An eddy covariance mesonet to measure the effect of forest age on land–atmosphere exchange

Goulden, Michael L.; Winston, G.; McMillan, Andrew M. S.; Litvak, M. E.; Read, E.; Rocha, A. V.; Elliot, J. Rob

doi:10.1111/j.1365-2486.2006.01251.x

Cited by 177 publications

(116 citation statements)

References 64 publications

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“…Despite the power of this approach, relatively few paired studies have addressed the roles of the presence/absence of forests on surface energy fluxes using comparative studies (Denmead, 1969;Eugster et al, 2000;Baldocchi et al, 2004;Juang et al, 2007;Rotenberg and Yakir, 2010). More often, scientists have tracked the effects of land use change on energy exchange using measurements across broad ecological gradients that may experience different weather and soils Lee et al, 2011;Krishnan et al, 2012) or across a chronosequence following disturbance (Amiro et al, 2006;Goulden et al, 2006).…”

Section: The Role Of This Study In Conjunction With the Literaturementioning

confidence: 99%

How will land use affect air temperature in the surface boundary layer? Lessons learned from a comparative study on the energy balance of an oak savanna and annual grassland in California, USA

Baldocchi¹,

Ma²

2013

Tellus B: Chemical and Physical Meteorology

104

117

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A B S T R A C TWe investigated the effect of land use on differences in air temperature. We based our analysis on a decade of weather and energy flux measurements, collected over two contrasting landscapes, an oak savanna and an annual grassland, growing under the same climate conditions. Over the decade, the daily-averaged, potential air temperature above the aerodynamically rougher and optically darker oak savanna was 0.58C warmer than that above the aerodynamically smoother and optically brighter annual grassland. However, air temperature differences were seasonal. Smallest differences in potential air temperature occurred towards the end of spring, when much of the soil moisture reservoir was depleted. Largest differences in potential air temperature occurred during the winter rain season when the grass was green and transpiring and when the trees were senescent or deciduous. To understand the effect of land use on the local climate, we examined the concomitant changes in net radiation, sensible and latent heat exchange, the aerodynamic roughness (R a ), the surface resistance to water transfer (R s ), aerodynamic surface temperature and the growth of the planetary boundary layer, with measurements and model computations. Overall, these biophysical variables provide us with mechanistic information to diagnose and predict how changes in air temperature will follow changes in land use or management. In conclusion, land use change is responsible for having a marked impact on the local climate of a region. At the local level, the change in the surface energy balance, towards a darker and rougher surface, will produce an additive increment to climate warming induced by a greater greenhouse gas burden in the atmosphere.

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Section: The Role Of This Study In Conjunction With the Literaturementioning

confidence: 99%

How will land use affect air temperature in the surface boundary layer? Lessons learned from a comparative study on the energy balance of an oak savanna and annual grassland in California, USA

Baldocchi¹,

Ma²

2013

Tellus B: Chemical and Physical Meteorology

104

117

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“…[8]. Net Ecosystem Production (NEP) from flux tower measurements was partitioned into Gross Ecosystem Production (GEP) and ecosystem respiration [9,13]. We computed the daytime daily average incident photosynthetically active radiation (PARi) and GEP throughout the full 2013 year and examined these fluxes for the days during the week of the campaign at half hour intervals for the time period between 09:30 and 15:30, to represent the fluxes during the flights.…”

Section: Flights and Ground Supportmentioning

confidence: 99%

The 2013 FLEX—US Airborne Campaign at the Parker Tract Loblolly Pine Plantation in North Carolina, USA

Middleton¹,

Rascher

Corp

et al. 2017

Remote Sensing

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Abstract:The first European Space Agency (ESA) and NASA collaboration in an airborne campaign to support ESA's FLuorescence EXplorer (FLEX) mission was conducted in North Carolina, USA during September-October 2013 (FLEX-US 2013) at the Parker Tract Loblolly Pine (LP) Plantation (Plymouth, NC, USA). This campaign combined two unique airborne instrument packages to obtain simultaneous observations of solar-induced fluorescence (SIF), LiDAR-based canopy structural information, visible through shortwave infrared (VSWIR) reflectance spectra, and surface temperature, to advance vegetation studies of carbon cycle dynamics and ecosystem health. We obtained statistically significant results for fluorescence, canopy temperature, and tower fluxes from data collected at four times of day over two consecutive autumn days across an age class chronosequence. Both the red fluorescence (F685) and far-red fluorescence (F740) radiances had highest values at mid-day, but their fluorescence yields exhibited different diurnal responses across LP age classes. The diurnal trends for F685 varied with forest canopy temperature difference (canopy minus air), having a stronger daily amplitude change for young vs. old canopies. The Photochemical Reflectance Index (PRI) was positively correlated with this temperature variable over the diurnal cycle. Tower measurements from mature loblolly stand showed the red/far-red fluorescence ratio was linearly related to canopy light use efficiency (LUE) over the diurnal cycle, but performed even better Remote Sens. 2017, 9, 612; doi:10.3390/rs9060612www.mdpi.com/journal/remotesensing Remote Sens. 2017, 9, 612 2 of 31 for the combined morning/afternoon (without midday) observations. This study demonstrates the importance of diurnal observations for interpretation of fluorescence dynamics, the need for red fluorescence to understand canopy physiological processes, and the benefits of combining fluorescence, reflectance, and structure information to clarify canopy function versus structure characteristics for a coniferous forest.

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“…3b). This is because the standing dead trees in the recently burnt site 17 partially mask winter snow cover and enhance turbulent mixing year round. The temperate site cluster (Fig.…”

mentioning

confidence: 99%

Observed increase in local cooling effect of deforestation at higher latitudes

Lee

Goulden

Hollinger

et al. 2011

Nature

Self Cite

599

715

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Deforestation in mid-to high latitudes is hypothesized to have the potential to cool the Earth's surface by altering biophysical processes [1][2][3] . In climate models of continental-scale land clearing, the cooling is triggered by increases in surface albedo and is reinforced by a land albedo-sea ice feedback 4,5 . This feedback is crucial in the model predictions; without it other biophysical processes may overwhelm the albedo effect to generate warming instead 5 . Ongoing land-use activities, such as land management for climate mitigation, are occurring at local scales (hectares) presumably too small to generate the feedback, and it is not known whether the intrinsic biophysical mechanism on its own can change the surface temperature in a consistent manner 6,7 . Nor has the effect of deforestation on climate been demonstrated over large areas from direct observations. Here we show that surface air temperature is lower in open land than in nearby forested land. The effect is 0.85 6 0.44 K (mean 6 one standard deviation) northwards of 456 N and 0.21 6 0.53 K southwards. Below 356 N there is weak evidence that deforestation leads to warming. Results are based on comparisons of temperature at forested eddy covariance towers in the USA and Canada and, as a proxy for small areas of cleared land, nearby surface weather stations. Night-time temperature changes unrelated to changes in surface albedo are an important contributor to the overall cooling effect. The observed latitudinal dependence is consistent with theoretical expectation of changes in energy loss from convection and radiation across latitudes in both the daytime and night-time phase of the diurnal cycle, the latter of which remains uncertain in climate models 8 .The latitudinal gradient of land-use impact is evident in the comparison of the surface air temperature recorded at FLUXNET (www.fluxnet.ornl.gov) forest towers 9 (Supplementary Table 1 and Supplementary Fig. 1) and surface weather stations in North America (Fig. 1a). Here we use the surface stations as proxies for cleared land. In accordance with the requirement of the World Meteorological Organization, these stations are located in open grassy fields that have biophysical characteristics similar to those of open land, such as being covered by snow in northern latitudes in the winter 10 . Latitude accounts for 31% of the variations in the temperature difference DT between the forest sites and the adjacent open lands (number of site pairs n 5 37). The rate of change in DT with latitude is 20.070 6 0.010 K per degree (mean 6 one standard error, s.e., P , 0.005). At these sites, the annual net all-wave radiation R n

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An eddy covariance mesonet to measure the effect of forest age on land–atmosphere exchange

Cited by 177 publications

References 64 publications

How will land use affect air temperature in the surface boundary layer? Lessons learned from a comparative study on the energy balance of an oak savanna and annual grassland in California, USA

How will land use affect air temperature in the surface boundary layer? Lessons learned from a comparative study on the energy balance of an oak savanna and annual grassland in California, USA

The 2013 FLEX—US Airborne Campaign at the Parker Tract Loblolly Pine Plantation in North Carolina, USA

Observed increase in local cooling effect of deforestation at higher latitudes

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