Optical stratification porosity as a measure of vertical canopy structure in a Japanese coastal forest

Zhu, Jiaojun; Matsuyama, Takashi; Gonda, Yutaka

doi:10.1016/s0378-1127(01)00813-1

Cited by 42 publications

(20 citation statements)

References 21 publications

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“…This converter provided with a simple polar projection or an equiangular projection of the tree elements. In order to get the image with higher resolution, monochrome hemispherical photographs were taken during the calm, overcast days (Saito 1996;Zhu et al 2003). The observed heights for the estimation of canopy openness were established at 1.0 m from the forest floor.…”

Section: Sampling Methodologymentioning

confidence: 99%

Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China

Zhu

Man

et al. 2007

Journal of Forest Research

120

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The effects of anthropogenic disturbances on forest structure and plant diversity of secondary forest ecosystems were evaluated based on the classification by site factors in the montane regions of northeastern China. Forty-five sample plots containing 720 sub-plots of overstory species (8 m · 8 m), 1,440 quadrats of understory species (2 m · 2 m), and 1,440 quadrats of herbaceous layer species (1 m · 1 m) were clustered into five groups (G1, G2, G3, G4 and G5) by site variables with Hierarchical Cluster Analysis. Meanwhile, the disturbance levels corresponding to the five groups were determined according to the factors influencing human disturbances (D0-G2, D1-G1, D2-G3, D3-G5, and D4-G4). Species diversities of overstory, understory, herbaceous layer and overall species were evaluated using species number, Margalef index, Pielou index, Shannon-Wiener index, and Simpson index; and b-diversities (Whittaker index, Cody index). Basal area of stands exhibited a decreasing trend along the disturbance level due to a gradual increase in the extraction of timber by the human disturbances. The indices of species diversity suggested that overstory and understory species were distributed evenly among the groups or disturbance levels. There were no absolutely dominant tree species in the secondary forest ecosystems. The differences in site factors and the current disturbance intensities were not intense enough to lead to loose changes in overstory and understory species. The species diversity indices exhibited the maximum values at D3 (G5) for herbaceous layer species; this may suggest that the current disturbance intensities were intense enough to lead the changes of herbaceous layer species. Three rare and endangered species (Juglans mandshurica, Fraxinus mandshurica and Acanthopanax senticosus) were found within the secondary forests. These rare and endangered species appeared in each clustered group or disturbance level, which suggested that the current disturbance intensity in the study area was not strong enough to influence the distribution of rare and endangered species. The current disturbances in the secondary forests may not lead to a decrease in stability and complexity of the overstory and understory species, but the higher disturbance level may be intense enough to change the habitat fitness for the herbaceous species.

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Section: Sampling Methodologymentioning

confidence: 99%

Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China

Zhu

Man

et al. 2007

Journal of Forest Research

120

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“…The lens was set to a small aperture and focused on infinity (Frazer et al 2001;Zhu et al 2003). The top of the image was oriented toward the magnetic north.…”

Section: Procedures Of Hpmmentioning

confidence: 99%

Estimation of canopy gap size and gap shape using a hemispherical photograph

Gong

et al. 2009

Trees

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Gap size and gap shape are two important properties of forest gaps that can influence microsite conditions in a forest stand and determine the recruitment and establishment of trees. There is no universally adopted method for measuring the gap size, although several options are available. In addition, few methods have been proposed for measuring the gap shape. This paper proposes a photographic method of estimating canopy gap size and gap shape. The proposed method is based on a vertical hemispherical photograph of the gap and is thus named the hemispherical photograph method (HPM). We tested the accuracy of the HPM measure of gap size by two groundbased methods and compared the HPM with other methods. Our results indicate that the HPM measurement of the canopy gap size is accurate, but is significantly influenced by the location of the camera. Compared with the groundbased methods, the HPM is more objective and repeatable. Compared with other photographic methods, HPM is more accurate due to the more actual assumptions, but is more labor-intensive because more field measurements are necessary. We conclude that the HPM is a powerful tool for comparative and long-term studies of forest gaps.

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“…It is difficult, however, to find the best aerodynamic porosity related to windbreak effectiveness. Recently developed optical stratification porosity methods for estimating aerodynamic porosity may help determine the appropriate amount of pruning for the dense deciduous windbreak (Zhu et al 2003). Pruning should also be approached carefully in the aspect of period and the quantity because of potential damage on habitats for diverse wildlife (Leal et al 2013).…”

Section: Resultsmentioning

confidence: 99%

“…Beyond that, in the wake zone, turbulence increases with eddy size and wind speed returns to upwind scale (McNaughton 1988). The windbreak porosity, which is defined as the ratio or percentage of pore space to the space occupied by tree stems, braches, twigs, and leaves (Loeffler et al 1992, Zhu et al 2003, mediates the effectiveness of wind speed reduction and the extent of the two different zones by influencing the rate of airflow passing through the windbreak pores (McNaughton 1988. Therefore, although height is important, porosity is considered the most important factor in determining horizontal patterns of wind speed reduction such as the position of minimum wind speed and the recovery rate of wind speed (Heisler and Dewalle 1988, Cleugh 1998).…”

Section: Study Site and Field Measurementsmentioning

confidence: 99%

Seasonal effectiveness of a Korean traditional deciduous windbreak in reducing wind speed

Koh¹,

Park²,

Kang³

et al. 2014

J. Ecol. Environ.

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Little is known about how the increased porosity of a deciduous windbreak, which results from loss of leaves, influences wind speed reduction. We hypothesized that, with loss of foliage, the wind speed reduction effectiveness of a deciduous windbreak decreases on near leeward side but not on further leeward side and that wind speed recovers faster in the full foliage season than in other seasons. During summer, autumn, and winter (full, medium, and non-foliage season, respectively), we observed wind speed and direction around a deciduous windbreak in a traditional Korean village on windward and near and further leeward sides (at -8H, 2H, and 6H; H = 20 m, a windbreak height). We used a linear mixed effects model to determine that the relative wind speed reduction at 2H significantly decreased from 83% to 48% (F 2,111.97 = 73.6, P < 0.0001) with the loss of foliage. However, the relative wind speed reduction at 6H significantly increased from 26% to 43% (F 2,98.54 = 18.5, P < 0.0001). Consequently, wind speed recovery rate between 2H and 6H in summer was two times higher than in autumn and ten times higher than in winter (F 2,102.93 = 223.1, P < 0.0001). These results indicate that deciduous windbreaks with full foliage seem to induce large turbulence and increase wind speed recovery rate on leeward side. Our study suggests that further research is needed to find the optimal foliage density of a deciduous windbreak for maximizing windbreak effectiveness regardless of seasonal foliage changes.

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Optical stratification porosity as a measure of vertical canopy structure in a Japanese coastal forest

Cited by 42 publications

References 21 publications

Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China

Plant diversity of secondary forests in response to anthropogenic disturbance levels in montane regions of northeastern China

Estimation of canopy gap size and gap shape using a hemispherical photograph

Seasonal effectiveness of a Korean traditional deciduous windbreak in reducing wind speed

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