Arizona republican., 1920-11-04

auxiliary measure to be applied where natural reproduction is unpromising. as. for example. where fire or destruc- tive numbering has removed the seed trees. In this role, planting will even tually assume an important place in the management of our forests.
 By means Of permanent sample plots if is possible to maintain an ac- curate record of what actually takes
 place in the forest. so that after 10. 20 or 30 years a complete and authen- tic history of areas under observation becomes available. From 1909 to 1913 42 plots having a total area of 193.5 acres were established on six national
 forests in Arizona and New Mexico. Each plot is mapped to scale. showing the exact location of every tree. group
 of seedlings. stun1ps logs, brush piles and other features. The diameter.
 height and full description of every tree is recorded by number. Periodic
 measurements show the rate of growth as well as death or injury from light ming. windfall. insects. disease and
 other agencies. Annual examinations on number Of plots furnish a record of the occurrence of seed crops ger
 imitation and survival of seedlings under various conditions These plots the oldest of which were established ] N I mass of information obtainable by no
 other means; but the records become more valuable each wear. and it is only ] after 20 or more years that anything approaching full returns will be i realized.
 Records in the forest and in asijoin- ing open areas have shown that the l forest greatly reduces wind and evapo- 1 ration, and modifies the extremes Of l temperature. particularly low temper
 ature. Snow melts more rapidly in the forest than in the open during the
 winter, but less rapidly in the spring
 The result is a less torrentia1 but more sustained surface rnnoff and less ero- sion on forested than on non forested
 areas
 In 1916 an investigation known as the study of forest types was Initiated. it's immediate object to secure an accurate i knowledge of the physical conditions prevailing in the various forest types 1 or forest tree associations. Having ob- tained this information it will be pos i sible to make a close estimate of the i soil and climatic requirements of diff 1 ferent species and particularly the fac 1 tors limiting their distribution. Since the occurrence of given tree species
 or association of species is indicative of physical conditions corresponding 10
 their requirements. trees may be used
 as Nindicators'' Of soil and climate
 From November. 1916. 10 Jan. 1, 1920
 a series of six instrument stations was
 maintained at various attitudes extend | ing from the woodland at 5100 feet to
 timber line at 11.5O0 feet. Continuous
 records of air temperature, soil tenn perature, precipitation. evaporation
 and wind were secured mainly by means of self recording instruments These stations were visited weekly
 summer and winter throughout the
 three years. Studies have also beer
 made of the moisture content and other
 properties of soils, and the relative
 moisture requirements of different
 tree species in the seedling stage. This
 investigation. which Is still in prog
 ress, is expected to yield valuable fun. damental data of direct or indirect ap- plication to many forest problems
 The problem which is of most imme, diate importance and which unfor. ] tunately, has proved to be the mos
 perplexing and time consuming is tha
 of securing natural reproduction O western yellow pine. A general surve, of the situation in 1908 resulted in es
 tablishing certain broad conclusions . 1t was found that, contrary to pre- vailing opinions. considerable number
 of seed trees were necessary: that largi
 crops of seedlings had become estab lished only under unusually favorabl combinations of seed production an, rainfall. and that under certain condi
 tons excessive damage was done b, | grazing, Later investigations substan tiated the above conclusions and de : Vcloped additional facts. Records dur ing the period Of F. years on the per r manent sample plots previously de scribed have shown that as rule see' ? crops are borne only every other yea ! and that good seed crops have occurre, . only at intervals of about years; tha ' the seed sometimes fails to germinat z for lack of moisture and that in som years when moisture conditions ar
 favorable there is no seed: hat of tn :, seedlings which do germi1ate rarel 1, 1 more than ] or per cent survive T that despite this great mortality a fey - seedlings survive from almost ever , seed crop, so that as a result of thi a slow but reasonably certsin cumulativ II process, areas which are well provide v with seed trees and properly protecte if against fires and unregulated grazin r may be expected to fully restock i
 about 20 years At irregular interval f. often longer than 2 years a singl Q crop followed by two or more years 0 W favorable moisture conditions may re T soIt in Lae sttbiishHent of See1ling in sufficient numoerl to couaH.et-ly re E stock an area SHsn CccuteFre-s ar, D hoN es eE. Loo Unccae-u iu l- relic