This update utilizes height-age pairs measured from 1982 - 1998. As a result, the number of observations available for analysis is 1,814 loblolly and 788 slash. It is anticipated that the equations in this Fall 1998 update may quantify the productivity of East Texas loblolly and slash pine plantations in a more accurate and reliable manner than the seven previous sets of equations

Abston, Jermey

Bledsoe, Jason

Davis, Tyson

Duncan, Cody

Guinn, Jason

Hilton, Steven

Jones, Gwen

Jones, Jennifer

Kellam, Jeff

Killburn, Bryan

Knox, Denver

Muncrief, William

Nelms, Jason

Pool, Chris

Ramey, Will

Rice, Keith

Roberts, Kevin

Stanford, Curtis

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Stephen F. Austin State UniversitySFA ScholarWorksInformal Project Reports East Texas Pine Plantation Research Project11-1998Project Report No. 62, Site Index Equations forLoblolly and Slash Pine Plantations in East Texas,Update: Fall 1998Jermey AbstonStephen F. Austin State UniversityJason BledsoeStephen F. Austin State UniversityTyson DavisStephen F. Austin State UniversityCody DuncanStephen F. Austin State UniversityJason GuinnStephen F. Austin State UniversitySee next page for additional authorsFollow this and additional works at: http://scholarworks.sfasu.edu/etpprp_project_reportsPart of the Other Forestry and Forest Sciences CommonsTell us how this article helped you.This Report is brought to you for free and open access by the East Texas Pine Plantation Research Project at SFA ScholarWorks. It has been acceptedfor inclusion in Informal Project Reports by an authorized administrator of SFA ScholarWorks. For more information, please contactcdsscholarworks@sfasu.edu.Recommended CitationAbston, Jermey; Bledsoe, Jason; Davis, Tyson; Duncan, Cody; Guinn, Jason; Hilton, Steven; Jones, Gwen; Jones, Jennifer; Kellam, Jeff;Killburn, Bryan; Knox, Denver; Muncrief, William; Nelms, Jason; Pool, Chris; Ramey, Will; Rice, Keith; Roberts, Kevin; andStanford, Curtis, "Project Report No. 62, Site Index Equations for Loblolly and Slash Pine Plantations in East Texas, Update: Fall1998" (1998). Informal Project Reports. Paper 8.http://scholarworks.sfasu.edu/etpprp_project_reports/8AuthorsJermey Abston, Jason Bledsoe, Tyson Davis, Cody Duncan, Jason Guinn, Steven Hilton, Gwen Jones, JenniferJones, Jeff Kellam, Bryan Killburn, Denver Knox, William Muncrief, Jason Nelms, Chris Pool, Will Ramey,Keith Rice, Kevin Roberts, and Curtis StanfordThis report is available at SFA ScholarWorks: http://scholarworks.sfasu.edu/etpprp_project_reports/8so 3~7 Pss site Index Equations for ({l{l >blolly and Slash Pine Plantations in East Texas Update: Fall 1998 by Jermey Abston Jason Bledsoe Tyson Davis Cody Duncan Jason Guinn Steven Hilton Gwen Jones Jennifer Jones Jeff Kellam Bryan Kilburn Denver Knox William Muncrief Jason Nelms Chris Pool Will Ramey Keith Rice Kevin Roberts Curtis Sanford (all of whom were FOR 3 7 7 students Fall '98) From the East Texas Pine Plantation Research Project Arthur Temple College of Forestry SFASU Nacogdoches, TX 75962 November ... 1998 PAGE • . • 2 SITUATION Site index prediction equations for loblolly ( Pinus taeda L. ) and slash ( Pinus elliottii Engelm. ) pine plantations in East Texas have been previously developed and published by: Lenhart, J.D. , E.V. Hunt, Jr. and J. A. Blackard. 1986. Site index equations for loblolly and slash pine plantations on non-old-field in ·East Texas. South. J . Appl. For. 10(2):109-112. Vaughn, A. B., J . Lapongan and J.D. Lenhart. 1993. Site index equations for loblolly and slash pine plantations in East Texas-Update: 1993. ETPPRP Report 27. College of Forestry. SFASU. 6 p. Members FOR 317 Class Spring '94. 1994. Site index equations for loblolly and slash pine plantations in East Texas -Update: 1994: ETPPRP Report 29. College of Forestry. SFASU. 7 p. Members FOR 317 Class Spring '95. 1995. Site index equations for loblolly and slash pine plantations in East Texas -Update: 1995. ETPPRP Report 37. College of Forestry. SFASU. 6 p. Members FOR 317 Class Spring '96. 1996. Site index equations for loblolly and slash pine plantations in East Texas -Update: 1996. ETPPRP Report 43. College of Forestry. SFASU. 6 p. Members FOR 317 Class Fall '96. 1996. Site index equations for loblolly and slash pine plantations in East Texas-Update: 1996. ETPPRP Report 50. College of Forestry. SFASU. 6 p. Members FOR 317 Class Fall '97. 1997. Site index equations for loblolly and slash pine plantations in East Texas -Update: 1997. ETPPRP Report 59. Arthur Temple College of Forestry. SFASU. 6 p . Each published set of equations was developed from analyses of East Texas Pine Plantation Research Project (ETPPRP) data collected from the array of ETPPRP permanent research plots located throughout East Texas. Since the ETPPRP plots are measured on a 3-year cycle, the number of age-height pairs available for site index analysis is increasing: This update utilizes height-age pairs measured from 1982 - 1998. As a result, the number of observations available for analysis is 1 ,814 loblolly and 788 slash. It is anticipated that the equations in this Fall 1998 update may quantify the productivity of East Texas loblolly and slash pine plantations in a more accurate and reliable manner than the seven previous sets of equations. PAGE 3 PLANTATION MEASUREMENTS Each ETPPRP piot consists of two subplots separated by a 60' buffei zone. An experimental design of this manner provides the opportunity to: • Evaluate models in an independent manner. • Explore effects of different treatments. • Investigate regression models. As was the practice in the two previous site index analyses, each subplot was considered a separate sampling unit in this Fall 1998 study. The characteristics of the 1,814 loblolly pine and 788 slash pine observations at least one year old and one foot in height that were utilized in this study can be summarized as: PAGE . . . 4 PREDICTING HEIGHT The same height prediction function used in 1986, 1993, 1994,1995, 1996 and 1997 was utilized in this Fall 1998 update. As a result of fitting the Richards' function, using non-linear regression analysis, to the age and height pairs, height can estimated as: LOBLOLLY H 81.98558[1-EXP{-0.09386{A))]1.68425 SLASH H = 120.27995[1-EXP{-0.04782{A))]1.28987 A residual analysis of equations (1) and (2) compared the predicted and observed heights for the evaluation subplot data sets and indicated no bias or adverse trends for either species. PREDICTING 5 IT E INDEX Using readily available procedures, the height estimation or guide curves (1) and (2) were converted into equations to estimate site index with index age = 25 years as: LOBLOLLY s = H{0.90430/[1-EXP{-0.09386{A))]}1.68425 SLASH s = H{0.69745/[1-EXP(-0.04782{A))]}1.28987 { 1 ) { 2 ) { 3 ) { 4) Equations (3) and (4) were rearranged to estimate H for a given A and S, and anamorphic site index curves were developed for each species (last two pages in this update). 110 100 90 ~ w ~ 80 en w w a: I-I-en w ....1 ....1 ~ z w 1-u.. 0 1-:::1: (!) w :I: w (!) c:( a: w > c:( 70 60 50 40 30 20 SITE INDEX CURVES FOR LOBLOLLY PINE PLANTATIONS IN EAST TEXAS (BASE AGE 25 YEARS) ~~0 I I I l.....-~ l VIT 1111 I _ll LI ~ T r1 _ll .. ~ w. 80 1='-v .~...~~~~~~~ ... ~-- w-v ~ rrw-I I I J I I I/ ,. T ~- U.. -I I ~~ --r -j l I I ~ L --- T 1- -, I~ _ ...... r7o -><-~ ...l-l-l-1 ~~ _w ~I I. 0 -I I I I I 71 ___ 1 I l I~ III VI I Yl I I I.Y " I .VI I I I~ ~Gfi:;Pl I ]7fT ll 1 ±~I 1:1 50 I I I II 7 I 7 I I 71 I I 1-1~ r lfl VI I Yl I I I ~ Jl I I~ I .VI I I I~ II III r I VI I I JA" I I 1/1 1./1 I I .Y 7171 A I :A' I I Y ,-,-vr-rr -r r 1111~ Ll"l II IIYYT.71" -, Y 1111 Tl Y Ill 'I Ll"l Y 117.71 A 17 7.TY Vl~ llllfl r 'IVT V HJJflL 7NL~ 'NY 10 lllilllllllllllllllllllllllllllll 0 0 5 10 15 20 25 30 35 PLANTATION AGE (YEARS) ~~ 110 100 90 ~ w w LL 80 ........ U) w w a: ~ 70 ~ U) w _. _. 60 ~ z w ~ 50 LL 0 ~ :::1: 0 40 Ui :::1: w 0 c:t 30 a: w > c:t 20 10 0 SITE INDEX CURVES FOR SLASH PINE PLANTATIONS IN EAST TEXAS (BASE AGE 25 YEARS) ~ 90 ~~ ~,.,. : , II" - -, 80-~-1/ """' ~ / -w-W-~" "' LL-, / ..._. / l/' ><-~ / 70-w-, / ~~ -c-/ ~ ~~ z---~ ~ / W-" ~ ~ !:::-, " , ~ / , .., 60 -U)-, ~ ~ ~ ~ 'f' / ~~ , / / """' / ~ ~ ~ , , ~., ... ~ 50 / , 'fl" . ~~ ~ , i~ ) , _J~ .... ~ , " 1/ ~~ ~'tfll"" ~ , ~ .J"' ~"' 1/ ~~ ~ ~, _.,.,.. J :f , ~,.,. ~ / J / , ... ~ ~ " ~ , ~~ , / , / ~~ i~ ~ / / """ , / .J ~ ~ ,. ~ , ~ ~ , , ~ , """ ,~ ~ / ~ ~ '/ 1/ ~ ~ "~ J " _J, Jrf " 1/ ~, ~~~ ~ ~ ,Jff "~ ~ " ,~ ~ , / ri.J ·~ ~ ~'j ~ ~ • Z'fl" , r 0 5 10 15 20 25 30 PLANTATION AGE (YEARS) . 

Project Report No. 62, Site Index Equations for Loblolly and Slash Pine Plantations in East Texas, Update: Fall 1998

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Project Report No. 62, Site Index Equations for Loblolly and Slash Pine Plantations in East Texas, Update: Fall 1998

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