Response of leaf area index to density for two contrasting tree species

1991 ◽  
Vol 21 (12) ◽  
pp. 1760-1764 ◽  
Author(s):  
Steven B. Jack ◽  
James N. Long
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Tree Species ◽  
Lodgepole Pine ◽  
Stand Density ◽  
Area Index ◽  
Subalpine Fir ◽  
Wide Range ◽  
Stable Leaf ◽  
The Relationship

It is commonly assumed that mature forest stands with closed canopies support constant amounts (weight or area) of foliage, independent of stand density. For stand leaf area to be constant, mean leaf area must be plastic with respect to density. We examined the relationship between density and both leaf area index and mean leaf area for two contrasting tree species, lodgepole pine (Pinuscontorta var. latifolia Engelm.) and subalpine fir (Abieslasiocarpa (Hook.) Nutt.). In lodgepole pine, leaf area index tended to be constant over a wide range of absolute and relative densities, but in subalpine fir, leaf area index increased with density. Consistent with these results, mean leaf area of lodgepole pine was more plastic with respect to density than mean leaf area of subalpine fir. The presumption of stable leaf area index independent of stand density, therefore, may not be as general as usually assumed owing to differential responses of mean leaf area to density. Differences in plasticity between the two species were attributed to differences in relative shade tolerance and the effect of shade on competitive interactions at high densities.

Effects of clumping on estimates of stand leaf area index using the LI-COR LAI-2000

1993 ◽  
Vol 23 (9) ◽  
pp. 1940-1943 ◽  
Author(s):  
N. J. Smith ◽  
J. M. Chen ◽  
T. A. Black
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Ground Surface ◽  
Stand Density ◽  
Plant Canopy ◽  
Allometric Relationships ◽  
Total Leaf Area ◽  
Area Index ◽  
Second Growth ◽  
Wide Range

Eighteen natural second-growth stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) from a wide range of stand densities and stocking levels were measured for stand leaf area index (LAI) from allometric relationships (direct LAI) and the LI-COR LAI-2000 plant canopy analyzer (indirect LAI). LAI was based on one-half total leaf area (m2) per square metre of ground surface area, normal to any slope. The LAI-2000 underestimated direct LAI by 62%. The underestimate of LAI was due to the confinement of needles within branches (74%) and nonrandom branch distribution (26%). In effect, the branches behaved like big leaves. The LAI-2000 can be used to estimate LAI across a variety of stand density and stocking levels by using a single stand clumping factor of 2.63.

scholarly journals Analogy-Based Crop Yield Forecasts Based on Temporal Similarity of Leaf Area Index

2021 ◽  
Vol 13 (16) ◽  
pp. 3069
Author(s):  
Yadong Liu ◽  
Junhwan Kim ◽  
David H. Fleisher ◽  
Kwang Soo Kim
Keyword(s):  
Time Series ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Crop Yield ◽  
Satellite Data ◽  
Growing Season ◽  
Environmental Data ◽  
Area Index ◽  
Current Season ◽  
Wide Range

Seasonal forecasts of crop yield are important components for agricultural policy decisions and farmer planning. A wide range of input data are often needed to forecast crop yield in a region where sophisticated approaches such as machine learning and process-based models are used. This requires considerable effort for data preparation in addition to identifying data sources. Here, we propose a simpler approach called the Analogy Based Crop-yield (ABC) forecast scheme to make timely and accurate prediction of regional crop yield using a minimum set of inputs. In the ABC method, a growing season from a prior long-term period, e.g., 10 years, is first identified as analogous to the current season by the use of a similarity index based on the time series leaf area index (LAI) patterns. Crop yield in the given growing season is then forecasted using the weighted yield average reported in the analogous seasons for the area of interest. The ABC approach was used to predict corn and soybean yields in the Midwestern U.S. at the county level for the period of 2017–2019. The MOD15A2H, which is a satellite data product for LAI, was used to compile inputs. The mean absolute percentage error (MAPE) of crop yield forecasts was <10% for corn and soybean in each growing season when the time series of LAI from the day of year 89 to 209 was used as inputs to the ABC approach. The prediction error for the ABC approach was comparable to results from a deep neural network model that relied on soil and weather data as well as satellite data in a previous study. These results indicate that the ABC approach allowed for crop yield forecast with a lead-time of at least two months before harvest. In particular, the ABC scheme would be useful for regions where crop yield forecasts are limited by availability of reliable environmental data.

On the relationship of NDVI with leaf area index in a deciduous forest site

2005 ◽  
Vol 94 (2) ◽  
pp. 244-255 ◽  
Author(s):  
Quan Wang ◽  
Samuel Adiku ◽  
John Tenhunen ◽  
André Granier
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Deciduous Forest ◽  
Forest Site ◽  
Area Index ◽  
Relationship Of ◽  
The Relationship

scholarly journals Above-Ground Net Primary Production, Leaf Area Index, and Nitrogen Dynamics in Early Post-Fire Vegetation, Yellowstone National Park

1997 ◽  
Vol 21 ◽  
pp. 130-134
Author(s):  
Monica Turner ◽  
Rebecca Reed ◽  
William Romme ◽  
Mary Finley ◽  
Dennis Knight
Keyword(s):  
Primary Production ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Yellowstone National Park ◽  
National Park ◽  
Net Primary Production ◽  
Lodgepole Pine ◽  
Fire Severity ◽  
Ecosystem Processes ◽  
Area Index

The 1988 fires in Yellowstone National Park (YNP), Wyoming, affected >250,000 ha, creating a striking mosaic of burn severities across the landscape which is likely to influence ecological processes for decades to come (Christensen et al. 1989, Knight and Wallace 1989, Turner et al.1994). Substantial spatial heterogeneity in early post-fire succession has been observed in the decade since the fires, resulting largely from spatial variation in fire severity and in the availability of lodgepole pine (Pinus contorta var. latifolia) seeds in or near the burned area (Anderson and Romme 1991, Tinker et al. 1994, Turner et al. 1997). Post­fire vegetation now includes pine stands ranging from relatively low to extremely high pine sapling density (ca 10,000 to nearly 100,000 stems ha-1) as well as non-forest or marginally forested vegetation across the Yellowstone landscape may influence ecosystem processes related to energy flow and biogeochemisty. We also are interested in how quickly these processes may return to their pre­ disturbance characteristics. In this pilot study, we began to address these general questions by examining the variation in above-ground net primary production (ANPP), leaf area index (LAI) of tree (lodgepole pine) and herbaceous components, and rates of nitrogen mineralization and loss in successional stands 9 years after the fires. ANPP measures the cumulative new biomass generated over a given period of time, and is a fundamental ecosystem property often used to compare ecosystems (Carpenter 1998). Leaf area (typically expressed as leaf area index [LAI], i.e., leaf area per unit ground surface area) influences rates of two fundamental ecosystem processes -­ primary productivity and transpiration -- and is communities (

scholarly journals Light dynamics and free-to-grow standards in aspen-dominated mixedwood forests

2002 ◽  
Vol 78 (1) ◽  
pp. 137-145 ◽  
Author(s):  
Victor J Lieffers ◽  
Bradley D Pinno ◽  
Kenneth J Stadt
Keyword(s):  
Leaf Area Index ◽  
Key Words ◽  
Leaf Area ◽  
Light Transmission ◽  
Stand Density ◽  
Canopy Gaps ◽  
Light Competition ◽  
Area Index ◽  
Mixedwood Forests ◽  
Key Words Competition

This study examines light competition between aspen and spruce during the sequence of aspen development. Leaf area index and light transmission were measured or estimated for aspen stands from 2 to 125 years old. Light transmission was lowest at 15-25 years, and in some stands, transmission was less than 5% of above-canopy light. Hypothetical aspen stands with various stem configurations and heights were developed, and positions were identified that would meet or fail Alberta free-to-grow (FTG) standards. Light transmission was estimated at each position with the MIXLIGHT forest light simulator. Positions in canopy gaps or at the northern sides of canopy gaps had higher light. In general, however, there was little difference in available light between positions that met or failed FTG criteria. Stand density and size of aspen trees appears to be a better index to predict light transmission and spruce success in juvenile aspen stands than current FTG criteria. Key words: competition, free to grow, hardwood, spruce, light

scholarly journals Evaluations of In-Furrow Insecticides and Fungicides, 1995

1996 ◽  
Vol 21 (1) ◽  
pp. 241-241
Author(s):  
Gene Burris ◽  
Don Cook ◽  
B. R. Leonard ◽  
J. B. Graves ◽  
J. Pankey
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Plant Height ◽  
Pest Control ◽  
Cotton Seed ◽  
Stand Density ◽  
Research Station ◽  
Area Index ◽  
Seed Rate

Abstract The test was conducted at the Northeast Research Station in St. Joseph, LA. Plots were replicated 4 times in a RCB design and were four rows (40-inch spacing) X 65 ft. ‘Stoneville LA 887’ cotton seed was planted 2 and 3 May on a commerce silt soil which was fertilized sidedress with 90 lb N/acre. Cotton seed were planted with a John Deere model 7100 series planter which was equipped with 10 inch seed cones mounted to replace the seed hoppers. The seed rate was 4 seed/row ft. Granular in-furrow treatments were applied with 8 inch belt cone applicators mounted to replace the standard granular applicators. Control of thrips and aphids was evaluated on 5 randomly selected plants/plot. Evaluations were made on 18, 19, 24, 26, and 29 May and 8 Jun. Plant height counts were taken on 10 randomly selected plants/plot on 8 Jun. Stand density and leaf area was determined by counting the number of plants in a randomly selected meter on 29 May. Leaf area was recorded using a Li Cor leaf area machine. The data was recorded as cm2 and converted to a leaf area index (LAI). Major pests and/or secondary pest control was initiated in Jun and continued on an “as needed” basis through Aug.

scholarly journals LaiPen LP 100 – a new device for estimating forest ecosystem leaf area index compared to the etalon: A methodologic case study

2018 ◽  
Vol 64 (No. 11) ◽  
pp. 455-468
Author(s):  
Jakub Černý ◽  
Jan Krejza ◽  
Radek Pokorný ◽  
Pavel Bednář
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Optical Methods ◽  
Ecological Studies ◽  
Area Index ◽  
New Device ◽  
Area Efficiency ◽  
Wide Range ◽  
World Standard

Fast and precise leaf area index (LAI) estimation of a forest stand is frequently needed for a wide range of ecological studies. In the presented study, we compared side-by-side two instruments for performing LAI estimation (i.e. LaiPen LP 100 as a “newly developed device” and LAI-2200 PCA as the “world standard”), both based on indirect optical methods for performing LAI estimation in pure Norway spruce (Picea abies (Linnaeus) H. Karsten) stands under different thinning treatments. LAI values estimated by LaiPen LP 100 were approximate 5.8% lower compared to those measured by LAI-2200 PCA when averaging all collected data regardless of the thinning type. Nevertheless, when we considered the differences among LAI values at each measurement point within a regular grid, LaiPen LP 100 overestimated LAI values compared to those from LAI-2200 PCA on average by 1.4%. Therefore, both instruments are comparable. Similar LAI values between thinning from above (A) and thinning from below (B) approaches were indirectly detected by both instruments. The highest values of canopy production index and leaf area efficiency were observed within the stand thinned from above (plot A).

Relationship between tillering and leaf area index: quantifying critical leaf area index for tillering in rice

2002 ◽  
Vol 138 (3) ◽  
pp. 269-279 ◽  
Author(s):  
X. ZHONG ◽  
S. PENG ◽  
J. E. SHEEHY ◽  
R. M. VISPERAS ◽  
H. LIU
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Planting Density ◽  
Coefficient Of Determination ◽  
Area Index ◽  
N Input ◽  
Major Factors ◽  
The Relationship ◽  
Changing Light ◽  
Input Level

A field study was conducted at the International Rice Research Institute (IRRI), Philippines during the dry seasons of 1997 and 1998 under irrigated conditions. The objectives of this study were to quantify the critical leaf area index (LAIc) at which tillering stops based on the relationship between tillering rate and LAI, and to determine the effect of nitrogen (N) on LAIc in irrigated rice (Oryza sativa L.) crop. Results showed that the relative tillering rate (RTR) decreased exponentially as LAI increased at a given N input level. The coefficient of determination for the equation quantifying the RTR-LAI relationship ranged from 0·87 to 0·99. The relationship between RTR and LAI was affected by N input level, but not by planting density. The N input level had a significant effect on LAIc with a high N input level causing an increase in LAIc. Tillering stopped at LAI of 3·36 to 4·11 when N was not limiting. Under N limited conditions LAIc reduced to as low as 0·98. Transplanting spacing and number of seedlings per hill had little effect on LAIc. Results from this study suggest that LAI and plant N status are two major factors that influence tiller production in rice crops. The possibility that LAI influences tillering by changing light intensity and/or light quality at the base of the canopy where tiller buds and young tillers are located is discussed.

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