National Forest Research Articles

Contribution of Fuel Wood Income from Natural Forests to Household Economy in Delanta District, Northeastern Ethiopia

For Ethiopia’s rural homes, particularly those in the Delanta district, fuelwood is the primary energy source. This suggests that the impact of fuel wood from the forest to family energy use or income is significant. The goal of the current study was to estimate how much annual fuel wood harvested from forests contributes to household consumption and monetary income. 96% of the forest’s income comes from fuelwood. In the study area, it contributes 2,013,539 Birr, or 33%, of all family income. 703,014 ETB, or 23.8% of the total subsistence income, and 1,310,525 ETB, or 40.65% of the total cash income of the tested households, are both covered by fuelwood from the forest. Both socioeconomic and physical characteristics close to the users influenced how dependent a household was on fuelwood income from the forest. The data obtained from randomly selected households by survey method have been subjected to multiple regression analysis and obtained that households’ reliance on fuelwood income from the forest was significantly influenced by factors such as age, educational level, number of trees owned, distance to forest, distance to market, and nonforest income, all of which had a negative and significant impact. The only significant factor that significantly and positively influences reliance on fuelwood income from the forest is the number of family members. Therefore, preserving a natural forest through the use of alternative energy sources, such as electricity, or encouraging a plantation on one’s own property is a potential discipline for mandating climate change prevention.

Chloroplast Haplotype Diversity in the White Oak Populations of the Italian Peninsula, Sicily, and Sardinia

A phylogeographic study on the chloroplast DNA of natural white oak forests (Quercus subgen. Quercus, sect. Quercus) was carried out to identify possible haplotype-structured distribution within the Italian Peninsula, Sicily, and Sardinia. Sixty white oak populations belonging to Q. frainetto, Q. robur and the collective groups Q. petraea and Q. pubescens were considered and analyzed by combining five Chloroplast Simple Sequence Repeat (cpSSR) markers. A total of 28 haplotypes were detected. Central and southern Italy displayed the highest variability (14 and 10 haplotypes, respectively), followed by northern Italy (7), Sardinia (7), and Sicily (5). A complex geographical structure of the haplotype distribution emerged, highlighting (i) a high number of low-frequency haplotypes; (ii) the marked isolation of Sardinia; (iii) the occurrence of haplotypes widely distributed throughout the Italian Peninsula; (iv) the idiosyncrasy of Sicily, which exhibits exclusive haplotypes, and haplotypes shared with Sardinia and the rest of the Italian Peninsula. The haplotype distribution was also found to be partially related to the taxonomic identity of the specimens, with the following features emerging: a geographic separation between the central Italy and southern Italy Q. frainetto populations, an unexpected discontinuity between the Calabrian and Sicilian Q. petraea subsp. austrotyrrhenica populations, and the absence of the most common haplotype among the Q. pubescens populations of central and southern Italy.

The effect of forest-environment construction on the physical activity among Chinese adults

The Chinese government attaches great importance to the construction of the National Forest City (NFC), aiming at creating a pleasant living environment beneficial for people’s health and well-being. This study aimed to estimate the effect of the NFC policy on the frequency of physical activity (PA) for people in mainland China. Using the nationally representative data from the China Family Panel Studies in 2010 and its follow-up in 2018, 17 704 participants aged 18 and older were analyzed in our study. We employed the two-way fixed estimator in the difference in difference setting to analyze the PA of the adults in the cohort with different development levels of the forest-environment construction measured by the number of NFCs, and explore the relative differences before and after the construction of NFC. Subgroup analysis of age group, gender and living areas and a series of robustness tests were further conducted. The mean age of 17 704 participants in 2010 was (45.03 ± 13.67) years old, 51.74% of which were female and 48.26% were male. DID results showed that after the construction of NFC, the frequency of PA increased by 1.35 (β = 1.35, 95% CI:0.73–1.98) per week compared to those in provinces without NFC after adjusting covariates. And the improving effect of the forest-environment construction on PA frequency was intensified in middle-aged and older adults aged 45 and above (β = 2.03, 95% CI:1.09–2.96), males (β = 1.26, 95% CI:0.39–2.12) and females (β = 1.49, 95% CI:0.58–2.40) and those living in urban areas (β = 1.29, 95% CI:0.57–2.00). Our findings showed that the forest-environment construction under the NFC strategy has a positive role in the PA of older adults, indicating the health-promoting effects of the national green low-carbon environmental strategy. Considering the heterogeneity, it is essential to promote the benefits of green exercise for young and rural adults.

Soil and climate‐dependent ingrowth inference: broadleaves on their slow way to conquer Swiss forests

Forests provide essential ecosystem services that range from the production of timber to the mitigation of natural hazards. Rapid environmental changes, such as climate warming or the intensification of disturbance regimes, threaten forests and endanger forest ecosystem services. In light of these challenges, it is essential to understand forests' demographic processes of regeneration, growth, and mortality and their relationship with environmental conditions. Specifically, understanding the regeneration process in present‐day forests is crucial since it lays the foundation for the structure of future forests and their tree species composition. We used Swiss National Forest Inventory (NFI) data covering vast bio‐geographic gradients over four decades to achieve this understanding. Trees that reached a diameter at breast height of 12 cm between two consecutive NFI campaigns were used to determine regeneration and were referred to as ingrowth. Employing three independent statistical models, we investigated the number, species, and diameter of these ingrowth trees. The models were subsequently implemented into a forest simulator to project the development of Swiss forests until the mid‐21st century. The simulation results showed an ingrowth decrease and a shift in its species composition, marked by a significant reduction in Norway spruce Picea abies and concurrent increases in broadleaves. Nevertheless, the pace of this change towards climatically better adapted species composition is relatively slow and is likely to slow down even further as ingrowth declines in the future, in contrast to the fast‐changing climatic conditions. Hence, support through adaptive planting strategies should be tested in case ingrowth does not ensure the resilience of forests in the future. We conclude that since the regeneration of forests is becoming increasingly challenging, the current level at which ecosystem services are provided might not be ensured in the coming decades.

Carbon carrying capacity in primary forests shows potential for mitigation achieving the European Green Deal 2030 target

Carbon accounting in the land sector requires a reference level from which to calculate past losses of carbon and potential for gains using a stock-based target. Carbon carrying capacity represented by the carbon stock in primary forests is an ecologically-based reference level that allows estimation of the mitigation potential derived from protecting and restoring forests to increase their carbon stocks. Here we measured and collated tree inventory data at primary forest sites including from research studies, literature and forest inventories (7982 sites, 288,262 trees, 27 countries) across boreal, temperate, and subtropical Global Ecological Zones within Europe. We calculated total biomass carbon stock per hectare (above- and below-ground, dead biomass) and found it was 1.6 times larger on average than modelled global maps for primary forests and 2.3 times for all forests. Large trees (diameter greater than 60 cm) accounted for 50% of biomass and are important carbon reservoirs. Carbon stock foregone by harvesting of 12–52% demonstrated the mitigation potential. Estimated carbon gain by protecting, restoring and ongoing growth of existing forests equated to 309 megatons carbon dioxide equivalents per year, additional to, and higher than, the current forest sink, and comparable to the Green Deal 2030 target for carbon dioxide removals.

The largest European forest carbon sinks are in the Dinaric Alps old-growth forests: comparison of direct measurements and standardised approaches

BackgroundCarbon (C) sink and stock are among the most important ecosystem services provided by forests in climate change mitigation policies. In this context, old-growth forests constitute an essential reference point for the development of close-to-nature silviculture, including C management techniques. Despite their small extent in Europe, temperate old-growth forests are assumed to be among the most prominent in terms of biomass and C stored. However, monitoring and reporting of C stocks is still poorly understood. To better understand the C stock amount and distribution in temperate old-growth forests, we estimated the C stock of two old-growth stands in the Dinaric Alps applying different assessment methods, including direct and indirect approaches (e.g., field measurements and allometric equations vs. IPCC standard methods). This paper presents the quantification and the distribution of C across the five main forest C pools (i.e., aboveground, belowground, deadwood, litter and soil) in the study areas and the differences between the applied methods.ResultsWe report a very prominent C stock in both study areas (507 Mg C ha− 1), concentrated in a few large trees (36% of C in 5% of trees). Moreover, we found significant differences in C stock estimation between direct and indirect methods. Indeed, the latter tended to underestimate or overestimate depending on the pool considered.ConclusionsComparison of our results with previous studies and data collected in European forests highlights the prominence of temperate forests, among which the Dinaric Alps old-growth forests are the largest. These findings provide an important benchmark for the development of future approaches to the management of the European temperate forests. However, further and deeper research on C stock and fluxes in old-growth stands is of prime importance to understand the potential and limits of the climate mitigation role of forests.

Benchmarking Under- and Above-Canopy Laser Scanning Solutions for Deriving Stem Curve and Volume in Easy and Difficult Boreal Forest Conditions

The use of mobile laser scanning for mapping forests has scarcely been studied in difficult forest conditions. In this paper, we compare the accuracy of retrieving tree attributes, particularly diameter at breast height (DBH), stem curve, stem volume, and tree height, using six different laser scanning systems in a managed natural boreal forest. These compared systems operated both under the forest canopy on handheld and unmanned aerial vehicle (UAV) platforms and above the canopy from a helicopter. The complexity of the studied forest sites ranged from easy to difficult, and thus, this is the first study to compare the performance of several laser scanning systems for the direct measurement of stem curve in difficult forest conditions. To automatically detect tree stems and to calculate their attributes, we utilized our previously developed algorithm integrated with a novel bias compensation method to reduce the overestimation of stem diameter arising from finite laser beam divergence. The bias compensation method reduced the absolute value of the diameter bias by 55–99%. The most accurate laser scanning systems were equipped with a Velodyne VLP-16 sensor, which has a relatively low beam divergence, on a handheld or UAV platform. In easy plots, these systems found a root-mean-square error (RMSE) of below 10% for DBH and stem curve estimates and approximately 10% for stem volume. With the handheld system in difficult plots, the DBH and stem curve estimates had an RMSE under 10%, and the stem volume RMSE was below 20%. Even though bias compensation reduced the difference in bias and RMSE between laser scanners with high and low beam divergence, the RMSE remained higher for systems with a high beam divergence. The airborne laser scanner operating above the forest canopy provided tree attribute estimates close to the accuracy of the under-canopy laser scanners, but with a significantly lower completeness rate for stem detection, especially in difficult forest conditions.

Linking phosphorus fertility to soil microbial diversity and network complexity in citrus orchards: Implications for sustainable agriculture

Continuous input of chemical fertilizers causes soil acidification, land degradation, and water eutrophication, but its impact on soil microbial communities and co-occurrence patterns of microboes is unclear. In this study, we evaluated the impact of chemical fertilizer on bacterial community diversity and ecological network at 75 citrus sites in a watershed where chemical fertilizer is continuously applied. In addition, 25 natural forest sites adjacent to citrus sites were used as references to compare the potential effects of land conversion from natural forests to citrus orchards on soil bacterial diversity and microbial network. The results showed that the cultivation of citrus results in soil phosphorus (P) accumulation, with significantly higher available and mineral-bound phosphate contents than those found in soils of natural forests. Citrus soil average soil available P was 73.2 mg/kg, which was 20 times higher than that in forest soils. As the P content accumulates, soil bacterial Shannon index linearly decreases from 7.06 to 5.93 and is significantly lower than that of adjacent natural forest soils (7.13). Low P fertility soils have higher microbial network complexity and stability, containing more microbial communities and tighter relationships between microbes compared to higher P fertility soils. Soil P content and soil pH regulates soil microbial network complexity and stability. In addition, soil bacterial community structure in soils of natural forests is significantly different from that in citrus soils, and the bacterial community structure in high P soils is different from that in medium and low P soils. Soil P fertility reduces the relative abundance of dominant communities including Proteobacteria, Bacteroidetes, and Gemmatimonadetes, and also changes the relative abundance of some functional microbial communities, such as some phosphorus cycling microorganisms, including Acetobacteraceae and Beijerinckiaceae. In conclusion, soil phosphate accumulation severely alters soil bacterial community diversity, complexity, stability, and functionality. This could have negative impacts on soil functional stability and the sustainability of citrus orchards.

Global carbon balance of the forest: satellite-based L-VOD results over the last decade

Monitoring forest carbon (C) stocks is essential to better assess their role in the global carbon balance, and to better model and predict long-term trends and inter-annual variability in atmospheric CO2 concentrations. On a national scale, national forest inventories (NFIs) can provide estimates of forest carbon stocks, but these estimates are only available in certain countries, are limited by time lags due to periodic revisits, and cannot provide spatially continuous mapping of forests. In this context, remote sensing offers many advantages for monitoring above-ground biomass (AGB) on a global scale with good spatial (50–100 m) and temporal (annual) resolutions. Remote sensing has been used for several decades to monitor vegetation. However, traditional methods of monitoring AGB using optical or microwave sensors are affected by saturation effects for moderately or densely vegetated canopies, limiting their performance. Low-frequency passive microwave remote sensing is less affected by these saturation effects: saturation only occurs at AGB levels of around 400 t/ha at L-band (frequency of around 1.4 GHz). Despite its coarse spatial resolution of the order of 25 km × 25 km, this method based on the L-VOD (vegetation optical depth at L-band) index has recently established itself as an essential approach for monitoring annual variations in forest AGB on a continental scale. Thus, L-VOD has been applied to forest monitoring in many continents and biomes: in the tropics (especially in the Amazon and Congo basins), in boreal regions (Siberia, Canada), in Europe, China, Australia, etc. However, no reference study has yet been published to analyze L-VOD in detail in terms of capabilities, validation and results. This paper fills this gap by presenting the physical principles of L-VOD calculation, analyzing the performance of L-VOD for monitoring AGB and reviewing the main applications of L-VOD for tracking the carbon balance of global vegetation over the last decade (2010–2019).

Extension of the geographical range of the primary burrowing crayfish Cambarus strigosus Hobbs, 1981 (Decapoda: Astacidea: Cambaridae) in South Carolina

Abstract Knowledge of the geographical distribution for many primary burrowing crayfishes is often limited to information presented in species descriptions or field notes associated with epigean crayfish surveys. Cambarus strigosusHobbs, 1981, a rare primary burrowing crayfish, was collected as part of a survey of the Sumter National Forest, South Carolina (SC), USA. Prior to this discovery, C. strigosus appeared to be endemic to mid-reaches of the Broad River Drainage in Georgia (GA). We conducted additional field sampling in SC and GA and used mitochondrial DNA (mtDNA) to compare the relative genetic distance between individuals across all populations in an effort to determine the identity of the specimens collected. Genetic data indicated that the crayfish collected in SC was C. strigosus, with one shared haplotype between SC and GA populations. Our genetic results exhibited geographic structuring and indicated that SC populations have a specific haplotype unique to them, providing strong evidence that SC populations are not introduced. Two additional SC records of C. strigosus from 1983 housed in the US National Museum were examined and determined to be C. strigosus. With these records, we hypothesized that like in GA, the distribution of C. strigosus in SC is limited to riparian habitats associated with the Savannah River Drainage. While the range of this species has been extended, it is still limited to small portions of this drainage. Thus, further sampling to determine the true extent of C. strigosus distribution within SC along with conservation efforts are needed to protect this globally rare species.

Effects of Large-Scale Agricultural Land Investment on Local Communities Livelihoods: Evidence from Bambasi Woreda, Western Ethiopia

Most of the African countries including Ethiopia are often known by problem of large scale agricultural land investment effects on the local community where land is being transferred to investment. Even though several efforts made so far to solve the overall effects of large scale agricultural land investment situation, the challenge is still widespread problem in Ethiopia. Hence the study project's purpose was to find out how large agricultural investments in Bambasi Woreda, Western Ethiopia impact the livelihoods of the surrounding populations and examine the local communities' participation in the large scale agricultural investment. In order to attain these objectives, data were collected from 330 randomly selected households in four purposively selected kebeles of the district for both control groups and treatment groups. The sample size was chosen using a multistage stratified random sampling technique. Both qualitative and quantitative data gathering techniques and instruments were employed in the study. Besides, the instruments utilized to collect the data were observations, focus groups, interviews, household surveys, and document reviews. Data was analyzed using both descriptive statistics and econometric methods. The study shows that out of the total sampled respondents 30 of the treatment group and 13 percent of control group reveal that the project provided opportunity in terms of employment opportunity, technology transfer, utilization of agricultural inputs, changing the working culture of the community and productivity. The chie square value shows there is statistical significance among treated and control group on opportunity investment provided for the household and community. A binary logit regression model was used to describe how large-scale agriculture land investment affected the local community's standard of living. The findings indicated that only six variables were found to be significant out of the characteristics that were expected to influence local community employment in large-scale agricultural land investment projects. These includes household's educational accomplishment, size of HH, occupation of HH, Loss of useful land due to investment Project and technology transfer significantly and positively affected the employment opportunity in large scale agricultural investment projects, whereas the distance of a household's home from an investment project has a negative impact. Large-scale agricultural investments have a detrimental influence on household wealth accumulation and income, according to the estimation results of the average treatment effects on the treated. The management and implementation of land transfer for large-scale agricultural investment projects is inadequate, lack of openness, absence of community consultation, natural forest degradation, socio-economic and ecological effects must be carefully considered before transferring the land for large-scale agricultural investment.

Impact of Malayan Uniform System and Selective Management System of Logging on Soil Quality in Selected Logged-over Forest in Johor, Malaysia

Understanding the effects of various forest management systems, including logging practices, on soil properties is essential for implementing sustainable management strategies. In Malaysia, two types of forest management systems were commonly used: Malayan Uniform System (MUS) and Selective Management System (SMS) practices. However, their effects on soil quality remained elusive, especially after decades of recovery. To address this need, we selected three plots for the MUS and SMS in Johor, Malaysia, to assess soil properties in logged-over forest plots. All the plots were natural forest reserves. Soil properties analyzed include soil acidity, electrical conductivity, cation exchange capacity, selected nutrient contents, and soil compaction. Generally, the results of the study indicate that forests logged using the SMS exhibit superior soil quality compared to those logged using the MUS according to several key soil properties. Specifically, significantly higher cation exchange capacity, potassium content, calcium content, and magnesium content with lower soil compaction was observed in the SMS when compared to MUS plots. In short, the SMS enhances soil quality more effectively than the MUS, even with a shorter logging cycle. This is because the SMS does not harvest all trees and distributes the impact of harvesting more evenly over time, rather than concentrating it at a single time point. Ultimately, this highlights that the SMS can play a significant role in promoting sustainable forest management practices by preserving soil quality.

Remote sensing of vegetation and soil moisture content in Atlantic humid mountains with Sentinel-1 and 2 satellite sensor data

The satellite monitoring of vegetation moisture content (VMC) and soil moisture content (SMC) in Southern European Atlantic mountains remains poorly understood but is a fundamental tool to better manage landscape moisture dynamics under climate change. In the Atlantic humid mountains of Portugal, we investigated an empirical model incorporating satellite (Sentinel-1 radar, S1; Sentinel-2 optical, S2) and ancillary predictors (topography and vegetation cover type) to monitor VMC (%) and SMC (%). Predictors derived from the S1 (VV, HH and VV/HH) and S2 (NDVI and NDMI) are compared to field measurements of VMC (n = 48) and SMC (n = 48) obtained during the early, mid and end of summer. Linear regression modelling was applied to uncover the feasibility of a landscape model for VMC and SMC, the role of vegetation type models (i.e. native forest, grasslands and shrubland) to enhance predictive capacity and the seasonal variation in the relationships between satellite predictors and VMC and SMC. Results revealed a significant but weak relationship between VMC and predictors at landscape level (R2 = 0.30, RMSEcv = 69.9 %) with S2_NDMI and vegetation cover type being the only significant predictors. The relationship improves in vegetation type models for grasslands (R2 = 0.35, RMSEcv = 95.0 % with S2_NDVI) and shrublands conditions (R2 = 0.52, RMSEcv = 45.3 %). A model incorporating S2_NDVI and S1_VV explained 52 % of the variation in VMC in shrublands. The relationship between SMC and satellite predictors at the landscape level was also weak, with only the S2_NDMI and vegetation cover type exhibiting a significant relationship (R2 = 0.28, RMSEcv = 18.9 %). Vegetation type models found significant associations with SMC only in shrublands (R2 = 0.31, RMSEcv = 9.03 %) based on the S2_NDMI and S1_VV/VH ratio. The seasonal analysis revealed however that predictors associated to VMC and SMC may vary over the summer. The relationships with VMC were stronger in the early summer (R2 = 0.31, RMSEcv = 90.1 %; based on S2_NDMI) and mid (R2 = 0.37, RMSEcv = 70.8 %; based on S2_NDVI), butnon-significant in the end of summer. Similar pattern was found for SMC, where the link with predictors decreases from the early summer (R2 = 0.33, RMSEcv = 16.0 %; based on S1_VH) and mid summer (R2 = 0.30, RMSEcv = 17.8 %; based on S2_NDMI) to the end of summer (non-significant). Overall, the hypothesis of a universal landscape model for VMC and SMC was not fully supported. Vegetation type models showed promise, particularly for VMC in shrubland conditions. Sentinel optical and radar data were the most significant predictors in all models, despite the inclusion of ancillary predictors. S2_NDVI, S2_NDMI, S1_VV and S1_VV/VH ratio were the most relevant predictors for VMC and, to a lesser extent, SMC. Future research should quantify misregistration effects using plot vs. moving window values for the satellite predictors, consider meteorological control factors, and enhance sampling to overcome a main limitation of our study, small sample size.

Effects of Eucalyptus wood and leaf litter on saproxylic insects in the southeastern United States

Although Eucalyptus is widely planted outside its native range for timber and pulp production, the effects of these exotic plantations on biodiversity relative to native semi-natural forests or plantations of native tree species remain incompletely understood. Here, we compare the diversity of saproxylic beetles (Coleoptera) and true bugs (Hemiptera) between non-native Eucalyptus benthamii Maiden and Cambage (Camden white gum) and native Pinus taeda L. (loblolly pine) stands on the upper Coastal Plain of South Carolina, U.S.A. We sampled insects emerging from logs of both species placed in both stand types after 1, 2, 6, and 12 months in the field. Beetle and true bug richness and diversity were both significantly lower from eucalypt than from pine wood. Moreover, the two communities were compositionally distinct. Whereas pine supported many species of host-specific phloeoxylophagous beetles, most species collected from eucalypts were mycophagous or predatory taxa capable of utilizing a wide range of hosts. Species richness did not differ between logs placed in eucalypt vs. pine stands but Shannon’s diversity was significantly higher in the eucalypt stands, possibly due to greater sun exposure in the latter. Contrary to a previous study, we found no support for the idea that eucalypt litter reduces the diversity of saproxylic insects. Our findings add to the growing body of evidence that non-native plantations are less favorable to biodiversity than those consisting of native tree species.

Effect of invasive species on forest composition in tropical dry forest: a case study of invasion by Gliricidia sepium

Ecological concerns caused by biological invasion have been considered an inevitable threat to global sustainability. The superior competitive ability of invasive plant species (IPS) has an impact on vegetation composition and loss of native flora. Recognising IPS at an early stage would significantly contribute to controlling invasive plants, protecting biodiversity and formulating appropriate strategies. Most of the studies available on invasive plants are descriptive and largely confined to non-woody species. The present study focused on the alien Gliricidia sepium, a tree species, to determine the invasive potential of its distribution in tropical dry deciduous forests of Central India. Forty square plots (25 × 25 m) were laid out at each uninvaded and invaded forest to enumerate phytosociological attributes to determine the impact of G. sepium on vegetation composition and community structure. Higher density (37.2 individuals ha−1), basal area (6.32 m2 ha−1) and importance value index (95.8) contributed by G. sepium clearly showed the suppression of seedlings, saplings and trees of native forest species at the invaded sites in terms of species richness, cover and other attributes as compared to at the uninvaded sites. Further, other invasive attributes such as higher seed production, dieback phenomenon, higher coppicing power and higher growth rate as observed during the study clearly affirmed the early speculation that the species might be invasive. The species has a strong potential to spread vigorously and may gradually become invasive throughout the country as already reported from various parts of India. In the present study area, G. sepium was introduced due to restoration and plantation programmes and our findings indicate its negative impact on the native vegetation. Thus, we strongly recommend the avoidance of this species for both plantation and restoration programmes, especially for Indian forests. The study helps in early recognition and rapid monitoring of G. sepium to control its spread throughout the country.

Land-use homogenization reduces the occurrence and diversity of frugivorous birds in a tropical biodiversity hotspot.

Understanding how human-modified landscapes maintain biodiversity and provide ecosystem services is crucial for establishing conservation practices. Given that responses to land-use are species-specific, it is crucial to understand how land-use changes may shape patterns of species diversity and persistence in human-modified landscapes. Here, we used a comprehensive data set on bird distribution from the Brazilian Atlantic Forest to understand how species richness and individual occurrences of frugivorous bird species responded to land-use spatial predictors and, subsequently, assess how ecological traits and phylogeny modulated these responses. Using Bayesian hierarchical modeling, we reveal that the richness of frugivorous birds was positively associated with the amount of native forest and negatively with both agriculture and pasture amount at the landscape scale. Conversely, the effect of these predictors on species occurrence and ecological traits was highly variable and presented a weak phylogenetic signal. Furthermore, land-use homogenization (i.e., the conversion of forest to pasture or agriculture) led to pervasive consequences for forest-dependent bird species, whereas several generalist species thrived in deforested areas, replacing those sensitive to habitat disturbances.

Modeling structural traits of Aleppo pine (Pinus halepensis Mill.) forests with low-density LiDAR

ABSTRACT Mediterranean forests of Aleppo pine (Pinus halepensis Mill.) have a crucial role in climate change, as they are extremely adaptive and provide valuable timber or carbon stocks. However, greater detail quantifying those attributes is needed: although National Forest Inventories are acceptable, continuous cover maps are normally lacking. Here, we use the public Spanish low-density LiDAR flights to model above-ground biomass, volume, tree density, basal area and dominant height of naturally regenerated Mediterranean Aleppo pine forests, comparing individual-tree detection and area-based approach. We found R2 and RRMSE among 0.51–0.66 and 40–34% for above-ground biomass, 0.54–0.70 and 34–28% for volume, 0.23–0.45 and 33–28% for tree density, 0.48–0.62 and 32–27% for basal area, and 0.70–0.69 and 11–11% for dominant height. In all cases but dominant height, the area-based approach outperformed the individual-tree detection. Neither time difference between LiDAR flight and ground measurement or past land use affected the area-based approach models, yet the latter had a strong effect on observed productivity. The different definitions of dominant height were equivalent and did not influence the dominant height models. We believe these models, and their corresponding maps, will be a great asset for policymakers and different stakeholders for Aleppo pine forests throughout the Mediterranean basin.

Intensive Citrus Cultivation Suppresses Soil Phosphorus Cycling Microbial Activity

Soil microbes are key drivers in regulating the phosphorus cycle. Elucidating the microbial mineralization process of soil phosphorus-solubilizing bacteria is of great significance for improving nutrient uptake and yield of crops. This study investigated the mechanism by which citrus cultivation affects the soil microbial acquisition strategy for phosphorus by measuring the abundance of the phoD gene, microbial community diversity and structure, and soil phosphorus fractions in the soils of citrus orchards and adjacent natural forests. The results showed that citrus cultivation could lead to a decrease in soil pH and an accumulation of available phosphorus in the soil, with a content as high as 112 mg·kg-1, which was significantly higher than that of natural forests (3.7 mg·kg-1). Citrus cultivation also affected the soil phosphorus fractions, with citrus soil having higher levels of soluble phosphorus (CaCl2-P), citrate-extractable phosphorus (Citrate-P), and mineral-bound phosphorus (HCl-P). The phosphorus fractions of natural forest soils were significantly lower than those of citrus soils, whereas the phoD gene abundance and alkaline phosphatase activity were significantly higher in natural forest soils than in citrus soils. High-throughput sequencing results showed that the Shannon diversity index of phosphate-solubilizing bacteria in citrus soils was 4.61, which was significantly lower than that of natural forests (5.35). The microbial community structure in natural forests was also different from that of citrus soils. In addition, the microbial community composition of phosphate-solubilizing bacteria in citrus soils was also different from that of natural forests, with the relative abundance of Proteobacteria being lower in natural forest soils than in citrus soils. Therefore, citrus cultivation led to a shift of soil microbial acquisition strategy for phosphorus, with external phosphorus addition being the main strategy in citrus soils, whereas microbial mineralization of organic phosphorus was the main strategy in natural forest soils to meet their growth requirements.

Climatic and disturbance impacts on temperate rainforest development since ∼18 ka in central-west Isla Grande de Chiloé (42.7°S)

Understanding the role of disturbance regimes on terrestrial ecosystems is often compounded by the paucity of time series sufficiently long and detailed to capture triggering events and the sequence of changes in species composition, community structure and dynamics along a time continuum until the present. Adding complexity to this problem, disturbance regimes and the distribution/competitive interactions of participating species may vary in time with shifts in mean climatic conditions and variability. Here we present results from sediment cores we collected from small closed-basin lakes near the Pacific coast of central Isla Grande de Chiloé, a sector with the lowest seasonality and recurrence of explosive volcanic events in Northwestern Patagonia (NWP). Our aim is examining vegetation development since the last glaciation and exploring potential climatic and disturbance impacts. We found rapid establishment of closed-canopy rainforests, which have persisted with little variation in terms of physiognomy until the present. Significant changes in species composition, structure, dynamics, and rates of change are evident over the last ∼18,000 years, along with fire maxima at ∼16.7 ka, ∼12.7 ka, between ∼11.7-9 ka, from ∼2 ka to the present, and minima in the interim. Fires precede major increases in disturbance favored taxa, which correspond in timing with fire activity maxima at NWP scale. The most recent ∼2000 years coincide with the highest number and ubiquity of human occupations at central-west and NWP scale, raising the possibility that fires were driven by human activities near our study sites. We detect a conspicuous increase in disturbance-favored trees ∼150 years after deposition of the Puma Verde Tephra (∼8.3 ka) and interpret their subsequent maintenance by frequent blowdown events after ∼7.5 ka in exposed sectors of the Coastal Range. We posit that enhanced storminess driven by stronger Southern Westerly Winds since ∼7.5 ka has favored early successional opportunistic trees in detriment of old-growth forests dominated by shade-tolerant species, generating a spatial mosaic of forest patches or gaps in different stages of recovery.

Dynamic Height Growth Equations and Site Index-Based Biomass Models for Young Native Species Afforestations in Spain

The expansion of forested areas through afforestation and reforestation is widely recognized as a highly effective natural solution for mitigating climate change. Accurately assessing the potential carbon uptake capacity of newly afforested areas requires modelling tools to estimate biomass stocks, including site index curves and biomass models. Given the unique conditions in terms of tree size, uniform spacing, and tree allometries observed in young afforestations compared to natural stands, specific tools are necessary. In Spain, over 800,000 ha has been afforested with native forest species since 1992, but specific modelling tools for these plantations are lacking. Using data from 370 stem analyses collected across an extensive network of plots in young afforestations, we developed dynamic height growth and site index models for the main native species (five pines and five oaks) commonly used in afforestation in Spain. We compared various nonlinear models, such as ADA (algebraic difference approach) and GADA (generalized algebraic difference approach) expansions. The developed site index models were then used to predict the total biomass stored in the afforestation. Our results underscore the necessity for specific site index models tailored to afforestations, as well as the potential of the established site index in predicting biomass and carbon fixation capacity in these young forests.