Sunday, August 21, 2016

Longleaf pine restoration - bring on the fire, but first....

Elsewhere on this blog I have discussed the importance of fire for the maintenance and recovery of longleaf pine (Pinus palustris) habitats. I have not discussed the numerous challenges in being able to do so, and they can be considerable. This page will not be a full accounting of these challenges but is predicated on some of these. Namely, long-unburned stands may have extraordinary fuel loads that can be explosive and dangerous to reintroduce fire into.

Longleaf pine stand and prescribed burn near the coast of North Carolina;
flame lengths and intensity are greater than many managers would prefer 

   Longleaf "flattop"; these trees often represent remnants of
earlier forests skipped over by loggers
                                                            Bringing fire back into long-unburned stands places serious stress on the very trees fire management is intended to support. In stands where longleaf pines are sparse (image above) or where the individuals include older relicts, each tree is precious and valuable (image left). Longleaf remnants with "cat faces" (signs of previous naval stores harvest) are especially susceptible to fire damage (image below).                                                                 
Mechanically reducing the fuels in such stands can help protect high-value individual trees and lower overall fire intensity. However, doing so across large and heavily overgrown stands takes a concerted approach. Several years ago, we stepped up and took one (a concerted approach, that is).

The "concerted approach"!
Skid steer equipped with forestry cutter
We acquired a skid steer equipped with tracks to minimize ground disturbance, a special cab to protect the operator, and a "forestry cutter".  Examples of how we used it are shown below:       
  Disappearing mower and mowed swath
 through heavy "bay" fuels
Brunswick Co, NC

Mower headed straight toward remnant longleaf pine, barely evident from
a distance due to tall shrub and Pond Pine (Pinus serotina) encroachment

In these circumstances it was the perfect way to go "looking for longleaf".  

The images below show this stand before and after treatment. Note the lone Longleaf pine with the Y-shaped canopy near the center. Amazingly, a young longleaf pine was hiding in the dense brush immediately in front of this tree (click & enlarge image right). After clearing, the stand displayed the open structure typically associated with longleaf pine savannas and woodlands - a restoration success?.  Comment appreciated! 

Longleaf pine stand with relicts, after mulching treatment (same stand as above)
Note - turpentine faces on 2 of the trees.
Brunswick Co, N.C.

Tuesday, August 16, 2016

Shenandoah sinkhole ponds

Virginia Sneezeweed (Helenium virginicum) is a federally-listed "threatened" species associated with Shenandoah Valley sinkhole ponds in Virginia. A number of years ago, the species was also confirmed in Missouri in similar habitat, creating "one of the great phytogeographic mysteries of the Eastern North American flora" (1).

Virginia Sneezeweed (Helenium virginicum)

Large patch of Virginia Sneezeweed along margin of sinkhole pond, Augusta County, VA


This is a seed-banking species whose populations fluctuate widely at a given site. Flowering stems can become prolific and abundant under the right conditions (2) (image left)

Water levels in the sinks vary widely and fluctuate seasonally. The example shown below held over 12" of water while immediately adjacent ponds were completely dry.  Not surprisingly, the vegetation may also be quite variable both seasonally and between sites. For more detailed descriptions see (3) & (4) below.

Shenandoah sinkhole pond with standing water (July 12, 2016)
Note: Pin Oak (Quercus palustris) overhanging branch  

Shenandoah sinkhole pond, same site as above (August 04, 2016)
standing water still present, emergent Persicaria and Polygonum spp. superficially dominant
Shenandoah sinkhole pond with Buttonbush (Cephalanthus occidentalis) and emergent Eriocaulon

The sinkhole ponds are biologically important features of the Shenandoah Valley region and they support many other species in addition to Virginia Sneezeweed. These ponds are also extremely important for dragonflies (5) and reptiles and amphibians (4), in part, because the ephemeral water levels often restrict predatory fish populations.
Spotted Turtle (Clemmys guttata) - the only populations west
of the Blue Ridge are found in sinkhole ponds (4)
Image from coastal plain of VA
Amphibian egg masses in sinkhole pond (03-23-16)

Dragonfly exuvia on Lowland Loosestrife (Lysimachia hybrida)
in sinkhole pond, Augusta Co

Lowland Loosestrife (left) is considered significantly rare in Virginia, and known from a handful of sinkhole ponds.

A number of other rare plants may also be found:

Boltonia montana  - Augusta Co., VA (08-4-16)

Valley doll's daisy (Boltonia montana) is an extreme global rarity, known from 4 VA sites, all within a few miles of one another in Augusta County's sinkhole ponds. Described as new to science in 2006, this species also has an unusual phytogeographic pattern.

Northern St. John's Wort (Hypericum boreale)  -- Significantly rare in Virginia; known from Shendandoah sinkhole ponds and disjunct to interdunal ponds near the coast.

The ponds themselves are globally-rare and imperiled, In the two examples shown below, one has been artificially deepened and stocked with fish and the other used as a mini-landfill.

It's hard to image more important and special habitats. I hope to be able to play a small part in protecting them.

(1) Virginia Plant Atlas:
(2) Draft Recovery Plan:
(3) Descriptive Ecology:
(4) See Montane Depression Wetland types and links here (
(5) A new species of Boltonia....SIDA 22:873-886.

Sunday, July 10, 2016

Longleaf Pine Sandhills - fire and wiregrass

The "sandhills region" of North Carolina supports some of the most extensive stands of longleaf pine remaining in the state. The preponderance of deep sandy soils not only gives the region its name, but helps explain why so much longleaf pine remains here given the even more substantial declines elsewhere in the state. The coarse, droughty sands are less conducive to most types of agriculture and, when forested, are not as easily overrun by other vegetation.  However, even when longleaf pine is present, regular burning is needed to maintain high quality stands.

Well-burned longleaf pine stand@Sandhills Gameland, NC
Note scorched boles, uneven spacing and diameters

Thankfully, certain land managers and owners are committed to the use of prescribed burning. They have maintained the best upland longleaf in the region through frequent and regular burning. These stands have open canopies, with minimal hardwoods, above dense swards of wiregrass (Aristida stricta).

Heavily fire-suppressed longleaf stand in Moore Co, NC
Note dense Turkey Oaks and absence of wiregrass

The vast majority of remaining stands are heavily altered due, in part to insufficient burning. On dry, sandy uplands these stands may become densely invaded by hardwoods like turkey oak (Quercus laevis), and wiregrass is sparse and barely evident. Such stands carry fire less readily and larger hardwoods become fire resistant and harder to control.

Moderately fire-suppressed longleaf stand in Moore Co., NC
Note patches of wiregrass, those in left foreground show greatly diminished vigor

Less severely fire suppressed stands retain patches of wiregrass and other herbaceous species. Hardwoods are less dominant, patchier, and often smaller. These smaller hardwood stems contribute less shade and litter, thus having less impact on fire dynamics and understory composition.

Wiregrass is a keystone species with a huge ecological impact. It flowers and seeds in the same season, primarily after being burned in the spring or summer, with upright flowering stalks emerging with the characteristic "three-awn" seeds. This happens only rarely in most stands where finds are either excluded or conducted only in the "dormant" season.

Wiregrass (Aristida stricta) flowering
@Pondberry Bay Plant Conservation Preserve, Sampson Co, NC

Wiregrass is a clump-forming bunchgrass whose narrow densely packed culms dry rapidly and carry fire even shortly after rain. In most relatively intact stands, wiregrass forms nearly continuous, dense ground cover. This density and continuity enhances the spread of low intensity fire which ultimately limits the establishment of woody stems.  Although we may imagine it take considerable time to convert an open, savanna-like stand to a dense, closed forest the changes occur surprisingly rapidly.

Dense swath of Wiregrass, note overlapping and draping culms
creating continuous fuel matrix for fire spread

Fire spreading across dense wiregrass layer

Longleaf pine - Turkey Oak Sandhill with suppressed and low density wiregrass,
stand has experienced infrequent, dormant season fire@Moore Co, NC
Longleaf pine - Turkey Oak Sandhill with dense wiregrass in good condition@Moore Co., NC
stand has experienced regular, somewhat frequent fire, but not recent growing season burning

Longleaf pine - with dense wiregrass after regular & frequent prescribed fire,
including growing season. Turkey Oak layer "burnt out" 

Sunday, April 24, 2016

"A shy-blooming thing" - Helonias bullata

Helonias bullata @ flowering peak, Atlantic coastal plain
April 08, 2016 Henrico Co, VA

"Few of our early spring flowers are more attractive or universally sought after by those who know it, than the "Swamp Pink"" said Stewardson Brown (Bartonia, 1910). Some seek them in the wet woods as I was lucky to do recently, but Brown indicated, "there are many people, however, who are familiar with and appreciative of its beauties, and equally keen to get it each spring, but who never saw and probably have no desire to see Helonias growing in its natural surroundings, but prefer to do their hunting along the curbs of Market Street" where plants .... were sold along the street each market day" (for a more thorough & colorful account, please read his original note which can be accessed online). 

Swamp Pink (Helonias bullata) was federally listed as a threatened species in 1988.  It is unclear whether or not over-collection was a factor in this listing decision. Brown's 1910 account certainly described both flower removals (thereby reducing seed production) and "clumps of roots offered also, a thing to be deplored in so rare a plant".  According to a recent assessment by the US Fish & Wildlife Service, "evidence of collection or trade of swamp pink as a garden plant remains patchy and anecdotal". However, several modern sources still encourage planting and trade in the threatened species. It seems clear such practices have done little to support permanent conservation and recovery of the species in its natural habitat. 

Remaining  natural Helonias populations are documented in widely separated regions from the New Jersey Pine Barrens, the Inner Coastal Plain of Virginia, the Valley & Ridge of Virginia, and the Southern Appalachians, including North Carolina. The map shown below illustrates the large territory lying in between these population centers and suggests the fact that the majority of the documented populations occur in the Atlantic Coastal Plain (New Jersey is considered to be the stronghold of the species (US Fish & Wildlife Service 5-Year Review: Summary and Evaluation, New Jersey Field Office).    

Helonias bullata range map

Courtesy of Kartesz, J.T.  2015.  Floristic Synthesis of North America. Version 1.0. Biota of North America Program (BONAP) (in press.)

Godt et al. (Conservation Biology, 1995) showed that Swamp Pink genetic diversity broadly corresponds with these regional population centers; Southern Appalachians being most diverse, Virginia intermediate, and New Jersey the most depauperate. As in many other species, such data suggest that the Southern Apps populations are more ancient, having persisted during glaciation, and more recently spread northward.  A logical conclusion follows that these "relictual" populations have particular conservation importance, due to their greater diversity.

Helonias bullata rosettes, suggestive of limited dispersal by ants
or slowly spreading rhizomes, although note former flower stalks

(Transylvania Co, NC)

Of course it is a mystery how Helonias could have "migrated" over such long distances post- glaciation. Its seeds have eliasomes (US Fish & Wildlife Service 5-year Review). These fleshy structures are believed to aid dispersal by ants (see my previous post on Sessile Trillium).
How long did it take those ants to carry seeds from North Carolina to New Jersey?

Most, but not all of the plants I have observed tend to appear highly concentrated, as expected from a species with localized seed dispersal. Another explanation is the plants are clonal, spreading rhizomatously; Sutter (Castanea 1984) believed seed production in the Southern Appalachians did little to maintain those populations. In part, this may be due to very low flower production. An 1872 note in the Bulletin of the Torrey Botanical Club (authorship unclear, at least to me) indicated, "the plant is a shy-blooming thing, only a few out of many sending up a scape, and those few being very far in between".

Swamp Pink maturing & elongating scape, amidst Spicebusg and Elderberry
Henderson Co., NC

After flowering scapes are produced, they rapidly elongate as they mature. The resulting scape may appear double or triple the length of the original inflorescence. Although few plants achieve this reproductive status, they apparently produce large numbers of seeds which drop shortly after maturing. Because seeds are short lived (US Fish & Wildlife Service Recovery Plan, 1991) localized conditions in the early spring strongly determine the likelihood of germination. Seeds falling into standing water and/or saturated condition germinate more rapidly than those dropping into dry conditions (Punsalan, unpublished thesis, 2013).

Helonias bullata flowering scape on hummock created by American Holly
Henrico Co, VA

Laidig et al. (Bulletin of Torrey Botanical Club, 2009) emphasized the "apparent limitation of Helonias to hummocks" in New Jersey.  The 1872 report (cited above) suggested, "the favorite situation for flowering seemed to be just on the edge of a swift stream or in rich moist earth.."  In my hazy recollections of sites visited, mucky wet soils were always present.  Only one population seemed to occur on obvious hummock and hollow topography (that being the one shown immediately above in the Atlantic Coastal Plain of Virginia).  One site, (shown below) crudely matched the first part of the 1872 habitat description.  A few other habitat examples are also shown below:

Helonias rosettes along headwater stream surrounded by Dog Hobble

The small population (right) was found directly on an elevated bank above a shallow and narrow headwater stream in the the Southern Appalachians of North Carolina. The rosettes present (yellow arrow) were found on the fairly steep bank above the normal water elevation; perhaps seeds washed in during higher water levels?

Helonias dense patch amidst Cinnamon & Royal Ferns 

A large, densely packed population (shown to the right) was found in a large, bowl shaped depression with no obvious flowing water and no surface out or inflow (Southern Appalachians of northern South Carolina). Note the shaded aspect with minimal dappling of light, and no flowering scapes present.

Helonias rosettes with fruiting scapes bordering Pitch Pine and Eastern Hemlock

A diffuse, widely scattered population occurred in an almost linear wetland basin or gentle valley (image right). The valley is wide enough and open enough to allow significant sunlight to the ground, where sphagnum appears to dominate. This is the only of the last 3 sites with flowering stems present.

Brown (Bartonia, 1910) pointed out that enthusiasts seeking Swamp Pink, "feel amply repaid by a few heads of its fragrant flowers, even if the getting entail some scratches, with wet feet thrown in".....I agree wholeheartedly! Seek them next spring, and take the "shy-blooming thing" the right way (see below).

Zach Bradford , Chesapeake Bay Region Steward with VA Natural Heritage Program
 "taking" Swamp Pink the right way