Jean Huffman - Academia.edu (original) (raw)

Papers by Jean Huffman

Journal of Tropical Ecology, May 1, 2000

Tapirs (Tapiridae) are the last representatives of the Pleistocene megafauna of South and Central... more Tapirs (Tapiridae) are the last representatives of the Pleistocene megafauna of South and Central America. How they affect the ecology of plants was examined by studying the diversity, abundance, and condition of seeds defecatedd by the lowland tapir (Tapirus terrestris) in Amazonian Brazil. Additionally, the spatio-temporal pattern of the seed-rain and seed-shadows generated by tapirs was recorded. Three hundred and fifty-six tapir faeces were examined. Eleven per cent were found in water (n = 41), while 88% were located on dry land (n = 315). Of those found on dry land, 84% were located at sites that flood seasonally, while 14% of the total were encountered at forest sites that do not flood. In 127 faeces checked in the laboratory over 12 906 seeds of at least 39 species were found. Seed viability ranged from 65% for Maximiliana maripa to 98% for Enterolobium schomburgkii. Of nine seed species planted in the laboratory, seven germinated within 4 wk, with one species achieving an 89% germination rate. For many species recruitment to the seedling stage was also high under natural conditions, with 13 plant species occurring as seedlings in older faeces. Tapir generated seed-rain occurred throughout the year, with seeds defecated in all months. Two temporal patterns in species seed rain occurred: (1) contiguous monthly occurrence with peaks in abundance, and (2) discontinuous occurrence (time clumped) with small (a few months) to large (many months to more than a year) temporal gaps. The highest diversity of seeds appeared in April, at the end of the dry season. As the last of the Pleistocene megafauna of the region, tapirs may have particular importance as dispersers of large seeds and generators of unique seed dispersion patterns.

The American Naturalist, Mar 1, 2023

Progress in Physical Geography: Earth and Environment

The longleaf pine ( Pinus palustris Mill.) and related ecosystem is an icon of the southeastern U... more The longleaf pine ( Pinus palustris Mill.) and related ecosystem is an icon of the southeastern United States (US). Once covering an estimated 37 million ha from Texas to Florida to Virginia, the near-extirpation of, and subsequent restoration efforts for, the species has been well-documented over the past ca. 100 years. Although longleaf pine is one of the longest-lived tree species in the southeastern US—with documented ages of over 400 years—its use has not been reviewed in the field of dendrochronology. In this paper, we review the utility of longleaf pine tree-ring data within the applications of four primary, topical research areas: climatology and paleoclimate reconstruction, fire history, ecology, and archeology/cultural studies. Further, we highlight knowledge gaps in these topical areas, for which we introduce the Longleaf Tree-Ring Network (LTRN). The overarching purpose of the LTRN is to coalesce partners and data to expand the scientific use of longleaf pine tree-ring d...

(Statement of Responsibility) by Jean M. Huffman(Thesis) Thesis (B.A.) -- New College of Florida,... more (Statement of Responsibility) by Jean M. Huffman(Thesis) Thesis (B.A.) -- New College of Florida, 1982(Supplements) Accompanying materials: Slides and photos included.(Electronic Access) RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.(Source of Description) This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.(Local) Faculty Sponsor: Mead, Gail; Morrill, Joh

Raw data used in multivariate models for Platt et al. 2016. Included are site context, fuel mass,... more Raw data used in multivariate models for Platt et al. 2016. Included are site context, fuel mass, fire characteristics, and post-fire regrowth

New Phytologist, 2019

Pyrogenic savannas with a tree-grassland 'matrix' experience frequent fires (i.e. every 1-3 yr). ... more Pyrogenic savannas with a tree-grassland 'matrix' experience frequent fires (i.e. every 1-3 yr). Aboveground responses to frequent fires have been well studied, but responses of fungal litter decomposers, which directly affect fuels, remain poorly known. We hypothesized that each fire reorganizes belowground communities and slows litter decomposition, thereby influencing savanna fuel dynamics. In a pine savanna, we established patches near and away from pines that were either burned or unburned in that year. Within patches, we assessed fungal communities and microbial decomposition of newly deposited litter. Soil variables and plant communities were also assessed as proximate drivers of fungal communities. Fungal communities, but not soil variables or vegetation, differed substantially between burned and unburned patches. Saprotrophic fungi dominated in unburned patches but decreased in richness and relative abundance after fire. Differences in fungal communities with fire were greater in litter than in soils, but unaffected by pine proximity. Litter decomposed more slowly in burned than in unburned patches. Fires drive shifts between fire-adapted and sensitive fungal taxa in pine savannas. Slower fuel decomposition in accordance with saprotroph declines should enhance fuel accumulation and could impact future fire characteristics. Thus, fire reorganization of fungal communities may enhance persistence of these fire-adapted ecosystems.

Journal of Hydrology, 2017

Understanding the long-term natural flow regime of rivers enables resource managers to more accur... more Understanding the long-term natural flow regime of rivers enables resource managers to more accurately model water level variability. Models for managing water resources are important in Florida where population increase is escalating demand on water resources and infrastructure. The Suwannee River is the second largest river system in Florida and the least impacted by anthropogenic disturbance. We used new and existing tree-ring chronologies from multiple species to reconstruct mean March-October discharge for the Suwannee River during the period 1550-2005 CE and place the short period of instrumental flows (since 1927 CE) into historical context. We used a nested principal components regression method to maximize the use of chronologies with varying time coverage in the network. Modeled streamflow estimates indicated that instrumental period flow conditions do not adequately capture the full range of Suwannee River flow variability beyond the observational period. Although extreme dry and wet events occurred in the gage record, pluvials and droughts that eclipse the intensity and duration of instrumental events occurred during the 16-19th centuries. The most prolonged and severe dry conditions during the past 450 years occurred during the 1560s CE. In this prolonged drought period mean flow was estimated at 17% of the mean instrumental period flow. Significant peaks in spectral density at 2-7, 10, 45, and 85year periodicities indicated the important influence of coupled oceanic-atmospheric processes on Suwannee River streamflow over the past four centuries, though the strength of these periodicities varied over time. Future water planning based on current flow expectations could prove devastating to natural and human systems if a prolonged and severe drought mirroring the 16th and 18th century events occurred. Future work in the region will focus on updating existing tree-ring chronologies and developing new collections from moisture-sensitive sites to improve understandings of past hydroclimate in the region.

Natural fires ignited by lightning strikes following droughts frequently are posited as the ecolo... more Natural fires ignited by lightning strikes following droughts frequently are posited as the ecological mechanism maintaining discontinuous tree cover and grass-dominated ground layers in savannas. Such fires, however, may not reliably maintain humid savannas. Pyrogenic shed leaves of savanna trees, however, might engineer fire characteristics in ways that maintain humid savannas through effects on ground layer plants. We explored our hypothesis in a high-rainfall, frequently-burned pine savanna in which the dominant tree, longleaf pine (Pinus palustris), produces resinous needles that become highly flammable when shed and dried. We postulated that pyrogenic needles should have much greater influence on fire characteristics at ground level, and hence post-fire responses of dominant shrubs and grasses, than other abundant fine fuels (shed oak leaves and grass culms). We further reasoned that these effects should increase with amounts of needles. We managed site conditions that affect fuels (time since fire, dominant vegetation), manipulated amounts of needles in ground layer plots, prescribed burned the plots, and measured fire characteristics at ground level. We also measured characteristics of ground layer oaks and grasses before, then 2 and 8 months after fires. We tested our hypotheses regarding effects of pyrogenic pine fuels on fire characteristics and vegetation regrowth and explored direct and indirect effects of fuels on fire characteristics and vegetation using a structural equation model. Pine needles influenced fire characteristics, elevating maximum temperature increases, durations of heating above 60 °C, and fine fuel consumption considerably above measurements when fuels only included other savanna plants. Presence of pine needles depressed post-fire numbers of oak stems and grass culms, especially in the interior of grass genets, as well as post-fire flowering of grasses. The structural equation model indicated strong direct and indirect pathways from pine needles to post-fire responses of oaks and grasses. The experimental field tests of hypotheses, bolstered by structural equation modeling, indicate pyrogenic fine fuels modify characteristics of prescribed fires at ground level, negatively affecting dominant ground layer oaks and grasses. Frequent fires fueled by pyrogenic needles should maintain humid savannas and generate spatial pyrodiversity that affects composition and dynamics of pine savanna ground layer vegetation

Fire Ecology, 2018

Understanding of historical fire seasonality should facilitate development of concepts regarding ... more Understanding of historical fire seasonality should facilitate development of concepts regarding fire as an ecological and evolutionary process. In

Tree-Ring Research, 2017

Few tree-ring based fire-history studies have been completed in pine ecosystems of the Southeaste... more Few tree-ring based fire-history studies have been completed in pine ecosystems of the Southeastern Coastal Plain, in part because of difficulties in finding old fire-scarred material. We propose specialized field methods that improve the likelihood of locating fire scars in dead trees (i.e. stumps, snags, and logs). Classic fire-history field methods developed in the southwestern United States involve targeting only trees with evidence of repeated external scarring, but we have found this approach to be less effective in our region given that trees without any external scarring may contain an abundance of buried scars. The buried scars occur primarily near the ground surface and can be sampled by collecting full cross-sections from the bases of old dead trees. We hope our insights foster further fire-history research in the Southeastern Coastal Plain.

258 Natural Areas Journal ABSTRACT: Fire regimes of pine savannas on barrier islands along the co... more 258 Natural Areas Journal ABSTRACT: Fire regimes of pine savannas on barrier islands along the coast of the Gulf of Mexico are unknown. We used dendrochronological techniques to precisely date scars from 52 slash pines (Pinus elliottii Engelm.) located within a 370 ha area on Little St. George Island, Florida, USA, an undeveloped barrier island. We determined the years and seasons of fires and turpentine operations, and mapped the spatial distribution of past fires. We identified five separate periods with different fire frequencies. Fires were frequent between 1866 and 1904 (mean fire-return interval of four years). No scars were found from 1905-1923, years during which turpentine operations (1912-1918) protected trees from fires. Frequent fires were again recorded from 1924-1945, (mean fire return interval of four years). During the period from 1945-1962, turpentine operations (1949-1956) again protected trees from fires, and no fire scars were found. The most recent period, 1963 ...

Southeastern coastal plain pine savannas lack direct evidence of past fire regimes. As a result, ... more Southeastern coastal plain pine savannas lack direct evidence of past fire regimes. As a result, uncertainty exists regarding the range of variation in frequency and seasonal timing of past fire regimes and the relative importance of anthropogenic and lightningignited fires. Characterization of past fire regimes is needed for effective restoration and management of these high-biodiversity ecosystems. I used dendrochronologically dated fire scars from stumps of old growth longleaf pines in a large coastal, mainland pine savanna and from dead slash pines on a small, coastal barrier island in north Florida to explore past fire regimes. In the mainland savanna, 71 different fires occurred from 1592-1883, based on a composite record of 109 fire scars from six fire-scarred trees. Almost all (95%) scars occurred during the middle growing season. Only three fires, all in the 1800s after European settlement of the local area, occurred during the dormant season. There was a 2-3 year fire retu...

Forest Ecology and Management

The reintroduction and maintenance of historical surface fire regimes are primary goals of ecolog... more The reintroduction and maintenance of historical surface fire regimes are primary goals of ecological restoration across many open, pine-dominated ecosystems in North America. In the United States, most of these ecosystems experienced long periods of fire exclusion in the 20th century, leaving few locations to serve as reference sites for ecological conditions associated with a continuous history of recurrent, low-severity fire. Here, we present a treering perspective of uninterrupted surface fire activity from three pine savanna sites in the Red Hills Region of northern Florida and southwestern Georgia, USA. Our sites include two old-growth stands of longleaf pine (Pinus palustris): the Wade Tract on Arcadia Plantation and the Larkin Tract on Millpond Plantation. We also sampled the largely second-growth mixed pine savannas of Tall Timbers Research Station. Documentary records for burning at these sites are limited to recent decades and are often incomplete, although regional land-use traditions and scattered historical records indicate frequent fire may have persisted through the 20th century to present day. Fire-scarred cross sections from externally-scarred stumps, dead trees, and live trees provided treering evidence of frequent fires occurring from the beginning of our fire-scar record in the late 19th century onward. Both fire frequency and seasonality were relatively consistent throughout time and among sites. Biennial and annual fire intervals were the most common. Most fire scars occurred in the dormant and earlyearlywood portions of the rings, indicating that these fires were human-set fires during the months of January to mid-April, before the main lightning-fire season. Our findings regarding post-settlement fire frequency are consistent with previous estimates of fire frequency during earlier centuries, resulting from lightning and Native American ignitions. We recommend that our sites be used as reference sites for restoration as they are among the relatively few areas in the United States with a continuous history of frequent low-severity fire without 20th century fire exclusion. Swetnam, 1994; Greenlee and Langenheim, 1990), southeastern longleaf pine (Pinus palustris) savannas (Stambaugh et al., 2011a; White and Harley, 2016), and in some oak-dominated ecosystems (Stambaugh et al., 2016, 2011b), among others. Efforts to deliberately suppress wildland fire and discourage intentional burning were led by the U.S. Forest Service and began in the early 1900s with the belief that wildland fires were destroying valuable forest resources, limiting tree regeneration, and endangering human lives (Covington and Moore, 1994; Donovan and Brown, 2007; Swetnam and Baisan, 1996). Although fire exclusion in the 20th century was widespread, fire persisted in some areas. Intentional fire (i.e., controlled burning, later called prescribed burning) continued in some fire-frequented natural

Oecologia

Frequent fires maintain nearly 50% of terrestrial ecosystems, and drive ecosystem changes that go... more Frequent fires maintain nearly 50% of terrestrial ecosystems, and drive ecosystem changes that govern future fires. Since fires are dependent on available plant or fine fuels, ecosystem processes that alter fine fuel loads like microbial decomposition are particularly important and could modify future fires. We hypothesized that variation in short-term fire history would influence fuel dynamics in such ecosystems. We predicted that frequent fires within a short-time period would slow microbial decomposition of new fine fuels. We expected that fire effects would differ based on dominant substrates and that fire history would also alter soil nutrient availability, indirectly slowing decomposition. We measured decomposition of newly deposited fine fuels in a Longleaf pine savanna, comparing plots that burned 0, 1, 2, or 3 times between 2014 and 2016, and which were located in either close proximity to or away from overstory pines (Longleaf pine, Pinus palustris). Microbial decomposition was slower in plots near longleaf pines and, as the numbers of fires increased, decomposition slowed. We then used structural equation modeling to assess pathways for these effects (number of fires, 2016 fuel/fire characteristics, and soil chemistry). Increased fire frequency was directly associated with decreased microbial decomposition. While increased fires decreased nutrient availability, changes in nutrients were not associated with decomposition. Our findings indicate that increasing numbers of fires over short-time intervals can slow microbial decomposition of newly deposited fine fuels. This could favor fine fuel accumulation and drive positive feedbacks on future fires.

New Phytologist , 2019