Don Plantations Research Articles

Impact of forest fire severity on soil physical and chemical properties in pine and scrub forests in high Andean zones of Peru

Forest fires are the main threat to ecosystems and human life. The frequency, seasonality, extent and severity of fires affect ecosystems and the physical and chemical properties of the soil by direct (heating) and indirect (ash) effects. This could affect biodiversity and forest residency in the face of climate change. In this study, we evaluated the impact of fire severity on soil physical and chemical properties caused by forest fires in a high Andean area of Peru. For this purpose, the severity levels, the degree of hydrophobicity, and the physical and chemical properties of the soil were analyzed by sampling in affected areas (Pinus radiata D. Don plantation and shrubland) and unaffected areas. The results showed a very low severity in soil components, with a strong hydrophobicity, more persistent in the forest plantation area than in the shrubland. The physical properties of the soil did not show variations; however, in the Pinus plantations they showed variations in their chemical properties such as pH, electrical conductivity, organic matter, nitrogen and cation exchange capacity compared to areas not affected by the forest fires. Likewise, in the study area an adequate regeneration process was evidenced; in fact, it is important to apply mechanisms to accelerate the restoration of the vegetation cover and the physical and chemical quality of the vegetation.

How much carbon do Argentine Pampas Pinus radiata plantations store?

Aim of study: To quantify the biomass and carbon stored in the main ecosystem components in Pinus radiata D. Don plantations across an age sequence in the Pampean region of Argentina.
 Area of study: Plantations were established on non-agricultural land, southeast of the province of Buenos Aires.
 Material and methods: Fourteen sites were selected of Pinus radiata plantations, 9-, 13-, 15-, 19- and 21-years-old, in a first forest rotation. Forty-two trees were destructively sampled, allometric functions were set and biomass was estimated for the different compartments (needles, branches, stem). Root biomass was estimated from equations adjusted by the sampling of twenty-four trees. At 4 sites, C-stock was determined in the tree component, in the forest floor and understory, and soil organic carbon (SOC) was determined to a 50 cm depth.
 Main results: C-stock in the tree component increased with stand age, whereas SOC and C-stock in the forest floor and understory were not related to stand age. The system-level C-stock was 273.1, 263.7, 269.7 and 324.1 Mg ha-1 for the 9-, 13-, 19- and 21-year-old stands. On average, 69% of the total system-level C-stock was in the soil, while 28% was in the tree biomass and 3% was in the forest floor and understory.
 Research highlights: The forestry component contributed to C sequestration with no changes in SOC-stocks reserves for the age range studied.

Characteristics of Soil Organic Carbon Fractions and Stability along a Chronosequence of Cryptomeria japonica var. sinensis Plantation in the Rainy Area of Western China

Soil organic carbon (SOC) is critical for carbon cycling and sequestration in forest ecosystems. However, how stand age affects SOC components and stability still remains poorly understood. Here, soil samples (0–20 cm) were collected from Cryptomeria japonica var. sinensis (L. f.) D. Don plantations of seven stand ages (6, 12, 23, 27, 32, 46, 52 a) in the rainy area of western China. SOC fractions, including soil particulate organic carbon (POC), easily oxidizable carbon (EOC), labile organic carbon (LOC), recalcitrant organic carbon (ROC), and light fraction organic carbon (LFOC), were determined to explore the nature of carbon components and stability across a chronosequence of C. japonica plantation. Soil carbon fractions first increased and then trended to be stable with an increase in stand age. SOC concentrations were the largest in mature forests (27 or 32 a), but the concentrations of other carbon components often peaked in early over-mature forests (46 a). The concentrations of all carbon fractions were the lowest in the young forests (6 a). The ratios of ROC/SOC increased and LOC/SOC decreased with increasing stand age. Almost all carbon fractions were positively correlated with soil bulk density and negatively correlated with soil moisture. The allometric exponent of ROC or HFOC and soil physicochemical properties was higher as compared to LOC and LFOC. The results noted in this study indicate that SOC components often accumulate fast over the first 20 years of afforestation and SOC stability increases with increasing stand age for C. japonica plantation in this specific region.

Estimating potential tree height in Pinus radiata plantations using airborne laser scanning data

Representing the spatial distribution of trees and competition interactions in growth models improves growth prediction and provides insights into spatially explicit forecasts for precise silvicultural interventions. However, this information is rarely taken into account over large areas because obtaining the spatial distribution of individual trees and estimating their competition is both expensive and time consuming. Airborne laser scanning enables rapid estimation of tree height and other attributes over large areas. In this study, we implemented an individual tree detection approach to first extract tree attributes of Pinus radiata D. Don plantations, and second to use this spatially explicit information on tree location and competition to forecast potential tree height, defined as a maximum projected tree height at rotation age. To do so, using a chronosequence of tree heights, we developed a tree height growth model using a Chapman–Richards function, utilizing the effect of inter-tree competition and stand-level top height (TH) on the tree height growth. The results showed that using chronosequence of heights, competition, and TH resulted in accurate predictions of potential tree height (root mean square error = 2.9 m; mean absolute percentage error = 0.154%). We concluded that individual tree height growth is significantly influenced by competition, with increased competition values associated with reductions in potential height growth by 22.2% at 30 years.

UAV-Based LiDAR Scanning for Individual Tree Detection and Height Measurement in Young Forest Permanent Trials

The installation of research or permanent plots is a very common task in growth and forest yield research. At young ages, tree height is the most commonly measured variable, so the location of individuals is necessary when repeated measures are taken and if spatial analysis is required. Identifying the coordinates of individual trees and re-measuring the height of all trees is difficult and particularly costly (in time and money). The data used comes from three Pinus pinaster Ait. and three Pinus radiata D. Don plantations of 0.8 ha, with an age ranging between 2 and 5 years and mean heights between 1 and 5 m. Five individual tree detection (ITD) methods are evaluated, based on the Canopy Height Model (CHM), where the height of each tree is identified, and its crown is segmented. Three CHM resolutions are used for each method. All algorithms used for individual tree detection (ITD) tend to underestimate the number of trees. The best results are obtained with the R package, ForestTools and rLiDAR. The best CHM resolution for identifying trees was always 10 cm. We did not detect any differences in the relative error (RE) between Pinus pinaster and Pinus radiata. We found a pattern in the ITD depending on the height of the trees to be detected: the accuracy is lower when detecting trees less than 1 m high than when detecting larger trees (RE close to 12% versus 1% for taller trees). Regarding the estimation of tree height, we can conclude that the use of the CHM to estimate height tends to underestimate its value, while the use of the point cloud presents practically unbiased results. The stakeout of forestry research plots and the re-measurement of individual tree heights is an operation that can be performed by UAV-based LiDAR scanning sensors. The individual geolocation of each tree and the measurement of heights versus pole and/or hypsometer measurement is highly accurate and cost-effective, especially when tree height reaches 1–1.5 m.

Hardwood mixture enhances soil water infiltration in a conifer plantation

Soil hydraulic properties affect soil infiltration capacity. Limited information is available about how hardwood mixture influences water infiltration in conifer plantations through its effects on soil hydraulic properties. We evaluated how, and to what extent, infiltration rates were affected by abiotic and biotic conditions along gradients of abundance and diversity of hardwoods and abundance of understory plants in nine stands representing three replicates of three different thinning intensities (unthinned [Control], 33% thinning [Weak], and 67% thinning [Intensive]) in a Cryptomeria japonica (Thunb. ex L. f.) D. Don plantation. Correlation analyses and a structural equation model (SEM) indicated that infiltration rates were enhanced by hardwood mixture (i.e., abundance and species richness of hardwoods) and abundance of understory plants, via increases in the fine root density and accumulation of broadleaf litter, because the fine root density decreased soil bulk density and accumulation of litter increased the porosity and both of which greatly improved the soil hydraulic conditions. In the Intensive treatment, complementarity effects stemming from vertical partitioning of resource acquiring organs (i.e., leaves) among species might have increased accumulation of broadleaf litter. If increased volumes of broadleaf litter promote increased earthworm abundance, earthworms may in turn cause higher porosity, because the burrowing activity of earthworms increases the number of macropores. Consequently, hardwood mixture with abundant understory plants promotes increased infiltration rates. Our results demonstrate that intensively thinned stands with an abundance and diversity of hardwoods, including broadleaf understory plants, can absorb and store more water compared to lightly thinned stands with only understory plants, owing to increased soil infiltration capacity. Our results point to the importance of hardwood mixture in enhancing ecosystem functioning in conifer plantations.

A Stand-Level Comparison of Carbon and Nitrogen Distribution in an Exotic Japanese Cedar Plantation and a Natural Oak Stand

This study compared carbon (C) and nitrogen (N) distribution at a stand level in an exotic Japanese cedar (Cryptomeria japonica D. Don) plantation and a natural Serrata oak (Quercus serrata Murray) stand growing under similar site conditions in South Korea. The aboveground biomass (stems, branches, and leaves) of 20 trees (10 of each species), the forest floor, and the mineral soils to a depth of 30 cm were sampled to determine C and N concentrations. Except in branches, C concentrations were significantly higher (p < 0.05) in the Japanese cedar plantation than in the Serrata oak stand, whereas N concentrations, except in the stem bark, were significantly lower in the Japanese cedar plantation. Reforestation with an exotic coniferous species significantly increased the C stocks in the aboveground biomass and the N stocks in the forest floor and mineral soils compared with a natural oak stand. The N stocks in the aboveground biomass were dependent on either the N concentrations or the C stocks in the tree components, whereas soil C and N stocks were negatively related to soil fertility parameters such as C/N ratio. Although it is uncertain which factors are responsible for the difference in aboveground C and soil N stocks following the establishment of Japanese cedar plantations on former natural Serrata oak stands, tree replacement may have an impact on C and N allocation within different forest compartments.

The influence of stocking levels, clone, fertilization, and weed control on surface CO2 efflux in a mid-rotation Pinus radiata D. Don plantation in Canterbury, New Zealand

Silvicultural practices applied in managed forest plantations may help counteract the effects of climate change by influencing soil surface CO2 efflux (Fs). Understanding the effects of silvicultural practices on Fs will provide unbiased estimates of carbon fluxes and allow better silvicultural decisions for carbon sequestration. Therefore, we assessed how Fs differed seasonally across silvicultural practices (i.e., stocking levels, clone, fertilization and weed control treatments) and evaluated the effects of soil temperature (Ts) and soil volumetric water content (θv) on Fs across these practices for a mid-rotation (14 year-old) Pinus radiata plantation in the Canterbury region of New Zealand. There were significant differences in Fs (p < 0.05) over the four seasons, three levels of stocking, and five clones. The effects of fertilization and weed control applied 12 years previously on Fs were insignificant. Annual estimate of Fs (mean ± 1 standard deviation) from the study site was 22.7 ± 7.1 t ha−1 a−1 in the form of CO2 (6.2 ± 2.1 t ha−1 a−1 in the form of C). Fs values were consistently higher in plots with 1250 stems ha−1 compared to 2500 stems ha−1, which may be related to a strong soil resource limitation because of the close spacing in the latter plantation. Significant differences in Fs across clones suggest that variations in carbon partitioning might explain their growth performance. Silvicultural treatments influenced Fs response to soil temperature (p < 0.05), resulting in models explaining 28–49% of the total variance in Fs. These findings provide insights into how silvicultural management decisions may impact Fs in mid-rotation radiata pine plantations, contributing towards developing more precise and unbiased plantation carbon budgets.

Reducing the Uncertainty of Radiata Pine Site Index Maps Using an Spatial Ensemble of Machine Learning Models

Site Index has been widely used as an age normalised metric in order to account for variation in forest height at a range of spatial scales. Although previous research has used a range of modelling methods to describe the regional variation in Site Index, little research has examined gains that can be achieved through the use of regression kriging or spatial ensemble methods. In this study, an extensive set of environmental surfaces were used as covariates to predict Site Index measurements covering the environmental range of Pinus radiata D. Don plantations in Chile. Using this dataset, the objectives of this research were to (i) compare predictive precision of a range of geostatistical, parametric, and non-parametric models, (ii) determine whether significant gains in precision can be attained through use of regression kriging, (iii) evaluate the precision of a spatial ensemble model that utilises predictions from the five most precise models, through using the model prediction with lowest error for a given pixel, and (iv) produce a map of Site Index across the study area. The five most precise models were all geostatistical and they included ordinary kriging and four regression kriging models that were based on partial least squares or random forests. A spatial ensemble model that was constructed from these five models was the most precise of those developed (RMSE = 1.851 m, RMSE% = 6.38%) and it had relatively little bias. Climatic and edaphic variables were the strongest determinants of Site Index and, in particular, variables that are related to soil water balance were well represented within the most precise predictive models. These results highlight the utility of predicting Site Index using a range of approaches, as these can be used to construct a spatial ensemble that may be more precise than predictions from the constituent models.

Stocks of litter and its morphological and fractional composition in Pinus pallasiana D. Don plantations at the Kryvyi Rih iron ore dump

Aim. The article aims to establish the morphological and fractional composition and stocks of a litter of pine plantations of Pinus pallasiana D. Don on the Kryvyi Rih iron ore dump depending on the relief conditions (different exposition and steepness of the slopes of the dump berms). Methods. The thickness, stocks and fractional composition of the litter were studied according to generally accepted methods (Vorobeychik, 1997; Rodin & Bazilevich, 1965). The litter was collected at five sites in 10 replicates (a total of 50 samples). According to the recommendations of L. O. Karpachevskiy (1968) active and inactive fractions of litter had been distinguished. The magnitude of the fall-litter coefficient and the intensity of the cycle were determined by the guidelines of L. Ye. Rodin, N. I. Bazilevich (1965). The thickness of the litter was ascertained according to the classification of L. G. Bogatyriov (1990). Results. We confirmed that the litter of pine plantations on the dump is characterized by different degrees of thickness. The accumulation of mortmass in pine stands varies in intensity – the most considerable rates was noted on the plateaus of the second and third berms – 6216.7 and 4748.1 g/m2, respectively, and the smallest ones – on the slope of the second berm – 1913.5 g/m2. The litter in 40-year-old pine plantations on the dump has a three-layer structure and only on the slope of the third berm is two-layered; it is characterized by different degrees of thickness: from 7.8 cm on the plateaus of the second and third berms to 3.9 cm on the slope of the second berm. It was found that an enormous contribution to the formation of litter was made by fragments ranging in size from 0.5 to 5 mm, the share of which could be 78.5%. The central part of the stocks of all studied litters in P. pallasiana plantations is the active fraction – from 74% to 98.7%. Conclusions. Plantations of P. pallasiana on the iron ore dump of Kryvyi Rih form significant stocks of litter. Thus, organic matter, thereby significantly improving the ecological and edaphic conditions for the development of biogeocenotic processes in these radically changed human-made ecotopes.

Merchantable wood volume response of P. radiate D. Don post thinned plots on coated and uncoated urea fertilizers

Our study was focused on whether the optimization of nutrition at various growth stages of Pinus radiate D. Don plantation was an important factor to increase its merchantable wood volume yield in Silviculture. The present study site is located within the ‘Green Triangle’ bordering the Australian states of South Australia and Victoria. A total of 24 sampling sub-plots, averaged to 12 super plots, were established in both the sites, and all the plots, except one set aside as 'controlled plot' in each site, were treated with 5 types of coated and un-coated urea fertilizers. The data on tree-height and diameter at breast height over bark (DBHOB) of all the standing trees were measured and recorded. A five-year sampling data from the 24 sub-plots consisting of two sites, namely Picks (Site 'A') and Hollands Lane (Site 'B') in post thinned condition were analysed. The specific target was to evaluate a productivity response in terms of merchantable volumes based on fertilizer types. The statistical analysis employing ANOVA, t-test, a neural network model, decision tree and box-plot model based on fertilizer treatment determined that Di-Ammonium Phosphate Entec Urea (DAPEU) fertilizer was found to be more effective in increasing productivity. As such, the merchantable wood volume increments measured after four years of application of DAPEU were found to be 48.61 m3 ha-1 at Site 'A' and 41.97 m3 ha-1 at Site 'B', higher than the 46.71 m3 ha-1 at Site 'A' and 39.79 m3 ha-1 at Site 'B' with 'control' treatment. Hence, the application of DAPEAU was found to be effective as compared to the 'control' treatment in silviculture to increase the merchantable wood volume.

SPATIOTEMPORAL DYNAMICS OF FOREST PLANTATION CLEARCUTTING AT LANDSCAPE LEVEL

Abstract. This study is about clearcutting sizes, their spatial distribution, and how this affects the structure of the whole landscape when they are assessed over time. We introduced the concept of "extended clearcutting patches" (ECPs), which are formed aggregating adjacent patches harvested in consecutive years. The main purpose of the study was to evaluate the spatiotemporal pattern of clearcutting and ECPs at landscape level. The chosen landscape was the coastal commune of Constitución, Maule Region, in Chile, dominated by Pinus radiata D. Don plantations with a high land cover dynamic due harvesting activities. We used Landsat 5, 7 and 8 images (Surface Reflectance Tier 1) to produce yearly land cover maps from 1999 to 2016 and the approach proposed by Zhao et al. (2016) to classify them. We used 32,516 control points in the classification step obtaining a mean global accuracy of 0.94. The spatial distribution of the harvested patches is aggregated in single o accumulate years showing the long-term spatiotemporal pattern if this forestry practice. In average, ECPs have double the size than yearly harvested parches but they can be much bigger in same cases. This intensive forestry practices creates some spatiotemporal harvested complex, or extended clearcutting patches, that can have a bigger impact in functional aspects of the landscape and the wildlife present in this type of landscapes.

Linking above-ground biomass production to below-ground carbon fluxes across stocking, clone, fertilization, and understory elimination in Pinus radiata D.Don plantations, New Zealand

The linkage between above-ground biomass production and below-ground carbon fluxes as influenced by silviculture has been insufficiently studied. We tested the effects of stocking, clone, fertilization, and follow-up herbicide treatments on below-ground carbon flux (BCF), above-ground biomass production (AGB), the ratio (BCF/AGB), tree diameter (DBH), height (H), basal area (G), and leaf area index (LAI) for a Pinus radiata D. Don plantation trial in the Canterbury region of New Zealand. Mixed-effects analysis of variance was carried out using data at the plot and clone levels.The H, DBH, G, AGB, BCF and the BCF/AGB ratio were influenced significantly by the main effects of stocking (p < .05), and the follow-up herbicide (p < .001). The main effects of clone had significant influence on H (p < .001), BCF (p < .01) and the BCF/AGB ratio (p < .01). Values of AGB and G increased with stand density, while DBH and H decreased with stand density. The significant stocking × follow-up herbicide interactions observed for DBH, G and AGB, suggested that follow-up weed control alleviated understory-induced water and nutrient stresses. Significant clone × follow-up herbicide interactions for DBH and AGB (p < .05), and clone × stocking interactions for G (p < .05), and no interaction of silvicultural treatments for BCF and BCF/AGB ratio were observed. Clones 1 and 3 exhibited greater AGB and smaller BCF/AGB ratio, compared to slower growing clones (i.e., Clones 4 and 5), suggesting certain clones were more productive above-ground at the expense of less carbon partitioned below-ground. These findings highlight that stocking, follow-up herbicide, and clone, in that order, had the greatest influence on above- and below-ground variables, suggesting that those silvicultural practices shifted carbon partitioning above-and below-ground. We conclude that well-performing clone planted with appropriate stand density and with follow-up weed control treatments may increase aboveground radiata pine productivity.

Comparison of Parametric and Nonparametric Methods for Estimating Size–Density Relationships in Old-Growth Japanese Cedar (Cryptomeria japonica D. Don) Plantations

Accurately quantifying the size–density relationships is important to predict stand development, estimate stand carrying capacity and prescribe silvicultural treatments. Parametric methods, such as segmented regression, were proposed to estimate the complicated trajectory of size–density relationships. However, applying nonparametric methods to assess stand development has not been explicitly examined. In this study, we compared parametric and nonparametric methods for estimating size–density relationships for Japanese cedar plantations in Taiwan. Specifically, we compared the efficacy of two segmented regression models with the penalized spline and random forest for regression methods. We also examined various stages in stand development for old-growth Japanese cedar stands. Data collected from 237 Japanese cedar permanent plots were used in model fitting and validation. Results indicated that the parametric and nonparametric methods used in this study can provide reliable estimates of the size–density relationship for Japanese cedar. Higher accuracy was achieved before the stands diverged from the self-thinning line. The penalized spline approach behaved consistently well regardless of datasets or stages in stand development, while the predictability of the random forest algorithm slightly decreased when the validation data was fitted. The results of this study provide insights on the use of methods to quantify the size–density relationships as well as enhance the understanding of long-term stand development.

Colonization of Pinus radiata D. Don Seedling Roots by Biocontrol Bacteria Erwinia billingiae and Bacillus simplex

Erwinia billingiae S31R1 and Bacillus simplex S11R41, isolated from the rhizosphere of a healthy tree located in a Pinus radiata D. Don plantation with high presence of fungal pathogens, are antagonists of pine root rot fungi Heterobasidion annosum and Armillaria mellea in vitro and in young trees. For effective biocontrol of these pathogens, the bacteria must stably colonize P. radiata roots following their application. To determine root colonization patterns, the bacteria were transformed with stable plasmids encoding green fluorescent protein (GFP). Transformed E. billingiae was visualized on roots 24 days after soil inoculation by confocal and epifluorescence microscopy, and GFP was detected by ELISA 31 days after inoculation. The presence of E. billingiae microcolonies, in some cases in root intercellular spaces, suggests that bacterial growth was active and localized. Fluorescence of B. simplex S11R41 was visualized on P. radiata roots 31 days after inoculation and its colonization pattern changed from scattered cells to localized microcolonies. Although the populations decreased over time, microcolony formation and localization in specific regions of roots indicated that E. billingiae, normally considered to be an epiphyte, and B. simplex can stably colonize roots of P. radiata.

Fungal Communities Associated with Bark Beetles in Pinus radiata Plantations in Northern Spain Affected by Pine Pitch Canker, with Special Focus on Fusarium Species

Fusarium spp., as well as other endophytic or pathogenic fungi that form communities, have been reported to be phoretically associated with bark beetles (Coleoptera; Scolytinae) worldwide. This applies to Fusarium circinatum Nirenberg and O’Donnell, the causal agent of pine pitch canker (PPC), which threatens Pinus radiata D. Don plantations in northern Spain. The main objective of this study was to study the fungal communities associated with bark beetles and their galleries in stands affected by PPC, with special attention given to Fusarium species. Funnel traps and logs were placed in a P. radiata plot known to be affected by F. circinatum. The traps were baited with different attractants: four with (E)-pityol and six with ethanol and α-Pinene. In addition, fresh green shoots with Tomicus piniperda L. feeding galleries were collected from the ground in 25 P. radiata plots affected by PPC. Extracts of whole insects and gallery tissues were plated on agar medium to isolate and identify the associated fungi. A total of 24 different fungal species were isolated from the bark beetle galleries constructed in logs and shoots, while 18 were isolated from the insect exoskeletons. Ten different Fusarium species were isolated from tissue and insects. Fusarium circinatum was isolated from bark beetle exoskeletons (1.05% of the Pityophthorus pubescens Marsham specimens harboured F. circinatum) and from the galleries (3.5% of the T. piniperda feeding galleries harboured the pathogen). The findings provide information about the fungal communities associated with bark beetles in P. radiata stands in northern Spain.

UAV Multispectral Imagery Can Complement Satellite Data for Monitoring Forest Health

The development of methods that can accurately detect physiological stress in forest trees caused by biotic or abiotic factors is vital for ensuring productive forest systems that can meet the demands of the Earth’s population. The emergence of new sensors and platforms presents opportunities to augment traditional practices by combining remotely-sensed data products to provide enhanced information on forest condition. We tested the sensitivity of multispectral imagery collected from time-series unmanned aerial vehicle (UAV) and satellite imagery to detect herbicide-induced stress in a carefully controlled experiment carried out in a mature Pinus radiata D. Don plantation. The results revealed that both data sources were sensitive to physiological stress in the study trees. The UAV data were more sensitive to changes at a finer spatial resolution and could detect stress down to the level of individual trees. The satellite data tested could only detect physiological stress in clusters of four or more trees. Resampling the UAV imagery to the same spatial resolution as the satellite imagery revealed that the differences in sensitivity were not solely the result of spatial resolution. Instead, vegetation indices suited to the sensor characteristics of each platform were required to optimise the detection of physiological stress from each data source. Our results define both the spatial detection threshold and the optimum vegetation indices required to implement monitoring of this forest type. A comparison between time-series datasets of different spectral indices showed that the two sensors are compatible and can be used to deliver an enhanced method for monitoring physiological stress in forest trees at various scales. We found that the higher resolution UAV imagery was more sensitive to fine-scale instances of herbicide induced physiological stress than the RapidEye imagery. Although less sensitive to smaller phenomena the satellite imagery was found to be very useful for observing trends in physiological stress over larger areas.

Comparison of high-density LiDAR and satellite photogrammetry for forest inventory

Point cloud data derived from stereo satellite imagery has the potential to provide large-scale forest inventory assessment but these methods are known to include higher error than airborne laser scanning (ALS). This study compares the accuracy of forest inventory attributes estimated from high-density ALS (21.1 pulses m−2) point cloud data (PCD) and PCD derived from photogrammetric methods applied to stereo satellite imagery obtained over a Pinus radiata D. Don plantation forest in New Zealand. The statistical and textural properties of the canopy height models (CHMs) derived from each point cloud were included alongside standard PCD metrics as a means of improving the accuracy of predictions for key forest inventory attributes. For mean top height (a measure of dominant height in a stand), ALS data produced better estimates (R2 = 0.88; RMSE = 1.7 m) than those obtained from satellite data (R2 = 0.81; RMSE = 2.1 m). This was attributable to a general over-estimation of canopy heights in the satellite PCD. ALS models produced poor estimates of stand density (R2 = 0.48; RMSE = 112.1 stems ha−1), as did the satellite PCD models (R2 = 0.42; RMSE = 118.4 stems ha−1). ALS models produced accurate estimates of basal area (R2 = 0.58; RMSE = 12 m2 ha−1), total stem volume (R2 = 0.72; RMSE = 107.5 m3 ha−1), and total recoverable volume (R2 = 0.74; RMSE = 92.9 m3 ha−1). These values differed little from the estimates of basal area (R2 = 0.57; RMSE = 12.2 m2 ha−1), total stem volume (R2 = 0.70; RMSE = 112.6 m3 ha−1), and total recoverable volume (R2 = 0.73; RMSE = 96 m3 ha−1) obtained from satellite PCD models. The statistical and textural metrics computed from the CHMs were important variables in all of the models derived from both satellite and ALS PCD, nearly always outranking the standard PCD metrics in measures of importance. For the satellite PCD models, the CHM-derived metrics were nearly exclusively identified as important variables. These results clearly show that point cloud data obtained from stereo satellite imagery are useful for prediction of forest inventory attributes in intensively managed forests on steeper terrain. Furthermore, these data offer forest managers the benefit of obtaining both inventory data and high-resolution multispectral imagery from a single product.

Moso bamboo (Phyllostachys edulis (Carriere) J. Houzeau) invasion affects soil phosphorus dynamics in adjacent coniferous forests in subtropical China

The invasion of moso bamboo ( Phyllostachys edulis (Carriere) J. Houzeau) into neighboring Cryptomeria japonica (L. f.) D. Don plantations significantly altered soil P status and dynamics. This alteration in phosphorus dynamics must be considered when assessing the ecological consequence of moso bamboo invasion in subtropical China. Moso bamboo is a native species that commonly invades into adjacent forests in Asia. Such invasions may significantly alter soil chemical characteristics because moso bamboo has very different traits compared with the tree species it displaces. However, few studies have investigated the effects of moso bamboo invasion on soil phosphorus (P) dynamics. The objective of this study was to investigate the effects of moso bamboo invasion on soil P dynamics. Specifically, we quantified soil total P, available P, acid phosphatase activity (APA), and microbial biomass P (MBP) in moso bamboo-invaded coniferous stands and compared them to uninvaded stands and pure moso bamboo stands. We compared seasonal dynamics of soil P (e.g., total P, available P, APA, and MBP) over a 24-month period among three stand types at Lushan mountain in subtropical China: Cryptomeria japonica plantation (CR), Cryptomeria japonica plantation invaded by Phyllostachys edulis (PH-CR), and Phyllostachys edulis stand (PH). Total soil P concentration was significantly lower in PH-CR than in CR and PH stands, but soil available P concentration was significantly lower in CR and PH stands. Soil APA was significantly higher in PH-CR than in CR and PH stands. Similarly, soil MBP concentration was higher in PH-CR than in CR and PH stands. Also, soil total P, available P, APA, and MBP concentrations displayed seasonal fluctuations in PH-CR, but remained relatively stable in CR and PH stands during the 2 years. The invasion of moso bamboo into adjacent C. japonica stands significantly increased soil available P, acid phosphatase activity, and microbial biomass phosphorus, but decreased soil total P. The implication of these changes to ecosystem composition, structure, and function must be explicitly considered in managing moso bamboo invasion in subtropical China.

Prediction of browse nutritive attributes in a Pinus radiata D. Don silvopastoral system based on visible-near infrared spectroscopy

Browse is an important source of food for rustic livestock, particularly when herbaceous forage is scarce. The Atlantic Basque Country (Northern Spain) forest landscape is dominated by Pinus radiata D. Don plantations where Rubus sp. and Ulex gallii are understorey dominant species. Knowledge of the nutritive value of these species is needed in the context of silvopastoralism, primarily because do not always meet livestock requirements. The objective of this study was to evaluate the potential of Visible-Near Infrared Spectroscopy to determine the quality attributes of Rubus sp. and U. gallii, using a Sample Turn Table probe to acquire spectra on non-dried samples. VIS–NIRS calibrations were developed for dry matter (DM), crude protein (CP), crude fibre (CF), neutral detergent fibre (NDF), acid detergent fibre (ADF) and ashes. Spectra were pre-treated and Partial Least Squares Regression models were constructed. Calibration models were accurate for most of the considered variables, both for Rubus sp. (DM: Rc2 = 0.95, RPD = 2.53; CP: Rc2 = 0.90, RPD = 2.39; CF: Rc2 = 0.86, RPD = 2.30; NDF: Rc2 = 0.93, RPD = 2.80; ADF: Rc2 = 0.95, RPD = 3.12; Ashes: Rc2 = 0.91, RPD = 2.15) and for U. gallii (DM: Rc2 = 0.98, RPD = 3.67; CP: Rc2 = 0.94, RPD = 1.84; CF: Rc2 = 0.98, RPD = 4.74; NDF: Rc2 = 0.94, RPD = 3.91; ADF: Rc2 = 0.98, RPD = 3.62; Ashes: Rc2 = 0.82, RPD = 1.65). In general, ADF and DM were the most accurately predictable variables and ash content, the least predictable one. The results showed VIS–NIRS potential for the rapid and accurate prediction of quality attributes in non-dried samples and proved as a useful tool for making decisions in silvopastoral systems.