• GENERAL BOTANICAL CHARACTERISTICS
• RAUNKIAER LIFE FORM
• REGENERATION PROCESSES
• SITE CHARACTERISTICS
• SUCCESSIONAL STATUS
• SEASONAL DEVELOPMENT

GENERAL BOTANICAL CHARACTERISTICS:

RAUNKIAER [58] LIFE FORM:

REGENERATION PROCESSES:

Pond pine cones open and release seeds soon after exposure to heat from fire. Intensity of heat does not adversely reduce viability of seeds. Even badly charred cones release seeds that are capable of germination. Mature cones can be opened by exposure to  333 to 336 ^oF (167-169 ^oC) dry heat for 20 seconds or by immersion in boiling water for a similar period [8]. Optimum stratification of pond pine seeds is 30 days at 33-41^oF (0.5-5 ^oC) in a moist medium [5,46]. Germination occurs in 24 days [5]. Pond pine seeds germinated in a nursery were unable to survive full saturation conditions [46].  

Among pine species, pond pine is somewhat unique in that it usually resprouts after being damaged by disturbance [8,19,20,24,82]. Seedlings or saplings usually sprout prolifically when cut, and older trees will sprout vigorously along the stem and branches even after intense scorching and defoliation by fire. These sprouts come from dormant buds in the axils of primary needles of young seedlings. Buds are dormant and are protected by bark. When the tree is injured, these buds resume growth and may give rise to clusters of buds and numerous short shoots [8]. In pocosins, seedlings of pond pine sprout prolifically, and stands up to sapling size are primarily reestablished by sprouting [29]. However, 1 study showed that most seedlings on pond pine plots, which were completely burned, did not resprout [66]. Evidence suggests that pond pine may not resprout indefinitely, and that frequent burning of any age pond pine stand may kill it [26].

SITE CHARACTERISTICS:

In eastern North Carolina, pond pine usually occurs on wet flats and extensive, poorly drained evergreen shrub bogs called pocosins. These pocosins have organic soils varying from 1 to 25 feet (0.3-7.6 m) deep [16,61].  Pocosins are highmoor, ombrotrophic bogs dominated by a continuous shrub cover 3.3 to 13 feet (1-4 m) high with scattered emergent trees, usually pond pine [61,87]. Pond pine is the only "important" pocosin tree, probably because of recurrent fire. Pocosins apparently represent the lower limit of site quality tolerated by pond pine [66].

A pond pine-slash pine association occurs in peaty swamps. Peaty swamps contain surface water only during a part of the growing season. Coniferous trees or shrubs, including many ericaceous species, exist in these swamps. Frutescent and herbaceous plants are also numerous. Peaty swamps are found on poorly drained, flat, interstream areas of lower terraces in the Atlantic and Gulf coastal plains [57]. 

Pine flatwoods is one of the most common vegetation types in Florida, and can be dominated by pond pine [50]. Flatwoods with a pH less than 4.5 are usually dominated by pond pine and those with pH above 4.5 by slash pine or longleaf pine [50,51]. Pond pine is a principal tree species characteristic of this wet pine type that is found in the coastal plain physiographic province from Delaware south to Florida and west to eastern Texas, primarily in the flatwoods of the outer marine terraces. Representative sites include boggy, nonriver flatlands; poorly-drained, seasonally-wet coastal flatlands; and lowlands adjacent to ponds, streams, and other wet areas. Soils range widely in texture from clay to sand. Moisture conditions are influenced by an impermeable clay soil layer that resists downward movement of water. Poor drainage limits aeration of the soils on many sites and peat mats commonly develop over mineral surfaces. Acidic conditions prevail on most sites [25].

The bay forest type, occurring exclusively in the Coastal Plain physiographic province ranging from Maryland to southeastern Texas, is restricted to coastal depressions or floodplains where saturated conditions prevail. Soils are usually organic, highly acidic and low in  nutrient availability [47]. Bay swamps, dominated by the redbay-sweetbay association, are characterized by a more or less dense growth of evergreen trees, including pond pine [57].  

Other sites that include pond pine are cypress-swamp tupelo (Nyssa biflora) and cane (Arundinaria spp.). On a cypress-swamp tupelo site, pond pine is most abundant where standing water or poor drainage renders the habitat more acidic [4]. Pond pine is often the overstory of cane habitats that generally occur on organic soils having fair internal drainage and 40% to 50% organic matter content in the upper 4 inches (10 cm) of soil, and a species composition of 70% to 100% reeds [6,29,85].  

Pond pine has excellent growth on better drained mineral soils, but the faster, earlier growth of slash and loblolly pine usually restricts it to a subordinate position on such sites [25]. Pond pine is relatively tolerant to waterlogging. Mature trees can tolerate prolonged flooding, but growth is slow. Pond pine also endures poor soil aeration and high acidity, and is confined mostly to ponds and bays of interstream areas [27,57].  

Another site characteristic important to maintenance of pond pine is the unique climate of the southeastern United States. Weather patterns in the Southeast spawn more lightning storms than in any other region of North America. The lightning fire season begins in early spring, is often most prevalent in May or June, then tapers off in July and August through early fall. The large majority of fires in the Southeast are caused by lightning [38].

SUCCESSIONAL STATUS:

Fire is an important aspect of succession in many habitat types in which pond pine is found. The long-term perpetuation of flatwoods, sand-pine scrub, pocosins, and savannas are tied to fire. Species diversity is highest immediately following fire and generally decreases thereafter [13]. 

Flatwoods ecosystems, along with the rest of the southeastern pine forests, have been classified as fire subclimax within the deciduous forest region [2]. Pine flatwoods are considered to be fire maintained but, without fire, they ultimately give way to hardwoods [50]. Pond pine flatwoods, if unburned, can develop either to bayheads or to mixed hardwood swamps [2,8]. Pond pine communities of North Carolina possess little herbaceous vegetation and are often changed by fire into shrub swamps in which pond pine occurs only as scattered relicts among the fire resistant shrubs [57]. Human alteration of natural fire frequency is thought to be the most common cause of successional change in flatwoods [2]. 

Pocosins, often with pond pine overstory, generally can be viewed as intermediate successional communities.  They are often maintained in a subclimax stage by fire and hydroperiod, with the mature vegetational stages being suppressed for long periods on the wettest sites but developing relatively quickly on drier sites [15]. 

The bay forest type, occurring exclusively in the Coastal Plain physiographic province, frequently reverts to pond pine or Atlantic white-cedar after severe fires [47]. If the original stand of southern white-cedar is destroyed, together with seed stored in the upper layer of peat, succession is toward a type in which pond pine predominates in Virginia, North Carolina and South Carolina [35]. With recurrent fire, the bay swamp, pond pine-slash pine wetlands, and Atlantic white-cedar bog may revert to shrub bogs [47]. It should be noted, however, that the shallow marsh is characterized by a mineral soil, and could not arise in a peaty area without aggradation of inorganic sediments [57]. The patchwork nature of evergreen bay forests is related to their extreme susceptibility to fire, after which they may revert back to any one of several freshwater, hydric vegetative cover types depending on the intensity of the burn and depth to the water table during and following the burn [47].  

Frequency of fire also determines the successional stage of many southeastern swamp forests. Serotiny of species such as pond pine may be selected for in regimes where fires are spaced with a frequency which allows maturation but does not "unreasonably exceed" this. Too frequent firing could eliminate pond pine from an area altogether [26] and produce a grass-sedge bog or savannah [8]. Wells [84] observed that fires started by Native Americans, and later even more frequently by European settlers, began to change stream-head swamp forests of the southeastern United States into grass-sedge bogs or savannahs. Under burning at least every decade, the native deciduous forest largely disappeared or became dominated by pond pine. With more frequent burning the pines were replaced by fire-resistant shrubs or shrubby trees with the ability to sprout from stumps or roots. Under annual fires, the shrubs practically disappeared and were replaced by grasses, sedges, and many bulbous herbs. These nearly treeless areas were called sub-tropical savannahs. Under reduced frequency of fires, savannahs revert to shrubby pocosins, and under no fire, savannahs and pocosins rapidly return to swamp forest.

Excluding fire, primary factors affecting plant succession in any hydric area are aggradation of the level of the substratum by inorganic and organic sediments, with consequent lowering of the water table and subsequent increase in oxygen tension above that level [57]. On organic soils subject to prolonged flooding, longleaf and slash pine are replaced by pond pine communities. Pond pine assumes dominance in Virginia and the Carolinas on the wettest sites and on organic soils [25]. On mineral soils, pond pine is in an intermediate stage of plant succession, where it may grow in pure even-aged stands until harvesting or mortality removes the dominant trees [8]. 

SEASONAL DEVELOPMENT:

Related categories for SPECIES: Pinus serotina | Pond Pine