Spatial　heterogeneity　within　canopies　and　woody　components　are　two　factors　that　limit　the　accuracy　of　indirect　leaf　area　index　(LAI)　measurements,　but　they　have　not　been　fully　considered　because　of　the　limitations　of　commercial　instruments.　This　study　combined　the　path　length　distribution　model　and　multispectral　canopy　imager　for　the　first　time　to　improve　the　accuracy　of　indirect　LAI　measurements.　Indirect　and　direct　in　situ　measurements　were　conducted　in　broadleaf　and　coniferous　forests.　Results　show　that　spatial　heterogeneity　within　canopies　underestimates　the　LAI　by　16-25%,　whereas　woody　components　overestimate　LAI　by　14-28%　in　four　forest　sites.　These　two　factors　exhibit　opposing　effects,　which　may　be　misleading　and　may　thus　complicate　the　quantification　and　validation　of　the　effect　of　each　factor.　Ignoring　woody　components　underestimates　the　degree　of　spatial　heterogeneity　or　clumping　in　forests.　Considering　both　nonrandomness　within　canopies　and　woody　components　is　necessary　in　indirect　LAI　measurements.　©　2016　IEEE.