Aims: We aim to examine the canopy gap characteristics and evaluatetheir influence on regeneration, dominance and the early growthof woody species in seasonally dry Shorea robusta forests (Salforests).

Methods: Sixty canopy gaps were surveyed in six randomly located transectsbelts in seasonally dry subtropical Sal forests of central Nepal.Each transect belt was followed until 10 gap sites were encountered.The equation for the area of an ellipse was used to calculatethe size of canopy gap, measuring the longest axis and its perpendicularshorter axis. Number, sizes, ages and causes of tree falls creatingcanopy gaps along with number and sizes of border trees wereidentified and recorded. Detailed gap inventories were carriedout using square 25-m² quadrats placed in the middle of eachgap. All individuals >2 m in height within the quadrat wereidentified at the species level and their diameter at breastheight was measured. We assigned a nested 4-m² quadrat to thecorner of each 25-m² quadrat, within which all woody individuals>10 cm tall were identified at the species level, and countedthem and their regeneration mechanisms were identified. Theheight and collar diameter of the tallest individuals were measured.Descriptive statistics was calculated for the variables of interestsand Pearson correlation, linear regression, independent-samplet-test and chi-square test were used to relate them and to testfor their associations.

Important Findings: The study found mean gap size of 283 m² and 50% gaps of 10–15years old. Gaps created by natural single-tree falls were significantlymore numerous, and their mean size was significantly smallerthan those resulting from artificial causes or multiple-treefalls. Gap size correlated with the basal area of felled trees,but it did not correlate with the number of tree falls. Whiletree fall basal area was significantly positively correlatedto the seed-originated seedling to resprout ratio, it was negativelycorrelated, along with gap area and the basal size of retainedtrees, to seedling growth. The relative seedling density ofTerminalia alata increased with increases in gap areas, whilethat of S.robusta decreased with increases in tree fall basalarea, thereby lowering the plot-level dominance. However, therelative seedling densities of Eugenia operculata and Syzigiumcumini were negatively and positively correlated, respectively,with tree fall basal area.