Research Article

Volume and Aboveground Biomass Models for Dry Miombo Woodland in Tanzania

Table 1

Volume and biomass equations for estimating total aboveground and stem (≥5 cm) volume and biomass of three dominant species in the Gangalamtumba Village Land Forest Reserve. All parameter estimates are significantly different from zero ( ).

SpeciesComponentEquation Regression parametersDbh range (cm)Adj. RMSEAvg. error (%)

Brachystegia spiciformis ( )Total volume
(df = 37)
3−9.3188
(0.166)
1.9663
(0.088)
0.9118
(0.174)
1.2–54.30.9970.1421.99
(df = 38)4−8.5018
(0.077)
2.4142
(0.027)
1.2–54.30.9950.1853.49
Stem volume
(df = 31)
3−11.7673
(0.379)
2.0335
(0.141)
1.6858
(0.314)
5–54.30.9900.209−0.02
(df = 32)4−9.8909
(0.203)
2.7460
(0.066)
5–54.30.9810.2862.14
Total biomass
(df = 37)
3−2.6071
(0.149)
2.0638
(0.078)
0.7847
(0.155)
1.2–54.30.9980.1271.60
(df = 38)4−1.9040
(0.068)
2.4492
(0.024)
1.2–54.30.9960.1622.67
(df = 38)6−9.3309
(0.108)
0.9827
(0.008)
1.2–54.30.9980.1271.66
Stem biomass
(df = 31)
3−5.0668
(0.343)
2.1424
(0.128)
1.5563
(0.284)
5–54.30.9920.189−0.57
(df = 32)4−3.3345
(0.185)
2.8002
(0.061)
5–54.30.9850.2621.17

Combretum molle ( )Total volume
(df = 38)
3−9.0504
(0.165)
1.9212
(0.099)
0.7712
(0.183)
2.2–26.50.9870.1712.90
(df = 39)4−8.5247
(0.130)
2.2972
(0.051)
2.2–26.50.9810.2044.24
Stem volume
(df = 30)
3−10.3990
(0.223)
2.0420
(0.126)
1.0908
(0.193)
5–26.50.9770.1464.64
(df = 31)4−9.8028
(0.277)
2.6237
(0.102)
5–26.50.9540.2064.98
Total biomass
(df = 38)
3−2.4539
(0.165)
1.9685
(0.099)
0.7545
(0.183)
2.2–26.50.9870.1702.88
(df = 39)4−1.9395
(0.129)
2.3364
(0.050)
2.2–26.50.9820.2034.20
(df = 39)6−8.8347
(0.230)
0.9371
(0.168)
2.2–26.50.9870.1702.98
Stem biomass
(df = 30)
3−3.7737
(0.230)
2.1112
(0.130)
1.0410
(0.199)
5–26.50.9760.1514.41
(df = 31)4−3.2047
(0.275)
2.6663
(0.101)
5–26.50.9560.2054.66

Dalbergia arbutifolia ( )Total volume
(df = 34)
3−9.3147
(0.191)
1.9701
(0.059)
0.8854
(0.152)
1.8–21.50.9910.1442.04
(df = 35)4−8.3253
(0.120)
2.2413
(0.051)
1.8–21.50.9820.2003.90
Stem volume
(df = 29)
3−13.8803
(0.761)
2.0113
(0.246)
2.7732
(0.455)
5–21.50.8710.35512.97
(df = 30)4−10.5743
(0.793)
2.7785
(0.313)
5–21.50.7150.52832.87
Total biomass
(df = 34)
3−2.7097
(0.199)
1.9900
(0.062)
0.9035
(0.159)
1.8–21.50.9900.1501.22
(df = 35)4−1.7001
(0.124)
2.2667
(0.052)
1.8–21.50.9810.2063.00
(df = 35)6−9.3782
(0.213)
0.9823
(0.016)
1.8–21.50.9900.1481.37
Stem biomass
(df = 29)
3−7.3073
(0.776)
2.0138
(0.250)
2.8503
(0.464)
5–21.50.8690.36211.53
(df = 30)4−3.9094
(0.812)
2.8023
(0.321)
5–21.50.7080.54130.54
(df = 30)6−14.5150
(1.467)
1.2961
(0.108)
5–21.50.8230.42117.00

Note: numbers in brackets indicate standard errors of the parameter estimates. Height (range): B. spiciformis: 2–17.2 m; C. molle: 2.6–9.4 m; and D. arbutifolia: 2.6–8.8 m. df is degrees of freedom; RMSE is the standard error of the residuals; Adj. is the adjusted coefficient of determination; Avg. is Average. Equation (3): . Equation (4): . Equation (6): ; is volume (m3) or biomass (kg); Dbh is diameter at breast height (cm); ht is total height (m); and wd is wood density (kg m−3).