Gerald E. Lang’s research while affiliated with West Virginia University and other places

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Publications (41)


FIGURE 1. Gerald Lang surveys his new plot of approximately 90-year-old secondary forest in 1968. Photo courtesy Smithsonian Institution.
Dynamics of a Late-Stage Secondary Forest on Barro Colorado Island
  • Chapter
  • Full-text available

November 2024

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15 Reads

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7 Citations

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Gerald E. Lang

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Dennis H. Knight

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p dir="ltr">Long-term late-stage changes in the composition and structure of a late-stage secondary forest were quantified by repeated censuses of a 1.5-ha plot starting in 1968. When first established, the plot lacked canopy gaps and was dominated by Gustavia superba. During the following 46 years, canopy gaps have been numerous, small in area, and clustered in a portion of the plot. The dominance by G. superba has declined, but the number of tree species has remained relatively constant (maximum, 129). Stem density declined largely because recruitment was low relative to nearby old-growth forest. BrayCurtis dissimilarity in tree species composition with nearby old-growth forest decli from 0.70 in 1968 to 0.57 in 2014, with most of the decline occurring before 2000. Tree basal area has fluctuated, which might be a characteristic of late-stage secondary forest as large pioneers die off. Much work remains to be done on tree growth rates, the dynamics of recruitment and mortality, and the gradual transition to the species composition of old-growth forest. </p

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Organic matter and major elements of the forest floors and soils in subalpine balsam fir forests

February 2011

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71 Reads

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23 Citations

Forest floors, fallen branches and fallen tree boles were sampled in 13 balsam fir (Abiesbalsamea (L.) Mill.) stands in the subalpine zone (1220–1450 m) of the White Mountains in New Hampshire, U.S.A. These 13 stands were distributed in three sites of contrasting exposure, slope, and rockiness. Soil pits were excavated in three of the stands representing each of the three sites. The ash-free dry weights and major elemental contents of the forest floor and dead wood were compared along chronosequences following natural disturbances, between sites, and with other forest types. No significant trends in these components were found along chronosequence comparisons. For sites that are dissimilar in terms of physical position on the landscape and in the appearance of the trees, compensating biotic and abiotic factors apparently underlie the convergence in forest floor and soil characteristics, thereby eliminating site differences as well. The forest floor is massive; ash-free dry weight averages 92 200 kg•ha−1. Total soil profile ash-free weight is 323 600 kg•ha−1. The forest floor and mineral soil horizons are unusually rich in nitrogen and phosphorus, with weighted average ash-free nitrogen and phosphorus concentrations of 2.42 and 0.23%, respectively, in the forest floor. Total nitrogen and phosphorus contents of the forest floor are 2300 and 217 kg•ha−1, respectively. The weight and nitrogen and phorphorus contents of the fir forest floor are greater than that found in other regional forests and coniferous forests in general.


Tissue chemistry of Abiesbalsamea and Betulapapyrifera var. cordifolia from subalpine forests of northeastern United States

February 2011

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52 Reads

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11 Citations

The concentrations of N, P, Ca, Mg, K, and Na are reported for leaf, twig, wood, bark, and root tissues for balsam fir (Abiesbalsamea (L.) Mill.) and heart-leaved paper birch (Betulapapyrifera var. cordifolia (Reg.) Fernald), the dominant tree species in subalpine forests of the Appalachian Mountains of northeastern United States. The N concentrations of birch leaves (2.79%) and especially current fir needles (2.48%) were high relative to comparable data in the literature. Ca and Mg concentrations of fir needles and birch leaves were relatively low, while the concentrations of P and K were typical. These chemical relationships generally, but not consistently, reflected the nutrient status of the forest floor and mineral soil in this environment. We believe that the foliar nitrogen values are partly a result of the chemical nature of the precipitation and cloud droplets impinging on these forests.


Gaps in our understanding of tree diversity in a tropical secondary forest

August 2010

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10 Reads

Background/Question/Methods I was an undergraduate student at UCSB in the 1970s, and Professor Connell's course in general ecology made at least two lasting impressions on me. The first was the way he carefully and critically presented the now well-recognized intermediate disturbance model of diversity. The second was the value of data obtained from long-term observations and experiments in permanent plots. Several years later I had an opportunity for fieldwork on Barro Colorado Island, Panama. There, in 1968, Knight and Lang had established a 1.5 ha permanent plot in 60 year old (at the time) secondary, lowland tropical forest, and they had periodically recorded abundance, distribution, size, recruitment and mortality of all plants greater then 2.5 cm diameter. I decided to extend the study by periodically mapping the dynamics of canopy gaps, i.e., a small-scale disturbance, and relate gaps to forest composition. The study is interesting because the whole forest was regenerating from agriculture, i.e., an extreme disturbance, during construction of the Panama Canal. Results/Conclusions There were no canopy gaps in 1968; however, gaps increased in frequency and size as the forest matured. Canopy gaps were spatially clustered, and thus there were gap-prone and gap-free parts of the plot. Occasional windstorms created the largest sized gaps. Small gaps (< 100 m2) were colonized quickly by in-growth of branches from surrounding trees and by advanced regeneration. Temporal trends in the forest include decrease density of individuals and minor change in diversity. Whether the various scales of disturbance, low recruitment rates, and slow growth rates in this forest characterize all maturing secondary forest is unclear.


Table 3 Potential Anaerobic Carbon Mineralization via Methanogenesis and Sulfate Reduction" 
Methane production in contrasting wetland sites—Response to organic-Chemical Components of peat and to sulfate reduction

January 2009

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281 Reads

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105 Citations

Geomicrobiology

Controls of methane production were studied in six contrasting Appalachian wetland sites using methane-production measurements of slurried peat. The sites differed widely in plant community composition and in rates of methane production. Three controlling factors of methane production were examined: organic-chemical components of the peat, concentrations of dissolved organic carbon, and rates of sulfate reduction. Peats from shrub-dominated sites contained mostly acid-insoluble organic matter, which was presumably recalcitrant to microbial decomposition. In contrast, peats from moss and sedge-dominated sites contained mostly acid-soluble organic matter, which was presumably labile. Differences in the organic-chemical components of the peat can explain about 50% of the variation in rates of methane production among samples from the sites. Rates of sulfate reduction were relatively high, despite low in situ concentrations of dissolved sulfate, sulfate reduction was not well correlated with rates of methane production, nor were concentrations of dissolved organic carbon. Amendments of methanol and trimethylamine to peat samples from any individual site did not stimulate rates of methane production. In general, glucose, hydrogen, and acetate amendments stimulated rates of methane production. Sulfate amendments that stimulated sulfate reduction also inhibited methane production by 90%; however, reversal of the inhibition was achieved by acetate and hydrogen amendments. Control of methane production in these organic-rich wetlands is related more to organic-chemical components of the peat than to the activity of coincident sulfate-reducing bacteria.


The chemistry and flux of throughfall and stemflow in subalpine balsam fir forest

June 2006

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31 Reads

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54 Citations

The fluxes of water and chemicals in throughfall and stemflow of three subalpine balsam fir forests of New Hampshire, USA were measured. The three fir stands were highly dissimilar in structural characteristics, serving as a test of the importance of stand structure on these fluxes. The sum of throughfall and stemflow water exceeded incident precipitation by more than 18 to 29%. This difference was attributed to the unmeasured input of cloud droplets impacted on canopy surfaces. The principal effect of stand structure was a positive relationship between stand density and stemflow. The flux of NH+4, Na+, SO=4 and Cl− in stemflow was also significantly higher in the most dense stand. The fir canopy effects on capture and chemical alterations of elements were compared with analogous behavior of a nearby deciduous forest. There were several major contrasts, the most striking of which was a flux/canopy pool ratio (leachability index) in the hardwood canopy ranging from two to 32 times higher than in the fir canopy.


Table 2 . Canopy gap regime in a secondary forest on Barro Colorado Island, Republic of Panama.
The Canopy Gap Regime in a secondary neotropical forest in Panama

August 1995

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104 Reads

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75 Citations

Journal of Tropical Ecology

We mapped the occurrence of canopy gaps periodically between 1978 and 1990 in a 1.5 ha study plot within a 70-year-old (in 1978) Neotropical forest on Barro Colorado Island (BCI), Republic of Panama. The total area of the forest under canopy gaps in the plot averaged 4.3% (3.1% to 5.7%, 95% CI). There was high year-to-year variability in the rate of new gap formation. On the basis of repeated observations for four yearly intervals, the annual rate of new gap formation ranged from 0.45% y−1 to 6.5% y−1. Most gaps were small. The mean size of individual gaps originally was 79 m2 (range: 8-604 m2). However, large gaps (≥150 m2) occurred more frequently than expected for a secondary forest on BCI. Gaps closed rapidly the first year after formation but the rate of closure slowed thereafter. Despite the absence of any obvious environmental gradients, gaps were spatially clustered. Even in this relatively small plot, there seemed to be distinct gap-prone and gap-free areas.


TABLE 2 . Spearman's Rank Correlation Coefficients for Correlation Between Net CH4 Flux From Big Run Bog, West Virginia, and Environmental Variables
CO2 and CH4 dynamics of a Sphagnum-dominated peatland in West Virginia

June 1993

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143 Reads

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30 Citations

Climatic change could bring about net release of carbon dioxide (CO2) and/or methane (CH4) from the deep peat deposits in northern peatlands into the atmosphere. To provide insight into this hypothesis, we studied net flux of CO2 and CH4 in Big Run Bog, West Virginia, which has a temperate climate, making it an analog to evaluate climatic change imposed on more northern counterparts. Net CO2 flux ranged from −564 to 300 mg C m−2 hr−l. Measurements made during the nighttime showed that net CO2 flux increased exponentially with increasing air temperature, whereas CO2 sequestration increased with increasing air temperature for daytime measurements. Net CH4 flux ranged from −2.3 to 70 mg C m−2 hr−l, showing no consistent relationship to temperature or water table level. Net efflux for both CO2 and CH4 was tenfold higher from peat cores incubated in a greenhouse compared to field measurements. Even cores drained and allowed to dry for 8 days showed moderately high flux for both CO2 and CH4. The enhanced efflux seemed to be due to altered hydrology rather than increased rates of bacterial production (measured in anoxic, in vitro incubations) which could account for only 50% of the whole-core flux. Presumably the remainder was CO2 and CH4 stored in the peat cores at the time of collection. Overall, the results suggest that a temperate climate imposed on northern peatlands could mobilize stored carbon and increase CO2 and CH4 efflux into the troposphere. Studies involving peat cores must insure that CO2 and CH4 dynamics measured in vitro mimic those in situ.


TABLE 2 . Selected Environmental Conditions on Each Sampling Date
Methane fluxes in wetland and forest soils, beaver ponds, and low-order streams of a temperate forest ecosystem

January 1991

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209 Reads

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79 Citations

Journal of Geophysical Research Atmospheres

This study was conducted to determine whether temperate wetlands and forests play important roles in the global balances of atmospheric methane. Flux measurements for methane in several different wetland, forest, and open-water (e.g., beaver pond and low-order stream) sites were determined using collection chambers placed over the soil- or water-air interface. All of the sites were located in the Appalachian Mountain region of West Virginia and western Maryland. Between June 1987 and April 1989 the wetland sites acted as small sources of atmospheric methane, with emission rates for methane usually lower than 200 mg CH4/sq m per day; consumption of atmospheric methane in the wetland soils was observed frequently.


Citations (39)


... Given that tree lifespans regularly exceed 150 years (Hartshorn, 1978;Chambers et al., 1998), the burned and potentially cleared forests of BCI and Gigante may be only several generations old. Successional trajectories of species composition in tropical forests commonly exceed 100 years (Poorter et al., 2016;Rozendaal et al., 2019;Poorter et al., 2021;Yavitt et al., 2024). Our work highlights how paleoecological and archaeological techniques and datasets can advance our understanding of past disturbances in relation to the later stages of forest succession. ...

Reference:

The Fire History of Old-Growth Forest in the Barro Colorado Nature Monument, Panama
Dynamics of a Late-Stage Secondary Forest on Barro Colorado Island

... Long-term meteorological data from nearby weather stations within the HBEF were used to calculate variables describing climate conditions expected to influence the energy budget of a snowpack (Fig 1). For temperature variables, we used the nearest weather station with a temperature record that matched the snow record in duration and adjusted the daily average temperature [53] up or down using a lapse rate of 0.0065˚C/m [54]. For SC2, the nearest station was weather station 1, located 77 m downslope and with a similar aspect. ...

Temperature and Evapotranspiration Gradients of the White Mountains, New Hampshire, U.S.A.
  • Citing Article
  • June 2018

Arctic and Alpine Research

... Input-output budgets are relevant because they give information about the N status of forests (section 3.1). Research on N leaching in relation to its potential impact on soil acidification already gained attention in the 1970s (e.g., Borman et al. 1977;Ugolini et al. 1977;Cronan et al. 1978). Those studies showed that the N cycle is generally closed (input by litterfall and mineralization equals uptake) in relatively unpolluted areas. ...

Forest Floor Leaching: Contributions from Mineral, Organic, and Carbonic Acids in New Hampshire Subalpine Forests
  • Citing Article
  • April 1978

Science

... Phenology, commonly defined as changes that occur in an organism due to seasonal variations, is one of the most noticeable and earliest attributes through which an organism reacts to the changing climate (Wieder et al. 1984;Parmesan 2006). Studies conducted throughout the globe have reported various changes in phenological patterns owing to several potential influencing factors in different parts of the world (Sparks et al. 2000;Menzel 2003;Parmesan 2006), such as changes in urban environment (Luo et al. 2007), soil temperature, moisture, pH (Ranjitkar et al. 2013), nutrient content (Smith et al. 2012), water potential (Tewari et al. 2016), rainfall (Singh 2014), photoperiod (Ziello et al. 2009;Basnett et al. 2019), elevation (Ziello et al. 2009;Bucher and Römermann 2020;Ahmad et al. 2021, Malsawmkima andSahoo 2021), age (Yelemou et al. 2009), etc. ...

FLOWERING PHENOLOGY AT BIG RUN BOG, WEST VIRGINIA
  • Citing Article
  • February 1984

American Journal of Botany

... Although these species were preselected because of their durability and some decay-resistant species were identified (e.g., Handroanthus guayacan), only 34% of stakes survived the 13-year study period. Two later studies quantified communitywide rates of natural wood decomposition in situ in the BCI forest, estimating residence times of 2-10 years for standing dead trees using various methods (Lang and Knight, 1979;Gora et al., 2019a). The decomposition rates of standing woody debris reported in these two studies are among the highest reported in any forest. ...

Decay Rates for Boles of Tropical Trees in Panama
  • Citing Article
  • December 1979

Biotropica

... This pattern was confirmed by lidar data covering the island's entire 1,500 ha in 2009, which showed that larger gaps were associated with old-growth forest and gentle slopes, whereas the fraction of area in gaps was also correlated with soil and aspect (Lobo and Dalling, 2013). Analyses of repeat drone photogrammetry data for 2015-2020 showed that gap formation rates were higher in old-growth than in secondary forest and further showed that gap formation varied almost four-fold across BCI, with significant effects of geology, soils, and topography (Cushman et al., 2022; for studies on gaps in secondary forest, see Lang and Knight, 1983;Yavitt et al., 1995Yavitt et al., , 2024. ...

Tree Growth, Mortality, Recruitment, and Canopy Gap Formation during a 10-year Period in a Tropical Moist Forest
  • Citing Article
  • October 1983

... Thus, aspect is likely a greater influence on the microclimate of the lateral gradient (Fig. 1). Some studies suggest that aspect plays a role in influencing lichen communities, specifically with greater frequencies, diversity, or cover of epiphytic species on the north aspect, where microclimatic conditions are cooler and more humid, and where sun exposure is lower (Gough 1975;Lang et al. 1980;Yarranton 1972). ...

Structure and Biomass Dynamics of Epiphytic Lichen Communities of Balsam Fir Forests in New Hampshire

... Light was accounted for by solar radiation (Austin & Van Niel, 2011). Temperature is primarily accounted for by elevation, as there is a strong relationship between elevation and temperature in our study area (Reiners et al., 1984;Sabo, 1980). Temperature is also correlated with TWI (Meineri et al., 2015) and solar radiation (Ashcroft, 2006). ...

Temperature and Evapotranspiration Gradients of the White Mountains, New Hampshire, U.S.A.

Arctic and Alpine Research

... Summers are warm and wet (mean July temperature and precipitation are 19°C and 105 mm, respectively), whereas winters are cold and drier (mean January temperature and precipitation are À9°C and 54 mm, respectively), with most winter precipitation falling as snow. Forest composition changes with elevation: northern hardwoods occur below 750 m a.s.l., sprucefir at 750-1200 m, balsam fir at 1200-1400 m, and alpine tundra above 1400 m (Reiners and Lang 1979). The southern and southeastern flanks of Mount Moosilauke currently are owned by Dartmouth College; the rest of the mountain is part of the White Mountain National Forest. ...

Vegetational Patterns and Processes in the Balsam Fir Zone, White Mountains New Hampshire

... It is particularly important in the nutrient budget of tropical forest ecosystems on nutrientpoor soils, where vegetation depends on recycling of nutrients contained in the plant detritus (Singh, 1968). Many reports suggested that density, basal area, age structure (Stohlgren, 1988), altitude (Reiners and Lang, 1987), latitude (Bray and Gorham, 1964) and season are factors that strongly influence litterfall dynamics in natural forests. Soil fertility, soil-water retention and species composition are important within the same climate range (Facelli and Pickett, 1991). ...

Changes in Litterfall Along a Gradient in Altitude