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1.
Black pine (Pinus nigra Arn.) is a pan-Mediterranean species of high ecological importance and one of the most important timber species in the area. We compare several site dependent height–age models for the species in three regions along its natural distribution area in Spain. The best model was a generalized algebraic difference approach (GADA) polymorphic model with variable asymptotes (Cieszewski, C.J., Bailey, R.L., 2000. Generalized algebraic difference approach: theory based derivation of dynamic site equations with polymorphism and variable asymptotes. For. Sci. 46, 116–126). There was no significant increase in error when a reduced model common to the three regions was tested instead of a full model with region-specific parameters. To study possible biases of the proposed model along the trees’ lifespan we carried out a LOWESS analysis of residuals in time. We detected deviations in the model residuals, and a patent growth reduction in the 1960s and 1970s, which might be related to climate and/or changing stand characteristics. Departures from estimated mean past growth should be monitored in the future to adapt models to a changing environment.  相似文献   

2.
We developed dominant height growth models for Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) in Norway using national forest inventory (NFI) data. The data were collected for a different purpose which potentially causes problems for dominant height growth modelling due to short time series and large age errors. We used the generalized algebraic difference approach and fitted 15 different models using nested regression techniques. Despite the potential problems of NFI data the models fitted to these data were unbiased for most of the age and site index range covered by the NFI data when tested against independent data from long-term experiments (LTE). Biased predictions for young stands and better site indices that are better represented in the LTE data, led us to fit models to a combined data set for unbiased predictions across the total data range. The models fitted to the combined data that were unbiased with little residual variation when tested against an independent data set based on stem analysis of 73 sample trees from southeastern Norway. No indications of regional differences in dominant height growth across Norway were detected. We tested whether the better growing conditions during the short time series (22 years) of the NFI data had affected our dominant height growth models relative to long-term growing conditions, but found only minor bias. The combination with LTE data that have been collected during a longer period (91 years) reduced this potential bias. The dominant height growth models presented here can be used as potential height growth models in individual tree-based forest growth models or as site index models.  相似文献   

3.
Whole-stand models normally require data on initial stand basal area and dominant height. Dominant height measurements are time-consuming and often imprecise, compromising subsequent predictions. Poplar plantations provide a special case where basal area correlates with site index; a whole-stand model could thus be based on stand basal area. We report a static model constructed by the generalized algebraic difference approach (GADA) for poplar plantations for three different hybrid poplars (Populus × euramericana (Dode) Guinier “I-214”, “MC”, and “Luisa Avanzo”) in northeast Spain. The transition function was based on current stand basal area and was fitted with data from 158 permanent plots ranging from 1- to 17-year-old plantations. Merchantable stand volume was estimated by a volume equation where height was predicted by a height–basal area relationship based on 458 temporary plots. The model differences between clones were compared using the nonlinear extra sum of squares method. Significant differences were detected, while Luisa Avanzo presented the highest merchantable volume at the end of the rotation. Errors in basal area predictions were below 20% within 6 years in the case of Luisa Avanzo and MC clones, and within 3 years in the case of I-214. Our research showed that satisfactory predictions can be obtained using GADA with a single transition function based on an easily measurable variable such as stand basal area.  相似文献   

4.
The varying (local) parameter(s) in site index models can be treated as fixed or random. Two primary subject-specific approaches to height modeling, the dummy variable method (fixed individual effects) and the mixed model method (random individual effects), were compared using Chapman–Richards type models fitted to second-rotation loblolly pine (Pinus taeda L.) data from a designed experiment. For height prediction of new growth series, tested on our validation subset data, the mixed model provides a new (local) parameter prediction method (termed as mixed predictor), which generally performed better than the traditional method of recovering local parameters (the least squares (LS) predictor we used). However, using the LS predictor, both the dummy variable estimation method and mixed model estimation showed almost identical prediction results. With multiple pairs of height–age measurements, no big difference was found in empirical site index prediction between the LS and mixed predictor. Theoretically, one main advantage of the mixed model approach is the ability of its mixed predictor to predict several local parameters using a single height–age pair. However, our empirical results failed to support this point.  相似文献   

5.
Three equations predicting height H = β1(t − 0.5)0.5, diameter D = β2(H − 1.3)/ln N, and mortality dN/N = −2(G/Gmax)3dD/D from plantation age (t), stocking (N) and basal area (G) can be calibrated with few data (even a single observation) for plantations in which re-measured data and growth models are unavailable. Despite having only three parameters to be estimated, these equations extrapolate reliably and allow objective forecasts of future plantation growth performance that may serve as useful first approximations until more precise growth models can be developed.  相似文献   

6.
Height growth equations for dominant trees are needed for growth and yield projections, to determine appropriate silvicultural regimes, and to estimate site index. Red alder [Alnus rubra Bong.] is a fast-growing hardwood species that is widely planted in the Pacific Northwest, USA. However, red alder dominant height growth equations used currently have been determined using stem analysis trees from natural stands rather than repeated measurements of stand-level top height from plantations, which may cause them to be biased. A regional dataset of red alder plantations was complied and used to construct a dynamic base-age invariant top height growth equation. Ten anamorphic and polymorphic Generalized Algebraic Difference Approach (GADA) forms were fit using the forward difference approach. The Chapman–Richards anamorphic and Schumacher anamorphic model forms were the only ones with statistically significant parameters that yielded biologically reasonable predictions across a full range of the available data. The Schumacher model form performed better on three independent datasets and, therefore, was selected as the final model. The resulting top height growth equations differed appreciably from tree-level dominant height growth equations developed using data from natural stands, particularly at the younger ages and on lower site indices. Both the rate and shape parameters of the Schumacher function were not influenced by initial planting density. However, this analysis indicates that the asymptote, which is related to site index, may be reduced for plantations with initial planting density below 500 trees ha−1. The final equation can be used for predictions of top height (and thus) site index for red alder plantations across a range of different growing conditions.  相似文献   

7.
Berries and mushrooms are increasingly appreciated products of Finnish forests. Therefore, there is a need to integrate them in silvicultural planning. Bilberry (Vaccinium myrtillus L.) is an economically important wild berry that is widely collected for household consumption and sale in North Karelia, Finland. In this study, bilberry yield models developed recently were included in a stand growth simulator and the joint production of timber and bilberry was optimized by maximizing soil expectation value (SEV) with 3% discounting rate, assuming that 75% of the bilberry yield is harvested. The effect of bilberry production on the optimal stand management increased with increasing bilberry price. With high bilberry prices (4–8 € kg−1) it was optimal to manage the mixed stand of Scots pine, Norway spruce and birch, and the pure stand of Norway spruce so as to promote bilberry production. In the Scots pine stand, where bilberry yields are higher, bilberry production affected optimal stand management already with a price of 2 € kg−1. Compared to timber production, joint production led to longer rotation lengths, higher thinning intensities, more frequent thinnings, and higher share of Scots pine in the mixed stand. The contribution of bilberries to the total SEV increased with increasing bilberry price and discounting rate. In the mixed stand and pine stand the SEV of bilberry production, calculated with 3% discounting rate, exceeded the SEV of timber production when bilberry price was 4 € kg−1.With 4% discounting rate this happened already with bilberry price of 2 € kg−1. It was concluded that forest management which promotes bilberry yields is the most profitable in pine stands where the potential bilberry yields are high.  相似文献   

8.
We compared soil organic carbon (SOC) stocks and stability under two widely distributed tree species in the Mediterranean region: Scots pine (Pinus sylvestris L.) and Pyrenean oak (Quercus pyrenaica Willd.) at their ecotone. We hypothesised that soils under Scots pine store more SOC and that tree species composition controls the amount and biochemical composition of organic matter inputs, but does not influence physico-chemical stabilization of SOC. At three locations in Central Spain, we assessed SOC stocks in the forest floor and down to 50 cm in the mineral in pure and mixed stands of Pyrenean oak and Scots pine, as well as litterfall inputs over approximately 3 years at two sites. The relative SOC stability in the topsoil (0-10 cm) was determined through size-fractionation (53 μm) into mineral-associated and particulate organic matter and through KMnO4-reactive C and soil C:N ratio.Scots pine soils stored 95-140 Mg ha−1 of C (forest floor plus 50 cm mineral soil), roughly the double than Pyrenean oak soils (40-80 Mg ha−1 of C), with stocks closely correlated to litterfall rates. Differences were most pronounced in the forest floor and uppermost 10 cm of the mineral soil, but remained evident in the deeper layers. Biochemical indicators of soil organic matter suggested that biochemical recalcitrance of soil organic matter was higher under pine than under oak, contributing as well to a greater SOC storage under pine. Differences in SOC stocks between tree species were mainly due to the particulate organic matter (not associated to mineral particles). Forest conversion from Pyrenean oak to Scots pine may contribute to enhance soil C sequestration, but only in form of mineral-unprotected soil organic matter.  相似文献   

9.
Litter quality and environmental effects on Scots pine (Pinus sylvestris L.) fine woody debris (FWD) decomposition were examined in three forestry-drained peatlands representing different site types along a climatic gradient from the north boreal (Northern Finland) to south (Southern Finland) and hemiboreal (Central Estonia) conditions. Decomposition (percent mass loss) of FWD with diameter ≤10 mm (twigs) and FWD with diameter >10 mm (branches) was measured using the litter bag method over 1–4-year periods. Overall, decomposition rates increased from north to south, the rate constants (k values) varying from 0.128 to 0.188 year−1 and from 0.066 to 0.127 year−1 for twigs and branches, respectively. On average, twigs had lost 34%, 19% and 19%, and branches 25%, 17% and 11% of their initial mass after 2 years of decomposition at the hemiboreal, south boreal and north boreal sites, respectively. After 4 years at the south boreal site the values were 48% for twigs and 42% for branches. Based on earlier studies, we suggest that the decomposition rates that we determined may be used for estimating Scots pine FWD decomposition in the boreal zone, also in upland forests. Explanatory models accounted for 50.4% and 71.2% of the total variation in FWD decomposition rates when the first two and all years were considered, respectively. The variables most related to FWD decomposition included the initial ash, water extractives and Klason lignin content of litter, and cumulative site precipitation minus potential evapotranspiration. Simulations of inputs and decomposition of Scots pine FWD and needle litter in south boreal conditions over a 60-year period showed that 72 g m−2 of organic matter from FWD vs. 365 g m−2 from needles accumulated in the forest floor. The annual inputs varied from 5.7 to 15.6 g m−2 and from 92 to 152 g m−2 for FWD and needles, respectively. Each thinning caused an increase in FWD inputs, up to 510 g m−2, while the needle inputs did not change dramatically. Because the annual FWD inputs were lowered following the thinnings, the overall effect of thinnings on C accumulation from FWD was slightly negative. The contribution of FWD to soil C accumulation, relative to needle litter, seems to be rather minor in boreal Scots pine forests.  相似文献   

10.
Stem analysis data of 432 trees were obtained from even-aged, pure natural stands of Calabrian pine in the central Mediterranean Region of Turkey. Eight dynamic site equations derived with the Generalized Algebraic Difference Approach (GADA) were compared, based on autoregressive analysis and a thorough evaluation of the goodness of fit. We used generalized nonlinear least squares methods for model fitting. The adjusted coefficients of determination (0.9825–0.9842), root-mean-square errors (0.8004–0.8435 m), and Akaike’s information criterion differences (0–145) indicated a good fit of the eight site index equations. The Hossfeld equation (M3) provided the best result. The Durbin-Watson test statistic did not reveal an autocorrelation issue while the Hossfeld equation provided a satisfactory solution to the serial correlation problem in stem analysis data as time series using autoregressive modeling. This study presents new site index models for Calabrian pine forests in the central Mediterranean region of Turkey where it is the most important commercial tree species. The site index equation, based on the Hossfeld model is recommended for height growth prediction and site classification of Calabrian pine stands in the central Mediterranean region of Turkey, providing a new basis for growth prediction and yield estimation in these important forest ecosystems.  相似文献   

11.
An important window of opportunity to increase and sustain productivity in short-rotation plantations is the period from felling through re-establishment to canopy closure. This paper explores the effects, interactions and response mechanisms of intensive silvicultural practices on plantation productivity and sustainability, using five South African case studies (a–e). (a) Land preparation trials showed that complete surface cultivation by ploughing had a significant beneficial effect when afforestation is done for the first time in grasslands, improving basal area growth by 11–52% over pitting only. However, similar treatments have not resulted in significant growth responses under re-establishment conditions. (b) Stand growth suppression resulting chiefly from soil compaction during mechanised harvesting operations is strongly related to soil type, soil textural class and residue management options. Volume growth reduction in short-rotation eucalypt crops ranged from 25% on compaction sensitive loamy soils to less than 2% in resistant sandy soils. (c) The response mechanism whereby vegetation management improves stand productivity is a reduction in both inter-specific and intra-genotypic competition for resources, as well as a decrease in stand variability. Operationally, the most important criteria in a vegetation management programme relate to the timing of control operations across diverse site conditions. In local trials, the primary factors controlling the time taken for competition-induced tree growth suppression to occur were related to altitude, slash burning and the interaction between these factors, which facilitated the development of regional vegetation management strategies. (d) Empirical fertilizer trials in short-rotation hardwood stands have shown significant improvements in final productivity (commonly 20–90 m3 ha−1 in eucalypts and 30–50 m3 ha−1 in Acacia), as well as wood density (15–30 kg m−3 for eucalypts) following improvements in early nutrition. Improved nutrition was achieved through fertilization at planting or indirectly through residue management. The response mechanism is primarily due to early canopy development and associated increases in light capture, coupled with a more modest increase in canopy quantum efficiency and above-ground carbon allocation on a dry site. On sites with abundant water supply, increased quantum efficiency is likely to be the dominant response mechanism. (e) A series of operational gains trials tested the interactive effect of genetic tree improvement, site–genotype interaction, stand density and vegetation management + fertilization on eucalypt stand growth across five sites. There were no significant interactions between factors, but importantly, the results were additive, emphasizing the need to optimise each practice in the value chain to achieve maximum productivity.  相似文献   

12.
In the climate change discussion, the possibility of carbon sequestration of forests plays an important role. Therefore, research on the effects of environmental changes on net primary productivity is interesting. In this study we investigated the influence of changing temperature, precipitation and deposition of sulphur and nitrogen compounds on forest growth. The database consisted of 654 plots of the European intensive monitoring program (Level II plots) with 5-year growth data for the period 1994–1999. Among these 654 plots only 382 plots in 18 European countries met the requirements necessary to be used in our analysis. Our analysis was done for common beech (Fagus sylvatica), oak (Quercus petraea and Q. robur), Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). We developed an individual tree growth model with measured basal area increment of each individual tree as responding growth factor and tree size (diameter at breast height), tree competition (basal area of larger trees and stand density index), site factors (soil C/N ratio, temperature), and environmental factors (temperature change compared to long-term average, nitrogen and sulphur deposition) as influencing parameters. Using a mixed model approach, all models for the tree species show a high goodness of fit with Pseudo-R2 between 0.33 and 0.44. Diameter at breast height and basal area of larger trees were highly influential variables in all models. Increasing temperature shows a positive effect on growth for all species except Norway spruce. Nitrogen deposition shows a positive impact on growth for all four species. This influence was significant with p < 0.05 for all species except common beech. For beech the effect was nearly significant (p = 0.077). An increase of 1 kg N ha−1 yr−1 corresponds to an increase in basal area increment between 1.20% and 1.49% depending on species. Considering an average total carbon uptake for European forests near 1730 kg per hectare and year, this implies an estimated sequestration of approximately 21–26 kg carbon per kg nitrogen deposition.  相似文献   

13.
A cork growth model for Spanish cork oak forests was developed using data from 432 cork samples. Ten dynamic equations derived from the generalised algebraic difference approach (GADA) were considered for analysis, and both numerical and graphical methods were used to compare alternative models. All of the equations are base-age invariant and directly estimate accumulated cork thickness in complete years at any moment of the cork rotation. The fittings were done using the nested iterative method of the stochastic regression approach. The GADA formulation derived by Krumland and Eng (2005) from the Richards model by considering a 1 and a 3 as related to site productivity was finally selected. The cork growth model developed in this study allows the total accumulated cork thickness in complete years to be estimated in the fourth year of cork rotation with close to 80% reliability for any debarking period, increasing to nearly 90% from the eighth year onwards.  相似文献   

14.
An accurate characterization of tree carbon (TC), forest floor carbon (FFC) and soil organic carbon (SOC) in tropical forest plantations is important to estimate their contribution to global carbon stocks. This information, however, is poor and fragmented. Carbon contents were assessed in patula pine (Pinus patula) and teak (Tectona grandis) stands in tropical forest plantations of different development stages in combination with inventory assessments and soil survey information. Growth models were used to associate TOC to tree normal diameter (D) with average basal area and total tree height (HT), with D and HT parameters that can be used in 6–26 years old patula pine and teak in commercial tropical forests as indicators of carbon stocks. The information was obtained from individual trees in different development stages in 54 patula pine plots and 42 teak plots. The obtained TC was 99.6 Mg ha−1 in patula pine and 85.7 Mg ha−1 in teak forests. FFC was 2.3 and 1.2 Mg ha−1, SOC in the surface layer (0–25 cm) was 92.6 and 35.8 Mg ha−1, 76.1 and 19 Mg ha−1 in deep layers (25–50 cm) in patula pine and teak, respectively. Carbon storage in trees was similar between patula pine and teak plantations, but patula pine had higher levels of forest floor carbon and soil organic carbon. Carbon storage in trees represents 37 and 60% of the total carbon content in patula pine and teak plantations, respectively. Even so, the remaining percentage corresponds to SOC, whereas FFC content is less than 1%. In summary, differences in carbon stocks between patula pine and teak trees were not significant, but the distribution of carbon differed between the plantation types. The low FFC does not explain the SOC stocks; however, current variability of SOC stocks could be related to variation in land use history.  相似文献   

15.
Accurate estimates of forest productivity are required for sustainable forest management. Height of dominant and codominant trees at a reference age is often used as a measure of site productivity. Eight algebraic difference equations based on the models proposed by Sloboda, Bertalanffy-Richards, Korf, Hossfeld, and McDill-Amateis were tested on the transformed, longitudinal data structure that considers all possible growth intervals. Autocorrelation was modelled by expanding the error term as an autoregressive process according to this data structure. Generalized nonlinear least squares methods were used for model fitting. Several numerical and graphic analyses were used to compare the different candidate models. The relative error in dominant height prediction was used to select 60 years as the best reference age. An algebraic difference equation based on the model proposed by Korf provided the best compromise between biological and statistical aspects and produced the most adequate site index curves. This model is therefore recommended for height growth prediction and site classification of pedunculate oak stands in Galicia. The model is polymorphic and base-age invariant, having only one asymptote. Predictions of height for age intervals between t1 and t2 of more than 15 years should be considered with caution because of the associated critical error.  相似文献   

16.
Above- and below-ground C pools were measured in pure even-aged stands of Nothofagusantarctica (Forster f.) Oersted at different ages (5–220 years), crown and site classes in the Patagonian region. Mean tissue C concentration varied from 46.3% in medium sized roots of dominant trees to 56.1% in rotten wood for trees grown in low quality sites. Total C concentration was in the order of: heartwood > rotten wood > sapwood > bark > small branches > coarse roots > leaves > medium roots > fine roots. Sigmoid functions were fitted for total C accumulation and C root/shoot ratio of individual trees against age. Total C accumulated by mature dominant trees was six times greater than suppressed trees in the same stands, and total C accumulated by mature dominant trees grown on the best site quality was doubled that of those on the lowest site quality. Crown classes and site quality also affected the moment of maximum C accumulation, e.g. dominant trees growing on the worse site quality sequestered 0.73 kg C tree−1 year−1 at 139 years compared to the best site where 1.44 kg C tree−1 year−1 at 116 years was sequestered. C root/shoot ratio decreased over time from a maximum value of 1.3–2.2 at 5 years to a steady-state asymptote of 0.3–0.7 beyond 60 years of age depending on site quality. Thus, root C accumulation was greater during the regeneration phase and for trees growing on the poorest sites. The equations developed for individual trees have been used to estimate stand C accumulation from forest inventory data. Total stand C content ranged from 128.0 to 350.9 Mg C ha−1, where the soil C pool represented 52–73% of total ecosystem C depending on age and site quality. Proposed equations can be used for practical purposes such as estimating the impact of silvicultural practices (e.g. thinning or silvopastoral systems) on forest C storage or evaluating the development of both above- and below-ground C over the forest life cycle for different site qualities for accurate quantification of C pools at regional scale.  相似文献   

17.
A stand basal area growth system for radiata pine (Pinus radiata D. Don) plantations in Galicia (Northwestern Spain) was developed from data corresponding to 247 plots measured between one and five times. Six dynamic equations were considered for analysis and both numerical and graphical methods were used to compare alternative models. The equation that best described the data was a dynamic equation derived from the Korf growth function by the generalized algebraic difference approach (GADA) and by considering two parameters as site-specific. This equation was fitted in one stage by the base-age-invariant dummy variables method. The system also incorporated an equation for predicting initial stand basal area, expressed as a function of stand age, site index, and the number of trees per hectare. This information can be used to establish the starting point for the projection equation when no inventory data are available. The effect of thinning on stand basal area growth was also analyzed and the results showed that the same projection equation can be used to obtain reliable predictions of unit-area basal area development in thinned and unthinned stands.  相似文献   

18.
In this work, we studied the impacts of climate change on timber production and regional risks of wind-induced damage to forests in Finland. The work employed: (i) national level forest inventory data, (ii) current baseline climate (1961–1990) and changing climate scenario (FINADAPT A2, 2001–2099), (iii) a forest ecosystem model (SIMA), (iv) a mechanistic wind damage model (HWIND), and (v) currently applied forest management recommendations as a baseline. The results showed that the timber production will increase significantly towards the end of this century under the changing climate, and in a relative sense the most in Northern Finland. At the same time, the share of Norway spruce (Picea abies L. Karst.) is expected to decrease, especially in southernmost Finland, mainly favoring the presence of birch (Betula spp.), but also Scots pine (Pinus sylvestris L.), when no species preference is given in management. As a result, the proportion of forest area in the two lowest critical wind speed classes (i.e. winds of 11–14 and 14–17 m s−1) will decrease in the autumn (birch without leaves) throughout Finland. However, in summertime (birch is in leaf) the proportion of forest area with such critical wind speeds will even increase in southernmost Finland. Even though, in summertime the risk of damage should be on average relatively low throughout Finland due to a lower occurrence of such wind speeds compared to the windiest time of the year (i.e. from autumn to early spring). The return period of critical wind speeds of 11–17 m s−1 is today about every two years in southernmost Finland. In Northern Finland, the critical wind speeds needed for wind damage are, on average, higher due to the larger share of Scots pine and on average lower height to breast height diameter ratios of trees compared to the south. To conclude, the climate change will affect clearly the forest growth and dynamics and, thus increase the need to manage forests more often and/or heavily (e.g. thinning, final felling), which in addition to species preference, will affect the risks of damages. The consideration of the risk of wind damage is crucial especially in Southern Finland when adapting forest management to the changing climate. This is because the unfrozen soil period is expected to increase significantly in Finland, which decreases tree anchorage during the windiest time of year.  相似文献   

19.
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20.
During 2005–2007, we used the eddy covariance and associated hydrometric methods to construct energy and water budgets along a chronosequence of loblolly pine (Pinus taeda) plantations that included a mid-rotation stand (LP) (i.e., 13–15 years old) and a recently established stand on a clearcut site (CC) (i.e., 4–6 years old) in Eastern North Carolina. Our central objective was to quantify the differences in both energy and water balances between the two contrasting stands and understand the underlining mechanisms of environmental controls. We found that the LP site received about 20% more net radiation (Rn) due to its lower averaged albedo (α) of 0.25, compared with that at the CC (α = 0.34). The mean monthly averaged Bowen ratios (β) at the LP site were 0.89 ± 0.7, significantly (p = 0.02) lower than at the CC site (1.45 ± 1.2). Higher net radiation resulted in a 28% higher (p = 0.02) latent heat flux (LE) for ecosystem evapotranspiration at the LP site, but there was no difference in sensible heat flux (H) between the two contrasting sites. The annual total evapotranspiration (ET) at the LP site and CC site was estimated as 1011–1226 and 755–855 mm year−1, respectively. The differences in ET rates between the two contrasting sites occurred mostly during the non-growing seasons and/or dry periods, and they were small during peak growing seasons or wet periods. Higher net radiation and biomass in LP were believed to be responsible to the higher ET. The monthly ET/Grass Reference ET ratios differed significantly across site and season. The annual ET/P ratio for the LP and CC were estimated as 0.70–1.13 and 0.60–0.88, respectively, indicating higher runoff production from the CC site than the LP site. This study implied that reforestation practices reduced surface albedos and thus increased available energy, but they did not necessarily increase energy for warming the atmosphere in the coastal plain region where soil water was generally not limited. This study showed the highly variable response of energy and water balances to forest management due to climatic variability.  相似文献   

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