Object-based Image Mapping of Conifer Tree Mortality in San Diego County based on Multitemporal Aerial Ortho-imagery

Freeman, Mary Pyott; Stow, DoulasA.; Roberts, DarA.

doi:10.14358/pers.82.7.571

Cited by 11 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This may prove challenging because of the difficulty in identifying a suitable representation of replicate study units at the landscape level, where "every landscape is different" and it can be problematic to control experimentally for confounding sources of environmental variation (Hargrove & Pickering, 1992). However, mapping of tree crowns within replicate tree line landscapes could be made more efficient using automated approaches to tree crown detection and delineation (Freeman, Stow, & Roberts, 2016 is generally more drought tolerant and can extend to lower elevations, whereas the pinyon pine is more cold tolerant (West, 1999).…”

Section: Differences In Pattern and Structure Among Upper And Lowermentioning

confidence: 99%

Upper and lower treeline biogeographic patterns in semi‐arid pinyon‐juniper woodlands

Garbarino

Malandra

Dilts

et al. 2020

Journal of Biogeography

View full text Add to dashboard Cite

Aim Upper and lower treelines are particularly exposed to a changing climate. It has been hypothesized that upper treelines are constrained by growing season temperature, whereas lower tree lines are water limited. We expect different causal mechanisms of upper versus lower tree line formation to generate distinct patterns of spatial heterogeneity. Here, we compare dynamics, spatial patterns and shape complexity of upper and lower tree lines of semi‐arid pinyon‐juniper woodlands. Location Toiyabe Range of the Nevada Great Basin (western US). Taxon Pinus monophylla Torr. & Frém. and Juniperus osteosperma (Torr.) Methods Within 20 sample plots (10 along the upper and 10 along the lower tree line), we mapped tree canopies through photointerpretation of high‐resolution imagery. We performed point pattern analyses to compare the spatial arrangement of trees and used LANDSAT 30‐year time series and NDVI to understand the vegetation dynamics of these ecotones. We adopted the surface roughness method to measure tree line shape complexity. Results Lower tree lines were denser and showed a stronger trend of increasing NDVI change over the 1984–2015 period. Trees at the lower tree line were more strongly aggregated than at the upper tree line at spatial scales ranging from 15 to 65 meters. Shape complexity was higher at upper tree lines, expressed by a higher mean surface roughness; however, the spatial structures of upper and lower tree lines were similar. Main conclusions Upper tree line expansion of pinyon‐juniper woodlands in the study area has been limited and highly variable, but lower tree line downslope expansion into adjacent shrub steppe vegetation was evident. The expected difference between energy‐ and water‐limited tree lines did not manifest in the observed spatial structures. Differences in tree line shape complexity were not significant, although lower tree lines exhibited less complex shapes, likely because they have been more strongly influenced by anthropogenic factors.

show abstract

Section: Differences In Pattern and Structure Among Upper And Lowermentioning

confidence: 99%

Upper and lower treeline biogeographic patterns in semi‐arid pinyon‐juniper woodlands

Garbarino

Malandra

Dilts

et al. 2020

Journal of Biogeography

View full text Add to dashboard Cite

show abstract

“…Safonova et al (2019)) or direct detection of coarse woody debris (e.g. Freeman et al (2016)) from high-resolution optical imagery. Currently, most approaches dealing with fallen trees focus on either analyzing groupings of pixels without a one-to-one correspondence to stems (e.g.…”

Section: Introductionmentioning

confidence: 99%

Instance segmentation of fallen trees in aerial color infrared imagery using active multi-contour evolution with fully convolutional network-based intensity priors

Polewski

Shelton

Yao

et al. 2021

ISPRS Journal of Photogrammetry and Remote Sensing

View full text Add to dashboard Cite

“…These aerial photographs are available as true color, infrared, or panchromatic photographs as hard or soft copies. The most commonly used method in mapping vegetation from aerial photography is manual digitization [22,23], which is not only time-consuming but also subject to the interpretation of the digitizing analyst, making repeatability and replication at the same accuracy and precision difficult.…”

Section: Introductionmentioning

confidence: 99%

Delineation of Tree Patches in a Mangrove-Marsh Transition Zone by Watershed Segmentation of Aerial Photographs

et al. 2020

View full text Add to dashboard Cite

Mangrove migration, or transgression in response to global climatic changes or sea-level rise, is a slow process; to capture it, understanding both the present distribution of mangroves at individual patch (single- or clumped trees) scale, and their rates of change are essential. In this study, a new method was developed to delineate individual patches and to estimate mangrove cover from very high-resolution (0.08 m spatial resolution) true color (Red (R), Green (G), and Blue (B) spectral channels) aerial photography. The method utilizes marker-based watershed segmentation, where markers are detected using a vegetation index and Otsu’s automatic thresholding. Fourteen commonly used vegetation indices were tested, and shadows were removed from the segmented images to determine their effect on the accuracy of tree detection, cover estimation, and patch delineation. According to point-based accuracy analysis, we obtained adjusted overall accuracies >90% in tree detection using seven vegetation indices. Likewise, using an object-based approach, the highest overlap accuracy between predicted and reference data was 95%. The vegetation index Excess Green (ExG) without shadow removal produced the most accurate mangrove maps by separating tree patches from shadows and background marsh vegetation and detecting more individual trees. The method provides high precision delineation of mangrove trees and patches, and the opportunity to analyze mangrove migration patterns at the scale of isolated individuals and patches.

show abstract

Object-based Image Mapping of Conifer Tree Mortality in San Diego County based on Multitemporal Aerial Ortho-imagery

Cited by 11 publications

References 0 publications

Upper and lower treeline biogeographic patterns in semi‐arid pinyon‐juniper woodlands

Upper and lower treeline biogeographic patterns in semi‐arid pinyon‐juniper woodlands

Instance segmentation of fallen trees in aerial color infrared imagery using active multi-contour evolution with fully convolutional network-based intensity priors

Delineation of Tree Patches in a Mangrove-Marsh Transition Zone by Watershed Segmentation of Aerial Photographs

Contact Info

Product

Resources

About