C.—3,

is definitely favourable to regeneration, as it serves to shelter seedlings from sun and wind and to conserve moisture. The covering of thistles' and other weeds which generally come in rapidly also assists regeneration in the same way, and slash burning, unless done very lightly, appears to be detrimental. Larch and Douglas fir show good results only under strip felling where the strips proceed against the prevailing wind. There are several good areas of P. radiata regeneration spreading into open country, and on one of these where the regeneration is of all ages between one and forty years the trees are of excellent form with few double leaders, and light branches. Experimental plots will be established for further observation and study. In most of the State exotic forests trial plantings have been made for years past with rarer tree species and varieties. In some instances these are the only criteria in the Dominion of the growth of such trees. Largely due to changes in forest staff, these plantings have in some instances been overlooked, and during the year steps were taken to have them located, cleaned, and pruned for observation and record of growth rates and suitability for further planting. An experimental broadcasting in 1939 of Californian redwood seed on cut-over indigenous podocarp forest yielded numerous seedlings, most of which, however, succumbed to sun-scald and wind exposure during the summer of 1940-41. The remaining seedlings, which are up to 6 in. in height, will be kept under observation. 41. Experimental Plots and Statistical. —Experimental plots established to study height growth of kauri saplings were remeasured, and while the yearly growth under strong suppression by mature manuka averages only ljin., saplings with overhead light and side shelter show a yearly height increment of 9 in. to 12 in. A plot formed in 1937 for studying natural seeding of kauri in a mature stand now shows 12 seedlings per square yard— i.e., 58,000 per acre. All shrubby ground cover was removed when the plot was established. Plots in Southland beech regeneration and poles, first formed in 1930, were remeasured, and a restudy was made of a number of growth plots in exotic-tree stands. On permanent experimental plots established in 1939 in Wellington Conservancy for the purpose of studying the effect of planting up indigenous forest that has been cut over and subsequently burned, exotics were pruned and remeasured, and further measurements were made in silver-pine natural" regeneration plots. Following a general inspection in 1939 of interplantings with exotic trees in unburned cut-over indigenous forest, a commencement was made with planned establishment of permanent experimental plots on these areas to study the interrelation between the indigenous species and the introduced exotic species, and during the year five plots were established in Erua State Forest, in Wellington Conservancy. For the purpose of following through the effect of different tree espacements from planting to maturity, two sets of replication plots were formed during the year, one of Pinus radiata and one of Cupressus lawsoniana. Section F. —Forest Botany. 42. Collection of records on dates of bud opening, pollen shedding, cone formation, and other phenological phenomena relating to the main exotic-tree species was pursued by the field officers and will be further continued. Eventually these data will enable the building-up of botanical life histories which will throw light on problems connected with seed collection, pruning, natural regeneration, and other forestry operations. Organized collection and testing of tree seeds was instituted during the year under control plan, both indigenous and exotic trees being embraced by this scheme. Under a plan for the establishment of a northern arboretum for subtropical tree species a start was made by securing several species of kauri (Agathis) from other countries, and seedlings of these are now under cultivation in one of the forest nurseries.

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