METHODOLOGY FOREST TYPE CLASSIFICATION PROCEDURE NON-FOREST LAND ZONE Lands incapable of producing commercial forests owing to climatic or soil limitations, or formerly forested lands now devoted to other use. Type 1. Non-Forest Land. Areas consisting of 50 percent or more of agricultural or grazing lands, cities and barrens. WOODLAND ZONE Type 2. - Woodland and Brush, predominating on 51 percent or more of ground area. Three sub-types are recognized: PLANTATION ZONE 2.1 Dry zone 2.2 Subalpine zone 2.3 Lower slopes humid zone Type 3. - Forest Plantations, covering 20 percent or greater portion of land area. In instances of possible conflict, type 3 supersedes types 1 and 2 above. Percent of area planted and type of remaining cover is specified. FOREST LAND ZONE Lands 51 percent or more by area, of natural timber stands, or lands which formerly supported natural timber forest, and not now devoted to other use. Type 4. Virgin Hardwoods. Timber forest predominantly of hardwood species in which no material amount of cutting has occurred. Type 5. Virgin Conifer Forests. Timber forest predominantly of conifer species in which no material amount of cutting has occurred. Based on predominance of species the following sub-types are recognized: Type 6. 5.1 Araucaria 5.2 Alerce 5.3 Cipres Partially Cut Forest. This type number is used in combinations with numbers 4 to 5.3 above to specify remaining cover, viz., 6 4 designates a selectively cut forest in which the remaining stand consists of hardwood species. Type 7. Natural Second-Growth of commercial species predominating. Age, species and stocking percent based on area coverage are specified. Type 8. - Deforested Lands. Lands formerly bearing timber forest 8-b Burned but not cut · Two Type 9. Rocky Non-Commercial. Areas having at least sparse forest cover, and occurring within the altitudinal and latitudinal range of commercial timber, but too rocky, too steep, or too exposed to produce commercial timber stands. Shown in combination with appropriate timber type, viz., 9 4, 95, etc. Procedure for Handling Mixed Types For prevailing types containing areas of other type too small to map out at the scale employed, the percentage of area covered by minor types is recorded. In such instances, proportion in plantations is recorded down to 5 percent by area; that in other types is shown for all occupying 10 percent or more of the ground surface. Stocking Classification All forest types, i.e., numbers 4, 5, 5.1, 5.2, 5.3, 6 and 7 are mapped in broad stocking classes based on density of crown-cover: It follows that deforested lands, type 8, include areas less than 10 percent stocked. FOREST INVENTORY METHODS All of Chile is considered in the forest inventory summaries presented in this report. From one source or another, the coverage is reasonably complete and accurate, and for the most part is based on new and original field work done during the months of January to March 1944, inclusive. The exceptions occur in the Province of Magallanes, where no original field work was done, and in portions of the provinces to the north of Arauco and Malleco, in which field mapping covered the natural timber forest areas completely, but forest plantation and natural woodland only partially. Best existing estimates (adjusted to eliminate known inaccuracies) were employed in these comparatively minor instances in which new field coverage was not attempted. It was found necessary to base inventory estimates on new field work in the principal forest areas, owing to the lack of desirable detail in the existing information. After consultation with local forestry authorities and preliminary inspection of typical areas, a forest and woodland type classification scheme was drawn up in sufficient detail to yield appropriate accuracy, but still simple enough to permit quick and easy recognition of each type. (See page 173.). Field Procedure The extensive reconnaissance method of survey was selected as the most promising means of quickly obtaining acceptably accurate results. Type of forest was shown in place on base maps by direct sketching from an airplane, flying in systematic courses over the terrain, one mapper sketching the ground cover on one side of the line of flight, another on the other. These sketch maps were later checked and in some instances adjusted on the ground. In general, their accuracy was found to be quite satisfactory, considering the speed at which they were drawn (a total of only 30 hours was spent in the air) and the lack of desirable detail and accuracy of the available base maps. Having located the forests from the air, the next step in the survey was to determine the timber volume, species, composition, and quality. This was done by a sampling process taking a series of equally-spaced 1/4 acre, circular plots along a compass line or route of travel in the principal stands. On such plots, trees 11.1 inches and larger in diameter at breast-height were tallied by species, diameter class, broad- age, vigor-class, and number of 16 foot logs, by log grade. Trees 5.1 inches to 11.0 inches in diameter were tallied on circular 1/20 acre plots in similar detail, except that total height instead of log-height was recorded. Defect and breakage was estimated by species for each group of plots in order that net recoverable volumes could be computed. In sampling planted forests a variety of plot sizes was used, and in young plantation stands trees 1.1 inches and larger in diameter were tallied. No samples were taken in the dry-zone woodland; the volume in this type was determined by direct estimate. Also as a part of the field procedure, detailed measurements were recorded for individual cut trees on logging operations to provide a basis for the construction of volume tables. Compilation of Data Forest and woodland type areas were determined by square-counting or planimetering tracings of the type maps made in the field. The unit area of compilation was a degree of latitude and longitude or a portion of such quadrangle within a province. Duplicate counts of type areas were checked against each other within such units. The secondary unit of compilation was the individual province, the next, the province group as shown in the summary tables. During the field mapping it was necessary to recognize some combination types, for example, assume a 10,000 hectare area mapped as: which is interpreted as an area, 0.7 of which is occupied by mediumstocked, dry zone woodland, 0.1 by natural second-growth, 0.2 by virgin hardwood forest in patches too small to map separately at the scale employed. Such a unit of type area was compiled as follows: Thus, when referring to the forest type map, it should be remembered that an area shown on the map as a single type may actually contain a considerable percentage of one or more other types on the ground. Areas of forest plantations were derived from the official 1943 statistics of the Chilean Ministerio de Agricultura. They were modified in some instances to conform with data collected in the field, and with information from certain plantation owners and Fomento foresters. The area of lower slope, dry zone woodland in the three northern province groups was estimated from official statistics of the Department of Forestry, Ministerio de Tierras and Colonizacion. Study of forest ownership was based on ownership maps, drawn by the Ministerio de Tierras and Colonizacion on which were overlaid the type map tracings made in the forest inventory phase. From these two maps, areas of sawtimber forest were compiled by ownership class and by province. con The first step in the compilation of timber volumes consisted in the construction of volume tables from the detailed measurements of cut trees made in the field. The resulting volume tables, 29 in total, are included in this appendix, pages 181 to 209 inclusive. They were structed by correlating volume of average log with diameter and height, or by the form factor method, as explained in each table. Since these tables are based on comparatively few measured trees, they should be regarded as preliminary until revised, substantiated or supplanted by more detailed tree-measurements available in the future. Sawtimber volumes on the sample plots taken in the field were computed by applying appropriate volume tables to the recorded stand tallies. In this way, average net volumes by species, per unit of area, were compiled by province for each forest type and stocking-class. These per unit volumes were then multiplied by corresponding type-stocking-class areas to build up total volume by species and by provinces. Cubic volumes were computed as follows: For each species, size of average tree was calculated from the field tally sheets. Using the volume tables previously constructed, the ratio of total cubic-foot volume to board feet of sawtimber for the tree of average size for each species was determined. These ratios multiplied by total board feet of sawtimber by species, gave the corresponding cubic volume in sawtimber trees. Cubic volume in trees too small or too rough for sawtimber was computed by multiplying unit-area volumes of such trees by corresponding type areas. Distribution of sawtimber volume by log grade was computed by applying the percentages given in the table on page 212, appendix, to the volumes of trees tallied by log grade in the field. The result in terms of comparative volumes is given in table 8, page 25 of the text. FOREST DEPLETION METHODS Fire Depletion Areas that had been deforested by fire and had not passed into a higher use were mapped directly by sketching from an airplane. Only areas judged to have once supported commercial sawtimber forest were included in this category, and it was assumed that the original timber volume per unit of area on these burns averaged the same as that remaining in the surrounding forest. Then, during field examination, the following data were estimated for the deforested land in each province: 1. The percentage of original stand killed by fire. vaged, 2. The percentage of stand killed that had been or will be sal3. The average number of years elapsed since the timber was killed on the mapped burns. The average volume killed, reduced by the volume salvaged, equals net volume loss. This volume, divided by number of years elapsed, is the estimated annual fire loss, in terms of timber volume. Annual loss was then converted to percent of total live timber volume, and these percentages multiplied by timber inventory to give total annual fire loss. As previously mentioned, a count was taken of differences in percent kill, percent salvage, number of years elapsed and volume of timber stand between the various provinces. Insect, Disease, Windfall, and Other Losses Depletion from these sources was, in the last analysis, determined by direct estimate, keeping in mind the general inverse correla tion between growth rate and loss rate in immature and in overmature trees. Tree size, thrift and maturity, all of which were recorded as a part of the inventory field work, and the computed average growth rates formed the statistical basis for the normal loss estimates. The basis for estimates of current epidemic tree mortality was obtained during the inventory field work by tallying separately all dead trees judged to have succumbed within one year. Cutting Depletion Estimates of forest depletion caused by the cutting of lumber products are based on official census reports for the years 1936 to 1943, inclusive. Depletion resulting from manufacture of veneer and plywood is estimated from statistics supplied by the producing companies. Records of purchases by the State railroads, during the period 1938 to 1942 supplied information on depletion from production of railroad crossties. Volumes of ties exported and used in private railroads during the same period were obtained from a previous Fomento report on wood preservation in Chile. Depletion resulting from cutting of poles is based on consumption statistics for the years 1938 to 1942, obtained from telephone, telegraph and electric power companies. Information was collected from mine operators regarding amount of wood used in mines. Volume of wood used for pulping was obtained from the local paper company. Volume of lumber and other products for export was obtained from census statistics. As explained in the text, the depletion figures given in this reare in terms of tree volume, and are directly comparable with similar forest inventory volumes. In general, depletion caused by cutting was estimated by collecting wood products production or use statistics, to which was added an estimated volume of wood waste occasioned by the production process. Forest depletion caused by cutting of posts, fencing, and minor agricultural uses is based on direct estimates for the several purposes included in this category. Such estimates were varied by province-group statistics regarding number and area of farms, and known differences in farm practices. Estimates of industrial fuelwood use are based on information obtained from census reports, from railroad statistics and specific industrial reports. Information on volume of fuelwood used for domestic cooking and heating was collected from fuel dealers, agricultural agents, fundo owners, lumbermen, business men, and individual home owners. Final figures employed, however, are based principally on per capita fuel use estimates derived from railroad, fuelwood tonnages, rural and urban population statistics, and data on use of competing fuels, such as coal. Per capita use of fuel for heating was varied by province group, a larger amount being allowed for the colder areas. Depletion caused by fuelwood cutting also includes that resulting from the production of charcoal, whether for industrial or domestic use. It was found that a considerable portion of the fuelwood is salvaged from waste left after cutting operations for other timber products. Such secondary depletion does not represent a direct drain on the forest, and its volume is not included in the primary depletion figures. Cubic volume depletion of trees less than sawtimber size was estimated directly. Depletion of sawtimber trees was first estimated directly in terms of board feet net contents. Corresponding total cubic depletion was then estimated by the use of cubic foot board foot ratios for trees of average size derived from the coordinated volume tables given in the appendix. |