Understory Plant Community Response to a Range of Restoration Scenarios in Northeast US Pitch Pine (Pinus rigida) Barrens

Post-fire logging produces minimal persistent impacts on understory vegetation in northeastern Oregon, USA

Describing a landscape mosaic: Forest structure and composition across community types and management regimes in inland northeastern pitch pine barrens

BackgroundSeveral insectivorous bat species are found in New England, yet research on them is still scarce. Current research shows the ecological importance of bats due to their control of insect populations, but they are endangered by habitat loss and White Nose Syndrome, among other threats. Pine barrens are an uncommon ecosystem found in New England that supports other rare taxa and could be important for these bat species.MethodsWith hand-held audio recorders, we surveyed for bats in Montague Plains Wildlife Management Area in Massachusetts and Concord Pine Barrens in New Hampshire in June 2022. Our study objectives were to (1) describe the most common bat species and (2) compare bat activity across different habitat types at two managed pine barrens in New England. In particular, we examined bat activity related to habitat type (scrub oak, mature pitch pine, treated pitch pine, hardwood forest), habitat structure (i.e., canopy closure), time since prescribed fire, and path width. We analyzed our data through generalized linear modeling and logistic regression.ResultsOverall, we were able to measure the presence of five out of the nine total species found in the area, including the endangered Myotis lucifugus (little brown bat). We recorded 293 bat calls, with the majority of calls from big brown bats (71%). We found significant differences (p < 0.05) in bat activity in relation to time since prescribed fire and habitat structure. The index of bat activity was greatest in pitch pine and hardwood forests and lowest in scrub oak and treated pitch pine habitats. With preliminary data, we also found that silver-haired bat presence was influenced by habitat type, with more detections at survey points in hardwood forests.DiscussionThese findings demonstrate the importance of pine barrens as an ecosystem that supports bats in New England. According to the activity of bats in our study, closed canopy and mature pitch pine habitats may be prioritized in conservation efforts at managed barrens for bat species. Further research is recommended to better understand the relationship between prescribed fires, which are common in managed barrens, and bat activity.

The influence of canopy patch mosaics on understory plant community composition in boreal mixedwood forest

Conceptual ecological models for the Long Island pitch pine barrens: implications for managing rare plant communities

Little is known about how differences in water availability within the “super humid” tropics can influence the physiology of understory plant species and the composition of understory plant communities. We investigated the variation in the physiological drought tolerances of hundreds of understory plants in dozens of plant communities across an extreme elevation and precipitation gradient. Specifically, we established 58 understory plots along a gradient of 400–3600 m asl elevation and 1000–6000 mm yr−1 rainfall in and around Manu National Park in southeastern Peru. Within the plots, we sampled all understory woody plants and measured three metrics of physiological leaf drought tolerance—turgor loss point (TLP), cuticular conductance (Gmin), and solute leakage (SL)—and assessed how the community-level means of these three traits related to the mean annual precipitation (MAP) and elevation (along the study gradient, the temperature decreases linearly, and the vapor pressure deficit increases monotonically with elevation). We did not find any correlations between the three metrics of leaf drought tolerance, suggesting that they represent independent strategies for coping with a low water availability. Despite being widely used metrics of leaf drought tolerance, neither the TLP nor Gmin showed any significant relationships with elevation or the MAP. In contrast, SL, which has only recently been developed for use in ecological field studies, increased significantly at higher precipitations and at lower elevations (i.e., plants in colder and drier habitats have a lower average SL, indicating greater drought tolerances). Our results illustrate that differences in water availability may affect the physiology of tropical montane plants and thus play a strong role in structuring plant communities even in the super humid tropics. Our results also highlight the potential for SL assays to be efficient and effective tools for measuring drought tolerances in the field.

Root endophytic fungal communities associated with pitch pine, switchgrass, and rosette grass in the pine barrens ecosystem

Mechanical forest restoration treatments stimulate understory plants in the Colorado Front Range

This study is part of a coordinated series to describe the pine barrens of New York, communities characteristic of disturbed sites with poor soils. Pitch pine (Pinus rigida Mill.) communities in the Hudson Valley region of New York were found on a sand dune, alluvium, a lacustrine delta and on conglomerate and sandstone outcrops. The alluvium and lacustrine delta sites supported more mesic communities with higher tree and herb species richness than the sand dune site, but lacked a shrub layer. The sand dune, sandstone outcrop and conglomerate sites supported open tree canopy communities in which ericaceous shrubs, especially Gaylussacia baccata, dominated a distinct shrub layer. Community types could be classified into three physiognomic forms. Probably the most disturbed were communities of dwarf vegetation dominated by either pitch pine or scrub oak (Quercus iliczfolia). A second type was characterized by an open canopy of short pitch pines with an extensive shrub layer of scrub oaks or ericaceous shrubs. The third type had a closed canopy of tall pitch pine, red maple (Acer rubrum), red oak (Q. rubra) and/or white oak (Q alba), few shrubs but a considerable number of forest floor herbaceous species. The southeastern area is of particular interest because two of the best known pine barrens in New York, the Albany Pine Bush and the Schawangunk Mountains dwarf forest are lo- cated there. The Pine Bush has been the subject of a number of publications, most ad- dressed to a general audience (Rittner, 1975, for example), but Milne (1985) made a de- tailed study of upland forests and their successional development. He suggested that areas dominated by scrub oak (Quercus ilicifolia) with scattered pitch pine were characteristic of very disturbed sites, especially those that burned often. In the absence of disturbance, Milne believed they would succeed to closed-canopy pitch pine forests, then to areas dominated by a mixture of pitch pine, white pine (Pinus strobus), red oak (Quercus rubra), white oak (Q alba), red maple (Acer rubrum) and white ash (Fraxinus americana). Schawangunk Mountain ridge vegetation was described by McIntosh (1959), who noted that bare rock surfaces of the ridges were covered with pitch pine, sometimes dwarfed, no more than 1-3 m tall. These dwarf ridge top communities graded into taller pitch pine and

Disturbance legacies structure communities and ecological memory, but due to increasing changes in disturbance regimes, it is becoming more difficult to characterize disturbance legacies or determine how long they persist. We sought to quantify the characteristics and persistence of material legacies (e.g., biotic residuals of disturbance) that arise from variation in fire severity in an eastern ponderosa pine forest in North America. We compared forest stand structure and understory woody plant and bird community composition and species richness across unburned, low‐, moderate‐, and high‐severity burn patches in a 27‐year‐old mixed‐severity wildfire that had received minimal post‐fire management. We identified distinct tree densities (high: 14.3 ± 7.4 trees per ha, moderate: 22.3 ± 12.6, low: 135.3 ± 57.1, unburned: 907.9 ± 246.2) and coarse woody debris cover (high: 8.5 ± 1.6% cover per 30 m transect, moderate: 4.3 ± 0.7, low: 2.3 ± 0.6, unburned: 1.0 ± 0.4) among burn severities. Understory woody plant communities differed between high‐severity patches, moderate‐ and low‐severity patches, and unburned patches (all p < 0.05). Bird communities differed between high‐ and moderate‐severity patches, low‐severity patches, and unburned patches (all p < 0.05). Bird species richness varied across burn severities: low‐severity patches had the highest (5.29 ± 1.44) and high‐severity patches had the lowest (2.87 ± 0.72). Understory woody plant richness was highest in unburned (5.93 ± 1.10) and high‐severity (5.07 ± 1.17) patches, and it was lower in moderate‐ (3.43 ± 1.17) and low‐severity (3.43 ± 1.06) patches. We show material fire legacies persisted decades after the mixed‐severity wildfire in eastern ponderosa forest, fostering distinct structures, communities, and species in burned versus unburned patches and across fire severities. At a patch scale, eastern and western ponderosa system responses to mixed‐severity fires were consistent.

Thinning forest to restore fire-dependent, open-canopy pine barrens is important for promoting shrubland and young forest biodiversity and wildlife habitat and to mitigate chances for extreme fire behavior. Crown fire potential at the wildland-urban interface is a concern in northeastern (USA) pine barrens which contain extremely volatile fuels adjacent to densely populated areas. We used the Crown Fire Initiation and Spread simulator to model pitch pine (Pinus rigida) crown fire potential under simulated stand density reductions to help develop strategies for long-term management and conservation of pine barrens communities. Empirical data for model inputs were collected from pitch pine stands at the Albany Pine Bush (New York State, USA). Canopy structure, surface fuel moisture, and wind speed were used to predict crown fire occurrence, type (active vs. passive), and rate-of-spread. At winds > 20 km hr−1 and ≤ 9% fine fuel moisture, passive crown fire probabilities exceed 60%, and one stand near sensitive human infrastructure appears vulnerable to active crowning. Simulations suggest thinning to < 50 trees ha−1, 10–30% mean canopy cover, or about 5–10 m2 ha−1 basal area to minimize crown fire threat and restore ecologically high-quality pine barrens.

Climate change is facilitating a novel range expansion of southern pine beetle (SPB) into globally rare north‐eastern pitch pine barrens. By assessing stand conditions present in SPB‐infested and uninfested pitch pine stands on Long Island, NY, USA, we developed a regionally‐calibrated hazard rating model that predicts stand‐level SPB susceptibility. The model indicates that a stand's SPB susceptibility increases with (1) increasing pitch pine basal area, (2) increasing instances of previous year SPB spots nearby, and (3) sandy soil texture. The model informs adaptation strategies to a novel pest dynamic by supporting the identification and prioritization of high hazard stands for prevention management. An alignment between treatments effective in reducing SPB vulnerability and conserving pine barrens communities indicates that pine barrens can be managed both to improve resilience to future threats and preserve historic ecological conditions.

The spatial patterning of individuals in a community can provide evidence of dynamic interactive forces of ecological importance within and between populations. Three patterns are possible: (1) uniform, (2) random, and (3) clumped (Hutchinson 1953). Patterns which are uniform are best interpreted as indicating repulsive forces (e.g. competition) among the individual organisms because mosaic substrates which are statically or dynamically uniform are improbable. In contrast, the interpretation of clumped patterns is ambiguous because clumping can be generated by attractive forces among individuals (e.g. mutualisms) or a heterogeneous environment in which the organisms live. In plants inefficient seed dispersal can lead to clustering of seedlings around the parent plant. The lack of significant patterning (i.e. patterns not statistically different from random) is not proof that important interactive forces are inoperative; disturbance factors such as stochastic vagaries of climate, severe fire, or rampant predation may simply be stronger than the forces of biotic interaction or the underlying patterns of the substrate. The spatial patterns of pines and oaks in the New Jersey Pine Barrens were measured for evidence of competition among natural populations. This remarkable biome was selected because the pine-oak forest is strikingly homogeneous over a large area, and the pattern of trees appeared uniform, in contrast to the usual clumping of plant dispersions (Greig-Smith 1964). A genuine tendency toward uniformity would indicate the existence of competition or other ecologically important negative interactions among individuals. A second motivation for the study was the quantitative documentation of the spatial patterning and the relative abundance of tree species in selected sites of the Pine Barrens after a known period of time since the last forest fire. Repeated at regular intervals, the set of such studies can provide information about the dynamics of upland Pine Barrens succession. Very little quantitative or experimental work has been carried out on plant population dynamics or community structure in the Pine Barrens (Wood 1938; Little & Moore 1949; Buell & Cantlon 1950, 1953; Andresen 1959) compared to the large literature on the endemic fauna and flora (see Stone 1911; Harshberger 1916; McCormick 1970 for reviews).

Linking overstory relative density to light availability and understory plant community composition in disturbance-dependent, Pinus rigida -dominated forests of the mid-Atlantic coastal plain, USA

Pine barrens ecosystem has acidic, sandy, and nutrient-poor soil and is prone to drought and fire. In the New Jersey Pine Barrens, the predominant pitch pine (Pinus rigida) consists of two ecotypes: the regular pitch pines with heights of 4.6–12 m, and the pygmy pines of low stature (1.2–1.8 m) in the New Jersey Pine Plains. Previous ecological studies suggested that the dwarf pines in the Pine Plains that are embedded within the Pine Barrens were an evolutionary adaptation to frequent fire. Pines are obligate ectomycorrhizal (EcM) mutualists, and their root mycobiota may contribute to stress protection and plant health. However, information on the mycobiota associated with plants in the pine barrens ecosystem is lacking. To have a holistic understanding of the evolution and adaptation in this stressed environment, we used both culture-independent metabarcoding and culture-based method to characterize the mycobiota from soil and root of the two ecotypes and to identify core mycobiota. We found that Agaricomycetes, Leotiomycetes, and Mucoromycotina are predominant fungi in the New Jersey Pine Barrens ecosystem, which is rich in root mutualistic fungi. We observed that the pygmy pine roots had significantly higher density of EcM tips than the regular pine roots. This was corroborated by our metabarcoding analysis, which showed that the pygmy pine trees had higher ratio of ectomycorrhiza-forming fungi than the regular-statured pines. We hypothesize that symbiotrophic EcM fungi associated with pygmy pines are capable of mitigating high fire stress in the Pine Plains.