Title: Initial plant community responses to hardwood control treatments in restoration of remnant longleaf pine (Pinus palustris) woodlands

Abstract

Changes in land use over the past century have contributed to substantial losses of longleaf pine (Pinus palustris) woodlands in the southeastern USA and replacement with higher density, mixed pine and hardwood stands that suppress understory development and limit application of prescribed fire. To increase understanding of limiting factors and identify potential approaches for restoring longleaf pine woodlands, we studied in this work initial availability of light and soil water and 2-year (2018–2019) plant community responses after controlling overstory hardwoods in five remnant longleaf pine woodlands having no evidence of previous agriculture at the Savannah River Site near Aiken, SC, USA. Seven hardwood control treatments and a non-treated check were compared in a randomized compete block experiment: cutting, cutting + shredding of logging residues, stem injection with imazapyr herbicide, cutting + basal spray with imazapyr herbicide, cutting + basal spray with triclopyr herbicide, cutting + directed foliar spray with a mixture of glyphosate and imazapyr herbicides, and cutting + broadcast foliar spray with the same herbicide mixture. In the year prior to hardwood cutting (2016), understory light availability averaged 23% of full sun. Throughout the year of treatment installation (2017), average soil water content (SWC) was below permanent wilting pointmore » (5.5% SWC) where overstory hardwoods were retained; whereas, it was above wilting point (7.5%) where they had been cut. Thus, combined effects of shade and root competition from overstory hardwoods probably limited cover of herbaceous species in the non-treated check. In the 2 years following treatment, hardwood survival averaged > 99%, 62%, 42% and < 1% for the non-treated check, cutting, shredding, and herbicide treatments, respectively. Relative to the non-treated check, herbaceous species richness was increased by shredding, stem injection, basal spray, or directed foliar treatments; herbaceous cover was increased by basal spray or directed foliar treatments; and woody cover was decreased by directed or broadcast foliar treatments. The directed foliar spray was the most effective treatment for achieving many of the desired understory characteristics of a longleaf pine woodland, including a diverse understory dominated by herbaceous vegetation capable of supporting periodic prescribed fires. Although the imazapyr basal spray treatment increased cover of remnant woodland indicator species, none of the treatments increased richness of this species group, suggesting that restoration of native species composition will be expedited by enrichment seedings or plantings.« less

Authors:

Harrington, Timothy B.  ^[1];

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Minogue, Patrick J.  ^[2];

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• Search DOE PAGES for ORCID "0000-0003-2332-9936"

Sutton, Randall A. ^[3]; Peter, David H. ^[1]; Blake, John I. ^[3]

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+ Show Author Affiliations

1. USDA Forest Service, Olympia, WA (United States)
2. Univ. of Florida, Gainesville, FL (United States)
3. USDA Forest Service, Savannah River, Aiken, SC (United States)

Publication Date:

Thu Apr 08 00:00:00 EDT 2021

Research Org.:

USDA Forest Service, Savannah River, New Ellenton, SC (United States)

Sponsoring Org.:

USDOE

OSTI Identifier:

1805173

Report Number(s):

21-03-P
Journal ID: ISSN 0378-1127; 21-03-P; TRN: US2212716

Grant/Contract Number:  

EM0003622

Resource Type:

Accepted Manuscript

Journal Name:

Forest Ecology and Management

Additional Journal Information:

Journal Volume: 491; Journal ID: ISSN 0378-1127

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

60 APPLIED LIFE SCIENCES; Plant community restoration; Species diversity; Competition; Herbicides; Microclimate