RESEARCH ARTICLE ABSTRACT: Southeastern United States habitats dominated by longleaf pine (Pinus palustris Miller) and associated plant species have declined dangerously. Conservation of rare and common plants of longleaf pine habitats may be aided by starting new popula- tions in the field. We review methods for initiating plant populations and integrate information from our studies of rare and common longleaf pine ground-layer plants of the outer South Carolina Coastal Plain. In our experience it is possible to start new populations of most longleaf pine ground-layer plants, including rare species if (1) seeds Starting New are collected from frequently burned sites with reasonably large populations of desired species; (2) appropriate media are used for seedling propagation; (3) outplanting of nursery grown seedlings or direct seeding is done during periods of sufficient soil Populations of moisture; and (4) introduction sites properly match habitat requirements (inferred from indicator plants) of desired species, and the sites can be managed with frequent prescribed Longleaf Pine fire. 3-ound-layer Plants Index terms: Longleaf pine, Pinus palustris, rare plants, reintroduction, southeastern United States in the Outer Coastal Plain of ranges (see Morse 1996, Gaston 1997 and references therein). These species typical- INTRODUCTION ;outh Carolina, USA ly appear on federal or state rare lists, and receive low G-ranks from The Nature Longleaf pine (Pinus palustris Miller) sa- Conservancy. Hardin and White (1989) vannas and woodlands are characterized and Walker (1993) compiled and published by a sparse tree canopy and a very rich Jeff S. Glitzenstein lists of longleaf pine associated species ground layer usually dominated by herbs that meet these traditional criteria for rar- Donna R. Streng (Bridges and Orzell 1989, Peet and Allard ity. Walker’s (1993) list included 389 spe- 1993). Decline of these biologically rich Tall Timbers Research Station cies, 187 of which were considered rare habitats, which once encompassed vast 13093 Henry Beadel Drive range-wide and vulnerable to extinction areas of the southeastern United States, is Tallahassee, FL 32312 USA (G-ranks = l-3). Most are herbaceous pe- well documented (Frost 1993, Harcombe rennials that depend on frequent natural et al. 1993). Only about 3% of an estimat- Dale D. Wade fire. More than half (65%) occur in moist ed 37 million ha remains. Contributing USDA Forest Service longleaf pine habitats (i.e., seasonally factors include logging, clearing, inten- Southern Research Station flooded flatwoods and savannas, depres- sive forestry, and, perhaps most important, 320 Green Street sions, shrub bog ecotones, seepage slopes, fire exclusion. Although precise data are Athens, GA 30602 USA pond margins), although many (45 spe- not available for many species, most her- cies, 24.2% of the total) occur in typical baceous plants in longleaf pine dominated John Brubaker mesic-dry upland habitats (Walker 1993). habitats apparently require frequent (i.e., An update of Walker’s (1993) list, avail- Medical University of South Carolina mean fire return intervals less than 5 years), able online at http://www.talltimbers.org/ Department of Pharmacology low-intensity fires for population mainte- research.html, includes 256 additional spe- Charleston, SC 29403 USA nance (Lemon 1949, Platt et al. 1991, cies. This large increase reflects, in part, Waldrop et al. 1992). (Plant nomenclature the endangerment of ever-larger numbers follows Kartesz [1994] unless otherwise of ground-layer plants of longleaf pine l indicated.) habitats. Given the continuing loss and endanger- The second group of at-risk species includes ment of high quality longleaf pine habitats formerly dominant, but still often locally (e.g., Percher et al. 1999), many of their abundant, “climax” grasses of North Amer- characteristic plants could, or should, be ican prairies and savannas. These grasses considered rare or endangered. Two groups tend to be shallow-rooted and are highly l Correspollding authorauthor e-mail: of species may be at greatest risk. The first [email protected] susceptible to even light to moderate distur- group includes species that fit the tradi- bance of upper soil horizons such as me- tional definition of rarity-species with chanical site preparation for artificial regen- Natural Areas Journal 21:89-110 small population sizes, few populations, eration of pine stands (e.g., Schultz 1976). or very limited geographic or ecological Volume 21 (I), 2001 Natural Areas journal 89 Wind-pollinated and limited in dispersal, has been going on for centuries, and his- mendations on seed sampling for genetic these plants may also be particularly vulner- torical evidence suggests that many cur- diversity, see Center for Plant Conserva- able to habitat fragmentation and declining rently rare species were more common tion (1991). population size (Tilman et al. 1997). prior to recent antbropogenic declines (El- liott 18161824, Percher 1848, Ravenel Fire history is an important factor in site Ecologists generally agree that conserva- 1876, Weakley 1999); and (3) if current quality for ground-layer plants of longleaf tion is a more effective tool for protecting trends continue, today’s common species pine habitats. Frequently burned sites have and maintaining biodiversity than restora- may be rare in the near future. In the first reduced competition from hardwood tion (Falk et al. 1996). Fortunately, some section of this paper we discuss seed is- shrubs and sprouts (Waldrop et al. 1992), large tracts of properly managed, high sues, including choice of collection sites resulting in more vigorous ground-layer - quality longleaf pine habitat remain on and dates, seed processing and storage, plants with larger inflorescences and great- private and public lands. Nevertheless, to and germination tests. The second section er seed production. On sites with a history counteract continuing loss of biodiversity, covers seedling issues and includes con- of frequent fire, canopy density can have _ it may be necessary to start new popula- siderations of seedling propagation, plant- an influence on seed viability. Means tions of the most threatened species (Falk ing sites, and seedling performance after (1997) found a negative correlation be- et al. 1996, Pavlik 1996). There are three outplanting. This section also contains re- tween density of overstory slash pine (Pi- basic strategies for starting plant popula- sults from a small translocation experi- nus elliottii) and seed viability of Aristida tions: translocation (i.e., moving individu- ment we conducted with Agrimonia in- beyrichiana Trinius and Ruprecht. Fire als or parts of individuals directly from cisa, a globally rare forb of subxeric history also influences seed predation, field populations), outplanting of nursery longleaf pine habitats. The third section which can have a major impact on seed grown seedlings or cuttings, and direct discusses direct seeding methods, and com- availability. Hiers et al. (2000) found that seeding (Guerrant 1996). Each strategy pares results from two of our own studies approximately 68% of Tephrosia virgini- involves several procedural issues. For of direct seeding that varied with respect ana pods in unburned control plots con- example, to successfully grow and out- to competition control. Finally, we briefly tained seed predators compared to only plant seedlings one must collect and pro- discuss native plant gardens and the po- 23% in burned plots. cess the seed, germinate it, select a growth tential role of gardens as refuges and source medium, choose a planting site, and man- populations. For each topic, we first pro- Seed production of most longleaf pine age the new population. Direct seeding vide a review of pertinent literature, and ground-layer species tends to decline with also involves seed collection and germina- when appropriate, present our own unpub- time since burning. Seeds are most abun- tion and requires information on the envi- lished data. We present data suggesting dant during the year of the bum, or, if the ronmental and biotic conditions needed to that it is not difficult to start new popula- bum occurs late in the year, the following maximize germination and establishment tions of longleaf pine ground-layer plants, growing season. However, some species, under field conditions. Translocation may including rare species, if the introduction such as Gymnopogon ambiguus , Aristida be the easiest initiation technique, although site is located in an appropriate habitat and purpurascens, and Muhlenbergia capil- it is often hard to justify ethically, and can be managed with frequent fire. laris, flower and produce abundant seed choice of planting site and transplant con- for several years following fire (Pfaff and ditions are critical concerns (Hall 1986). Gonter 1996). It is not known whether I: SEED ISSUES seed quality in these species declines with This paper reviews methods for starting time since fire. Seed Collection Sites and Dates populations of ground-layer plants of longleafpine savannas and woodlands, and Finding a quality seed collection site is Season of burning can affect seed produc- includes some of our own unpublished usually the first step in starting a new plant tion. Many pine savanna grasses, and some data. We emphasize species additions to population. Unfortunately, there is little composites, flower more prolifically after relatively intact communities. In contrast, information on collection site quality