قارن الطرق

	كسر فجوة المظلة	مؤشر مساحة الورقة	مؤشر كثافة الحراج (SDI)
المجال	علوم الغابات	علم المحاصيل	علوم الغابات
العائلة	Process / pipeline	Process / pipeline	Process / pipeline
سنة النشأة	1979	1947	1933
صاحب الطريقة	John Norman	Donald J. Watson	Louis Reineke
النوع	measurement pipeline	Plant morphometric measurement	density measurement
المصدر التأسيسي	Machado, J.-L., & Reich, P. B. (1999). Evaluation of several measures of canopy openness. Canadian Journal of Forest Research, 29(9), 1439–1444.	Watson, D. J. (1947). Comparative physiological studies on the growth of field crops: I. Variation in net assimilation rate and leaf area between species and varieties, and within and between years. Annals of Botany, 11(43), 375-407.	Reineke, L. H. (1933). Perfecting a stand-density index for even-aged forests. Journal of Agricultural Research, 46(7), 627–638.
الأسماء البديلة	gap fraction, canopy openness	LAI, Leaf area, Canopy structure	SDI, Reineke density index
ذات صلة	2	3	2
الملخص	Canopy gap fraction quantifies the proportion of sky visible through the forest canopy, expressed as a percentage. Developed to measure light availability in the understory, it is a standard metric in forest ecology for characterizing canopy structure and microhabitat conditions. This measure is essential for understanding light-limited photosynthesis and seedling establishment in closed-canopy forests.	Leaf Area Index (LAI) is a dimensionless quantity that measures the total one-sided area of leaves per unit ground area covered by a canopy. It quantifies canopy density and structure: LAI = 0 for bare soil, LAI = 1 for a thin crop, LAI = 3-6 for dense cereal or grass canopies, and LAI > 8 for dense forest. LAI is a key variable in crop growth models, evapotranspiration estimation, and remote sensing because it directly controls light interception, photosynthesis, and water loss from vegetation.	The Stand Density Index (SDI), introduced by Reineke in 1933, is a dimensionless measure of forest density that accounts for both tree number and size. It expresses the number of trees per hectare in a stand, adjusted to a reference quadratic mean diameter (QMD) of 25 cm, providing a standardized metric for comparing tree density across different forest types and sizes. SDI is widely used in forest management to assess stocking levels and to guide thinning decisions.