方法对比

	蓄积密度指数	冠层空隙率	立地指数曲线
领域	林学	林学	林学
方法族	Process / pipeline	Process / pipeline	Process / pipeline
起源年份	1933	1979	1954
提出者	Louis Reineke	John Norman	Joseph Westveld
类型	density measurement	measurement pipeline	productivity index
开创性文献	Reineke, L. H. (1933). Perfecting a stand-density index for even-aged forests. Journal of Agricultural Research, 46(7), 627–638.	Machado, J.-L., & Reich, P. B. (1999). Evaluation of several measures of canopy openness. Canadian Journal of Forest Research, 29(9), 1439–1444.	Clutter, J. L., Fortson, J. C., Pienaar, L. V., Brister, G. H., & Bailey, R. L. (1983). Timber Management: A Quantitative Approach. John Wiley & Sons.
别名	SDI, Reineke density index	gap fraction, canopy openness	site productivity, growth intercept
相关	2	2	1
摘要	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.	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.	A site index curve is a family of curves relating tree height to stand age, used to quantify the productivity of a forest site. Site index is conventionally defined as the height of dominant trees at a reference age (typically 50 years in temperate forests). These curves enable foresters to classify sites by productivity class and to predict growth rates for planning timber harvests and silvicultural treatments. Site index curves are among the most fundamental tools in forest growth and yield modeling.