Eucalyptus Grandis Plantations Research Articles

Changes in the Arbuscular Mycorrhizal Fungal Community in the Roots of Eucalyptus grandis Plantations at Different Ages in Southern Jiangxi, China.

Eucalyptus roots form symbiotic relationships with arbuscular mycorrhizal (AM) fungi in soil to enhance adaptation in challenging environments. However, the evolution of the AM fungal community along a chronosequence of eucalypt plantations and its relationship with soil properties remain unclear. In this study, we evaluated the tree growth, soil properties, and root AM fungal colonization of Eucalyptus grandis W. Hill ex Maiden plantations at different ages, identified the AM fungal community composition by high-throughput sequencing, and developed a structural equation model among trees, soil, and AM fungi. Key findings include the following: (1) The total phosphorus (P) and total potassium (K) in the soil underwent an initial reduction followed by a rise with different stand ages. (2) The rate of AM colonization decreased first and then increased. (3) The composition of the AM fungal community changed significantly with different stand ages, but there was no significant change in diversity. (4) Paraglomus and Glomus were the dominant genera, accounting for 70.1% and 21.8% of the relative abundance, respectively. (5) The dominant genera were mainly influenced by soil P, the N content, and bulk density, but the main factors were different with stand ages. The results can provide a reference for fertilizer management and microbial formulation manufacture for eucalyptus plantations.

Soil Quality Evaluation in Mono and Mixed Eucalypt Plantation

Soil quality (SQ) pertains to the intricate and ongoing capacity of soil to function as a thriving ecosystem that supports the growth of plants and animals. However, there is a limited understanding of SQ assessment in mixed forest plantations. Therefore, we formulated and tested the hypothesis that the inclusion of a nitrogen-fixing tree species (such as Acacia mangium) improves SQ indicators in mixed treatments involving Eucalyptus trees. To evaluate the changes in SQ, we conducted a field experiment that employed the Soil Management Assessment Framework (SMAF) tool to analyze pure and mixed plantations of Eucalyptus grandis and A. mangium. Soil samples were collected at a depth of 0–20 cm from different treatments, including pure E. grandis without nitrogen fertilization (E), pure A. mangium (A), pure E. grandis with nitrogen fertilization (E + N), and mixed E. grandis and A. mangium (E + A). Sampling took place at 27 and 39 months after planting. We selected seven indicators of SQ: two biological indicators (soil microbial biomass carbon and β-glucosidase enzyme activity), four chemical indicators (soil organic carbon, pH, available phosphorus, and potassium), and one physical indicator (bulk density). By applying the SMAF tool, we determined the SQ scores for each indicator. The results revealed that E + A stands exhibited higher SMAF scores than pure stands, particularly in terms of pH (0.49 and 0.52 at 27 and 39 months, respectively) and phosphorus levels (0.84 and 0.82, at 27 and 39 months), respectively. Forest management practices and the sampling period had the most pronounced impact on biological and chemical indicators. Notably, significant positive correlations were observed between SMAF scores and pH, available phosphorus content, enzymes, soil organic carbon, and microbial biomass in both sampling periods. This study effectively provided novel information that introducing a nitrogen-fixing tree species in combination with eucalyptus trees enhances SQ, as indicated by the SMAF tool, which could reduce the need for external inputs (e.g., mineral fertilizers) by the farmers. Future studies should analyze the effects of A. mangium not only with other E. grandis varieties but also with other forestry essences.

Changes in light use efficiency explains why diversity effect on biomass production is lower at high planting density in mixed-species plantations of Eucalyptus grandis and Acacia mangium

Understanding the effect of planting densities and species proportions on light absorption and light use efficiency can help to improve the management of mixed-species forest plantations. Our study aimed to disentangle the role of light interception and light use efficiency (LUE) on the biomass production of Eucalyptus grandis (E), a highly productive species in tropical conditions, and Acacia mangium (A), a N2-fixing species, in monocultures and mixed-species plantations for contrasting planting densities. A randomized block experiment set up over 4 ha in southern Brazil was intensively monitored for 14 months at mid rotation. The absorbed photosynthetically active radiation (APAR) was simulated for each tree of the experiment using the tri-dimensional MAESPA model parameterized with detailed in situ measurements of tree and foliage. LUE for stem wood production was estimated as the ratio of measured stem biomass production (SBP) and simulated APAR. The APAR of Eucalyptus trees did not significantly differ between monocultures and mixed plantations, the reduction of Eucalyptus density being compensated by an increase in light absorption of Eucalyptus individuals. The LUE of Eucalyptus trees in monoculture and mixed-species stands was found to be comparable only at low planting densities. The replacement of Eucalyptus trees with Acacia trees resulted in a reduction in Eucalyptus LUE only at high planting density. The SBP of Eucalyptus trees was mainly explained by differences in APAR, while both APAR and LUE explained the SBP of Acacia trees. The maximum stand production was obtained with monoculture of Eucalyptus at high density and no mixture reached this productivity. Reducing the proportion of Eucalyptus in mixture lead to a substantial decrease in stand production at high planting density due to a decrease in LUE, while this stand production reduction was offset at low planting density, underlying a higher diversity effect at low planting density. In the perspective of increasing diversity in forest plantations to foster multifunctionality, mixed plantations of Acacia and Eucalyptus at low planting density can be an interesting option to maintain a relatively high productivity, which is similar to Eucalyptus monocultures at the same low planting density.

Influence of knots on the adhesion of wood from young Eucalyptus grandis plantations

ABSTRACT The structural use of wood from young trees requires gluing smaller timber pieces to form large elements. In young Eucalyptus timber of structural dimensions, knots do not significantly diminish the mechanical properties, yet their influence on wood adhesion has not been widely studied. Therefore, the aim of the study was to assess the influence of knots on the bond quality of face-glued wood from young E. grandis. Wood from seven-year-old E. grandis trees was tested in shear on the bond-line (polyurethane adhesive) using paired samples of knot-containing and clear wood samples. Knot features did not correlate with shear strength or wood failure percentage. Knot-containing samples had a lower percentage of wood failure (5.8%), but the same shear strength as clear wood samples. Below a wood density of 650 kg m−3, clear and knot-containing wood behaved similarly, but above this value, knots influenced wood adhesion negatively. By simulating glulam beams with high-density wood on the outer lamellas, it was possible to show that shear stress on those bond-lines is lower than the minimum shear strength observed on dense knot samples. Hence, lower adhesion caused by knots on denser wood probably does not represent a significant problem for glued laminated products from young Eucalyptus grandis trees.

Short-term cultivation limiting soil aggregate stability and macronutrient accumulation associated with glomalin-related soil protein in Eucalyptus urophylla × Eucalyptus grandis plantations

The relationship between glomalin-related soil protein (GRSP) and soil aggregation has been a hot topic of research for its close link to soil stability and quality. However, the short-term cultivation of Eucalyptus poses serious threats to soil stability and nutrient stocks, and the effects of GRSP on soil aggregate stability and macronutrient accumulation remain unclear. The aim is to clarify the potential mechanisms affecting soil aggregate stability and macronutrient accumulation in short-term Eucalyptus plantations. Five Eucalyptus urophylla × Eucalyptus grandis plantations with different cultivation periods (1–5 years) in this study were investigated, and a native evergreen broadleaf forest (0 year) was selected as control. The mean weight diameter index increased in the first 3 years and then significantly decreased during 5 years cultivation of Eucalyptus. Soil organic carbon (SOC) and total nitrogen also decreased after planting Eucalyptus for 3 years, but variation in total phosphorus was not obvious. The relative abundance of Glomeraceae and Claroideoglomeraceae decreased in the 5-year-old Eucalyptus plantations and was positively correlated with GRSP content. In pathway modeling, nutrient-acquisition enzyme activities positively affected GRSP and macronutrient content. Total GRSP (T-GRSP) had higher total effects than easily extractable GRSP on soil aggregate stability, and positively correlated with SOC in macroaggregates. Both T-GRSP and SOC had positive and direct effects on soil aggregate stability. Variance partitioning analysis further explained the contribution of GRSP and SOC to aggregate stability, particularly in >2 and 2–0.25 mm macroaggregates. Our results suggested that GRSP was directly associated with SOC content and soil aggregate stability, and was a potential key factor affecting soil aggregate stability in Eucalyptus plantations. Improving T-GRSP and SOC are efficient approaches for preventing the gradual deterioration of soil aggregate stability. Short-term cultivation should be carefully used in Eucalyptus plantations, and a new cultivation period is needed.

Understory plant diversity and phenolic allelochemicals across a range of Eucalyptus grandis plantation ages

Understory plant diversity and phenolic allelochemicals across a range of Eucalyptus grandis plantation ages

Variation in above and below ground carbon storage in a Eucalyptus grandis plantation established in a grassland with a chronosequence of age

Variation in above and below ground carbon storage in a Eucalyptus grandis plantation established in a grassland with a chronosequence of age

Responses of Fungal Community Structure and Functional Composition to Short-Term Fertilization and Dry Season Irrigation in Eucalyptus urophylla × Eucalyptus grandis Plantation Soils

Plantation forests productivity is severely limited by the seasonal drought and fertilization practices in South China. Soil nutrient and water availability influence soil fungal community, functional group diversity and the variation of plant productivity; however, the effects of irrigation and fertilization on fungal responses have rarely been studied. Here, we investigate the responses of fungal community structure and functional groups in Eucalyptus plantation soils to short-term fertilization (F), dry-season irrigation (W), short-term fertilization combined with dry-season irrigation (FW), and control (CK) treatments for ten months. A higher proportion of Basidiomycota was observed in the irrigation and/or fertilization treatments; conversely, lower proportions of Ascomycota and Mucoromycotina were observed in the only irrigation and fertilization treatments. Higher soil carbon contents and symbiotroph fungi (mainly Ectomycorrhizas) proportion were detected in the FW treatment, while low proportions of saprophytic and pathogenic fungi were observed in the FW treatment when compared with those in other treatments. These results may indicate that Eucalyptus tree growth under irrigation and fertilization condition was better than under fertilization only, irrigation only, or neither management. The results highlight that short-term fertilization and dry-season irrigation can shift fungal community structure and functional groups by regulating available soil moisture and nutrients. They also provide a theoretical basis for the development of more appropriate management approaches in the early stages of forest plantation.

Root-soil facilitation in mixed Eucalyptus grandis plantations including nitrogen-fixing species

The success of mixed plantation systems is ultimately the net result of positive and negative interactions, including belowground interactions, among the respective species. Despite increasing knowledge on positive interactions on biomass and productivity in mixed-species plantations, relatively little is known about the mechanisms underlying belowground interactions. Based on biodiversity data from four mixed Eucalyptus grandis plantations, we determined the optimal ecological facilitative interactions of mixed plantation, i.e., E. grandis and Alnus formosana. We then investigated in situ root exudation of E. grandis using a cuvette-based method and analysed root patterns, defence chemicals, bacterial communities, and biochemical properties of rhizosphere soils in mixed E. grandis with alder. Compared with pure Eucalyptus plantations, the fine root production by E. grandis was higher in subsoil layers (40–80 cm) in mixed plantations with alder. Autotrophic root respiration and associated enzymes were also increased in mixed plantations. Root exudates and defence allelochemicals of E. grandis changed in the presence of alder. Compared with the pure Eucalyptus plantations, E. grandis roots in mixed plantations reduced the release of potential allelochemicals, such as phenolic acids, flavonoids, unsaturated lactone, and glycosides. Methyl jasmonate, a common signal chemical, was significantly decreased in mixed-species plantations. The bacterial community of E. grandis rhizosphere soil was improved in mixed stands and recruited more nitrifying, N-fixing, and cellulose-decomposing bacteria, such as family Nitrosomonadaceae, genera MND1, Marmoricola, and Rikenellaceae RC9 gut groups. Thus, belowground ecological facilitative interactions occurred in mixed plantations with alder, which were due to E. grandis altering its rooting pattern, reducing the levels of released allelochemicals, recruiting more beneficial bacteria, and improving the biochemical properties of rhizosphere soil. This mechanism may be useful in reforestation programs for Eucalyptus monocultures that are suffering from problems associated with low biodiversity and reduced soil fertility.

Estimation of the leaf area index from Sentinel images in Eucalyptus grandis W.Hill plantations

Eucalyptus grandis plantations are of great importance, from a social point of view due to their great commercial value, and from an ecological point of view because they are capable of harboring a certain biodiversity of species. The leaf area index (LAI) is an important indicator to measure the health of these plantations related to productivity. The objective of this research is to estimate the LAI from Sentinel images in Eucalyptus grandis plantations. Sentinel satellite images were used to estimate the LAI in the plantations, later the statistical analyzes were carried out by means of a comparison of independent means. Values ​​were obtained as the mean that was 2.0 of the leaf area index in the plantations, these results were very similar to those obtained in other investigations carried out in the field. Therefore, it is recommended to use this methodology in other types of plantations, since it can be used to be applied in other equations to calculate the potential yield of crops.

First record in Brazil ofBrachymeria annulata(Fabricius) (Hymenoptera: Chalcididae) andTrichospilus diatraeaeCherian and Margabandhu (Hymenoptera: Eulophidae) parasitising pupae ofIridopsis panoplaProut (Lepidoptera: Geometridae) in eucalyptus (Myrtaceae)

AbstractIridopsis panopla(Lepidoptera: Geometridae) is a defoliator of eucalyptus (Myrtaceae).Iridopsis panoplapupae were collected on a commercial plantation ofEucalyptus grandis, in the locality of Ribas do Rio Pardo, Mato Grosso do Sul, Brazil. After 18 days, the hymenopteran parasitoidsBrachymeria annulata(Chalcididae) andTrichospilus diatraeae(Eulophidae) emerged from theI. panoplapupae. This is the first host record of these parasitoids from this important eucalyptus pest. Biological aspects ofT. diatraeaewere evaluated under laboratory conditions.

Soil Cu and Zn pools and their availability in response to forest residue management and micronutrient fertilization in a Eucalyptus grandis plantation

Eucalyptus is one of the most commonly planted genera worldwide for commercial timber purposes. Brazil has approximately 25% of the total Eucalyptus spp. planted worldwide. However, nutritional disorders caused by copper (Cu) and zinc (Zn) deficiencies have been more frequent in Eucalyptus plantations. Furthermore, the scientific knowledge regarding micronutrient fertilization is scarce. Sequential extraction can determine the distribution of metals in the soil, giving an order of magnitude to its bioavailability. The present study aimed to assess the soil Cu and Zn pools and evaluate the effects of mineral Cu and Zn fertilization on the nutritional status and nutrient fractionation in a Ferralsol in a cultivated Eucalyptus grandis plantation. The study considered two conditions—namely, forest residue management or removal of forest residues. The treatments included complete fertilization, no application of Cu, no application of Zn, maintenance of forest residues, and total removal of forest residues. High quantities of Cu and Zn were found in the soil, mainly in the low plant-available forms (>60%). There were no differences in the nutritional status of the trees, despite the absence of Cu and Zn via fertilizers and the removal of harvest residues. Foliar Cu concentration was positively correlated with soil exchangeable and oxide-bound Cu content, whereas foliar Zn concentration was positively correlated with soil exchangeable and organic matter-bound Zn content. The access to moderately labile forms of Cu and Zn by eucalypts may justify the absence of response to mineral fertilization, especially in areas where forest residues remain on the soil, and consequently, work as a source of Cu and Zn.

Nutritional status of Eucalyptus plantation and chemical attributes of a Ferralsol amended with lime and copper plus zinc

Brazil is a global reference in forest management for wood production (e.g., pulp and solid wood products), and large areas are planted mainly in acidic and poorly fertile soils, with a predominance of Eucalyptus species. Liming is widely adopted in acidic soils in humid tropical regions planted with Eucalyptus to increase the availability of some nutrients and supply Ca and Mg. However, liming decreases the availability of some micronutrients, such as Cu and Zn, depending on the lime content. Copper and Zn fertilization for Eucalyptus is usually intended to replace the amount of micronutrients extracted after wood harvesting. However, few studies have been carried out to investigate the combined effects of lime and Cu plus Zn application on forest plantations in tropical soils. Here, the effects of these factors on soil chemical-attributes, as well as nutrition, and growth performance of Eucalyptus grandis plantations were evaluated on a medium-textured Ferralsol. The stem volume yield improved after liming, regardless of the rate of application, and after Cu plus Zn fertilization. Liming increased soil pH and Ca and Mg availability and reduced Cu and Zn availability. Overall, liming reduced soil Cu and Zn contents in the residual-fraction, while increasing the fraction bound to organic-matter. High contents of Cu and Zn were linked to the organic-matter fraction in the soil under the Eucalyptus plantation. Eucalyptus trees grown in soils amended with lime had higher values for leaf area index and leaf Ca and Mg concentrations but showed reduced Cu and Zn concentrations. The combined application of lime and Cu plus Zn improved Eucalyptus growth, with the higher contribution of lime compared to Cu and Zn. In conclusion, the combined application of lime and Cu plus Zn is a useful strategy to provide balanced nutrition and optimize stem volume yields.

Organic carbon stored in soils under different land uses and soil textures in southeast Argentinean Mesopotamia

Soil use affects soil organic carbon (OC) stocks by regulating the quantity and quality of incorporated organic matter. Understanding how soil texture and other factors control OC concentration and accumulation would be useful for designing sustainable soil management practices in order to promote and preserve OC storage. The aim of this work was to evaluate the effects of land use and soil texture on the vertical distribution and stock of OC in soils of the Argentinean Mesopotamia. In Entre Ríos Province, Argentina, the following sites were selected: native forest in a Typic Halacuept soil (fine to medium texture), agriculture and Eucalyptus grandis plantations of different ages (2–4 and 8–10 years) in Argic Peluderts soils (fine textures) and E. grandis plantations of different ages (2–4 and 8–10 years) in Oxic Udifluvents soils (coarse textures). OC concentration and stock were quantified up to 1 m depth, analysing distribution across the depth of the soil profile. The major differences in OC stock in equivalent mass were associated with texture; the average for coarse Oxic Udifluvents soils was 57.2 Mg OC ha−1 and 162.3 Mg OC ha−1 for Typic Halacuept and Argic Peluderts (fine to medium textures). Forest sites with fine textures stored three times more OC in equivalent mass than coarse textures under similar land use. No significant differences were observed between OC stock in equivalent mass in agricultural versus Eucalyptus plantations of similar texture. Sites with 8–10-year-old forest plantations in coarse soils were a special case, as they presented a great proportion of OC (60%) under 40 cm depth, due to a strong textural gradient with depth.

Increased hydraulic constraints in Eucalyptus plantations fertilized with potassium.

Fertilization is commonly used to increase growth in forest plantations, but it may also affect tree water relations and responses to drought. Here, we measured changes in biomass, transpiration, sapwood-to-leaf area ratio (As :Al ) and sap flow driving force (ΔΨ) during the 6-year rotation of tropical plantations of Eucalyptus grandis under controlled conditions for throughfall and potassium (K) fertilization. K fertilization increased final tree height by 8m. Throughfall exclusion scarcely affected tree functioning because of deep soil water uptake. Tree growth increased in K-supplied plots and remained stable in K-depleted plots as tree height increased, while growth per unit leaf area increased in all plots. Stand transpiration and hydraulic conductance standardized per leaf area increased with height in K-depleted plots, but remained stable or decreased in K-supplied plots. Greater Al in K-supplied plots increased the hydraulic constraints on water use. This involved a direct mechanism through halved As :Al in K-supplied plots relative to K-depleted plots, and an indirect mechanism through deteriorated water status in K-supplied plots, which prevented the increase in ΔΨ with tree height. K fertilization in tropical plantations reduces the hydraulic compensation to growth, which could increase the risk of drought-induced dieback under climate change.

Changes in taxonomic and functional diversity of plants in a chronosequence of Eucalyptus grandis plantations

Tree plantations have become one of the fastest-growing land uses and their impact on biodiversity was evaluated mainly at the taxonomic level. The aim of this study was to analyze environmental changes after the Eucalyptus plantation in an area originally covered by natural grasslands, taking into account the alpha and beta (taxonomic and functional) diversity of plant communities. We selected nine plantation ages, along a 12 years chronosequence, with three replicates per age and three protected grasslands as the original situation. At each replicate, we established three plots to measure plant species cover, diversity and environmental variables. Results showed that species richness, and all diversity indices, significantly declined with increasing plantation age. Canopy cover, soil pH, and leaf litter were the environmental drivers that drove the decrease in taxonomic and functional diversity of plants through the forest chronosequence. Based on the path analyses results, canopy cover had an indirect effect on plant functional diversity, mediated by leaf litter depth, soil pH, and plant species richness. The high dispersal potential, annual, barochorous, and zoochorous plant species were the functional traits more affected by the eucalypt plantations. We recommend two management practices: reducing forest densities to allow higher light input to the understory and, due to the fact that leaf litter was negatively associated with all diversity facets, we recommend reducing their accumulation or generate heterogeneity in its distribution to enhance biodiversity.

Quantile regression: prediction of growth and yield for a eucalyptus plantation in northeast Brazil

Regression analysis is a traditional technique to fit equations and predict tree and forest attributes. However, problems may occur when the data show high dispersion around the mean of the regressed variable, limiting the use of traditional methods such as the Ordinary Least Squares (OLS) estimator. Hence, the objectives were to propose a Quantile Regression (QR) methodology to predict tree growth and yield of a forest plantation without using the site index and compare it with the predictive accuracy of the Clutter model. The data came from clonal plantations of Eucalyptus grandis x E. urophylla located in the north of Bahia state (Brazil), and age ranged from 20 to 89-months-old. The set of permanent plots was divided into 50% for model training and the remaining for validation. The volume prediction methods, Clutter and QR, were evaluated using scatter plots of the relative error and graphs of the observed versus predicted volumes, as well as by the following statistics: mean prediction bias in percentage (BIAS %) and root mean square error in percentage (RMSE %). The volume predictions by QR resulted in higher accuracy compared to those obtained by the Clutter model. The QR demonstrated efficiency to predict volumes for different ages of eucalyptus plantations and can also be adapted to other forest areas and species worldwide.

Prediction of the suitable distribution of Eucalyptus grandis in China and its responses to climate change

Assessment of potentially suitable geographic areas in China and their response to climate change can provide a reference for sustainable development of Eucalyptus grandis plantations. Under current and future conditions, the potentially suitable areas for this species were predicted using MaxEnt modelling from known successful plantings of E. grandis in China. The dominant environmental factors affecting the distribution of E. grandis and ecological similarities between the species’ natural distribution in Australia and the suitable areas in China were analysed. Results show that the majority of the highly suitable areas identified for E. grandis in China are concentrated in the Sichuan Basin and southeastern hilly regions. Under future climate scenarios, the most suitable area for E. grandis is expected to increase through to the 2070s. The distribution of suitable areas in the Sichuan Basin are predicted to expand eastward to lower elevations, and suitable areas in China’s southeastern hilly regions would move to areas experiencing high solar radiation and lower seasonal temperature variances. The dominant ecological factors affecting the distribution of E. grandis were found to be: solar radiation, altitude, seasonal temperature and precipitation variance, maximum temperature of the warmest month, annual mean temperature, slope, isothermality, soil available water content, precipitation in the driest quarter and mean diurnal temperature range. Collectively, these factors account for over 85.1% of the variation in suitable areas. Compared with the species’ natural distribution in Australia, suitable areas in China feature higher precipitations during the driest quarters; a condition favourable to rapid growth of E. grandis.

Effects of human interference on species diversity and biomass of Eucalyptus grandis plantation in Cangping Mountain Park in Ya’an

Objective This study aims to reveal the effects of human interference on species diversity and biomass in E. grandis plantations. Method 12 sample plots of E. grandis plantations (20 m×20 m) with different interference intensities were set up by typical plot method in Cangping Mountain Park in Ya’an City of Sichuan Province, to investigate the species composition, species diversity(richness index D, Shannon-Wiener index H, Simpson dominance index H', Pielou evenness index Jsw), and plant layer biomass. Result There were 87 species of vascular plants belonging to 55 families and 82 genera. The number of species in E. grandis plantation decreased with increasing interference. The D, H and H' indices of tree layer and herb layer decreased with the increase of interference intensity. The D, H and H' indices of shrub layer reached the maximum under moderate disturbance. The difference of D and H indices in tree layer was significant (P＜0.05). With the increase of disturbance intensity, the biomass of each plant layer showed different changing trends. The tree layer had the highest volume (12.01 m3·hm−2) under moderate disturbance, while the biomass of shrub layer (394.533 kg·m−2) and herb layer (359.680 g·m−2) was the highest under light disturbance. The D index of tree layer and H' index of herb layer were significantly positively correlated with aboveground biomass and total biomass of herb layer (P＜0.05). The Jsw index of herb layer was significantly positively correlated with total biomass of herb layer (P＜0.05). Conclusion Moderate disturbance will increase species diversity and biomass in E. grandis plantation. The relationship between species diversity and biomass is subject to human interference and natural conditions, and there is no fixed relationship. [Ch, 2 fig. 3 tab. 25 ref.]

Stand Characterization of Eucalyptus spp. Plantations in Uruguay Using Airborne Lidar Scanner Technology

Airborne lidar scanner (ALS) technology is used in a variety of applications, including forestry. ALS has enormous potential for the estimation of relevant biometric parameters in forest plantations. This study investigates the use of an object-oriented semi-automated segmentation algorithm for stands delineation, based on modeling ALS data, in plantations of Eucalyptus grandis and E. dunnii in Uruguay. The results show that non-parametric methods delivered more accurate and less biased results for total volume (TV) with R2 0.93, RMSE 20.04 m3 h−1 for E. grandis and R2 0.93, RMSE 18.43 m3 h−1 for E.dunnii; and above ground biomass (AGB) with R2 0.95, RMSE 70.2 kg h−1 for E. grandis and R2 0.96, RMSE: 71.2 Kg h−1 for E. dunnii. Parametric methods performed better for dominant height (Ho) with R2 0.98, RMSE 0.67 m and R2: 0.96, RMSE: 0.8 m for E. grandis and E. dunnii, respectively. The most informative ALS metrics for the estimation of AGB and TV were metrics related to the elevation in parametric models (Elev.70 and Elev.75), while for the non-parametric models (k-NN) they were Elev.75 and canopy density. For Ho, the ALS metrics selected were also related to elevation both in the parametric (Elev.90 and Elev.99) and random forest models (Elev.max and Elev.75). The segmentation methodology proposed here matched closely the segments delineated by human operators, and provides a low-cost, cost-effective, easy to apply and update model aimed at generating AGB or TV maps for harvest tasks, based on rasters derived from ALS metrics. The present research shows the capacity of ALS metrics to improve extensive strategic inventories; validating and promoting the adoption of ALS technology for inventory forest stands of Eucalyptus spp. in Uruguay.