Eucalyptus Plantations Research Articles

Monitoring Seasonal Growth of Eucalyptus Plantation under Different Forest Age and Slopes Based on Multi-Temporal UAV Stereo Images

Eucalyptus grows rapidly and can grow up to 10 m per year, making them an important source of wood supply. Guangxi is a typical karst terrain, with hills and plains being the main growth areas for Eucalyptus. The differences in terrain can affect the seasonal growth of Eucalyptus plantations at different forest ages, which in turn affects the stocking of Eucalyptus. Currently, indiscriminate logging and management not only cause resource waste but also bring economic losses to operators. In this study, an unmanned aerial vehicle (UAV) was used to obtain multi-temporal stereo images to investigate the seasonal growth differences in structural parameters of individual Eucalyptus trees under different forest ages and slopes, providing data support for the precise management of Eucalyptus resources. The results showed that the tree height, crown width, diameter at breast height (DBH), and aboveground biomass (AGB) of individual trees, extracted based on UAV stereo images, are highly correlated with the field measured data, with an R2 of 0.99, 0.78, 0.75, and 0.92, and RMSE of 0.21 m, 0.16 m, 1.17 cm, and 3.79 kg/tree, respectively. The growth of Eucalyptus structural parameters varies in different seasons, with faster growth in spring and autumn, accounting for 76.39%, 73.75%, 73.65%, and 73.68% of the total annual growth, respectively. The growth of different structural parameters of individual trees is closely related to forest age, with tree height, crown width, and DBH gradually slowing down with the increase in forest age, while AGB shows a trend of first increasing and then decreasing. The differences in terrain also have a certain impact on the growth of individual Eucalyptus tree structural parameters. For individual 1-year-old and 3-year-old Eucalyptus trees, those located on gentle slopes grow faster in spring and autumn than those located on flat land. However, those located on flat land grow faster in summer and winter than those located on gentle slopes. For tree height, crown width, DBH, and AGB, the maximum annual growth differences between Eucalyptus trees on gentle slopes and flat are 3.17 m, 0.26 m, 1.9 cm, and 9.27 kg/tree, respectively. The results indicate that based on UAV stereo images, the individual tree structural parameters in Eucalyptus plantations under different forest ages and slopes can be extracted, as well as seasonal growth can be monitored, providing data support for logging, planting, and management of Eucalyptus plantations.

Comparison of different spectral indices to differentiate the impact of insect attack on planted forest stands

Eucalyptus plantations are an important contributor to the South African economy and are geographically concentrated in the productive Zululand region. However, this area is becoming increasingly vulnerable to various forest disturbances such as insect attacks and drought. Information of the location, extent and duration of insect infestation is therefore crucial for sustainable timber production and forest management planning, and remote sensing approaches have been successful in the retrieval and analysis of such information along with field surveys. Sappi Forests frequently conduct field surveys to establish the nature of disturbances to improve the performance of trees, as these may be difficult to distinguish from other disturbances such as droughts. Great effort has been made to remotely detect the impact of G. scutellatus using single-date high-resolution commercial satellites, whose application is restricted by high costs. Here, we compare the performance of spectral indices for detecting the impact of G. scutellatus infestation in KwaMbonambi plantations using publicly available Landsat data and also apply anomaly detection framework to further test their performance for detecting the impact of insect damage on trees and other disturbances that occurred on the same compartment over time. Our results showed high performance of short-wave infrared (SWIR) band for detecting the impact of insect damage, followed by the normalized difference infrared index (NDII) and normalized difference vegetation index NDVI, when anomaly detection was applied. Without anomaly detection, the spectral indicators showed changes even to drought impact in 2015, which did not when anomaly detection was used. We believe that indices containing the SWIR would perform better for detecting anomalous changes, and further research is required to explore this. Anomaly detection only showed the impact of insect damage and clearcutting as anomalous changes. Overall, we demonstrated the benefit of identifying vegetation anomalies caused by the impact of insect damage and other disturbances using freely available Landsat time-series data, particularly in data-poor regions that have restricted computational resources.

Soil Enzyme Activity Differs among Native Species and Continuously Planted Eucalyptus Plantations

In recent years, monoculture and multi-rotation successional Eucalyptus plantations have given rise to several environmental issues, including the degradation of soil quality and nutrient imbalance, and the conversion of logging sites to multi-rotation Eucalyptus plantations has attracted considerable attention from the scientists involved. However, the effects of different management strategies on soil extracellular enzyme activities (EEAs) and enzyme stoichiometry (ES) in degraded Eucalyptus plantations are not clear. In this study, we investigated the responses and mechanisms of soil physicochemical properties, microbial biomass, carbon, and nitrogen- and phosphorus-acquiring enzyme activities, as well as the microbial resource requirements of Eucalyptus plantations, under different management strategies. The findings revealed that second-rotation (TWE) and third-rotation (THE) continuous plantings of pure Eucalyptus plantations resulted in significant decreases in soil organic carbon (SOC), total nitrogen (TN) and effective available phosphorus (AP) contents, while soil nutrient contents increased after the introduction of Manglietia glauca to form mixed forests (EM) with Eucalyptus or pure Manglietia glauca (M). Meanwhile, phosphorus-acquiring enzymes significantly increased with successive rotations of Eucalyptus (TWE and THE), while EEAC:P and EEAN:P gradually decreased and phosphorus limitation gradually increased compared to that of a native-species-mixed plantation (CK). After the introduction of Manglietia glauca (EM and M), phosphorus-acquiring enzyme activities showed lower levels and there were significant increases in EEAC:P and EEAN:P compared to those of continuous plantings of pure Eucalyptus plantations, which reduced microbial phosphorus demand. Moreover, soil nutrients played a more significant role in altering the EEAs and ES than did microbial biomass (0–10 cm: 72.7% > 53.3%, 10–20 cm: 54.5% > 32.6%). The results showed that EM and M improved soil fertility quality conditions and alleviated soil nutrient phosphorus limitations for soil microorganisms. Therefore, the introduction of Manglietia glauca, either to form mixed forests with Eucalyptus or in rotation with Eucalyptus, can be used as technical means for the conversion of multi-rotation successive Eucalyptus plantations.

Wildfire exposure and risk in pulp paper companies’ plantations under extreme weather conditions: A case study in North-Western Portugal

Since the 1960's, Portugal has been affected by profound land use/land cover changes, which have boosted fuel continuity and fire-proneness nationwide. Within this context, the assets of pulp paper companies are exposed to large wildfires, which may cause severe economic losses. Wildfire simulations can help to scenarize and anticipate fire spread, contributing to efficiently allocate resources to protect values at risk.To test this framework, we assessed wildfire hazard in a 115,000 ha landscape, including 3,720 ha owned by two companies, with the aim of identifying the management units most exposed to large wildfires and the ones most at risk. We used Minimum Travel Time algorithm to estimate Burn Probability (BP), Fire Size (FS) and Conditional Flame Length (CFL). Wildfire hazard and exposure were assessed at the landscape-level; risk was estimated in production eucalypt plantations, by combining the annual BP with potential economic losses, based on management costs, loss of revenue and salvage wood.Our results showed that eucalypt plantations not managed by the companies represent a major threat to their patrimony. Industrial plantations with ages between 6 and 9 years have proven the most exposed. Very large wildfires (≥5,000 ha) can potentially spread in 53 % of the landscape, affecting 75 % of young eucalypt (<5 years) area. The 90th percentile of the risk ranges from 213 to 429 €ha−1 year−1 (9.6 % of production eucalypt area). This work resulted in a flexible methodology, replicable in Mediterranean regions with similar landcover. The information produced can provide additional guidance for wildfire prevention and risk management.

Insight to phytochemical investigation and anti-hyperlipidemic effects of Eucalyptus camaldulensis leaf extract using in vitro, in vivo and in silico approach

Hyperlipidemia is a key risk factor mainly for hypertension and cardiac abnormalities. Previously eucalyptus plant (river red gum) had been used for its medicinal value for the treatment of many ailments. This study focused on phytochemical examination, investigation of an in vitro potential and in vivo effects in mice fed with high cholesterol diet, GC-MS analysis of extracts of Eucalyptus camaldulensis leaves and further confirmation of anti-hyperlipidemic potential of different constituents of plant extracts by using in silico technique. For in vitro study screening of different extracts of Eucalyptus camaldulensis leaves was performed by using pancreatic lipase enzyme inhibition assay. Ethanolic extract presented the highest potential among all the extracts by inhibiting pancreatic lipase having IC50–11.88 µg/mL. For in vivo study mice were fed with high cholesterol diet for induction of Hyperlipidemia. Water extract showed great anti-hyperlipidemic potential by reducing the level of cholesterol, triglycerides, low density lipoproteins and increasing high density lipoproteins level significantly (p < 0.05). Moreover, molecular docking and prime MM-GBSA study were applied for screening of compounds having anti-hyperlipidemic potential which showed that Alpha-cadinol was the lead compound for inhibition of pancreatic lipase enzyme having docking score (-6.604). The ADMET properties and toxicity profile of the top docked compounds were also detailed for ensuring their safety aspects. In this way in silico analysis substantiate the experimental findings by showing anti-hyperlipidemic potential in constituents of eucalyptus plant. Thus, there is a need of advanced research for isolation of active constituents having said anti-hyperlipidemic potential in the Eucalyptus camaldulensis plant. Communicated by Ramaswamy H. Sarma

Growth response of clonal eucalyptus to varying levels of iron application and soil texture

Deficiency symptoms of iron (Fe) appear in eucalyptus (Eucalyptus spp.) plantations grown on different type of soils in Punjab, India. Therefore, a pot experiment was conducted to study the response of eucalyptus to application of Fe in soils of different textures. The treatments comprised of six levels of Fe as soil application (0, 15, 30, 45, 60, and 75 mg Fe kg−1 soil applied as chelated Fe through Fe-EDTA) and two foliar sprays (0.5% and 1% FeSO4·7H2O) replicated thrice in soils of three textures (loamy sand, sandy loam, and sandy clay) in a completely randomized design. Plant growth parameters, Fe concentration in soils, and Fe uptake by different plant parts were determined after nine months of eucalyptus growth. These parameters were significantly and positively influenced with the application of Fe. Dry weight of shoot and root was the highest at 30 mg Fe kg−1 whereas Fe concentration and uptake of Fe by shoot and root were the highest at 45 mg Fe kg−1. With 1% spray, the root dry weight, Fe concentration in leaves and its uptake by leaves and shoot were the highest. Loamy sand soil exhibited maximum shoot biomass and uptake response to applied Fe by eucalyptus. The Fe concentration in soil was positively and significantly related to Fe concentration (r = 0.436*–0.772**) and its uptake (r = 0.643**- 0.866**) by different plant parts. Conclusively, application of Fe to eucalyptus significantly increased the growth parameters, its uptake and response by the plants.

Integrating variation in bacterial‐fungal co‐occurrence network with soil carbon dynamics

Abstract Bacteria and fungi are core microorganisms in diverse ecosystems, and their cross‐kingdom interactions are considered key determinants of microbiome structure and ecosystem functioning. However, how bacterial‐fungal interactions mediate soil organic carbon (SOC) dynamics remains largely unexplored in the context of artificial forest ecosystems. Here, we characterised soil bacterial and fungal communities in four successive planting of Eucalyptus and compared them to a neighbouring evergreen broadleaf forest. Carbon (C) mineralisation combined with five C‐degrading enzymatic activities was investigated to determine the effects of successive planting of Eucalyptus on SOC dynamics. Our results indicated that successive planting of Eucalyptus significantly altered the diversity and structure of soil bacterial and fungal communities and increased the negative bacterial‐fungal associations. The bacterial diversity significantly decreased in all Eucalyptus plantations compared to the evergreen forest, while the fungal diversity showed the opposite trend. The ratio of negative bacterial‐fungal associations increased with successive planting of Eucalyptus due to the decrease in SOC, ammonia nitrogen (NH4+‐N), nitrate nitrogen (NO3−‐N) and available phosphorus (AP). Structural equation modelling indicated that the potential cross‐kingdom competition, based on the ratio of negative bacterial‐fungal correlations, was significantly negatively associated with the diversity of total bacteria and keystone bacteria, thereby increasing C‐degrading enzymatic activities and C mineralisation. Synthesis and applications: Our results highlight the regulatory role of the negative bacterial‐fungal association in enhancing the correlation between bacterial diversity and C mineralisation. This suggests that promoting short‐term successive planting in the management of Eucalyptus plantations can mitigate the impact of this association on SOC decomposition. Taken together, our study advances the understanding of bacterial‐fungal negative associations to mediate carbon mineralisation in Eucalyptus plantations, giving us a new insight into SOC cycling dynamics in artificial forests.

Investigating Soil Pore Network Connectivity in Varied Vegetation Types Using X-ray Tomography

The ecological environment in southwestern China is fragile. Due to the significant preferential flow in vertical and horizontal directions and poor water conservation ability, vegetation degradation still exists under conditions of abundant rainfall. Therefore, the pore connectivity and infiltration characteristics in shallow soil under typical local vegetation need to be studied. A calculation model for the vertical connectivity of soil macropores was independently constructed, and differences in soil macropore structures and the degree of vertical connectivity in typical vegetation types (natural secondary forest, natural grassland, Yunnan pine plantation, eucalyptus plantation, cypress plantation, mulberry bushes) were investigated by CT scanning technology of undisturbed soil columns. The results showed that the vertical connectivity of large pores in the shallow soil of the region can be quantitatively described by X-ray tomography, and the total surface area and cumulative curvature of macropores in natural grassland soil were two or three times that in artificial vegetation. The concentration area of macropores in the soil of artificial forestland was closer to the surface, and the tendency of macropore preferred path decreased by 76.18% around 30 cm depth in the soil. The vertical connection of soil macropores in artificial forests was significantly lower than that of natural secondary forestlands (33.03%) and natural grasslands (36.75%). The restoration of the plantation improved surface soil pore structure, and the vertical connectivity of soil is nearly 20% less than that of natural vegetation types (natural secondary forestland, natural grassland), which reduced water outflow rate by nearly 44% and electrolyte content by nearly 14% at a depth of 30 cm. This study provided data and research directions for the study of hydrological processes in local forest vegetation and technical support for solving the problems of soil water loss and forestland water conservation in southwestern China.

Support vector machine-based spatiotemporal land use land cover change analysis in a complex urban and rural landscape of Akaki river catchment, a Suburb of Addis Ababa, Ethiopia

Intense level of land use land cover (LULC) changes has been observed in Sub-Saharan Africa, particularly in the central highlands of Ethiopia, due to rapid population growth and urbanization process. However, quantifying and identifying the rural-urban landscape changes are challenging. In this study, LULC changes during the years 1984, 1990, 2000, 2010, and 2021 have been analyzed using satellite imageries and Support Vector Machine (SVM) algorithms in a heterogenous rural and urban landscape of the Akaki river catchment, central highlands of Ethiopia. The LULC change drivers were evaluated by applying LULC thematic change analysis combined with key informants’ interviews. Seven LULCs that include: Built-up area (BTA), Cropland (CL), Grassland (GL), Waterbody (WB), Plantation Forest (PF), Woodland (WL), and Bareland (BL) were detected. The result shows that 51.3 % of the catchment area has been transformed into other land uses. BTA increased by 24.7 % while GL and WL reduced by 18.1 % and 5.9 % respectively. Large areas of CL (61 %) and GL (22 %) were changed into an urban landscape. The spatial and non-spatial analysis revealed that the major spatiotemporal LULC change drivers between 1984 and 2005 were land use policy and legislation change and the Eucalyptus tree plantation campaign. Whereas, low-cost housing programs, informal settlers, market opportunity, and real estate development were the main drivers for the LULC changes between 2006 and 2021. The study also found the key informant observation and SVM image classification results are aligned and therefore, we found the SVM-based classifications are suited for such complex rural-urban landscape change and pattern analysis. The outcome of this research can contribute to improving land use policy, its management, and public understanding of the LULC dynamics and its implications.

Influence of soil properties and near-surface roots on soil infiltration process in short-rotation eucalyptus plantations in southern subtropical China

Soil infiltration capacity is a measure of the rate of water infiltrating into a soil. The influence of soil properties and near-surface roots on the soil infiltration process remains unclear in short-rotation eucalyptus plantations. A series of field experiments were conducted to determine the soil infiltration capacities of differently aged (1, 2, 3, and 5 years) eucalyptus plantations by using a surface-positioned double-ring infiltration instrument. The biomass of fine root (<2 mm) and medium root (2–10 mm) on near-surface soil (0–50 cm) and soil samples (0–60 cm with 20 cm interval) was collected for analyzing the effects of near-surface fine root biomass (FRB), medium root biomass (MRB), soil organic matter (SOM), soil bulk density (BD), soil total porosity (TP), soil macroaggregate, and water-stable macroaggregate on soil infiltration. Results showed that the average infiltration rate (762–1463 mm h−1), initial infiltration rate (5420–8454 mm h−1, infiltration rate of stage I (3130–5421 mm h−1), infiltration rate of stage II (1594–2257 mm h−1), infiltration rate of stage III (484–934 mm h−1), and steady infiltration rate (318–510 mm h−1) increased with increasing forest age. The near-surface FRB (4.25–14.71 g) decreased with increasing forest age. Near-surface FRB showed a strong plugging effect on soil infiltration in both initial and steady infiltration stages, but this effect weakened with increasing forest age because of FRB decreasing. Near-surface MRB had no significant effects on soil infiltration. The TP and SOM in near-surface soil promoted soil infiltration capacity. The soil infiltration capacity of short-rotation eucalyptus plantations significantly improved after the third year of planting. Our finding contributes to understanding the effects of near-surface root biomass and soil properties on soil infiltration capacity in eucalyptus plantations, and provides a scientific reference for eco-hydrological study in such plantations.

Impact of Simulated Acid Rain on Soil Base Cations Dissolution between Eucalyptus Pure Plantations and Eucalyptus–Castanopsis fissa Mixed Plantations

The soils of Eucalyptus pure plantations and Eucalyptus–Castanopsis fissa mixed plantations were studied using soil column leaching experiments with acid solutions to mimic the effects of acid rain on the soils. This helped researchers learn more about how soil base ions react to acid deposition and their ability to protect the soil from excessive acidity under pure and mixed-species plantations. The results showed that acid rain leaching increased the leaching loss, desorption, and desorption rate of soil base ions while decreasing the soil pH value, adsorption, and adsorption rate of soil base ions. The soil pH value and the leaching loss ranges of K+, Na+, and Mg2+ were all greater in the pure plantations than in the mixed plantations, while the leaching range of Ca2+ was greater in the mixed plantation than in the pure plantations. In the two types of plantations, the adsorption rates of Ca2+ and Na+ in the mixed plantations were higher than in the pure plantations, while K+ and Mg2+ showed higher adsorption rates in the pure plantations than in the mixed plantations. Therefore, soil pH and base ions were greatly affected by the pH value of acid rain. Compared with the pure plantations, the establishment of Eucalyptus–Castanopsis fissa mixed plantations can slow soil acidification and leaching of K+, Na+, and Mg2+ and contribute to the adsorption of Ca2+ and Na+, which is beneficial for the soil nutrient fixation of Eucalyptus plantations. The mixed plantations were found to increase the exchange reaction between H+ and base ions, thereby improving the acid buffer performance of the soil. This, in turn, helped to mitigate the decline in soil fertility. Therefore, establishment of Eucalyptus–Castanopsis fissa mixed-species plantations can slow down the impact of acid rain on soil acidification in artificial plantation land to a certain extent and play an important role in optimizing the plantation structure of Eucalyptus stands and maintaining their productivity.

“Cash Tree” or “Poisonous Tree”: A Study on the Collective Action Dilemma of Eucalyptus Planting in Neilong Village, China

“Cash Tree” or “Poisonous Tree”: A Study on the Collective Action Dilemma of Eucalyptus Planting in Neilong Village, China

Cumin and eucalyptus essential oil standardization using fractional distillation: Data-driven optimization and techno-economic analysis

Cumin and eucalyptus essential oils (EOs) are among the most important and widely used EOs with a broad range of applications in the pharmaceuticals, cosmetics, and food industries. The seeds and leaves of cumin (Cuminum cyminum) and eucalyptus (Eucalyptus globulus) plants are processed with extraction techniques to retrieve their EOs, yet certain product specifications need to be met to achieve a high-quality product. Based on the International Organization for Standardization (ISO), the essential oils of cumin and eucalyptus should contain certain amounts of cuminaldehyde and 1,8-cineole to be of acceptable quality. In this study, we design and optimize a dynamic fractional distillation process that enriches cumin and eucalyptus EOs to the ISO standards, with concentrations of 42% cuminaldehyde and 80% of 1,8-cineole achieved for each EO respectively. The dynamic model of this process is simulated via Aspen Plus using data from a pilot-scale fractional distillation unit, and the operating conditions that minimize the operational cost in the simulated environment are identified using the NOMAD algorithm. The optimization results show that the operating cost of standardization processes for cumin and eucalyptus EOs are $0.688/batch and $0.6973/batch, with process efficiencies of 69.56% and 59.77%, respectively. Furthermore, the techno-economic analysis for these two standardization processes showed that the total annualized cost was approximately $510,600 for both processes.

Early and long-distance uptake by Eucalyptus grandis of N, K and Ca tracers injected down to a depth of 7 m

Eucalyptus plantations are commonly fertilized at planting to sustain high biomass production over successive rotations in nutrient-poor soils. However, the dynamics of nutrient uptake by tree roots in the early stages of stand development, depending on the lateral distance from the trees and the depth in the soil, are poorly documented. We assessed the potential uptake of N, K and Ca, from 6 to 18 months after planting, by Eucalyptus grandis trees depending on: i) the lateral distance from the tracer injection point and ii) the depth in the soil. At 6 months after planting, we injected 15NO3–, Rb+, Sr2+ and Cs+ tracers at depths of 1, 3, 5, and 7 m, respectively. Recently expanded leaves were then sampled monthly on 16 target E. grandis trees located at lateral distances ranging from 0.75 to 11.1 m from the injection points, and on 4 more distant E. grandis control trees; 15N contents (atom %) and concentrations of Rb, Cs and Sr in the leaves were determined at each sampling date, and compared to those of control trees to detect the dates of tracer uptake for each individual. A LOESS model was applied to account for the temporal trend and inter-tree variability among the control trees. Tracer uptake by a target tree was detected if the measurements exceeded the upper limit of the prediction interval (α = 0.005) generated by the model. Only the 6 target trees located within 2.0 m from the injection point took up the 15NO3– tracer. However, Rb+, Sr2+ and Cs+ tracers were taken up to lateral distances of approx. 11 m from the injection point. Tracer uptake occurred as early as 9, 7, 8 and 9 months after planting for 15NO3–, Rb+, Sr2+ and Cs+, respectively. Four trees located within 2.8 m from the injection point took up the 3 cation tracers, injected between the depths of 3 m and 7 m. All but one of the target trees took up at least one cation tracer. The potential of Eucalyptus trees to take up nutrients early, at long distance and at depth, can be promoted by silvicultural practices enhancing rapid root development after planting, as subsoiling in commercial plantations and large planting holes in smallholder plantations. Our results also suggest that fertilization could be applied only once at planting in Eucalyptus stands established on deep tropical soils, with low risks of nutrient losses by deep drainage.

Tropical montane forest (Shola) tree species can regenerate under abandoned exotic tree plantations in the Western Ghats of India

Abstract Whether environmental conditions under exotic tree plantations abandoned in the Western Ghats of India can facilitate the natural regeneration of tropical montane forest (Shola forest) tree species is being debated. In many cases, the exotic tree plantations are being cleared to allow for the restoration of native ecosystems. In this paper, we examined whether exotic tree plantations have indeed a negative effect on the regeneration of Shola forest tree species. For this, we assessed the abundance, diversity, and composition of the regeneration of Shola forest tree species in plantations, each with different dominant tree species (Acacia mearnsii, Pinus sp., and Eucalyptus sp.). We tested the abundance of regenerating native tree species against the main plantation canopy species (plantation type) as well as other environmental factors (aspect, distance to nearest Shola forest, structural diversity, slope, elevation, presence of herbivores, and canopy closure). We found that the number of native tree species regenerating in all plantation types was at an acceptable level: 1960, 1773, and 462 individuals ha−1 for Acacia, Eucalyptus, and Pinus plantations, respectively. A rare fraction analysis showed that the highest number of Shola tree species were regenerating under Acacia mearnsii (25) followed by Eucalyptus (19) and Pinus (8) plantations. The density and diversity of regenerating Shola trees was greatest under Acacia plantations and northern aspects but declined with increasing elevation. The presence of herbivores also reduced the density and diversity of Shola tree regeneration. We concluded that the restoration of Shola forest in the Western Ghats is possible in existing stands of exotic tree species and this process can be accelerated with appropriate silvicultural methods. We additionally recommend that studies involving long-term exclosures can provide valuable insights into the effects of browsing on regeneration and species composition.

Vegetation Trend Detection Using Time Series Satellite Data as Ecosystem Condition Indicators for Analysis in the Northwestern Highlands of Ethiopia

Vegetation is an essential component of the terrestrial ecosystem and has changed significantly over the last two decades in the Northwestern Highlands of Ethiopia. However, previous studies have focused on the detection of bitemporal change and lacked the incorporation of entire vegetation time series changes, which are considered significant indicators of ecosystem conditions. The Normalized Difference Vegetation Index (NDVI) time series dataset from the Moderate-Resolution Imaging Spectroradiometer (MODIS) is an efficient method for analyzing the dynamics of vegetation change over a lengthy period using remote sensing techniques. This study aimed to utilize time series satellite data to detect vegetation changes from 2000 to 2020 and investigate their links with ecosystem conditions. The time-series satellite processing package (TIMESAT) was used to estimate the seasonal parameter values of NDVI and their correlation across the seasons during the study period. Break Detection for Additive Season and Trend (BFAST) was applied to identify the year of breakpoints, the direction of magnitude, and the number of breakpoints. The results were reported, analyzed, and linked to ecosystem conditions. The overall trend in the study area increased from 0.58 (2000–2004) to 0.65 (2015–2020). As a result, ecosystem condition indicators such as peak value (PV), base value (BV), amplitude (Amp), and large integral (LI) exhibited significant positive trends, particularly for Acacia decurrens plantations, Eucalyptus plantations, and grasslands, but phenology indicator parameters such as start of season (SOS), end of season (EOS), and length of season (LOS) did not show significant trends for almost any vegetation type. The most abrupt changes were recorded in 2015 (24.7%), 2012 (18.6%), and 2014 (9.8%). Approximately 30% of the vegetation changes were positive in magnitude. The results of this study imply that there was an improvement in the ecosystem’s condition following the establishment of the Acacia decurrens plantation. The findings are considered relevant inputs for policymakers and serve as an initial stage for the assessment of the other environmental and climatic implications of Acacia decurrens plantations at the local scale.

N2-Fixing Tree Species Help to Alleviate C- and P-Limitation in Both Rhizosphere and Non-Rhizosphere Soils in the Eucalyptus Plantations of Subtropical China

The extracellular enzyme activity (EEA) and enzymatic stoichiometry (EES) of soil are useful indicators of shifts in soil nutrition and microbial resource requirements. Nevertheless, it is uncertain how the limitation of soil microbial nutrients is altered by a Eucalyptus plantation mixed with a N2-fixing tree species. Our study examined the microbial nutrient limitation in two plantations: a pure Eucalyptus plantation (PP) and a mixed plantation (Eucalyptus and Erythrophleum fordii, MP) in rhizosphere and non-rhizosphere soils, beginning with two indicators, soil EEA and EES. In this study, the soil EEA was considerably (p &lt; 0.05) greater in the MP contrasted to the PP, and the enzyme C:N:P ratios of the PP (1.12:1:1.10) and MP (1.07:1:1.08) both diverged from the global average EEA (1:1:1), and the deviation degree of the PP was greater. The results of the vector analysis demonstrated that the vector angle (VA) and vector length (VL) were considerably (p &lt; 0.05) smaller in the MP contrasted to the PP. In comparison to the PP, the MP had a considerably (p &lt; 0.05) poorer carbon quality index (CQI). Additionally, both microbial and soil properties have a considerable impact on soil EEA and EES, according to variance partitioning analysis (VPA) and redundancy analysis (RDA). In summary, our results show that the restriction of microorganisms on C and P in rhizosphere soils is usually weaker than that in non-rhizosphere soils and that the addition of N2-fixing tree species to Eucalyptus plantations can lessen but not completely remove the restriction of soil microorganisms on C and P. Future management practices involving mixed plantations with N2-fixing trees species could help decrease microbial nutrient limitation and promote sustainable plantations.

Soil C–N–P Stoichiometric Characteristics at the Aggregate Scales in Eucalyptus Plantations with Different Stand Types in Subtropical China

Soil C–N–P Stoichiometric Characteristics at the Aggregate Scales in Eucalyptus Plantations with Different Stand Types in Subtropical China

Estimating the Trade-Offs between Wildfires and Carbon Stocks across Landscape Types to Inform Nature-Based Solutions in Mediterranean Regions

Climate and land-use changes have been contributing to the increase in the occurrence of extreme wildfires, shifting fire regimes and driving desertification, particularly in Mediterranean-climate regions. However, few studies have researched the influence of land use/cover on fire regimes and carbon storage at the broad national scale. To address this gap, we used spatially explicit data from annual burned areas in mainland Portugal to build a typology of fire regimes based on the accumulated burned area and its temporal concentration (Gini Index) between 1984 and 2019. This typology was then combined with carbon stock data and different landscapes to explore relationships between landscape types and two important ecosystem services: wildfire reduction and carbon stock. Multivariate analyses were performed on these data and the results revealed a strong relationship between landscapes dominated by maritime pine and eucalypt plantations and highly hazardous fire regimes, which in turn hold the highest carbon stocks. Shrubland and mixed landscapes were associated with low carbon stocks and less hazardous fire regimes. Specialized agricultural landscapes, as well as mixed native forests and mixed agroforestry landscapes, were the least associated with wildfires. In the case of agricultural landscapes, however, this good wildfire performance is achieved at the cost of the poorest carbon stock, whereas native forests and agroforestry landscapes strike the best trade-off between carbon stock and fire regime. Our findings support how nature-based solutions promoting wildfire mitigation and carbon stock ecosystem services may prevent and revert land degradation harming Mediterranean regions.

Can Eucalyptus plantations influence the distribution range of mesocarnivores?

ContextThe expansion of exotic plantations can impose conservation challenges on wildlife, and the Iberian Peninsula has one of the widest planted areas of exotic Eucalyptus sp. in Europe. Since mesocarnivores are pivotal elements of ecosystems’ functioning and Eucalyptus have been modifying the Portuguese landscape context in the last half century, it is crucial to understand how these systems may affect carnivores’ range.ObjectivesWe aim to identify the drivers of five mesocarnivores’ distribution in Portugal (e.g., land-cover, ecogeographic predictors, mammal prey availability) and understand the influence of Eucalyptus plantations in their distribution range.MethodsUsing generalized linear models, we modelled the distribution range of mesocarnivores. The initial dataset was randomly split for model training and validation, and the multicollinearity between the predictors was tested. Then, we examined the potential relationship between theEucalyptus plantations area and the predicted probability presence of each species. ResultsWe detected species-specific patterns explained by different drivers, including climatic, land cover and mammal prey related ones. Furthermore, in areas of Eucalyptus plantations, the probability of occurrence of most Portuguese mesocarnivores is lower: red fox,stone marten,European badger, and Egyptian mongoose. ConclusionsManagers must take action to adapt their management to promote native forest patches within plantation, and allow the development of some understory within stands, to improve this plantation’s permeability to mesocarnivores. This will increase the spatial heterogeneity and enhance resource availability, reducing the constraints that plantations might have on the range of mesocarnivores in Portugal.