Forest structure estimation and pattern exploration from discrete-return lidar in subalpine forests of the central Rockies

2008 ◽  
Vol 38 (8) ◽  
pp. 2081-2096 ◽  
Author(s):  
K. R. Sherrill ◽  
M. A. Lefsky ◽  
J. B. Bradford ◽  
M. G. Ryan
Keyword(s):  
Leaf Area ◽  
Forest Structure ◽  
Stand Structure ◽  
Forest Biomass ◽  
Canopy Structure ◽  
Primary Source ◽  
Subalpine Forest ◽  
Stand Age ◽  
Area Index ◽  
The North

This study evaluates the relative ability of simple light detection and ranging (lidar) indices (i.e., mean and maximum heights) and statistically derived canonical correlation analysis (CCA) variables attained from discrete-return lidar to estimate forest structure and forest biomass variables for three temperate subalpine forest sites. Both lidar and CCA explanatory variables performed well with lidar models having slightly higher explained variance and lower root mean square error. Adjusted R2 values were 0.93 and 0.93 for mean height, 0.74 and 0.73 for leaf area index, and 0.93 and 0.85 for all carbon in live biomass for the lidar and CCA explanatory regression models, respectively. The CCA results indicate that the primary source of variability in canopy structure is related to forest height, biomass, and total leaf area, and the second most important source of variability is related to the amount of midstory foliage and tree density. When stand age is graphed as a function of individual plot scores for canonicals one and two, there is a clear relationship with stand age and the development of stand structure. Lidar-derived biomass and related estimates developed in this work will be used to parameterize decision-support tools for analysis of carbon cycle impacts as part of the North American Carbon Program.

Canopy light transmittance in a chronosequence of mixed-species deciduous forests

1994 ◽  
Vol 24 (8) ◽  
pp. 1694-1703 ◽  
Author(s):  
Martin J. Brown ◽  
Geoffrey G. Parker
Keyword(s):  
Leaf Area ◽  
Geometric Mean ◽  
Canopy Structure ◽  
Three Dimensional ◽  
Distinct Pattern ◽  
Light Transmittance ◽  
Dimensional Structure ◽  
Stand Age ◽  
Area Index ◽  
Frequency Distributions

We measured the photosynthetically active radiation transmitted through the canopies of 24 Maryland forest stands, each around midday in midsummer. We then compared the observed values of PAR transmittance with stand age and measures of canopy structure. Generally, transmittance was low, with positively skewed frequency distributions. The geometric mean transmittance followed a distinct pattern with stand age. It was lowest (about 1%) in the youngest stands, increased to about 2.5% as forests approached ages of about 50 years, and then declined with age in the oldest sites (65–340 years). Transmittance was not significantly correlated with many simple measures of forest structure, including estimated aboveground biomass and leaf area index. Better predictions of transmittance used information on the vertical arrangement of the canopy, such as leaf area density. The results are contrary to the common assumptions that forests get consistently darker through time, and that transmittance is inversely proportional to the sheer mass or leaf area of the canopy. The Beer–Lambert extinction coefficient, k, changed with stand age and structure and was especially high in very young stands. We suggest that the variation in light transmittance, and k, can be explained by successional changes in the three-dimensional structure of the canopy.

scholarly journals Optimizing the Remote Detection of Tropical Rainforest Structure with Airborne Lidar: Leaf Area Profile Sensitivity to Pulse Density and Spatial Sampling

2019 ◽  
Vol 11 (1) ◽  
pp. 92 ◽  
Author(s):  
Danilo Roberti Alves de Almeida ◽  
Scott C. Stark ◽  
Gang Shao ◽  
Juliana Schietti ◽  
Bruce Walker Nelson ◽  
...  
Keyword(s):  
Grain Size ◽  
Leaf Area ◽  
Laser Scanning ◽  
Forest Canopy ◽  
Primary Source ◽  
Airborne Lidar ◽  
Area Index ◽  
Pulse Density ◽  
Optimal Values ◽  
And Function

Airborne Laser Scanning (ALS) has been considered as a primary source to model the structure and function of a forest canopy through the indicators leaf area index (LAI) and vertical canopy profiles of leaf area density (LAD). However, little is known about the effects of the laser pulse density and the grain size (horizontal binning resolution) of the laser point cloud on the estimation of LAD profiles and their associated LAIs. Our objective was to determine the optimal values for reliable and stable estimates of LAD profiles from ALS data obtained over a dense tropical forest. Profiles were compared using three methods: Destructive field sampling, Portable Canopy profiling Lidar (PCL) and ALS. Stable LAD profiles from ALS, concordant with the other two analytical methods, were obtained when the grain size was less than 10 m and pulse density was high (>15 pulses m−2). Lower pulse densities also provided stable and reliable LAD profiles when using an appropriate adjustment (coefficient K). We also discuss how LAD profiles might be corrected throughout the landscape when using ALS surveys of lower density, by calibrating with LAI measurements in the field or from PCL. Appropriate choices of grain size, pulse density and K provide reliable estimates of LAD and associated tree plot demography and biomass in dense forest ecosystems.

Himalayan yew: stand structure, canopy damage, regeneration and conservation strategy

1998 ◽  
Vol 25 (4) ◽  
pp. 334-341 ◽  
Author(s):  
H.C. RIKHARI ◽  
L.M.S. PALNI ◽  
S. SHARMA ◽  
S.K. NANDI
Keyword(s):  
Stand Structure ◽  
Canopy Structure ◽  
Conservation Strategy ◽  
Cancer Drug ◽  
Taxus Baccata ◽  
Area Index ◽  
Canopy Volume ◽  
Anti Cancer ◽  
Canopy Removal ◽  
Canopy Damage

Taxus baccata L. subsp. wallichiana (Zucc.) Pilger has come into prominence in recent times due to its uncontrolled harvesting from the Himalayan wilds for the extraction of the anti-cancer drug Taxol. It is a very slow growing tree with poor regeneration, and the extent of canopy damage is likely to have serious consequences on biomass yield, plant survival and natural regeneration by affecting 'seed' output. The present study in the Jageshwar area of the Central Himalaya aimed to determine the stand and canopy structure, microsite characteristics, extent of canopy removal, and regeneration in human-disturbed and undisturbed sites. The number of trees, saplings and seedlings varied amongst plots. Leaf area index and canopy volume increased with increasing circumference at breast height. Of the total canopy volume, 57.4% was found to have been removed from the study area (9.54 ha; representing about 8% of the total T. baccata habitat). Regeneration of the species was found to be better in moist and shady microsites at undisturbed locations than in disturbed sites. Efforts made thus far for its conservation, and future strategies are discussed.

scholarly journals Development of the leaf area and the productivity structure of the sunflower hybrids in the north-eastern Forest-Steppe of Ukraine

2019 ◽  
pp. 33-39
Author(s):  
М.М. Sakhoshko ◽  
M.I. Kravchenko ◽  
V.M. Yatsenko ◽  
I.O. Kolosok
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Unit Area ◽  
Geographical Area ◽  
Main Element ◽  
Forest Steppe ◽  
Area Index ◽  
The North ◽  
North Eastern ◽  
Sunflower Crop

At the present stage, the model of leaf plant development is increasingly considered as the main element of genotypes adaptation to specific cultivation conditions, geographical area, etc. Under these conditions, the potential of the hybrid, the range of its adaptation to environmental conditions is determined by the level of interaction between the development of the assimilation apparatus and the generative organs. An urgent task aimed at improving the productivity of sunflower crop due to the use of genotypes adapted to the conditions of the north-eastern Forest-Steppe and Polyssya of Ukraine is to identify typical schemes of interaction of photosynthetic potential and parameters of plant productivity and crop yields. The studies were conducted in accordance with the program for the development of a variety model for the conditions of the north-eastern Forest-Steppe and Polyssya of Ukraine. Field experiments were carried out in 2016‒2019 at the Sumy National Agrarian University and the Institute of the Agriculture of North East of Ukraine. In the studies, 28‒56 hybrids of different originators were tested annually. Sunflower was cultivated according to the technology recommended for the area, with pre-harvesting density of 60 thousand plants / ha. Harvesting was done manually, from two central rows of a 4-rows plot. The results were processed using the Statistics package. The data on yield indices and values of leaf area coefficient (LAC) of crop for groups of varieties separated by the duration of growing season were analyzed. It was found that the increasing of leaf area was accompanied by an increasing of yield in case of comparing groups with dates of technological maturation until 20 August, 1 September and 10 September. In all cases, the maximum value of the leaf area index ranged from 3.12‒3.52 m2/m2. These dynamics of indicators indicated to the regulatory nature of the values of leaf area coefficient (LAC) of modern sunflower crop and the absence of genotypes (or conditions) capable of maintaining these values at the level of more than 3.3‒3.5 m2/m2. According to the analysis of correlation pleiades, the presence of several levels was found and the relative independence of the relationships between the group of parameters, determining the morphological structure of plants and the vertical structure of crop and the group of parameters, characterizing the content of chlorophyll and its concentration per unit area of leaf surface. In practical terms, the results of the analysis indicated the potential informative nature of the complex use of parameters characterizing the morpho-structure of plants, primarily the index of leaf area and the index of chlorophyll concentration per unit area. In order to isolate the typical schemes characteristic of different levels of adaptation to the conditions of the zone, data on 29 sunflower hybrids distributed in the region were clustered. The results of the analysis allowed to distinguish three significantly different algorithms for the realization of the vegetative and generative potential of sunflower hybrids in the area of the north-eastern Forest-Steppe of Ukraine. It has been established that one of the factors for successful realization of the generative potential of sunflower hybrids in the conditions of the zone is the ability to preserve and (in some cases) to improve the structure of relations between the dynamics and parameters of the plant leaf apparatus and the parameters of their generative development.

scholarly journals Using terrestrial laser scanning to constrain forest ecosystem structure and functions in the Ecosystem Demography model (ED2.2)

2021 ◽  
Author(s):  
Félicien Meunier ◽  
Sruthi M. Krishna Moorthy ◽  
Marc Peaucelle ◽  
Kim Calders ◽  
Louise Terryn ◽  
...  
Keyword(s):  
Leaf Area ◽  
Forest Structure ◽  
Laser Scanning ◽  
Initial Conditions ◽  
Structural Parameters ◽  
Terrestrial Laser Scanning ◽  
Dimensional Structure ◽  
Forest Site ◽  
Ecosystem Structure ◽  
Area Index

Abstract. Terrestrial Biosphere Modeling (TBM) is an invaluable approach for studying plant-atmosphere interactions at multiple spatial and temporal scales, as well as the global change impacts on ecosystems. Yet, TBM projections suffer from large uncertainties that limit their usefulness. A large part of this uncertainty arises from the empirical allometric (size-tomass) relationships that are used to represent forest structure in TBMs. Forest structure actually drives a large part of TBM uncertainty as it regulates key processes such as the transfer of carbon, energy, and water between the land and atmosphere, but remains challenging to measure and reliably represent. The poor representation of forest structure in TBMs results in models that are able to reproduce observed land fluxes, but which fail to realistically represent carbon pools, forest composition, and demography. Recent advances in Terrestrial Laser Scanning (TLS) techniques offer a huge opportunity to capture the three-dimensional structure of the ecosystem and transfer this information to TBMs in order to increase their accuracy. In this study, we quantified the impacts of integrating structural observations of individual trees (namely tree height, leaf area, woody biomass, and crown area) derived from TLS into the state-of-the-art Ecosystem Demography model (ED2.2) at a temperate forest site. We assessed the relative model sensitivity to initial conditions, allometric parameters, and canopy representation by changing them in turn from default configurations to site-specific, TLS-derived values. We show that forest demography and productivity as modelled by ED2.2 are sensitive to the imposed initial state, the model structural parameters, and the way canopy is represented. In particular, we show that: 1) the imposed openness of the canopy dramatically influenced the potential vegetation, the optimal ecosystem leaf area, and the vertical distribution of light in the forest, as simulated by ED2.2; 2) TLS-derived allometric parameters increased simulated leaf area index and aboveground biomass by 57 and 75 %, respectively; 3) the choice of model structure and allometric coefficient both significantly impacted the optimal set of parameters necessary to reproduce eddy covariance flux data.

The influence of stand structure on ecophysiological leaf characteristics of Pinus ponderosa in western Montana

2001 ◽  
Vol 31 (12) ◽  
pp. 2173-2182 ◽  
Author(s):  
Linda M Nagel ◽  
Kevin L O'Hara
Keyword(s):  
Leaf Area ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Stand Structure ◽  
Structural Difference ◽  
Leaf Nitrogen ◽  
Western Montana ◽  
Light Extinction ◽  
Area Index ◽  
Canopy Depth

The effects of vertical arrangement of foliage in even-aged and multiaged stand structures of ponderosa pine (Pinus ponderosa Dougl. ex P. Laws. & C. Laws.) on overall stand growth, light interception, and physiological leaf properties were tested on five plot pairs in western Montana. The primary structural difference between stand structures involves greater canopy depth and stratification of foliage in the multiaged stands. Both area- and mass-based maximum photosynthetic rates (Aarea and Amass) were relatively constant with canopy depth in both stand structures. Area- and mass-based leaf nitrogen (Narea and Nmass) decreased with increasing canopy depth in the even-aged stand structures but not in the multiaged. Specific leaf area (SLA) tended to increase with increasing canopy depth, although this relationship was only significant in the multiaged stand structures. The typical linear relationship observed for many species between photosynthetic rate and leaf nitrogen was not present in either stand structure; however, Narea was highly correlated to SLA in both even-aged and multiaged stand structures (R2 = 0.66 and R2 = 0.52, respectively). There were no differences in the light extinction coefficient (k), basal area growth or efficiency, or stand-level leaf area index between even-aged and multiaged plot pairs. Relative constancy in leaf physiology combined with similarities in site occupancy and growth rates help explain how different stand structures of ponderosa pine maintain similar rates of woody biomass productivity.

Yield, leaf-area index and photosynthetic rate in some perennial ryegrass (Lolium perenne L.) selections

1972 ◽  
Vol 78 (3) ◽  
pp. 509-511 ◽  
Author(s):  
Ian Rhodes
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Lolium Perenne ◽  
Photosynthetic Rate ◽  
Perennial Ryegrass ◽  
Canopy Structure ◽  
Base Population ◽  
Area Index ◽  
Lolium Perenne L ◽  
Unit Leaf

SUMMARYYield, critical LAI and apparent photosynthetic rate per unit leaf area were measured in four families selected from L. perenne S. 321. Differences in yield were attributable to differences in canopy structure producing differing critical LAI. The most productive family, which was 33% more productive than the base population, produced the largest critical LAI but had the lowest photosynthetic rate.

scholarly journals Review of Available Products of Leaf Area Index and Their Suitability over the Formerly Soviet Central Asia

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
M. W. Kappas ◽  
P. A. Propastin
Keyword(s):  
Leaf Area Index ◽  
Central Asia ◽  
Leaf Area ◽  
Primary Source ◽  
Data Sets ◽  
Environmental Modelling ◽  
Remotely Sensed Data ◽  
Area Index ◽  
Research Activities ◽  
Soviet Central Asia

Leaf area index (LAI) is a key biophysical variable for environmental process modelling. Remotely sensed data have become the primary source for estimation of LAI at the scales from local to global. A summary of existing LAI data sets and a discussion of their appropriateness for the formerly Soviet Central Asia, especially Kazakhstan, which is known for its huge grassland area (about 2 million km2), are valuable for environmental modelling in this region. The paper gives a brief review of existing global LAI products, such as AVHRR LAI, MODIS LAI, and SPOT-VEGETATION LAI, and shows that validation of these products in Kazakhstan as well as in other countries of the formerly Soviet Central Asia has not been carried out yet. Apart from the global LAI products, there are just a few data sets retrieved by remote sensing methods at subregional and regional scales in Kazakhstan. More research activities are needed to focus on the validation of the available global LAI products over the formerly Soviet Central Asia and developing new LAI data sets suitable for application in environmental modelling at different scales in this region.

Impact of stand structure on surface fire ignition potential in Picea abies and Pinus sylvestris forests in southern Finland

2005 ◽  
Vol 35 (2) ◽  
pp. 410-420 ◽  
Author(s):  
Heidi Tanskanen ◽  
Ari Venäläinen ◽  
Pasi Puttonen ◽  
Anders Granström
Keyword(s):  
Picea Abies ◽  
Pinus Sylvestris ◽  
Stand Structure ◽  
Weather Data ◽  
Stand Age ◽  
Small Scale ◽  
Age Classes ◽  
Area Index ◽  
Fire Weather Index ◽  
Fire Ignition

Forest fire ignition potential was investigated in Picea abies (L.) Karst. (Norway spruce) and Pinus sylvestris L. (Scots pine) dominated stands of 0, 15, 30–45, and 40–60 years of age. A series of small-scale (<0.5 m2) ignition tests were carried out in experimental plots on 61 different days in June, July, and August. Ignition success percentages were analyzed in relation to stand structural properties, preclassified stand types, and the output of the Canadian Fire Weather Index system. In addition, the number of average stand-type-specific fire days was estimated based on weather data (June–August) for southern Finland for the years 1991–2002. Factors in stand structure that significantly correlated with the ignition success percentage were canopy depth and leaf area index, the correlation coefficients being –0.575 (p < 0.005) and –0.582 (p < 0.005), respectively. In Pinus sylvestris dominated stands, ignition tests produced self-sustained surface fires in 32.0%, 24.0%, and 19.3% of cases in 0-, 15-, and 30- to 45-year age classes, respectively. In Picea abies dominated sites conditions were favorable for fire in 12.0% and 4.6% of trials in the 0- and 40- to 60-year age classes, respectively. The output of the FWI-system correlated well with the ignition success in June and July but poorly in August. Based on the 12-year time series analysis, there were on average per year 27, 18, and 14 potential fire days in 0-, 15-, and 30- to 45-year-old Pinus sylvestris stands, and 10 and 4 potential fire days in 0- and 40- to 60-year-old Picea abies stands, respectively. We concluded that the dominance of Picea abies or Pinus sylvestris and stand age appear to modify the ignition conditions significantly and should be used as threshold indicators in fire occurrence predictions.

Comparing nondestructive measures of forage structure and phytomass

2000 ◽  
Vol 80 (3) ◽  
pp. 565-573 ◽  
Author(s):  
B. E. Olson ◽  
R. T. Wallander ◽  
J. M. Beaver
Keyword(s):  
Radiative Transfer ◽  
Leaf Area ◽  
Canopy Structure ◽  
Plant Canopy ◽  
Native Range ◽  
Area Index ◽  
Crested Wheatgrass ◽  
Canopy Volume ◽  
Peak Standing Crop ◽  
Intercepted Radiation

Nondestructive radiative transfer and canopy volume methods were compared with the destructive hand-clipping method to determine forage structure and phytomass. On a native range site, fifteen 1-m2 circular plots were located at each of five microsites. On a crested wheatgrass site, thirty 1-m2 plots were located in grazed and in ungrazed areas. At peak standing crop, all plots were measured with a LI-COR Plant Canopy Analyzer to determine leaf area index (LAI), diffuse non-intercepted radiation (DNIR), and mean tilt angle (MTA) of leaves. Then, plants within plots were measured with a ruler to determine volume. Finally, all phytomass within plots was harvested. At the native range site, plant volume was related with LAI and DNIR on four of five microsites. Phytomass was related with LAI and DNIR on two microsites. At the crested wheatgrass site, volume and phytomass were related with LAI, DNIR, and MTA on grazed plots. Only phytomass was related with LAI and DNIR on ungrazed plots. The Plant Canopy Analyzer measures canopy structure and phytomass; it is fast, and its data are transferred directly to a computer. Measuring plant volume is inexpensive and requires minimal training. Determining phytomass by clipping is accurate and requires minimal training, but it is time-consuming and destructive. Key words: Leaf area, canopy, volume, phytomass, radiative transfer

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