Dynamics of leaf area index and canopy openness of three forest types in a warm temperate zone

Abstract. Leaf area index (LAI) is an important parameter related to carbon, water and energy exchange between canopy and atmosphere, and is widely applied in the process models to simulate production and hydrological cycle in forest ecosystems. However, fine-scale spatial heterogeneity of LAI and its controlling factors have not been fully understood in Chinese subtropical forests. We used hemispherical photography to measure LAI values in three subtropical forests (i.e. Pinus massoniana – Lithocarpus glaber coniferous and evergreen broadleaved mixed forests, Choerospondias axillaris deciduous broadleaved forests, and L. glaber – Cyclobalanopsis glauca evergreen broadleaved forests) during period from April, 2014 to January, 2015. Spatial heterogeneity of LAI and its controlling factors were analysed by using geostatistics method the generalised additive models (GAMs), respectively. Our results showed that LAI values differed greatly in the three forests and their seasonal variations were consistent with plant phenology. LAI values exhibited strong spatial autocorrelation for three forests measured in January and for the L. glaber – C. glauca forest in April, July and October. Obvious patch distribution pattern of LAI values occurred in three forests during the non-growing period and this pattern gradually dwindled in the growing season. Stand basal area, crown coverage, crown width, proportion of deciduous species on basal area basis and forest types affected the spatial variations in LAI values in January, while species richness, crown coverage, stem number and forest types affected the spatial variations in LAI values in July. Floristic composition, spatial heterogeneity and seasonal variations should be considered for sampling strategy in indirect LAI measurement and application of LAI to simulate functional processes in subtropical forests.

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ANALYSIS OF SPATIO-TEMPORAL PATTERNS OF LEAF AREA INDEX IN DIFFERENT FOREST TYPES OF INDIA USING HIGH TEMPORAL REMOTE SENSING DATA

ISPRS - International Archives of the Photogrammetry Remote Sensing and Spatial Information Sciences ◽

10.5194/isprsarchives-xxxviii-8-w20-119-2011 ◽

2012 ◽

Vol XXXVIII-8/W20 ◽

pp. 119-124

Author(s):

A. Chhabra ◽

S. Panigrahy

Keyword(s):

Remote Sensing ◽

Leaf Area Index ◽

Leaf Area ◽

Remote Sensing Data ◽

Temporal Patterns ◽

Forest Types ◽

Area Index ◽

Sensing Data ◽

Spatio Temporal

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Phenological patterns of defoliation and refoliation processes of rubber tree clones in the Colombian northwest

Revista Facultad Nacional de Agronomía Medellín ◽

10.15446/rfnam.v73n3.80546 ◽

2020 ◽

Vol 73 (3) ◽

pp. 9293-9303

Author(s):

Juan José Guerra-Hincapié ◽

Óscar De Jesús Córdoba-Gaona ◽

Juan Pablo Gil-Restrepo ◽

Danilo Augusto Monsalve-García ◽

Juan David Hernández-Arredondo ◽

...

Keyword(s):

Principal Component Analysis ◽

Leaf Area Index ◽

Leaf Area ◽

Management Strategies ◽

Rubber Tree ◽

Principal Component ◽

Canopy Openness ◽

Area Index ◽

The Relationship ◽

Climatic Characteristic

The knowledge of the defoliation-refoliation process in rubber cultivation allows the development of management strategies in the production system to improve rubber yield. The objective of this study was to determine the intensity and duration of defoliation-refoliation of rubber clones FX 3864, IAN 710 and IAN 873 in the municipality of Tarazá and the FX 3864 and IAN 873 clones in the municipality of Nechí (northwestern Colombia). From October 2015 to June 2016, the measurements of the necromass were carried out in each location for each clone. The light environment was quantified, employing the hemispheric photographs technique to estimate canopy openness percentage (CO) and leaf area index. The assessed weeks were grouped by Principal Component Analysis (PCA) based on the original phenology and climatic variables. The defoliation-refoliation process was analyzed descriptively using graphical representations of the trend for the phenological variables that best described this process. The relationship between climatic and phenological variables in the period evaluated was evidenced; the rainfall was the most critical climatic characteristic in the induction of the defoliation process. The leaf area index was reduced to a minimum value in February, with values of 0.52 for IAN 710 clone in Tarazá, and 0.64 for the IAN 873 clone in Nechí, which corresponded to the highest defoliation stage in both locations. The refoliation period was short (4 to 6 weeks) and occurred during the dry season for all the clones in both places.

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