Low Tree Density Research Articles

Anthropological impacts determine the soil fungal distribution of Mediterranean oak stands

Quercus pyrenaica-dominated forests are very widely distributed in Mediterranean ecosystems. Traditional forest use, such as coppicing to obtain firewood or livestock grazing under silvopastoral systems, and the current social abandonment of the rural environment have given rise to forest structures of different ages and at different stages of development. Thus, on the one hand, there are large areas of Q. pyrenaica coppice systems that produce a large amount of biomass that have a very high risk of driving forest fires. On the other hand, dehesas, which have very low tree density and are composed of very old trees that are susceptible to different types of environmental stress and have serious regeneration problems and a weak phytosanitary status. In addition, previous studies have suggested that the production of economically valuable edible mushrooms is negatively impacted by silvicultural management. To determine the effects of land management on these ecosystems, we analyzed the soil fungal communities associated with coppice stands (i.e., high-density coppice), high forest stands (i.e., low-density coppice that received silvicultural management 15 years ago to reduce the risk of wildfire), and old stands (i.e., dehesas) to assess their potential ecological roles in their conservation and the diversity of edible mushrooms. We also analyzed the edaphic variables associated with these systems (carbon, pH and the carbon/nitrogen ratio) to understand the dynamics of these fungal communities. We observed two distinguishable communities: pathogen-, parasite-, and endophyte-dominated dehesas and saprotroph- and ectomycorrhizal (ECM)-dominated coppice stands, with a mixed composition in high forest stands. ECM fungi correlated with stand age and structure, showing higher richness levels in high forest stands, particularly ECM fungi with short hyphal exploration type. Finally, the influence of stand age and structure due to land management significantly affected the variety of some edible genera, such as Boletus, Tuber or Terfezia.

Forest canopy height variation in relation to topography and forest types in central Japan with LiDAR

Spatial variations of maximum canopy height are key indicators of many ecosystem processes such as above-ground biomass and productivity. With rapid advances in remote sensing techniques, such as airborne laser scanning (ALS), we can now measure canopy height, tree density, and canopy gaps from local to large scales. But these data are yet to be fully exploited for a better understanding of canopy height variations in relation to fine topographical heterogeneities and neighborhood conditions at the landscape level (>100 km2). In this study, we analyzed ALS data to extract spatial variations in canopy height and topographic features for a forest-dominated area of 230 km2 in Kyoto, Japan. The study area spanned an elevational range from 70 to 1000 m a.s.l and included four forest types, i.e., cedar or cypress plantations (PL), natural evergreen needle leaf forests (ENF), deciduous broadleaved forests (DBF), and evergreen broadleaved forests (EBF). PL had a greater mean canopy height than ENF, both of which were taller than DBF and EBF. Canopy height exhibited a hump-shaped relationship with elevation with the peak value at mid-altitude (461–560 m) in all forest types. Canopy height was greater by 5-10 m in the concave valleys than on the convex slopes and ridges. Trees were taller at greater distances from forest gaps and with lower tree density in the neighborhood. Local tree density, distance from the nearest canopy gap, and topographic curvatures were the most significant predictors in the best-fitted model (Random Forest: R2 = 0.41). The analytical approach developed in this study provides a useful tool for planning proper land use and maintaining a healthy forest stand at the regional scale.

Authority and consensus in group decision making with fallible individuals

This paper compares the performance, in terms of expected opportunity loss of mistakes, of group decision making with fallible members, under different organization structures. These structures result from combining the decision mechanisms of authority and consensus with the communication networks of star, tree, and full network. Simulation results from Agent Based Modeling show that the authority (consensus) is preferred when the time to reach a group decision matters (not matters), and in organizational environments of high (low) risk and high (low) prospects of growth. Additionally, the results of the paper recommend that organizations that want to migrate from authority to consensus decision making, as defined here, should switch from the low-density tree like connecting network, common in hierarchical structures, to a high-density full network.

Untargeted metabolomics in primary murine bone marrow stromal cells reveals distinct profile throughout osteoblast differentiation

IntroductionSkeletal homeostasis is an exquisitely regulated process most directly influenced by bone resorbing osteoclasts, bone forming osteoblasts, and the mechano-sensing osteocytes. These cells work together to constantly remodel bone as a mechanism to prevent from skeletal fragility. As such, when an individual experiences a disconnect in these tightly coupled processes, fracture incidence increases, such as during ageing, gonadal hormone deficiency, weightlessness, and diabetes. While therapeutic options have significantly aided in the treatment of low bone mineral density (BMD) or osteoporosis, limited options remain for anabolic or bone forming agents. Therefore, it is of interest to continue to understand how osteoblasts regulate their metabolism to support the energy expensive process of bone formation.ObjectiveThe current project sought to rigorously characterize the distinct metabolic processes and intracellular metabolite profiles in stromal cells throughout osteoblast differentiation using untargeted metabolomics.MethodsPrimary, murine bone marrow stromal cells (BMSCs) were characterized throughout osteoblast differentiation using standard staining protocols, Seahorse XFe metabolic flux analyses, and untargeted metabolomics.ResultsWe demonstrate here that the metabolic footprint of stromal cells undergoing osteoblast differentiation are distinct, and while oxidative phosphorylation drives adenosine triphosphate (ATP) generation early in the differentiation process, mature osteoblasts depend on glycolysis. Importantly, the intracellular metabolite profile supports these findings while also suggesting additional pathways critical for proper osteoblast function.ConclusionThese data are the first of their kind to characterize these metabolites in conjunction with the bioenergetic profile in primary, murine stromal cells throughout osteoblast differentiation and provide provocative targets for future investigation.

Denosumab versus zoledronate for the treatment of low bone mineral density in male HIV-infected patients

IntroductionWe aimed to compare annual changes in the bone mineral density (BMD) at the lumbar spine (LS) and the femoral neck (FN) in males with HIV-associated osteoporosis treated with either zoledronate (ZOL) or denosumab (Dmab). MethodsIn this open label, 12-month, prospective, multicenter, cohort study, 23 male people living with HIV (PLWH) under antiretroviral therapy (ART) with low BMD were administered either a single iv infusion of ZOL 5 mg (n = 10) or Dmab 60 mg sc injections biannually (n = 13). Fourteen age-matched male PLWH with normal BMD served as controls. BMD was measured at baseline and at 12 months. ResultsLS-BMD increased within both treatment groups at 12 months (ZOL 5.43% ± 3.60%, p = 0.001; Dmab 5.76% ± 3.44%, p < 0.005) and decreased in controls (−2.58% ± 4.12, p = 0.04). FN-BMD increased in both treatment groups at 12 months (ZOL 7.23% ± 5.46%, p = 0.003; Dmab 3.01% ± 2.46%, p < 0.005), and remained unchanged in controls (1.22% ± 2.09, p = 0.06). LS-BMD changes did not differ between the two treatment groups, but FN-BMD changes were more prominent in the ZOL group (p < 0.05). None of our study cohort sustained new fragility fractures during the 12-month study period, and no case of acute phase response was recorded in the ZOL group. ConclusionsIn male PLWH under ART requiring osteoporosis treatment both ZOL and Dmab are efficient and well tolerated therapeutic options achieving BMD increases at least for the first year of treatment.

Understanding Grass Invasion, Fire Severity, and Acacia koa Regeneration for Forest Restoration in Hawaiʻi Volcanoes National Park

With invasive grasses increasing wildfire occurrence worldwide, a better understanding of the relationships between native plants, fire, and invasive grass is needed to help restoration plans facilitate ecosystem resilience. Invasive grasses are particularly problematic for altering fire regimes in the tropics, yet in Hawaiʻi, restoration sites are often planted with monocultures of the native tree Acacia koa, which can promote grass growth via nitrogen fixation. This, combined with the difficulty of estimating pre-fire grass cover under thick canopies, complicates attempts to restore Hawaiian ecosystems. We studied the 2018 Keauhou Ranch Fire in Hawaiʻi to investigate three questions: (1) at what level of precision can pre-fire grass cover be accurately estimated from oblique aerial photos? (2) how are post-fire A. koa regeneration densities affected by fire severity? and (3) how are post-fire A. koa regeneration densities affected by pre-fire grass cover and its interaction with fire severity? We collected burn severity and post-fire regeneration data from 30 transects stratified across mid-elevation woodland, montane woodland, and montane shrubland communities. We evaluated visual estimates of pre-fire grass cover from oblique aerial imagery with quantitative in situ data from 60 unburned transects of the same cover types. Pre-fire estimates of grass cover categories were 67% accurate in montane woodland (n = 9) and 100% accurate in montane shrubland (n = 11), but only 20% accurate in mid-elevation woodland (n = 10). In montane woodlands with low pre-fire tree densities, A. koa regeneration densities were higher with increased fire severity, but this trend reversed when pre-fire tree densities were high. We detected no effect of pre-fire grass cover, nor its interaction with fire severity, on A. koa regeneration density. This indicates that restoration through the planting of A. koa may be successful in promoting fire-resilient A. koa forest, although there are potential issues to consider regarding the effects that A. koa’s grass promotion may have on other species within the ecosystem.

Effects of stocking density on growth and skin quality of grower Nile crocodiles (Crocodylus niloticus)

Intensive Nile crocodile (Crocodylus niloticus) farming operates with considerable variation in housing and stocking density. In this study, current commercial stocking densities for crocodilians were investigated using 261 grower-phase crocodiles (15 months old, average total body length 94.5 cm, and average weight 2.7 kg). Low (2.60 m2 per crocodile), medium (1.24 m2 per crocodile), and high (0.41 m2 per crocodile) stocking densities were tested. Growth, morphometric measures, Fulton’s condition scores and skin qualities were assessed over a six-month (May - November 2017) period. High stocking density had no adverse effects on the growth of grower Nile crocodiles. Crocodiles stocked at medium and high densities outperformed those that were stocked at low density in Fulton’s body condition scores, change in body condition from the start to the end of the trial, and feed conversion efficiencies. However, the high and, to a lesser extent, the medium stocking densities resulted in lower skin quality scores compared with those in the low-density treatment because of teeth marks from more aggressive behaviour. The results indicated that the medium pen density treatment is closer to the ideal than either the high or low stocking density groups. Stocking densities that provide 0.41 m2 per crocodile or less should be avoided because of lower skin quality scores, which weigh more heavily than growth and feed efficiency responses in the financial viability of commercial crocodile farming in typical South African production systems.

High aboveground carbon stock of African tropical montane forests.

Tropical forests store 40-50per cent of terrestrial vegetation carbon1. However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests2. Owing to climatic and soil changes with increasing elevation3, AGC stocks are lower in tropical montane forests compared with lowland forests2. Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4megagrams of carbon per hectare (95% confidence interval 137.1-164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network4 and about 70per cent and 32per cent higher than averages from plot networks in montane2,5,6 and lowland7 forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa8. We find that the low stem density and high abundance of large trees of African lowland forests4 is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to helpto guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse9,10 and carbon-rich ecosystems.

Do Javan gibbons (Hylobates moloch) use fruiting synchrony as a foraging strategy?

Tropical rainforests are characterized by a high diversity of plant species. Each plant species presents with differential phenological patterns in fruit production. In some species, all individual trees produce fruit simultaneously within clustered periods; whereas in others, each individual tree fruits at irregular time intervals. By observing this pattern, some primate species use the presence of fruits in one tree as a cue to find fruit in other trees of the same synchronously fruiting tree species. Here, we investigated whether the highly frugivorous Javan gibbons (Hylobates moloch) in Gunung Halimun-Salak National Park in Indonesia have knowledge of synchronous characteristics of fruiting trees and whether they can further distinguish fruit species with different synchrony levels, that is, tree species with highly synchronous fruiting patterns versus tree species with less synchronous fruiting patterns. Across 12 months we collected biweekly phenological data on 250 trees from 10 fruit species and observed Javan gibbons' visits to those species. We found that a fruit discovery in the beginning of fruiting seasons triggered gibbons to visit trees of the same fruit species. However, gibbons' visit rates did not differ between highly synchronous and asynchronous species. Our results suggest that Javan gibbons have knowledge of synchronous characteristics of fruiting trees in general, but they do not differentiate highly synchronous versus asynchronous fruit species. We speculate that Javan gibbons, who live in relatively small ranges with very low tree density of preferred fruit species, are likely able to track and remember fruiting states of individual trees without needing to distinguish fruit species with different synchrony levels. Moreover, gibbons may make little benefit of distinguishing highly synchronous versus asynchronous fruit species, probably due to gibbons' heavy use of asynchronous figs. Our study provides an insight into how gibbon's foraging strategies may have been shaped in response to their ecological environment.

Forest status under fire regime: A case study from Upper Kosi watershed in Almora district, Uttarakhand, India

The ever-increasing incidents of forest fire in the Himalayan region cause a threat to flora, fauna, livelihoods, and the environment. The Chir pine (Pinus roxburghii) forests are especially susceptible to forest fires due to their resin-rich leaf litter. This study investigates forest structure, regeneration, biomass-carbon dynamics, leaf-litter, and soil physio-chemical properties in two Chir pine stands in the Upper-Kosi watershed, Almora district, Uttarakhand. Both stands exhibited lower tree density, good regeneration potential, biomass-carbon, and litter mass due to intense biotic pressure. Although, stand 2 has been subjected to oak-plantation in recent years and showed an improving status. The study revealed that Chir pine stands are subjected to fodder collection, grazing, and resin extraction, while its litter is susceptible to fire which leads to the release of a significant flux of biogenic carbon back to the atmosphere. This highlights the need to manage Chir pine stands on a priority basis. Recommendations for improving Chir pine stands with the support of village panchayats (i.e. Van panchayats) have been given.

Natural factors but not anthropogenic factors affect native and non–native mammal distribution in a Brazilian National Park

Protected areas, designed for biodiversity conservation, are currently affected by invasive species as most of them have documented biological invasions. This study aimed to test whether non–native mammal species richness influences the local distribution of native mammals and how distance from human settlement, elevation and vegetation characteristics influence native and non–native mammal richness in a national park in Brazil.We recorded 20 mammal species in the park, 17 native species and three non–native species. Native mammal richness was higher at intermediate elevations and in forests with lower tree densities and tree basal area. Non–native mammal richness was greater at higher elevations and in forests with low tree densities. Non–native mammals did not influence native mammal presence. In conclusion, the distribution of both native and non–native mammal species was affected by elevation and vegetation but not by distance from human settlements or non–native mammal presence.

Partitioning of Environmental and Taxonomic Controls on Brazilian Foliar Content of Carbon and Nitrogen and Stable Isotopes

The Neotropics harbor some of the most diversified woody species in the world, and to understand the nutrient dynamics in these ecosystems, it is crucial to understand the role of plant taxonomy. In addition, biological nitrogen (N) fixation (BNF) in the tropics is one of the key processes affecting the global N cycle. Our objective was to (i) investigate the role of taxonomy and sampling site as predictors of foliar carbon (C) and N concentration and its stable isotopes (i.e., δ13C and δ15N); (ii) assess differences in foliar N, C:N ratio, and δ15N among three functional groups: species of N2-fixers and non-fixers of the Fabaceae family, as well as non-Fabaceae species; and (iii) examine the effect of wood density on tree foliar properties. We hypothesized that Fabaceae specimens in symbiosis with N2-fixers would possess a higher foliar N than non-fixing plants, including those of the Fabaceae family, as well as high-density trees would have higher foliar C and C:N ratio relative to low-density trees, where the latter invest in nutrients instead of structural C. We used a data set composed of 3,668 specimens sampled in three main biomes of Brazil: Amazon, Atlantic Forest, and Cerrado. The partitioning of variance had a higher influence of taxonomy on leaf C, N, and C:N ratio. Conversely, foliar δ13C and δ15N were environmentally constrained. While family was the most important taxonomy level for C, N, and C:N ratio, species played a major role for δ13C and δ15N. Foliar N followed the pattern fixers &amp;gt; non-fixers &amp;gt; non-Fabaceae, while C:N ratio had an opposite trend. In addition, foliar C was correlated with wood density, where high-density &amp;gt; medium-density and low-density woods. The large variability of δ15N was observed among Fabaceae species, demonstrates the complexity of using δ15N as an indicator of BNF. The higher foliar N of Fabaceae non-fixers than non-Fabaceae specimens support the hypothesis that an N-demanding lifestyle is an inherent pattern in this family. Lastly, although observed in some studies, the prediction of foliar properties using wood density is challenging, and future research on this topic is needed.

Parental selection for growth and early-life low stocking density increase the female-to-male ratio in European sea bass

In European sea bass (Dicentrarchus labrax), as in many other fish species, temperature is known to influence the sex of individuals, with more males produced at relatively high temperatures. It is however unclear to what extent growth or stress are involved in such a process, since temperature is known to influence both growth rate and cortisol production. Here, we designed an experiment aiming at reducing stress and affecting early growth rate. We exposed larvae and juveniles originating from both captive and wild parents to three different treatments: low stocking density, food supplemented with tryptophan and a control. Low stocking density and tryptophan treatment respectively increased and decreased early growth rate. Each treatment influenced the stress response depending on the developmental stage, although no clear pattern regarding the whole-body cortisol concentration was found. During sex differentiation, fish in the low-density treatment exhibited lower expression of gr1, gr2, mr, and crf in the hypothalamus when compared to the control group. Fish fed tryptophan displayed lower crf in the hypothalamus and higher level of serotonin in the telencephalon compared to controls. Overall, fish kept at low density produced significantly more females than both control and fish fed tryptophan. Parents that have been selected for growth for three generations also produced significantly more females than parents of wild origin. Our findings did not allow to detect a clear effect of stress at the group level and rather point out a key role of early sexually dimorphic growth rate in sex determination.

Unsupervised algorithms to detect single trees in a mixed-species and multilayered Mediterranean forest using LiDAR data

Accurate measurement of forest growing stock is a prerequisite for implementing climate-smart forestry strategies. This study deals with the use of airborne laser scanning data to assess carbon stock at the tree level. It aims to demonstrate that the combined use of two unsupervised techniques will improve the accuracy of estimation supporting sustainable forest management. Based on the heterogeneity of tree height and point cloud density, we classified 31 forest stands into four complexity categories. The point cloud of each stand was further divided into three horizontal layers, improving the accuracy of tree detection at tree level for which we calculated volume and carbon stock. The average accuracy of tree detection was 0.48. The accuracy was higher for forest stands with lower tree density and higher frequency of large trees, as well as a dense point cloud (0.65). The prediction of carbon stock was higher with a bias ranging from –0.3% to 1.5% and a root mean square error ranging from 0.14% to 1.48%.

NATURAL REGENERATION AND ARTIFICIAL THINNING FOR EARLY FOREST RESTORATION ON A PERMANENTLY CLOSED SKI SLOPE

: In recent decades, numerous ski resorts in Japan have had to close due to financial difficulties. Forest restoration on these abandoned ski slopes is necessary for landscape management and to prevent avalanches and landslides. However, forest restoration activities are hindered by the scarcity of nutrients due to topsoil removal at the time of ski slope construction. In this study, the effect of thinning on alleviating competition for soil nutrients was examined. The study site was located on Mt. Tateshina in central Japan. The study site's ski slope was closed permanently in 1997, and the first natural regeneration of larch occurred in 1998. Chubu Regional Forest Office performed artificial thinning in 2003. Two thinned, nine un-thinned quadrat plots in 2016 were established and measured the total height and diameter at all living and dead trees' breast height. Tree-ring analysis of nine sample trees in each of the un-thinned and thinned plots at 1 m height intervals was performed to clarify tree growth. The un-thinned field had a high tree density, small tree size, and numerous dead trees, suggesting the existence of severe competition. Conversely, the thinned plot was characterized by a lower tree density, large tree size, and fewer dead trees. According to the tree-ring analysis, artificial thinning improved the survival rate and smaller trees' growth rate. It was concluded that the artificial thinning of natural forests on ski slopes is useful for accelerating tree growth and early forest development.

A functional variant of the long noncoding RNA AL110200 is associated with the risk of ischaemic stroke recurrence.

This study aimed to test the hypothesis that long noncoding RNA (lncRNA) AL110200 exerts a proinflammatory effect on atherosclerosis and that the variant rs901681 contributes to ischaemic stroke incidence and recurrence. The expression of AL110200 was analyzed in THP-1 cells treated with oxidized low-density lipoprotein and in human peripheral blood in a coronary heart disease and control population to determine the role of AL110200 in atherosclerosis. The effect of AL110200 on cell adhesion and invasion was tested. The plasma level of leukotriene B4 and rs901681 genotype distribution were assessed in 220 participants. In 1004 ischaemic stroke patients and 1434 controls, the association between rs901681 and stroke incidence was analyzed by logistic regression, and the association of rs901681 and stroke prognosis was analyzed using Kaplan-Meier analysis and the Cox proportional hazards model. Increased expression of AL110200 was observed in THP-1 cells under oxidized low-density lipoprotein treatment. Knockdown of AL110200 reduced the adhesive and invasive ability of THP-1 cells. AL110200 expression in peripheral blood was significantly higher in the coronary heart disease group than in the controls. The GG genotype of rs901681 is associated with reduced plasma leukotriene B4. In the ischaemic stroke population, rs901681 was not associated with ischaemic stroke incidence (p=0.686). Patients carrying rs901681 GG had a lower risk for stroke recurrence at age ≥60years (p=0.001), cardiovascular stroke death (p=0.022) and all-cause mortality (p=0.034) in the all-age group. AL110200 might exert a proinflammatory effect on atherosclerosis, and the variant rs901681 might be a strong predictor of stroke prognosis in ischaemic stroke patients.

Effects of low-density pulsed ultrasound treatment on transforming growth factor-beta, collagen level, histology, biomechanics, and function in repaired rat tendons.

Objectives The aim of this study is to compare the effects of low-density pulsed ultrasound (LIPUS) treatment on growth factors/collagen production, histological, biomechanical, and function of rats with Achilles tendon injury. Materials and methods A total of 44 Wistar Albino rats were used in the study between April 2017 and June 2018. The rats were randomized to two treatment groups. Group 1 (n=6) received LIPUS treatment (0.3 Watt/cm2; 1 MHz, 1:5 pulse mode) and Group 2 (n=6)received sham ultrasound (US) treatment following Achilles tendon surgery. Transforming growth factor-beta 1 (TGF-β1) and collagen gene expression levels were evaluated using polymerase chain reaction. The histological evaluation was performed with the Bonar scoring system. The tensile strength was measured by biomechanical testing and the function was evaluated with the Achilles Functional Index (AFI). Results Although TGF-β1 expression and tensile strength evaluation showed a tendency to improve in favor of the LIPUS group, no statistically significant difference was found (p=0.065 and p=0.053, respectively). The COL3 gene expression in the LIPUS group and the COL1 expression in the sham US group were significantly higher. Bonar scores and AFI scores showed a statistically significant improvement in the LIPUS group, compared to the sham US group. Conclusion Our study results show that LIPUS yields positive effects on tendon histology and functional status in repaired Achilles tendon in rats.

Assessment of the external contribution to Olea pollen levels in southeastern Spain

The province of Alicante (southeastern Spain) has a low density of olive trees; however, a substantial increase in the number of patients with allergic sensitization to Olea has been observed in recent years. The present work seeks to identify and quantify the transport of Olea pollen from other source regions, defining a new parameter called External Pollen Index (EPI). The second objective of the study was to determine Olea pollen exposure levels in Alicante city using a new method based on statistical percentiles and linear regression analysis. For these purposes, a study of daily and 2-hour average concentrations of Olea pollen combined with cluster analysis of 2-hour back-trajectories was carried out during the pollination period of 2010–2015.The annual levels of olive pollen recorded in Alicante showed a significant contribution from the Western Iberian Peninsula. Thus, the EPI is defined as the sum of the contributions of pollen transported by air masses from southwestern and northwestern Spain. The good linear correlation beetween the EPI and the APIn (R2 = 0.818; p-value 0.013) suggests that the total contribution of pollen from western regions may be a good predictor of the annual concentration of Olea pollen registered in Alicante. It has been estimated that, in the absence of external contributions, the Olea pollen concentration at the study area would be around 1300 pollen grains⋅m−3. Olea pollen exposure levels determined in Alicante were: Low (<20 pollen grains⋅m−3), Moderate (20–50 pollen grains⋅m−3), High (51–100 pollen grains⋅m−3) and Very High (>100 pollen grains⋅m−3). High and very high exposure levels were associated with northwestern and southwestern contributions, respectively. Future research should consider external contributions (EPI) in prediction models in order to get a better estimation of pollen levels and, consequently, improve the information provided to the allergic population.

The effects of outdoor access and stocking density on the performance of broilers reared under tropical conditions

ABSTRACT 1. The effects of housing system and stocking density on growth performance and carcase yield of a commercial strain of broiler chickens reared under tropical environmental conditions may differ from temperate conditions. 2. In two experimental periods, carried out during two contrasting seasons of the year (winter and summer), 240 Cobb 500 male chickens were randomly assigned in groups of 60 to 1 of 4 treatments, with 6 replicates in each, low stocking density with outdoor access (LO, 5 birds/m2); high stocking density with outdoor access (HO, 10 birds/m2); low stocking density indoors (LI, 5 birds/m2); high stocking density indoors (HI, 10 birds/m2). From 21 to 42 d old, body weight (BW) and feed intake (FI) were weekly recorded. Mortality was measured daily and carcase weight at slaughter. Indoor and outdoor temperature and relative humidity were measured daily. 3. There was a tendency for chickens raised in the outdoor access to be heavier than those raised in the indoor treatments. Chickens raised in the low-density treatments in the first experimental period were significantly heavier, gained more weight and had lower value for feed conversion ratio (FCR) than those reared at high density. In the second experimental period mortality significantly increased on week 4 due to heat stress. Birds raised with outdoor access had an increased carcase yield compared to those raised exclusively indoors. 4. In conclusion, low stocking density in combination with low environmental temperatures had enhancing effects on BW, BWG, FI and FCR, and the effects of housing system depended on stocking density. Low stocking density and outdoor access had positive effects on carcase yield.

TREE STRATIFICATION BASED ON ERUPTION DAMAGE LEVEL IN MOUNT MERAPI NATIONAL PARK YOGYAKARTA INDONESIA

Mount Merapi’s eruption has caused damage to the forests in the Mount Merapi National Park (MMNP). Nine years after the eruption, the vertical structure of vegetation can illustrate the progress of succession. This study aimed to analyze the tree composition and stratification in different forest damage levels after the 2010 Merapi eruption. The study was conducted in March 2019 at three stations, namely station A (heavy damage area), station B (moderate damage area), and station C (minor damage area). Vegetation parameters in each station were taken in a 10x100 plot and were processed using a tree profile diagram. Abiotic parameters were measured in each plot and analyzed using the correlation test. The results showed that the three stations were still dominated by the tree in Stratum C, but the tree density and tree height varied in proportion to the damage level. Station A in the heavy damage area has the lowest tree density (23 trees/0.1 ha) with a maximum tree height of 12 meters, in contrast to Station C in the minor damage area with tree density reaching 195 trees/0.1 ha and maximum tree height reaching 30 meters. Nine years after the Mount Merapi big eruption, the MMNP forests in Yogyakarta Province are still classified as young secondary forests. &#x0D; Key words: diagram, profile, succession, structure, vertical