Water use and carbon exchange of red oak- and eastern hemlock-dominated forests in the northeastern USA: implications for ecosystem-level effects of hemlock woolly adelgid

Hadley, Julian L.; Kuzeja, Paul S.; Daley, Michael J.; Phillips, Nathan; Mulcahy, T. M.; Singh, S. K.

doi:10.1093/treephys/28.4.615

Cited by 59 publications

(46 citation statements)

References 26 publications

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“…Gaps in HEM data were filled using non-linear regression (Hadley et al 2008). For those times when neither partitioned nor gap-filled NEE data (Barr et al 2004, Amiro et al 2006 to estimate R e because it gave good agreement with available gap-filled values from HEM (Appendix: Fig.…”

Section: Ecosystem-scale Co 2 Measurementsmentioning

confidence: 99%

“…The longest time series of soil temperature at 10-cm depth in a forested area was collected at the Little Prospect Hill (LPH) eddy-covariance site, with half-hourly data available from 2002 to 2009 (herein T s10,LPH ; Hadley et al 2008). Red oak is the dominant tree species at the LPH site; this is the same species that dominates the EMS tower footprint, although the LPH stand is younger.…”

Section: Estimation Of R S At Eddy-covariance Sitesmentioning

confidence: 99%

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Soil respiration in a northeastern US temperate forest: a 22‐year synthesis

et al. 2013

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Abstract. To better understand how forest management, phenology, vegetation type, and actual and simulated climatic change affect seasonal and inter-annual variations in soil respiration (R s ), we analyzed more than 100,000 individual measurements of soil respiration from 23 studies conducted over 22 years at the Harvard Forest in Petersham, Massachusetts, USA. We also used 24 site-years of eddy-covariance measurements from two Harvard Forest sites to examine the relationship between soil and ecosystem respiration (R e ). R s was highly variable at all spatial (respiration collar to forest stand) and temporal (minutes to years) scales of measurement. The response of R s to experimental manipulations mimicking aspects of global change or aimed at partitioning R s into component fluxes ranged from À70% to þ52%. The response appears to arise from variations in substrate availability induced by changes in the size of soil C pools and of belowground C fluxes or in environmental conditions. In some cases (e.g., logging, warming), the effect of experimental manipulations on R s was transient, but in other cases the time series were not long enough to rule out long-term changes in respiration rates. Inter-annual variations in weather and phenology induced variation among annual R s estimates of a magnitude similar to that of other drivers of global change (i.e., invasive insects, forest management practices, N deposition). At both eddy-covariance sites, aboveground respiration dominated R e early in the growing season, whereas belowground respiration dominated later. Unusual aboveground respiration patterns-high apparent rates of respiration during winter and very low rates in mid-to-late summer-at the Environmental Measurement Site suggest either bias in R s and R e estimates caused by differences in the spatial scale of processes influencing fluxes, or that additional research on the hard-to-measure fluxes (e.g., wintertime R s , unaccounted losses of CO 2 from eddy covariance sites), daytime and nighttime canopy respiration and its impacts on estimates of R e , and independent measurements of flux partitioning (e.g., aboveground plant respiration, isotopic partitioning) may yield insight into the unusually high and low fluxes. Overall, however, this data-rich analysis identifies important seasonal and experimental variations in R s and R e and in the partitioning of R e above-vs. belowground. v www.esajournals.org 1

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Section: Ecosystem-scale Co 2 Measurementsmentioning

confidence: 99%

Section: Estimation Of R S At Eddy-covariance Sitesmentioning

confidence: 99%

Soil respiration in a northeastern US temperate forest: a 22‐year synthesis

et al. 2013

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“…Th is contrasts with studies that predicted signifi cant changes in water use due to the loss of hemlock canopies and a resulting change in soil water content. For example, Hadley et al (2008) measured water use in red oak (Quercus rubra L.) and hemlock forests in the U.S. Northeast and their data suggested that following an initial increase in soil water content due to reduced evapotranspiration, replacement of hemlock by hardwood species would probably decrease the summertime soil water content due to increased water use by hardwoods. used a combination of sap fl ow measurements and modeling to predict the impacts of HWA on transpiration and predicted a 30% decrease in total transpiration during the winter and spring following complete loss of hemlock.…”

Section: ) -------------P Input G P Ha −1 -------------mentioning

confidence: 99%

“…Although hemlock defoliation was occurring rapidly, the dense R. maximum evergreen understory maintained shaded conditions, which may have prevented changes in the soil temperature with time. For soil water content, increased water uptake by hardwood species (Hadley et al, 2008) may have off set decreased water uptake by hemlock. Additionally, predicted transpiration declines in winter and spring only, a time when soils are near fi eld capacity due to limited water use by hardwoods.…”

Section: ) -------------P Input G P Ha −1 -------------mentioning

confidence: 99%

Hemlock Infestation and Mortality: Impacts on Nutrient Pools and Cycling in Appalachian Forests

Knoepp

Vose

Clinton

et al. 2011

Soil Science Society of America Journal

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E astern hemlock is a major component of riparian forests in the southern Appalachian Mountains (Narayanaraj et al., 2010). As the dominant conifer in riparian areas, this species plays an important role in regulating nutrient cycling processes and climatic conditions in both terrestrial and aquatic environments (Ellison et al., 2005). Th e hemlock woolly adelgid (Homoptera: Adelgidae), an exotic pest, was introduced to the mid-Atlantic region of North America from Asia in the 1950s and has spread throughout most of the range of eastern hemlock, moving north toward Canada and to the southern Appalachians. Pontius et al. (2006) examined the mortality of eastern hemlock following infestation with HWA and found that some trees can live for >10 yr following infestation. From county-level data on the spread of HWA, Evans and Gregoire (2007) found the rate of spread in Pennsylvania and north was 8.13 km yr −1 , while the rate of spread in the south was greater: 15.6 km yr −1 . Th e diff erence was attributed to colder temperatures in the north. Morin et al. (2009) modeled the spread of HWA north and south. While they concurred that spread to the north was limited by temperature, they concluded that the rate of spread to the south and west was related to host density. Indeed, in the southern part of hemlock's natural range, infestations were fi rst observed in the early 2000s and the rate of spread and mortality have been much faster than observed in northern areas Nuckolls et al., 2009 Eastern hemlock [Tsuga canadensis (L.) Carrière] trees serve an important ecological role in riparian ecosystems in the southern Appalachians. Signifi cant hemlock mortality is occurring due to infestation by the hemlock woolly adelgid (HWA) (Adelges tsugae Annand), a non-native invasive pest. Our objective was to quantify the impacts of HWA and hemlock mortality on nutrient cycling pools and processes. In 2004, we established eight research plots in riparian areas with >50% basal area in hemlock and four reference plots in riparian areas without hemlock (hardwood). All hemlock plots were infested with HWA. In four of the hemlock plots, all hemlock trees were girdled to induce defoliation and rapid mortality. By fall 2006, there was 90 and 10% mortality in the girdled and nongirdled hemlock plots, respectively. Measurements included soil temperature and moisture, nutrient pools, N transformations, litterfall and forest fl oor amount and chemistry, and throughfall and soil solution chemistry. From 2004 to 2008, litterfall composition changed, with an initial increase in the hemlock needle percentage followed by a decline. Hemlock plots had cooler spring soil temperatures than hardwood plots. Hemlock plots had greater surface soil and forest fl oor total C than hardwood plots; soil C content did not change during the 4 yr of measurement. Th ere were no diff erences in N mineralization rates or soil solution N concentrations among treatments. Diff erences between litterfall and forest fl oor nutrient contents in hemlock and hardwood plots ...

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“…In the mosaic of eastern forests, stands of hemlock provide stark contrast to the matrix of deciduous and pine forests. In riparian areas, where they often dominate, hemlocks moderate stream flow and diurnal temperature fluxes (Ellison et al 2005, Hadley et al 2008.…”

Section: Introductionmentioning

confidence: 99%

A foundation tree at the precipice:Tsuga canadensishealth after the arrival ofAdelges tsugaein central New England

et al. 2012

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Abstract. Hemlock (Tsuga canadensis) plays a unique role in Eastern forests, producing distinctive biogeochemical, habitat, and microclimatic conditions and yet has begun a potentially irreversible decline due to the invasive hemlock woolly adelgid (Adelges tsugae; HWA) that causes foliar damage, crown loss, and mortality of host trees. Understanding the regional, landscape, site, and stand factors influencing HWA spread and impact is critical for predicting future landscape dynamics and directing effective management. Using aerial photographs, we documented hemlock distribution throughout central Massachusetts and subsampled 123 stands to examine the spatial pattern of HWA and its impact on tree vigor and mortality since its arrival in 1989. In the study region, over 86,000 ha of hemlock forest were mapped in 5,127 stands. White pine (Pinus strobus), red oak (Quercus rubra), red maple (Acer rubrum), and black birch (Betula lenta) were common overstory associates. Hemlock abundance increased from south to north, commonly on western and northwestern slopes. Average stand size was 55 ha, overstory basal area ranged from 23 to 55 m 2 ha À1 and overstory stem densities averaged 993 ha À1 .By 2004, 40% of sampled stands were infested, but most stands remained in good health overall; only 8 stands contained high HWA densities and only two had lost .50% overstory hemlock. Out of fifteen stand and landscape predictor variables examined, only latitude and winter climate variables were related to HWA density. Cold temperatures appear to be slowing the spread and impact of HWA at its northern extent as HWA infestation intensity and hemlock mortality and vigor were significantly correlated with average minimum winter temperature. Contrary to predictions, there was no regional increase in hemlock harvesting. The results suggest that regional HWA-hemlock dynamics are currently being shaped more by climate than by a combination of landscape and social factors. The persistence and migration of HWA continues to pose a significant threat regionally, especially in the northern portion of the study area, where hemlock dominates many forests.

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Water use and carbon exchange of red oak- and eastern hemlock-dominated forests in the northeastern USA: implications for ecosystem-level effects of hemlock woolly adelgid

Cited by 59 publications

References 26 publications

Soil respiration in a northeastern US temperate forest: a 22‐year synthesis

Soil respiration in a northeastern US temperate forest: a 22‐year synthesis

Hemlock Infestation and Mortality: Impacts on Nutrient Pools and Cycling in Appalachian Forests

A foundation tree at the precipice:Tsuga canadensishealth after the arrival ofAdelges tsugaein central New England

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