Isolating Individual Trees in a Savanna Woodland Using Small Footprint Lidar Data

Chen, Qi; Baldocchi, Dennis; Gong, Peng; Kelly, Maggi

doi:10.14358/pers.72.8.923

Cited by 476 publications

(409 citation statements)

References 20 publications

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“…Deciduous blue oaks (Quercus douglasii) dominate the savanna site with 144 stem per hectare in a 200 by 200 m sampling plot. Their average height is 9.41 ± 4.33 m, and their mean basal area is 0.074 ± 0.0869 m 2 (Chen et al 2006). The mean annual temperature is 16.3°C, and 559 mm of precipitation fall per year, as determined from over 30 years of data from a nearby weather station at Ione, California.…”

Section: Site Descriptionmentioning

confidence: 99%

Plant-soil interactions and acclimation to temperature of microbial-mediated soil respiration may affect predictions of soil CO2 efflux

Yuste

Baldocchi

2009

Biogeochemistry

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It is well known that microbial-mediated soil respiration, the major source of CO 2 from terrestrial ecosystems, is sensitive to temperature. Here, we hypothesize that some mechanisms, such as acclimation of microbial respiration to temperature and/or regulation by plant fresh C inputs of the temperature sensitivity of decomposition of soil organic matter (SOM), should be taken into account to predict soil respiration correctly. Specifically, two hypotheses were tested: (1) under warm conditions, temperature sensitivity (Q 10 ) and basal rates of microbial-mediated soil respiration (Bs 20, respiration at a given temperature) would be primarily subjected to presence/absence of plant fresh C inputs; and (2) under cold conditions, where labile C depletion occurred more slowly, microbial-mediated soil respiration could adjust its optimal temperatures to colder temperatures (acclimation), resulting in a net increase of respiration rates for a given temperature (Bs 20 ). For this purpose, intact soil cores from an oak savanna ecosystem were incubated with sufficient water supply at two contrasting temperatures (10 and 30°C) during 140 days. To study temperature sensitivity of soil respiration, short-term temperature cycles (from 5 to 40°C at 8 h steps) were applied periodically to the soils. Our results confirmed both hypotheses. Under warm conditions ANCOVA and likelihood ratio tests confirmed that both Q 10 and Bs 20 decreased significantly during the incubation. Further addition of glucose at the end of the incubation period increased Bs 20 and Q 10 to initial values. The observed decrease in temperature sensitivity (Q 10 ) in absence of labile C disagrees with the broadly accepted fact that temperature sensitivity of the process increases as quality of the substrate decreases. Our experiment also shows that after 2 months of incubation cold-incubated soils doubled the rates of respiration at cold temperatures causing a strong increase in basal respiration rates (Bs 20 ). This suggest that microbial community may have up-regulated their metabolism at cold conditions (cold-acclimation), which also disagrees with most observations to date. The manuscript discusses those two apparent contradictions: the decrease in temperature sensitivity in absence of labile C and the increase in microbial-mediated soil respiration rates at cold temperatures. While this is only a case study, the trends observed could open the controversy over the validity of current soil respiration models.

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Section: Site Descriptionmentioning

confidence: 99%

Plant-soil interactions and acclimation to temperature of microbial-mediated soil respiration may affect predictions of soil CO2 efflux

Yuste

Baldocchi

2009

Biogeochemistry

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“…Since the early to mid 1980s, several studies using full waveform sensors have been performed for forest inventory [8], merchantable timber volume estimation [9], and forest canopy characterization [10]. Recently, several researchers have applied discretely emitted laser pulses for the individual-and stand-level TH estimation [5,[11][12][13] and height-based timber volume estimates [14,15].…”

Section: Introductionmentioning

confidence: 99%

Estimating Crown Variables of Individual Trees Using Airborne and Terrestrial Laser Scanners

Jung¹,

Kwak

Park

et al. 2011

Remote Sensing

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Abstract:In this study, individual tree height (TH), crown base height (CBH), crown area (CA) and crown volume (CV), which were considered as essential parameters for individual stem volume and biomass estimation, were estimated by both an airborne laser scanner (ALS) and a terrestrial laser scanner (TLS). These ALS-and TLS-derived tree parameters were compared because TLS has been introduced as an instrument to measure objects more precisely. ALS-estimated TH was extracted from the highest value within a crown boundary delineated with the crown height model (CHM). The ALS-derived CBH of individual trees was estimated by k-means clustering method using the ALS data within the boundary. The ALS-derived CA was calculated simply with the crown boundary, after which CV was computed automatically using the crown geometric volume (CGV). On the other hand, all TLS-derived parameters were detected manually and precisely except the TLS-derived CGV. As a result, the ALS-extracted TH, CA, and CGV values were underestimated whereas CBH was overestimated when compared with the TLS-derived parameters. The coefficients of determination (R

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“…We reviewed 24 peer-reviewed papers covering this research (table 1). Some papers focus on oak woodlands and savannas (Chen et al 2006;Chen et al 2007) and coast redwood (Chen 2010;Gonzalez et al 2010), but the majority focus on the conifer and mixed-conifer forests in the Sierra Nevada. The Sierra National Forest is the forest that has been most often remotely sensed in California; nine of the papers we reviewed focused on this forest; it has been mapped with large-and small-footprint, discrete and waveform Lidar, as well as with Landsat, Quickbird and other sensors.…”

Section: Lidar Use In California Forestsmentioning

confidence: 99%

“…The ability to delineate individual trees from a Lidar point cloud has been proven for heterogeneous and complex forests such as oak savanna (Chen et al 2006;Chen et al 2007) and mixed-conifer stands (Li et al 2012). Delineating the individual trees is done by segmenting the Lidar-derived canopy height modelthe raster image interpolated from Lidar points depicting the top of the vegetation canopy (e.g., Chen et al 2006) -by delineating the trees directly from the point cloud (Li et al 2012) or by a combination of these methods (Jakubowski, Li et al 2013).…”

Section: Lidar Use In California Forestsmentioning

confidence: 99%

“…Delineating the individual trees is done by segmenting the Lidar-derived canopy height modelthe raster image interpolated from Lidar points depicting the top of the vegetation canopy (e.g., Chen et al 2006) -by delineating the trees directly from the point cloud (Li et al 2012) or by a combination of these methods (Jakubowski, Li et al 2013). After accurate segmentation, relationships can be derived between Lidarand field-measured structural attributes such as tree height, crown diameter and canopy base height, which are directly measured, and basal area, diameter at breast height, wood volume, biomass and species type, which are derived by correlations (Chen et al 2006;Chen et al 2007).…”

Section: Lidar Use In California Forestsmentioning

confidence: 99%

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Mapping forests with Lidar provides flexible, accurate data with many uses

Kelly¹,

Tommaso²

2015

Cal Ag

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Isolating Individual Trees in a Savanna Woodland Using Small Footprint Lidar Data

Cited by 476 publications

References 20 publications

Plant-soil interactions and acclimation to temperature of microbial-mediated soil respiration may affect predictions of soil CO2 efflux

Plant-soil interactions and acclimation to temperature of microbial-mediated soil respiration may affect predictions of soil CO2 efflux

Estimating Crown Variables of Individual Trees Using Airborne and Terrestrial Laser Scanners

Mapping forests with Lidar provides flexible, accurate data with many uses

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