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<br />PONDEROSA PINE RESPONSE SUMMARY <br />(FOR VOLCANIC. SOIL! <br />REDUCING BASAL AREA FROM 120 TO 60 SQUARE FT. PER ACRE <br />150]SAWTIMBER " 1200F" <br /> <br />8~::~ 0 r ~ I I POUN~:O~_~ I <br /> <br />o 20 40 60 80 100 120 0 20 40 60 <br /> <br />00071~' <br /> <br />forest Iypes. presumably because the pine forests <br />are drier. ShorHenn increases of 110 3 inches rnav <br />becxpel.t'~d from dearculling ponderosa pinHwith <br />basal area in pxcess of 100 square feet per acre. <br />although Iht'se increases would nol continue in- <br />dpfinilelv without mainten.lnce of the dearcut <br />conditio"n. Under a multiple Use managt~mt!nt <br />framework. ill which timber, range. wildlife. recre- <br />ation. and waler would all he considPred in tht: <br />product mix. the long-term increases of 0.1 to 1 <br />inch are mure realistic expectations (II. Brown cl <br />al. 197-l). The actual amount depends 011 the forest <br />co\'er present bdnre IreatnlPnt and the amount and <br />method of forest TnduUion (fig. 101. Tht~ i)\'erage <br />incn:ase is probahly about OIw-half inch, unless <br />special emphasis is plat.:nd un wilter productioll, <br />Under a wilter-llIl1phasis plan. about I inch might <br />be expected where substantial reductions can be <br />made in th" forest cO\'er b~' patch or strip cuts or <br />severe thinning to a stud,iog le\'!" of abuut -10 <br />square feel basal im~i1 pt'r acre. Current low to in- <br />termedialt~ stocking It~\'els on approximately <br />two-thirds of the ponderosa pillt! (Schubert P17-1j <br />{fig. I7J may preclude water increases from these <br />areas regardless of the management emphasis. I!X- <br />cept for clf!ilrCulling. <br /> <br />Chaparral <br />The chaparral type (fig. 18) is restricted almost <br />entire!\' to the Luwer Basin. whme it covers ap- <br />proximately :1,5 million acres. nearly all in <br />Arizollil. Ahout one-half is in the Natiun.t1 Forest <br />system; the remainder is nearly cquallv divided <br />between tht' Bureau of Land Management. the <br />State of Arizolla. and private and Indian uwner- <br />ship. Unlike tht! mounlilin brush in Colorado and <br />Utah.lhe chaparral species tend tu be low-growing <br />shrubs with Ihick, evergreen lea\'es welladilPted 10 <br />ht'at and drought. The t~'pe is found most com- <br />nIOnly on rugged terrain from 3.UOU to O.UOO feet <br />~Ie\'ation. Shrub lin. oak is most abundant. fol- <br />lowed hv mountainmahngany. Other common <br />shrubs are manzanita. Emor)' oak. silktassel, desert <br />ceanothus, and sligar sumac. <br />~Iost species sprout prolifically from rool <br />uowns after burning ur cutting; most aw difficult <br />to eradi{:atB. Pwdpitation averages 20to 22 inches <br />overall. but ranges frulTl as low as 1fi inches in the <br />Imn~r fringe areas to more than 25 inches in the <br />well est sites. Half or more of the precipitation falls <br />in the winter. mostly m; rain. \Vater yield varies <br />greatly depending on precipitation. clt!vation. and <br /> <br />t <br /> <br />I <br />80 <br /> <br />I <br />100 <br /> <br />120 <br /> <br />,~~O f'~ <br /> <br />~.7 <br />o 20 40 60 80 100 120 <br /> <br />:~:'~~5 I <br />O.5~'~ I <br />o 20 40 60 80 100 120 <br /> <br />~L055 <br /> <br />_GAIN <br /> <br />"~ <br />INDEX ------ - <br /> <br />02 <br />o 20 40 60 80 100 120 <br /> <br />Figure 16.-Oiflerences In resource outputs resulting Itom chlJnges in timber blSl1 Irel In <br />ponderosa pine (Biker and Bro....n 1974), <br /> <br />13 <br />