Untitled

Chokkalingam, U.; White, Alan S.

doi:10.1023/a:1012639109366

Cited by 47 publications

(5 citation statements)

References 70 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The compound diameter distribution in this stand is comparable to distributions previously described for other mature and old-growth deciduous stands, in which several tree cohorts have been identiWed (Chokkalingam and White 2001;Fajardo and Alaback 2005;Piovesan et al 2005). Component A corresponds to a young generation of trees whose ages range between 11 and 104 years (Rozas 2006).…”

Section: Discussionsupporting

confidence: 79%

Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain

2009

View full text Add to dashboard Cite

Five contrasting deciduous forest stands were studied to characterize the spatial structural variability in human-inXuenced forests. These stands are representative of cultural forest types widely represented in western Europe: one plantation, two coppices, one wood-pasture forest and one high forest stand. All stems with DBH > 5 cm were measured and mapped, and stem DBH distributions, spatial structure of DBH, spatial point patterns and spatial associations were analysed. Spatial autocorrelation for DBH was calculated with Moran's I correlograms and semivariograms. Complete spatial randomness hypothesis for spatial point patterns, and both independence and random labelling hypotheses for spatial associations were analysed using Ripley's K function. The results showed that tree sizes were conditioned by particular former management systems, which determined unimodal symmetric, positively skewed or compound DBH distributions. Spatial structure was more complex when human inXuence became reduced. Coppice stands showed clumped spatial patterns and independence among size classes, as a consequence of sexual and vegetative establishment of new stems in open areas. The largest clumping intensity was observed in the wood-pasture with an intermediate disturbance frequency and low inter-tree competition. The high forest stand displayed spatial traits consistent with the gap-dynamics paradigm, such as clumping of smaller trees, random arrangement of larger trees, negative association between juveniles and adults, and high structural heterogeneity. It can be expected that after cessation of human interference, coppices and wood-pastures would evolve to a more heterogeneous structure, probably with a higher habitat and species diversity.

show abstract

Section: Discussionsupporting

confidence: 79%

Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain

2009

View full text Add to dashboard Cite

show abstract

“…The penetration depth for the human skin at 5 GHz is approximately 1 cm, so the backscattered fields from internal organs are assumed negligible [Gabriel, 1996;Vander Vorst et al, 2006]. The components of the forest, i.e., trunks and branches, are modeled using PEC cylinders, with characteristics as shown in Table 1, based on literature [Ulaby et al, 1990;Chokkalingam and White, 2001].…”

Section: Simulation Resultsmentioning

confidence: 99%

Detection of moving human micro‐Doppler signature in forest environments with swaying tree components by wind

et al. 2015

View full text Add to dashboard Cite

The objective of this paper is to investigate human motion in forest medium with swaying tree components due to time-varying wind effects and to observe the characteristics of the received Doppler signature from the scene. We provide the results of an accurate model accounting for the key contributions to the Doppler signature in this scenario. A realistic walking motion is generated using an analytical model extracted from empirical data. The swaying canopy motion is modeled by employing a spring response mechanism to the wind force. The backscattered field calculations from the scene comprise of contributions from the forest (including trunks, branches, and the ground) and human, and the interactions between them. An analytical forest scattering model, which accounts for the ground effects, is used to calculate the contribution from the forest. The attenuation effects due to the vegetation are accounted for. In order to characterize the effects of human motion accurately, a full wave technique, namely, method of moments (MOM) enhanced with fast multipole method (FMM), is employed for the human scattering calculations. A parallel version of MOM-FMM is implemented on a graphics processing unit based cluster to handle the large problem size. The human walking signatures created by the model are analyzed for different winds.

show abstract

“…Then, distances between the reference point and all trees clearly visible from the reference point were recorded using a laser device (Bosch Laser Distance/Range Measurer). We also recorded the azimuth bearing of each tree from the reference point using a digital compass 32 . Then, another reference point was chosen, and the same surveying procedure was followed until all trees within the area were marked.…”

Section: Methodsmentioning

confidence: 99%

Fine-scale topographic influence on the spatial distribution of tree species diameter in old-growth beech (Fagus orientalis Lipsky.) forests, northern Iran

Mohammadi

Tobin

Jalali

et al. 2022

Sci Rep

View full text Add to dashboard Cite

The Hyrcanian forest in northern Iran is threatened by human use and encroachment and has suffered degradation in some areas. The forest has been declared a World Heritage Site and management in the region is shifting from timber production to conservation. There is considerable interest in developing a greater understanding of these diverse forest communities to inform forest management and multiple use plans to maintain the diversity and resilience of these forests. The Hyrcanian forest is characterized by a complex topography of catenas ranging up mountain slopes. Topographic gradients greatly influence microhabitat conditions which in turn impact tree distribution. To date there has been limited research on the impacts of this diverse topography on the spatial distribution of tree species and tree diameters in Hyrcanian forests. Such information is necessary to better understand the regional traits of tree diameters in these natural mixed temperate forests before forest management occurs. We examined the influence of the area’s catena topography on the spatial pattern of tree species and on species stand structure in terms of tree diameter distribution. To quantify these dynamics, we conducted a complete enumeration inventory of all trees with dbh >12 cm within a 7.947 ha study area that included three C-shaped (concave) and three V-shaped (convex) catenas. Geostatistical variogram analysis and Clark and Evans aggregation index were utilized to study the spatial distribution of tree diameters. Beech, alder, hornbeam, linden and Persian maple exhibited clustered patterns, and sour cherry, ash, and oak exhibited random patterns. Geostatistical analysis clearly revealed the substantial influence of catena topography on the diameter distributions of alder and linden, more subtle influence on the diameter distributions of beech, and a possible influence on Persian maple, providing valuable insight into stand structure over neighborhood-based indices alone. Alder and linden both exhibited strong spatial structure in their diameter distributions (56% and 86%, respectively) where their diameter was strongly correlated with trees within 108 m and 83 m, respectively, sharing more similar diameters to each other than trees beyond that distance. Beech, maple, and hornbeam exhibited very weak if any spatial structure over short distances. These findings can be used to support the alignment of forest management practices in managed Hyrcanian forests with goals of protecting and maintaining biodiversity and sustainable forest ecosystems, and to inform geospatial modeling of species diameter distributions in areas where a complete stem-map is not feasible.

show abstract

Untitled

Cited by 47 publications

References 70 publications

Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain

Spatial structure of deciduous forest stands with contrasting human influence in northwest Spain

Detection of moving human micro‐Doppler signature in forest environments with swaying tree components by wind

Fine-scale topographic influence on the spatial distribution of tree species diameter in old-growth beech (Fagus orientalis Lipsky.) forests, northern Iran

Contact Info

Product

Resources

About