Pauline Stenberg, Miina Rautiainen, Terhikki Manninen, Pekka Voipio, Heikki Smolander. (2004). Reduced simple ratio better than NDVI for estimating LAI in Finnish pine and spruce stands. Silva Fennica vol. 38 no. 1 article id 431. https://doi.org/10.14214/sf.431

Keywords: Landsat ETM ; Leaf Area Index; spectral vegetation indices; boreal coniferous forests

Abstract | View details | Full text in PDF | Author Info

Estimation of leaf area index (LAI) using spectral vegetation indices (SVIs) was studied based on data from 683 plots on two Scots pine and Norway spruce dominated sites in Finland. The SVIs studied included the normalised difference vegetation index (NDVI), the simple ratio (SR), and the reduced simple ratio (RSR), and were calculated from Landsat ETM images of the two sites. Regular grids of size 1 km2 with gridpoints placed at 50 m intervals were established at the sites and measurements of LAI using the LAI-2000 instrument were taken at the gridpoints. SVI-LAI relationships were examined at plot scale, where the plots were defined as circular areas of radius 70 m around each gridpoint. Plotwise mean LAI was computed as a weighted average of LAI readings taken around the gridpoints belonging to the plot. Mean LAI for the plots ranged from 0.36 to 3.72 (hemisurface area). All of the studied SVIs showed fair positive correlation with LAI but RSR responded more dynamically to LAI than did SR or NDVI. Especially NDVI showed poor sensitivity to changes in LAI. RSR explained 63% of the variation in LAI when all plots were included (n = 683) and the coefficient of determination rose to 75% when data was restricted to homogeneous plots (n = 381). Maps of estimated LAI using RSR showed good agreement with maps of measured LAI for the two sites.

Stenberg, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: pauline.stenberg@helsinki.fi
Rautiainen, Department of Forest Ecology, P.O. Box 27, FIN-00014 University of Helsinki, Finland E-mail: mr@nn.fi
Manninen, Finnish Meteorological Institute, Meteorological research, Ozone and UV radiation research, P.O. Box 503, FIN-00101 Helsinki, Finland E-mail: tm@nn.fi
Voipio, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: pv@nn.fi
Smolander, Finnish Forest Research Institute, Suonenjoki Research Station, FIN-77600 Suonenjoki, Finland E-mail: hs@nn.fi

article id 575, category Research article

Sylvie Mussche, Roeland Samson, Lieven Nachtergale, An De Schrijver, Raoul Lemeur, Noël Lust. (2001). A comparison of optical and direct methods for monitoring the seasonal dynamics of leaf area index in deciduous forests. Silva Fennica vol. 35 no. 4 article id 575. https://doi.org/10.14214/sf.575

Keywords: Leaf Area Index; mixed deciduous forest; LAI-2000 plant canopy analyser; hemispherical photography; litter trap

Abstract | View details | Full text in PDF | Author Info

During the 1996 growing season the seasonal dynamics of the Leaf Area Index (LAI) were determined by 3 different methods in two forest types: a mixed oak (Quercus robur L.) – beech (Fagus sylvatica L.) stand and an ash dominated (Fraxinus excelsior L.) stand. The results obtained from the two indirect methods, i.e. hemispherical photography and LAI-2000 Plant Canopy Analyser (Li-COR), were compared with the results of the direct measurement of litter fall collected in litter trap systems. In this study the direct method is considered to be the reference, giving the most accurate LAI-values. Both the hemispherical photography and the LAI-2000 PCA introduced an underestimation of LAI when the actual canopy leaf distribution in the crown layer deviates from a random distribution of leaf area in space as is found in the mixed oak/beech stand. However, when the condition of random leaf distribution is nearly fulfilled (ash stand), the LAI-2000 PCA gave LAI-values which were close to the results obtained from the direct method. Regression curves with R2 > 0.93 could be calculated for both indirect methods.

Mussche, Laboratory of Forestry, Ghent University, Geraardsbergse Steenweg 267, B-9090 Melle, Belgium E-mail: sm@nn.be
Samson, Laboratory of Plant Ecology, Ghent University, Coupure Links 653, B-9000 Gent, Belgium E-mail: rs@nn.be
Nachtergale, Laboratory of Forestry, Ghent University, Geraardsbergse Steenweg 267, B-9090 Melle, Belgium E-mail: ln@nn.be
De Schrijver, Laboratory of Forestry, Ghent University, Geraardsbergse Steenweg 267, B-9090 Melle, Belgium E-mail: An.Deschrijver@rug.ac.be
Lemeur, Laboratory of Plant Ecology, Ghent University, Coupure Links 653, B-9000 Gent, Belgium E-mail: rl@nn.be
Lust, Laboratory of Forestry, Ghent University, Geraardsbergse Steenweg 267, B-9090 Melle, Belgium E-mail: nl@nn.be

Category : Research note

article id 1549, category Research note

Francesco Chianucci, Luca Salvati, Tessa Giannini, Ugo Chiavetta, Piermaria Corona, Andrea Cutini. (2016). Long-term response to thinning in a beech (Fagus sylvatica L.) coppice stand under conversion to high forest in Central Italy. Silva Fennica vol. 50 no. 3 article id 1549. https://doi.org/10.14214/sf.1549

Keywords: continuous cover forestry; thinning; Leaf Area Index; coppice management; Plant Canopy Analyzer

Highlights: Canopy recovery after medium-heavy thinning reveals the prompt response of beech to intensive thinning cycles; Active management practices accelerate the transition from coppice to high forest.

Abstract | Full text in HTML | Full text in PDF | Author Info

European beech (Fagus sylvatica L.) forests have a long history of coppicing, but the majority of formerly managed coppices are currently under conversion to high forest. The long time required to achieve conversion requires a long-term perspective to fully understand the implication of the applied conversion practices. In this study, we showed results from a long-term (1992–2014) case-study comparing two management options (natural evolution and periodic thinning) in a beech coppice in conversion to high forest. Leaf area index, litter production, radiation transmittance and growth efficiency taken as relevant stand descriptors, were estimated using both direct and indirect optical methods. Overall, results indicated that beech coppice showed positive and prompt responses to active conversion practices based on periodic medium-heavy thinning. A growth efficiency index showed that tree growth increased as the cutting intensity increased. Results from the case study supported the effectiveness of active conversion management from an economic (timber harvesting) and ecological (higher growth efficiency) point of view.

Chianucci, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy http://orcid.org/0000-0002-5688-2060 E-mail: fchianucci@gmail.com
Salvati, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Research Centre for the Soil-Plant System, via della Navicella 2–4, 00184 Roma, Italy E-mail: bayes00@yahoo.it
Giannini, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy E-mail: tessa.giannini@entecra.it
Chiavetta, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy E-mail: ugo.chiavetta@entecra.it
Corona, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy E-mail: piermaria.corona@unitus.it
Cutini, Consiglio per la Ricerca in Agricoltura e l’Analisi dell’Economia Agraria – Forestry Research Centre, viale Santa Margherita 80, 52100 Arezzo, Italy E-mail: andrea.cutini@entecra.it

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