’s growing season and lead to a reduction in the longleaf pine ecosystem’s carbon sequestration capacity.


2021 ◽  
Author(s):  
John P McGuire ◽  
John S Kush ◽  
J Morgan Varner ◽  
Dwight K Lauer ◽  
J Ryan Mitchell

Abstract Efforts to restore longleaf pine (Pinus palustris Mill.) in the southeastern US require substantial artificial regeneration. Once established, important questions remain about when to introduce fire. We investigated the impact of initial planting density on tree branching and how prescribed fire might interact with tree architecture and survival. A particular focus was on how prescribed fires could “prune” lower branches. Lower density plantings (897 trees ha−1) had more and larger live lower branches than higher density plantings (2,243 trees ha−1). Fire was effective in pruning lower branches regardless of season burned, but fire in the growing season was more effective at pruning. Branches up to a height of 1.5 to 2 m were killed by fire. Fire applied in August caused greater damage with more needles scorched and/or consumed and more stem char. Prescribed fire did not impact longleaf pine tree survival. In general, fire applied to longleaf pine facilitated pruning lower branches that affect long-term wood quality, an additional argument for its utility in restoration and management of these ecosystems.


2020 ◽  
Vol 14 (2) ◽  
pp. 413-433
Author(s):  
William J. McFarland, ◽  
Danielle Cotton, ◽  
Mac H. Alford ◽  
Micheal A. Davis

Longleaf pine (Pinus palustris Mill.) ecosystems exhibit high species diversity and are major contributors to the extraordinary levels of regional biodiversity and endemism found in the North American Coastal Plain Province. These forests require frequent fire return intervals (every 2–3 years) to maintain this rich diversity. In 2009, a floristic inventory was conducted at the Lake Thoreau Environmental Center owned by the University of Southern Mississippi in Hattiesburg, Mississippi. The Center is located on 106 ha with approximately half covered by a 100+ year old longleaf pine forest. When the 2009 survey was conducted, fire had been excluded for over 20 years resulting in a dense understory dominated by woody species throughout most of the forest. The 2009 survey recorded 282 vascular plant species. Prescribed fire was reintroduced in 2009 and reapplied again in 2010, 2012, 2014, 2016, and 2018. A new survey was conducted in 2019 to assess the effects of prescribed fire on floristic diversity. The new survey found an additional 268 species bringing the total number of plants species to 550. This study highlights the changes in species diversity that occurs when fire is reintroduced into a previously fire-suppressed system and the need to monitor sensitive areas for changes in species composition.


Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 181
Author(s):  
John R. Butnor ◽  
Kurt H. Johnsen ◽  
Christopher A. Maier ◽  
C. Dana Nelson

Prescribed fire is an essential tool that is widely used for longleaf pine (Pinus palustris Mill.) stand management; periodic burning serves to reduce competition from woody shrubs and fire-intolerant trees and enhance herbaceous diversity. Low-intensity, prescribed burning is thought to have minimal long-term impact on soil chemistry in southern pine forests, although few studies report the intra-annual variation in soil chemistry after burning. We monitored changes in C, N, oxidation resistant C (CR), pH and elemental nutrients in the forest floor and soil (0–5, 5–10 cm depths) before and after burning (1, 3, 6, 12 months) in a mature longleaf pine plantation at the Harrison Experimental Forest, near Saucier, Mississippi. Prescribed fire consumed much of the forest floor (11.3 Mg ha−1; −69%), increased soil pH and caused a pulse of C, N and elemental nutrients to flow to the near surface soils. In the initial one to three months post-burn coinciding with the start of the growing season, retention of nutrients by soil peaked. Most of the N (93%), Ca (88%), K (96%) and Mg (101%), roughly half of the P (48%) and Mn (52%) and 25% of the C lost from the forest floor were detected in the soil and apparently not lost to volatilization. By month 12, soil C and N pools were not different at depths of 0–5 cm but declined significantly below pre-burn levels at depths of 5–10 cm, C −36% (p < 0.0001), N −26% (p = 0.003), contrary to other examples in southern pine ecosystems. In the upper 5 cm of soil, only Cu (−49%) remained significantly lower than pre-burn contents by month 12, at depths of 5–10 cm, Cu (−76%), Fe (−22%), K (−51%), Mg (−57%), Mn (−82%) and P (−52%) remain lower at month 12 than pre-burn contents. Burning did not increase soil CR content, conversely significant declines in CR occurred. It appears that recovery of soil C and N pools post-burn will require more time on this site than other southern pine forests.


2006 ◽  
Vol 36 (11) ◽  
pp. 2724-2736 ◽  
Author(s):  
R J Mitchell ◽  
J K Hiers ◽  
J J O'Brien ◽  
S B Jack ◽  
R T Engstrom

The longleaf pine (Pinus palustris Mill.) forest ecosystems of the US southeastern Coastal Plain, among the most biologically diverse ecosystems in North America, originally covered over 24 × 106 ha but now occupy less than 5% of their original extent. The key factor for sustaining their high levels of diversity is the frequent application of prescribed fire uninterrupted in time and space. Pine fuels, critical to application of fire and regulated by canopy distribution, provide the nexus between silviculture and fire management in this system. Typical silvicultural approaches for this type were, in large part, developed to maximize the establishment and growth of regeneration as well as growth and yield of timber, with much less regard to how those practices might influence the ability to sustain prescribed burning regimes or the associated biodiversity. However, many landholdings in the region now include conservation of biodiversity as a primary objective with sustained timber yield as an important but secondary goal. This review synthesizes the literature related to controls of biodiversity for longleaf pine ecosystems, and silvicultural approaches are compared in their ability to sustain natural disturbance such as fire and how closely they mimic the variation, patterns, and processes of natural disturbance regimes while allowing for regeneration.


2004 ◽  
Vol 28 (1) ◽  
pp. 48-54 ◽  
Author(s):  
Craig L. Ramsey ◽  
Shibu Jose

Abstract A field study was conducted in Santa Rosa County, FL to evaluate the effects of two herbicides, hexazinone and sulfometuron methyl, on longleaf pine seedling (Pinus palustris Mill.) survival, growth, and physiological functions over a 2 yr period (2001–2002). An old-field site was planted with 1-yr-old container-grown seedlings in January 2001, and herbicides were band-applied overtop of the seedlings in April 2001. Hexazinone rates were 0.56 and 1.12 kg ai/ha, and the sulfometuron methyl rates were 0.21 and 0.42 kg ai/ha. Volumetric soil moisture was also measured in May, July, August, and October in each treatment. At the end of the first growing season (2001), survival was not improved by any of the herbicide applications. However, root collar diameter (RCD) increased for hexazinone applied at 0.56 and 1.12 kg ai/ha, and sulfometuron methyl applied at 0.42 kg ai/ha at the end of the first growing season compared to the control. At the end of the second growing season, RCD was 28.7, 30.9, 30.5, 32.1, and 33.3 mm for the control, sulfometuron methyl applied at 0.21 and 0.42 kg ai/ha, and hexazinone applied at 0.56 and 1.12 kg ai/ha, respectively. Also, the percentage of seedlings out of the grass stage at the end of the study was 72, 74, 79, 81, and 89% for the control, sulfometuron methyl applied at 0.21 and 0. 42 kg ai/ha, and hexazinone applied at 0.56 and 1.12 kg ai/ha, respectively. Foliar responses, such as net photosynthesis, stomatal conductance, and transpiration were measured in October 2001. There was no evidence of herbicide injury on foliar physiological functions relative to the control seedlings 6 months after treatment. During 2001, soil moisture was related to hexazinone and sulfometuron methyl application rates in May and July, but not in August or October. Averaged across May and July, soil moisture increased from 5.4% in the control to 7.6 and 7.5% in the highest hexazinone and sulfometuron methyl treatments, respectively. Based on seedling survival, growth, and herbicide costs, the most effective treatment was hexazinone applied at 0.56 kg ai/ha. South. J. Appl. For. 28(1):48–54.


Fire ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 39 ◽  
Author(s):  
Raien K. Emery ◽  
Justin L. Hart

To investigate fuel flammability, we quantified burning characteristics of 21 fuel categories in a longleaf pine (Pinus palustris Mill.) woodland in central Alabama, USA. Litter was burned under controlled laboratory conditions. Flammability characteristics, including resistance to ignition, flaming duration, smoldering duration, maximum flame height, and percent consumption, were measured. The fuels were hierarchically clustered into five groups of similar flammability characteristics that explained 89% of the variance. Percent consumption and maximum flame height values ranged from 7% ± 1 standard errors (SE) and 12 cm ± 1 SE for the low flammability group (bark and charcoal), to 86% ± 1 SE and 62 cm ± 3 SE for the high flammability group (bracken fern (Pteridium latiusculum (Desv.) Hieron. ex R.E.Fr. = {syn: P. aquilinum}), grass, and fire-facilitating oak (Quercus spp.) leaves). Results support observed flammability differences between fuel types such as oak and pine (Pinus spp.) litter, and duff, and provide a previously unquantified comparison of surface fuels comprehensive of a longleaf pine community. Further, clustering analysis indicated that plant species that become abundant post-disturbance may help maintain fire-vegetation feedbacks in the absence of pine litter. Understanding flammability characteristics of surface fuels may further inform prescribed fire application in stands where fuels have been altered.


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