A total of 74 Japanese black pine (
Epidemic outbreaks of insects or pathogens in forest ecosystems in recent years have been unusually widespread and severe (
Biomass, C and N content in forest ecosystems are commonly estimated by using allometric equations (
Pine wilt disease (PWD), caused by the pine wood nematode (
Japanese black pine (
The study was conducted in natural black pine stands in four different regions (Goheung: GH1, GH2; Gwangyang: GY; Sacheon, SA; and Jinju: JJ1, JJ2, JJ3, JJ4) and natural red pine stands in five different regions (Hadong: HD; Hamyang: HY; Jinju: JJ5; Sancheong: SC; and Uiryeong, UR), located in the south-central part of Korea (
The annual average precipitation and temperature in HD are higher than for other regions in the study area (Tab. S1 in Supplementary material). The soils in HD, HY, GH, GY and SC are well-drained, slightly wet, brown forest soils (mostly Inceptisols or Alfisol, USDA soil taxonomy) originating from granite with a loamy texture, while the soils in JJ, SA and UR are slightly dry, dark brown forest soils (Inceptisol) originating from sandstone with a silt loam texture. Because the black pine and red pine species are distributed in various environmental site conditions, the sampling for this study was planned to cover a broad range of site characteristics such as parent materials and stand age class, to provide a regional representation applicable at a landscape scale (Tab. S1 in Supplementary material).
The experimental design consisted of a 20 × 20 m plot within each site in the PWD-infected districts (
To develop allometric equations, a complete tree inventory was carried out for each stand to characterize the stem diameter distribution. Five or eight diameter classes based on the DBH ranges were established for each site, and sample trees were randomly chosen within each DBH class. However, it was preferable to select trees with a maximum and minimum DBH from each site. The trees were destructively sampled and separated into components (
The allometric equations developed for each of the tree components (stem wood, stem bark, branches, needles, roots) were of the following form (
where
The C concentration among the tree components was not correlated with DBH (
Mean C and N concentrations varied significantly among the tree components and tree species (
The relationships between biomass, C and N content for all the tree components and DBH or D20 are shown in
Mean biomass and C content among tree components in the sampled trees were not significantly different between the observed values and the predicted values using the DBH or D20 allometric equations except for N content in needles (
Increased DBH values might be expected to entail higher C concentrations because of increase in lignin concentration within lignified wood tissues (
There was a clear influence of DBH on N concentrations in stem wood, stem bark and branches, which were negatively correlated with increasing DBH in black pine. Negative relationships between N concentration and increasing DBH are commonly observed in tree stems (
There were no species-specific differences in mean C concentrations between both pine species except for stem bark. Genetic differences in biomass allocation among tree species might result in different mean C concentrations of stem bark, which was significantly higher in the red pine than in the black pine. For example, the greater mean C concentration of bark tissues in red pine is likely due to a difference in bark thickness and branch biomass compared to black pine. In this study, the mean bark biomass of the sampled red pines was 9.9 kg tree-1, whereas that of black pines was 16.7 kg tree -1 (
Mean C concentrations among tree components were highest in needles, lowest in roots, and slightly lower in stem bark and branches than in stem wood. High C concentrations in needles could be non-structural C compounds such as sugar and starch (
The mean N concentrations of stem wood, branches, needles and roots in red pine were significantly greater than those of the respective components in black pine. The N concentrations in tree components were significantly affected by tree species, as the N concentration among tree components are controlled by factors such as the combined effects of the available N status of the soil, tree growth, and climate factors (
The species-specific allometric equations to estimate biomass, C and N content for tree components in the black pine and red pine stands were highly significant (
In this study the slope coefficient (
Although the predicted values were generally overestimating biomass and C content or underestimating N content as compared to the observed values, those measures in both pine species were not significantly different between the observed and the predicted values, except for needle N content of black pine. This result indicates that the biomass, C and N content equations developed in this study can provide a means for estimating these values in other stands. However, the equations available for large-scale landscape, such as disturbed forests, should be applied with caution because such sites might have variation in tree biomass and its allocation to tree components (
Allometric equations for estimating biomass, C and N content of black pine and red pine stands in PWD-disturbed forests were developed based on DBH and D20. The accuracy of estimates for the C and N content in PWD-disturbed forests has been improved by the measurement of C and N concentrations per tree components in the allometric equations, because the C and N concentrations vary between different tree species and among tree components. This study emphasizes the importance of separating tree species and tree components to estimate the C and N content by tree biomass in the PWD-disturbed forest ecosystems.
CK performed the experiment and wrote the paper, SJ and KL provided constructive suggestions on the study, and BY designed the experiments. We thank one anonymous referee and the subject editor for helpful reviews of the manuscript. This study was carried out with the support of Southern Forest Resource Research Center, National Institute of Forest Science, Korea.
Location of the study site (black pine, GH: Goheung, GY: Gwangyang, SA: Sacheon, JJ: Jinju; red pine, HY: Hamyang, SC: Sancheong, UR: Uiryeong, HD: Hadong, JJ: Jinju).
Correlation between carbon or nitrogen concentrations and diameter at breast height (DBH) among tree components (a-b: stem wood, c-d: stem bark, e-f: branches, g-h: needles, i-j: root) in black pine and red pine.
Mean values of biomass, carbon and nitrogen concentration for tree species and tree components in black pine (n = 49) and red pine (n = 25). Vertical bars represent standard error. Different letters among tree components in each tree species and asterisks between both pine species indicate a significant difference at
Relationship between biomass (left column), carbon (central column) and nitrogen (right column) content of tree components (a-c: stem wood, d-f: stem bark, g-i: branches, j-l: needles, o-q: root, r-t: aboveground) between DBH and D20 in black pine (n=49). Observed (open circle)
Relationship between biomass (left column), carbon (central column) and nitrogen (right column) content of tree components (a-c: stem wood, d-f: stem bark, g-i: branches, j-l: needles, o-q: root, r-t: aboveground) between DBH and D20 in red pine (n=25). Observed (open triangle)
Regression parameters for species-specific allometric equations of biomass estimation in tree components of black pine (n = 49) and red pine (n = 25). Allometric equation form is log10
Variable | Tree species | Treecomponent ( |
Coefficient | Adj. |
RMSE | CF | ||
---|---|---|---|---|---|---|---|---|
|
|
|||||||
DBH | Black pine | Stem wood (kg) | -1.4410 | 2.6504 | 0.94 | 0.1272 | <0.0001 | 1.019 |
Stem bark (kg) | -1.9608 | 2.3352 | 0.94 | 0.1124 | <0.0001 | 1.015 | ||
Branch (kg) | -1.7242 | 2.4042 | 0.87 | 0.1823 | <0.0001 | 1.039 | ||
Needle (kg) | -1.2966 | 1.8446 | 0.73 | 0.2186 | <0.0001 | 1.057 | ||
Aboveground (kg) | -0.9897 | 2.4486 | 0.97 | 0.0856 | <0.0001 | 1.008 | ||
Root (kg) | -1.5416 | 2.4869 | 0.94 | 0.2193 | <0.0001 | 1.012 | ||
Red pine | Stem wood (kg) | -1.3140 | 2.4272 | 0.90 | 0.1547 | <0.0001 | 1.028 | |
Stem bark (kg) | -1.3024 | 1.7847 | 0.95 | 0.0786 | <0.0001 | 1.007 | ||
Branch (kg) | -1.7527 | 2.2283 | 0.78 | 0.2387 | <0.0001 | 1.068 | ||
Needle (kg) | -1.4507 | 1.6100 | 0.69 | 0.2115 | <0.0001 | 1.053 | ||
Aboveground (kg) | -0.8916 | 2.2289 | 0.94 | 0.1117 | <0.0001 | 1.014 | ||
Root (kg) | -1.2218 | 1.9272 | 0.72 | 0.1940 | 0.005 | 1.044 | ||
D20 | Black pine | Stem wood (kg) | -2.0111 | 2.9152 | 0.91 | 0.1594 | <0.0001 | 1.030 |
Stem bark (kg) | -2.4595 | 2.5659 | 0.91 | 0.1422 | <0.0001 | 1.024 | ||
Branch (kg) | -2.3117 | 2.6962 | 0.87 | 0.1794 | <0.0001 | 1.038 | ||
Needle (kg) | -1.7701 | 2.0852 | 0.75 | 0.2122 | <0.0001 | 1.053 | ||
Aboveground (kg) | -1.5361 | 2.7078 | 0.95 | 0.1130 | <0.0001 | 1.015 | ||
Root (kg) | -2.5432 | 3.0676 | 0.93 | 0.1192 | <0.0001 | 1.016 | ||
Red pine | Stem wood (kg) | -1.7845 | 2.5909 | 0.92 | 0.1481 | <0.0001 | 1.026 | |
Stem bark (kg) | -1.5500 | 1.8304 | 0.88 | 0.1226 | <0.0001 | 1.017 | ||
Branch (kg) | -2.2507 | 2.4288 | 0.82 | 0.2161 | <0.0001 | 1.055 | ||
Needle (kg) | -1.8706 | 1.8004 | 0.77 | 0.1833 | <0.0001 | 1.039 | ||
Aboveground (kg) | -1.3259 | 2.3809 | 0.95 | 0.1024 | <0.0001 | 1.012 | ||
Root (kg) | -1.5667 | 2.0282 | 0.72 | 0.1921 | <0.005 | 1.043 |
Regression parameters of species-specific allometric equations of carbon content in tree components of black pine (n = 49) and red pine (n = 25). Allometric equation form is log10
Variable | Tree species | Tree component ( |
Coefficient | Adj. |
RMSE | CF | ||
---|---|---|---|---|---|---|---|---|
|
|
|||||||
DBH | Black pine | Stem wood (kg) | -1.7618 | 2.6479 | 0.94 | 0.1267 | <0.0001 | 1.019 |
Stem bark (kg) | -2.2675 | 2.3261 | 0.94 | 0.1124 | <0.0001 | 1.015 | ||
Branch (kg) | -2.0378 | 2.4021 | 0.87 | 0.1824 | <0.0001 | 1.039 | ||
Needle (kg) | -1.5977 | 1.8429 | 0.73 | 0.2185 | <0.0001 | 1.057 | ||
Aboveground (kg) | -1.3014 | 2.4421 | 0.97 | 0.0846 | <0.0001 | 1.008 | ||
Root (kg) | -1.8359 | 2.4472 | 0.94 | 0.1111 | <0.0001 | 1.014 | ||
Red pine | Stem wood (kg) | -1.6616 | 2.4455 | 0.90 | 0.1557 | <0.0001 | 1.028 | |
Stem bark (kg) | -1.6362 | 1.8048 | 0.95 | 0.0797 | <0.0001 | 1.007 | ||
Branch (kg) | -2.0936 | 2.2473 | 0.77 | 0.2391 | <0.0001 | 1.067 | ||
Needle (kg) | -1.7803 | 1.6330 | 0.69 | 0.2118 | <0.0001 | 1.053 | ||
Aboveground (kg) | -1.2293 | 2.2427 | 0.94 | 0.1116 | <0.0001 | 1.014 | ||
Root (kg) | -1.6365 | 1.9712 | 0.70 | 0.1940 | 0.006 | 1.052 | ||
D20 | Black pine | Stem wood (kg) | -2.3335 | 2.9142 | 0.91 | 0.1580 | <0.0001 | 1.029 |
Stem bark (kg) | -2.7648 | 2.5564 | 0.91 | 0.1418 | <0.0001 | 1.023 | ||
Branch (kg) | -2.6253 | 2.6942 | 0.87 | 0.1794 | <0.0001 | 1.098 | ||
Needle (kg) | -2.0714 | 2.0839 | 0.75 | 0.2120 | <0.0001 | 1.053 | ||
Aboveground (kg) | -1.8485 | 2.7022 | 0.95 | 0.1109 | <0.0001 | 1.014 | ||
Root (kg) | -2.8181 | 3.0162 | 0.93 | 0.1194 | <0.0001 | 1.017 | ||
Red pine | Stem wood (kg) | -2.1329 | 2.6084 | 0.91 | 0.1502 | <0.0001 | 1.026 | |
Stem bark (kg) | -1.888 | 1.8522 | 0.89 | 0.1235 | <0.0001 | 1.018 | ||
Branch (kg) | -2.5957 | 2.4493 | 0.82 | 0.2140 | <0.0001 | 1.054 | ||
Needle (kg) | -2.2052 | 1.8253 | 0.77 | 0.1830 | <0.0001 | 1.039 | ||
Aboveground (kg) | -1.6642 | 2.3941 | 0.95 | 0.1034 | <0.0001 | 1.012 | ||
Root (kg) | -1.9957 | 2.0842 | 0.71 | 0.2043 | <0.0001 | 1.049 |
Regression parameters of species-specific allometric equations of nitrogen content in tree components of black pine (n = 49) and red pine (n = 25). Allometric equation form is log10
Variable | Treespecies | Treecomponent ( |
Coefficient | Adj. |
RMSE | P-value | CF | |
---|---|---|---|---|---|---|---|---|
|
|
|||||||
DBH | Black pine | Stem wood (kg) | -4.1655 | 2.0247 | 0.72 | 0.2444 | <0.0001 | 1.071 |
Stem bark (kg) | -4.3109 | 2.1106 | 0.86 | 0.1645 | <0.0001 | 1.032 | ||
Branch (kg) | -4.1078 | 2.1884 | 0.86 | 0.1748 | <0.0001 | 1.036 | ||
Needle (kg) | -3.3399 | 1.7995 | 0.73 | 0.2172 | <0.0001 | 1.056 | ||
Aboveground (kg) | -3.1703 | 1.9378 | 0.89 | 0.1309 | <0.0001 | 1.020 | ||
Root (kg) | -3.7581 | 2.0185 | 0.66 | 0.2509 | <0.0001 | 1.075 | ||
Red pine | Stem wood (kg) | -4.0840 | 2.1108 | 0.83 | 0.1878 | <0.0001 | 1.041 | |
Stem bark (kg) | -4.1892 | 1.9772 | 0.91 | 0.1242 | <0.0001 | 1.018 | ||
Branch (kg) | -4.2092 | 2.1941 | 0.73 | 0.2608 | <0.0001 | 1.081 | ||
Needle (kg) | -3.4831 | 1.6452 | 0.73 | 0.1941 | <0.0001 | 1.044 | ||
Aboveground (kg) | -3.2812 | 1.9287 | 0.90 | 0.1283 | <0.0001 | 1.019 | ||
Root (kg) | -3.6781 | 1.9577 | 0.77 | 0.1711 | 0.003 | 1.034 | ||
D20 | Black pine | Stem wood (kg) | -4.6370 | 2.2534 | 0.72 | 0.2479 | <0.0001 | 1.073 |
Stem bark (kg) | -4.7760 | 2.3297 | 0.84 | 0.1781 | <0.0001 | 1.037 | ||
Branch (kg) | -4.6553 | 2.4635 | 0.87 | 0.1681 | <0.0001 | 1.033 | ||
Needle (kg) | -3.7952 | 2.0294 | 0.73 | 0.2125 | <0.001 | 1.053 | ||
Aboveground (kg) | -3.6380 | 2.1688 | 0.89 | 0.1305 | <0.001 | 1.020 | ||
Root (kg) | -4.6538 | 2.5506 | 0.69 | 0.2398 | <0.0001 | 1.068 | ||
Red pine | Stem wood (kg) | -4.4445 | 2.2164 | 0.81 | 0.1990 | <0.0001 | 1.047 | |
Stem bark (kg) | -4.4313 | 2.0035 | 0.82 | 0.1726 | <0.0001 | 1.035 | ||
Branch (kg) | -4.7166 | 2.4044 | 0.79 | 0.2363 | <0.0001 | 1.066 | ||
Needle (kg) | -3.9173 | 1.8436 | 0.83 | 0.1597 | <0.0001 | 1.030 | ||
Aboveground (kg) | -3.6734 | 2.0727 | 0.92 | 0.1146 | <0.0001 | 1.015 | ||
Root (kg) | -3.8574 | 1.9264 | 0.66 | 0.2097 | 0.009 | 1.052 |
Mean observed and predicted (DBH and D20) values (± standard error) using allometric equations in black pine (n = 49) and red pine (n = 25). Different letters among observed and predicted values indicate significant differences after Tukey’s test (
Biomass or nutrient | Tree species | Obs/Pred values | Tree component (kg tree-1) | |||||
---|---|---|---|---|---|---|---|---|
Stem wood | Stem bark | Branch | Needle | Above ground | Root | |||
Biomass | Black pine | Obs. | 151.4 ± 18.4 a | 16.7 ± 2.0 a | 37.9 ± 4.7 a | 16.9 ± 1.8 a | 222.8 ± 26.2 a | 62.9 ± 11.9 a |
DBH | 171.1 ± 23.1 a | 17.4 ± 2.1 a | 41.7 ± 5.2 a | 18.4 ± 1.8 a | 235.2 ± 29.3 a | 64.4 ± 11.8 a | ||
D20 | 183.7 ± 26.7 a | 17.9 ± 2.3 a | 42.5 ± 5.7 a | 18.5 ± 2.0 a | 262.6 ± 36.7 a | 66.1 ± 12.7 a | ||
Red pine | Obs. | 72.3 ± 14.3 a | 9.9 ± 1.6 a | 15.5 ± 3.6 a | 4.3 ± 0.6 a | 102.1 ± 19.5 a | 14.4 ± 3.6 a | |
DBH | 79.9 ± 15.7 a | 9.9 ± 1.4 a | 16.7 ± 3.1 a | 4.4 ± 0.6 a | 114.5 ± 23.9 a | 14.8 ± 3.1 a | ||
D20 | 77.6 ± 14.4 a | 9.8 ± 1.3 a | 16.1 ± 2.9 a | 4.3 ± 0.6 a | 107.8 ± 19.2 a | 15.2 ± 3.5 a | ||
Carbon | Black pine | Obs. | 71.8 ± 8.8 a | 8.0 ± 0.9 a | 18.3 ± 2.3 a | 8.4 ± 0.9 a | 106.4 ± 12.5 a | 28.1 ± 12.7 a |
DBH | 79.9 ± 10.8 a | 8.2 ± 1.0 a | 19.6 ± 2.5 a | 8.8 ± 0.9 a | 109.7 ± 14.0 a | 28.7 ± 5.5 a | ||
D20 | 84.8 ± 12.3 a | 8.4 ± 1.0 a | 20.0 ± 2.7 a | 8.9 ± 1.0 a | 122.1 ± 17.0 a | 29.3 ± 5.5 a | ||
Red pine | Obs. | 34.3 ± 6.8 a | 4.9 ± 0.8 a | 7.5 ± 1.7 a | 2.1 ± 0.3 a | 48.9 ± 9.3 a | 6.5 ± 1.8 a | |
DBH | 37.2 ± 7.4 a | 4.8 ± 0.7 a | 7.7 ± 1.5 a | 2.1 ± 0.3 a | 53.0 ± 11.1 a | 6.3 ± 1.3 a | ||
D20 | 36.2 ± 6.8 a | 4.8 ± 0.7 a | 7.5 ± 1.3 a | 2.1 ± 0.3 a | 50.6 ± 9.1 a | 6.5 ± 1.6 a | ||
Nitrogen | Black pine | Obs. | 0.043 ± 0.005 a | 0.037 ± 0.004 a | 0.079 ± 0.010 a | 0.133 ± 0.014 a | 0.291 ± 0.031 a | 0.104 ± 0.031 a |
DBH | 0.030 ± 0.003 a | 0.032 ± 0.004 a | 0.067 ± 0.010 a | 0.109 ± 0.011 ab | 0.270 ± 0.029 a | 0.096 ± 0.016 a | ||
D20 | 0.031 ± 0.004 a | 0.032 ± 0.009 a | 0.069 ± 0.009 a | 0.088 ± 0.012 b | 0.220 ± 0.028 a | 0.074 ± 0.013 a | ||
Red pine | Obs. | 0.052 ± 0.014 a | 0.025 ± 0.005 a | 0.049 ± 0.012 a | 0.044 ± 0.006 a | 0.170 ± 0.034 a | 0.053 ± 0.011 a | |
DBH | 0.039 ± 0.007 a | 0.021 ± 0.003 a | 0.034 ± 0.006 a | 0.036 ± 0.005 a | 0.162 ± 0.030 a | 0.046 ± 0.011 a | ||
D20 | 0.038 ± 0.006 a | 0.019 ± 0.003 a | 0.036 ± 0.006 a | 0.056 ± 0.008 a | 0.149 ± 0.024 a | 0.043 ± 0.010 a |
Tab. S1 - General site and stand characteristics of black pine and red pine stands in the study sites.
Tab. S2 - General characteristics of sampled trees in black pine and red pine.
Tab. S3 - Dry weight, N and C concentration of black pine and red pine tree sampled from study sites.
Tab. S4 - Nitrogen and Carbon concentration of black pine and red pine tree sampled from study sites.
Tab. S5 - Root dry weight, nitrogen and carbon concentration of black pine and red pine tree sampled from study sites.