Characteristics of shortwave and longwave irradiances under a Douglas-fir forest stand

1991 ◽  
Vol 21 (7) ◽  
pp. 1020-1028 ◽  
Author(s):  
T. Andrew Black ◽  
Jing-Ming Chen ◽  
Xuhui Lee ◽  
Robert M. Sagar
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Forest Canopy ◽  
Incident Angle ◽  
Forest Stand ◽  
Douglas Fir ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Area Index ◽  
Effective Leaf Area Index

Measurements of the spatial mean values of global irradiance, photosynthetic photon flux density, and the downward longwave irradiance under a 26-year-old, second-growth Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) forest canopy on a 26° south-facing slope were made with a tramway system, which scanned a 20-m transect in 12 min. The diffuse solar irradiance under the canopy was measured with a stationary pyranometer equipped with a shadow band. The extinction coefficients for the direct, global, and photon components were derived as functions of the solar incident angle over the range of 15° to 85°. The extinction coefficient for the diffuse radiation was found to correlate well with the ratio of the direct to diffuse irradiance above the canopy. Complete diurnal cycles of the downward longwave irradiance were simulated with a simple model based on the air temperature inside the stand. Analyses of the measurements of all the shortwave and longwave components were made using an effective leaf area index, which was derived from the measurements of the direct irradiance above and below the stand. It was found that the distribution of the leaf inclination angle of a Douglas-fir canopy has strong planophile characteristics, and that in the case of a forest stand on a slope, it is critical to obtain the characteristics of the light transmission through the canopy over the entire incident angle range before effective leaf area index is calculated. Warren Wilson's 57.5° approximation did not hold for the Douglas-fir canopy, which had distinct foliage clumping features.

Eight-year responses of light interception, effective leaf area index, and stemwood production in fertilized stands of interior Douglas-fir (Pseudotsuga menziesii var. glauca)

2000 ◽  
Vol 30 (5) ◽  
pp. 733-743 ◽  
Author(s):  
Nick J Balster ◽  
John D Marshall
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Pseudotsuga Menziesii ◽  
Growth Efficiency ◽  
Light Interception ◽  
Douglas Fir ◽  
Area Index ◽  
Volume Production ◽  
High Fertilization ◽  
Effective Leaf Area Index

Data from 72 Douglas-fir (Pseudotsuga menziesii var. glauca (Beissn.) Franco) plots across the Interior Northwest were used to determine whether (i) increased intercepted photosynthetically active radiation (%IPAR), effective leaf area index (LAIe), and stemwood volume production (cubic metres stemwood per hectare per year) could still be detected 7 or 8 years after nitrogen fertilization and (ii) fertilization would increase the efficiency by which light is converted into stemwood volume. Projected LAIe varied from 1.82 to 6.07 m2·m-2 on the control plots. The fertilized plots intercepted 9-11% more light than the control plots (P < 0.001); they also had 22-25% higher LAIe than the control plots (P < 0.001). Stemwood volume production increased by 25-29% relative to the control (P < 0.001) and increased exponentially with %IPAR across all study plots (R2 = 0.57). Stemwood growth efficiency averaged 12.0 ± 0.4 (mean ± SE), 13.5 ± 0.4, and 13.7 ± 0.4 m3·ha-1·a-1 per IPAR for the control, low fertilization, and high fertilization plots, respectively (P < 0.01). Fertilization thus induced increases in both light interception and the efficiency with which intercepted light was converted to stemwood across the region.

scholarly journals Extinction coefficient and interception efficiency of the photosynthetic photon flux density in cherry tomato under levels of nitrogen in greenhouse conditions

2019 ◽  
pp. 1749-1755
Author(s):  
Mariana de Oliveira Pereira ◽  
Gustavo Bastos Lyra ◽  
Guilherme Bastos Lyra ◽  
Leonardo Duarte Batista Silva ◽  
José Leonaldo de Souza ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Flux Density ◽  
Extinction Coefficient ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Cherry Tomato ◽  
Photosynthetic Photon Flux ◽  
Area Index

Cherry tomato (Perinha Água Branca cultivar) was cultivated under organic management in greenhouse conditions set up in the municipality of Seropédica, Rio de Janeiro state, Southeastern Brazil. The crop was subjected to different nitrogen doses (N) ranging from 0 to 400% based on the reference value for the crop (100 kg ha-1) applied by means of dairy cattle wastewater. In order to estimate the extinction coefficient (k) and interception efficiency (Ԑint), weekly measurements of the photosynthetic photon flux density (PPFD) were performed below (PPFDb) and above the canopy (PPFDa) and the Leaf Area Index (LAI) was estimated. The extinction coefficient k for each treatment was obtained based on the model proposed by Monsi and Saeki. Ԑint was estimated by the quotient between PPFD absorbed by the canopy (PPFDabs = PPFDa – PPFDb) and PPFDa. Statistical tests were applied to k and Ԑint to evaluate the distribution of data (Kolmorogov-Smirnov) and their significance (Kruskal-Wallis), considering the treatments applied. No statistically significant differences were observed for k (p<0.05), which indicated canopy structure uniformity. The median k value was 0.792. Similar to k, Ԑint showed no statistically significant differences (p<0.05) between treatments; however, the highest interception efficiency was achieved by treatment with 300% N (Ԑint = 0.825), which coincided with the highest leaf area index and the lowest by treatment with 100% N (Ԑint = 0.521). The nitrogen did not interfere in the plant canopy architecture; however, it provided greater leaf area index to plants submitted to nitrogen doses two and three times above that recommended for the crop. Treatment with three times the recommended nitrogen dose reached in a shorter time interval the maximum efficiency value

scholarly journals UAV Based Estimation of Forest Leaf Area Index (LAI) through Oblique Photogrammetry

2021 ◽  
Vol 13 (4) ◽  
pp. 803
Author(s):  
Lingchen Lin ◽  
Kunyong Yu ◽  
Xiong Yao ◽  
Yangbo Deng ◽  
Zhenbang Hao ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Point Cloud ◽  
Forest Canopy ◽  
Estimation Method ◽  
Vertical Direction ◽  
Estimation Accuracy ◽  
3D Point Cloud ◽  
Area Index ◽  
Better Than

As a key canopy structure parameter, the estimation method of the Leaf Area Index (LAI) has always attracted attention. To explore a potential method to estimate forest LAI from 3D point cloud at low cost, we took photos from different angles of the drone and set five schemes (O (0°), T15 (15°), T30 (30°), OT15 (0° and 15°) and OT30 (0° and 30°)), which were used to reconstruct 3D point cloud of forest canopy based on photogrammetry. Subsequently, the LAI values and the leaf area distribution in the vertical direction derived from five schemes were calculated based on the voxelized model. Our results show that the serious lack of leaf area in the middle and lower layers determines that the LAI estimate of O is inaccurate. For oblique photogrammetry, schemes with 30° photos always provided better LAI estimates than schemes with 15° photos (T30 better than T15, OT30 better than OT15), mainly reflected in the lower part of the canopy, which is particularly obvious in low-LAI areas. The overall structure of the single-tilt angle scheme (T15, T30) was relatively complete, but the rough point cloud details could not reflect the actual situation of LAI well. Multi-angle schemes (OT15, OT30) provided excellent leaf area estimation (OT15: R2 = 0.8225, RMSE = 0.3334 m2/m2; OT30: R2 = 0.9119, RMSE = 0.1790 m2/m2). OT30 provided the best LAI estimation accuracy at a sub-voxel size of 0.09 m and the best checkpoint accuracy (OT30: RMSE [H] = 0.2917 m, RMSE [V] = 0.1797 m). The results highlight that coupling oblique photography and nadiral photography can be an effective solution to estimate forest LAI.

Comparison of Methods of Estimating Leaf-Area Index In Old-Growth Douglas-Fir

Ecology ◽  
1986 ◽  
Vol 67 (4) ◽  
pp. 975-979 ◽  
Author(s):  
J. D. Marshall ◽  
R. H. Waring
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Douglas Fir ◽  
Comparison Of Methods ◽  
Old Growth ◽  
Area Index

scholarly journals Algorithm for assessing forest stand productivity index using leaf area index

2019 ◽  
Vol 16 (3) ◽  
pp. 1311
Author(s):  
Faid Abdul Manan ◽  
Muhammad Buce Saleh ◽  
I Nengah Surati Jaya ◽  
Uus Saepul Mukarom
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Basal Area ◽  
Forest Stand ◽  
Productivity Index ◽  
Estimation Model ◽  
Area Index ◽  
Study Objective ◽  
Stand Productivity ◽  
Variable Combination

This paper describes a development of an algorithm for assessing stand productivity by considering the stand variables. Forest stand productivity is one of the crucial information that required to establish the business plan for unit management at the beginning of forest planning activity. The main study objective is to find out the most significant and accurate variable combination to be used for assessing the forest stand productivity, as well as to develop productivity estimation model based on leaf area index. The study found the best stand variable combination in assessing stand productivity were density of poles (X2), volume of commercial tree having diameter at breast height (dbh) 20-40 cm (X16), basal area of commercial tree of dbh &gt;40 cm (X20) with Kappa Accuracy of 90.56% for classifying into 5 stand productivity classes. It was recognized that the examined algorithm provides excellent accuracy of 100% when the stand productivity was classified into only 3 classes. The best model for assessing the stand productivity index with leaf area index is y = 0.6214x - 0.9928 with R2= 0.71, where y is productivity index and x is leaf area index.

Measuring effective leaf area index, foliage profile, and stand height in New England forest stands using a full-waveform ground-based lidar

2011 ◽  
Vol 115 (11) ◽  
pp. 2954-2964 ◽  
Author(s):  
Feng Zhao ◽  
Xiaoyuan Yang ◽  
Mitchell A. Schull ◽  
Miguel O. Román-Colón ◽  
Tian Yao ◽  
...  
Keyword(s):  
New England ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Forest Stands ◽  
Area Index ◽  
Full Waveform ◽  
Ground Based Lidar ◽  
Stand Height ◽  
Effective Leaf Area Index
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