Ample evidence has indicated that mixed tree plantations are the most appropriate option for providing a broad range of goods and environmental services, but still debate continues about whether ...mixed plantations can achieve greater productivity than can monocultures. In this study, a meta-analysis of published studies was performed to synthesize results of growth in mixed plantations and monocultures across differing regions and species. A total of 14 studies representing 46 tree species from tropical and temperate ecosystems were included to test three hypotheses: stand composition affects tree height growth rate; stand composition affects tree diameter growth rate; and presence of nitrogen-fixing tree species in mixed tree plantations affects the diameter growth rate of non-fixing species. It was found that mixed plantations did not have larger height growth rates, but that the diameter growth rate was higher in mixed plantations, with a moderate but statistically significant effect size. Nitrogen-fixing tree species had a positive effect on the diameter growth rate of non-fixing species, with a large and statistically significant effect size. This study suggests that mixing tree species generally increases plantation growth rate. Furthermore, mixed tree plantations can play an important role in satisfying economic needs by shortening rotations yet adding other ecological benefits. Silviculturalists should adopt mixed plantations more widely across degraded landscapes, as well as nitrogen-fixing tree species to maximize positive interactions in mixed plantations.
Individual leaf area (LA) is a key variable in studies of tree ecophysiology because it directly influences light interception, photosynthesis and evapotranspiration of adult trees and seedlings. We ...analyzed the leaf dimensions (length - L and width - W) of seedlings and adults of seven Neotropical rainforest tree species (Brosimum rubescens, Manilkara maxima, Pouteria caimito, Pouteria torta, Psidium cattleyanum, Symphonia globulifera and Tabebuia stenocalyx) with the objective to test the feasibility of single regression models to estimate LA of both adults and seedlings. In southern Bahia, Brazil, a first set of data was collected between March and October 2012. From the seven species analyzed, only two (P. cattleyanum and T. stenocalyx) had very similar relationships between LW and LA in both ontogenetic stages. For these two species, a second set of data was collected in August 2014, in order to validate the single models encompassing adult and seedlings. Our results show the possibility of development of models for predicting individual leaf area encompassing different ontogenetic stages for tropical tree species. The development of these models was more dependent on the species than the differences in leaf size between seedlings and adults.
Twenty-four native species with high timber value and well-known for wildlife use were planted in open pasture, young secondary forest (10 years old) and mature forest without causing major ...disturbances to natural vegetation. Plots were established in cooperation with local farmers in the Sixaola River valley in Talamanca, Limón, Costa Rica. In the center of each 64-tree single species plot, a 36-tree plot (6 × 6 trees) was defined as the measurement plot. The averages of total height, diameter at breast height (dbh), basal area, volume and survival were calculated for each plot. Mean annual increment in volume (MAIV) was used to compare species performance. The most productive species in open pasture were Rollinia microsepala (MAIV = 33.3 m³/ha/year), Virola koschnyi (MAIV = 24.4 m³/ha/year), Abarema idiopoda (MAIV = 20.0 m³/ha/year), Inga coruscans (MAIV = 14.4 m³/ha/year) and Terminalia amazonia (MAIV = 14.0 m³/ha/year). The most productive species in young secondary forest were Cordia alliodora (MAIV = 12.5 m³/ha/year), Rollinia microsepala (MAIV = 8.3 m³/ha/year), Abarema idiopoda (MAIV = 5.5 m³/ha/year) and Terminalia oblonga (MAIV = 4.6 m³/ha/year). All plots in mature forest showed low productivity, where the largest MAIV was achieved by Hyeronima alchorneoides and Virola sebifera. Species showed differences in survival and growth among habitats. Sebanyak 24 spesies asli yang mempunyai nilai kayu yang tinggi serta berguna untuk hidupan liar ditanam di kawasan padang rumput yang terdedah, hutan sekunder muda berusia 10 tahun dan juga di hutan matang. Sepanjang kajian, kami pastikan agar gangguan terhadap tumbuhan asal sentiasa terkawal. Plot dibina dengan kerjasama peladang tempatan di lembah Sungai Sixaola di Talamanca, Limón, Costa Rica. Di tengah-tengah plot yang mengandungi 64 spesies tunggal itu, satu plot 36 pokok (6 × 6 pokok) di kenal pasti sebagai plot ukuran. Purata ketinggian keseluruhan, diameter aras dada (dbh), isi padu dan kemandirian dikira bagi setiap plot. Tambahan tahunan min isi padu (MAIV) diguna untuk membandingkan prestasi spesies. Spesies yang paling produktif di padang rumput terdedah ialah Rollinia microsepala (MAIV = 33.3 m³/ha/tahun), Virola koschnyi (MAIV = 24.4 m³/ha/tahun), Abarema idiopoda (MAIV = 20.0 m³/ha/tahun), Inga coruscans (MAIV = 14.4 m³/ha/tahun) dan Terminalia amazonia (MAIV = 14.0 m³/ha/tahun). Di hutan sekunder muda, spesies yang paling produktif pula ialah Cordia alliodora (MAIV = 12.5 m³/ha/tahun), Rollinia microsepala (MAIV = 8.3 m³/ha/tahun), Abarema idiopoda (MAIV = 5.5 m³/ha/tahun) and Terminalia oblonga (MAIV = 4.6 m³/ha/tahun). Semua plot di hutan matang menunjukkan produktiviti yang rendah. MAIV tertinggi dicapai oleh Hyeronima alchorneoides and Virola sebifera. Spesies di ketiga-tiga habitat yang dikaji tidak menunjukkan sebarang perbezaan dalam kemandirian serta pertumbuhan.
The global extent and distribution of forest trees is central to our understanding of the terrestrial biosphere. We provide the first spatially continuous map of forest tree density at a global ...scale. This map reveals that the global number of trees is approximately 3.04 trillion, an order of magnitude higher than the previous estimate. Of these trees, approximately 1.39 trillion exist in tropical and subtropical forests, with 0.74 trillion in boreal regions and 0.61 trillion in temperate regions. Biome-level trends in tree density demonstrate the importance of climate and topography in controlling local tree densities at finer scales, as well as the overwhelming effect of humans across most of the world. Based on our projected tree densities, we estimate that over 15 billion trees are cut down each year, and the global number of trees has fallen by approximately 46% since the start of human civilization.
To develop recommendations for investigation and monitoring of children with Raynaud's syndrome, based on paediatric evidence collated by a systematic review.
A systematic review was undertaken to ...establish the paediatric evidence for assessment and monitoring of Raynaud's syndrome. An expert panel including members of the Paediatric Rheumatology European Society (PRES) Scleroderma Working Group, were invited to a consensus meeting where recommendations were developed based on evidence graded by the systematic review and where evidence was lacking, consensus opinion. A nominal technique was used where 75% consensus was taken as agreement.
The expert panel recommended testing anti-nuclear antibody (ANA), more specific antibodies associated with connective tissue disease and nail-fold capillaroscopy in all children presenting with Raynaud's syndrome as data suggests these can be risk factors for evolution into a connective tissue disease. The frequency of follow-up recommended depends on presence of these risk factors with the aim to detect evolving connective tissue disease early in high risk individuals. Those with no abnormalities on capillaroscopy and negative autoantibodies were deemed low risk of progression, whereas those with ANA positivity, specific autoantibodies and/or nailfold capillary changes were deemed high risk and more frequent follow-up was recommended.
Recommendations, primarily based on consensus opinion, were agreed regarding investigation and monitoring of children who present with Raynaud's syndrome. Further prospective studies are needed to better define the risk factors for progression to connective tissue disease.
to describe normal patterns of nailfold videocapillaroscopy (NVC) in healthy children and adolescents; to quantify the relationship between age and capillary dimensions, intercapillary distance and ...number of capillaries/mm; to evaluate the inter and intraobserver concordance.
Cross-sectional study including 100 healthy participants aged 5 to 18 years. Capillary dimensions (capillary loop length, capillary width and intercapillary distance) and number of capillaries/mm were evaluated in 900 capillaries using stereomicroscope under 100x magnification. Intra and inter observer agreements were tested.
The capillary dimensions (mean ± SD) were: capillary loop length 278.6±60.3 μm, intercapillary distance 124.1±28.1 μm, capillary width 15.0±2.6 μm. Teenagers between 15 and 18 years had longer and more enlarged capillaries than the other age groups (p<0.001 and p=0.012 respectively). We also found a significant increase in the number of capillaries/mm with age (p<0.001). There was a positive correlation between age and number of capillaries/mm, capillary length, and capillary width (p<0.001, R=0.796; p<0.001, R=0.368; p=0.004, R=0.285, respectively). There was a good intra and interobserver concordance. Enlarged capillary and avascular areas were present in 11% and 10% of capillaries respectively. A weak negative correlation was found between the intercapillary distance and the number of capillaries/mm (p=0.05; R=-0.20).
There is a wide variability in the capillary morphology among healthy individuals. There was a positive correlation between age and number of capillaries/mm, capillary length, and capillary width. In addition, NVC has been shown to be a reproducible method.
In Costa Rica, most reforestation trials with native species were established in the tropical humid regions. In the dry tropics, research on the performance of native species in forest plantations is ...incipient and trials comparing pure and mixed designs are limited. This paper presents the results of two experimental plantations with native trees in pure and mixed plots in the dry tropics of Costa Rica. The growth and productivity of 13 native species in pure and mixed plantations was compared with
Tectona grandis (L.f.) Lam., an exotic species broadly used in the region. In a plantation of relatively slower growing species, measurements taken at 68 months of age resulted in
Samanea saman (Jacq.) Merril. and
Dalbergia retusa Hemsl. demonstrating the best growth, followed by
Astronium graveolens Jacq. and
Swietenia macrophylla King. Measurements in a plantation of relatively faster growing species, at 68 months of age, showed that growth of
Schizolobium parahyba (Vell.) Blake was greatest in the pure and mixed plots, followed by
Terminalia oblonga (Ruiz & Pav.) Steud.,
Anarcadium excelsum (Bert. & Balb. ex Kunth) Skeels and
Pseudosamanea guachapele (Kunth) Harms. The native species grew better in the mixed plots. The pure plots of
T. grandis (L.f.) Lam. were the most productive, compared to all species and the mixture of species. Plantations of
T. grandis (L.f.) Lam. seem to be well adapted to the region and are certainly a commercially interesting alternative. Nevertheless, mixed plantations with native species would contribute more to sustainable management, because while single-species plantations do not provide a great range of goods and services when compared to the natural forest, mixed plantations are likely to increase this range of benefits.
The objectives of this study were to evaluate the dynamic behaviour of digital skin microvascular blood flow before and after cold stimulation using laser Doppler imaging (LDI) in children and ...adolescents with RP secondary to juvenile systemic sclerosis (JSS), primary RP (PRP) and healthy controls and to compare functional abnormalities measured by LDI with structural microvascular abnormalities evaluated by nailfold capillaroscopy (NFC).
Five JSS patients, five children and adolescents with PRP and five healthy controls matched for gender and age were included. All subjects had NFC performed. Finger blood flow (FBF) was measured using the LDI system (Moor Instruments) at baseline and after cold stimulus (CS).
There were a decreased number of capillaries, a greater number of enlarged capillaries and a higher deletion score in JSS patients compared with controls and patients with PRP. The mean baseline FBF was significantly lower in JSS patients compared with controls. There was no difference between the mean baseline FBF in JSS patients compared with patients with PRP. There was a significant decrease in FBF 1 min after CS in all groups followed by blood flow recovery at 20 min after CS in comparison with basal FBF values in controls, but not in JSS and PRP patients.
In JSS patients, LDI showed a lower FBF before and after CS compared with healthy controls and may be an objective and sensitive method for the measurement of digital skin blood flow in RP children.
Exotic tree species predominate in reforestation in tropical regions worldwide. However, some native species are suitable for plantations, providing a wider variety of products. Adequate government ...programs of incentives, coupled with good technical advice to farmers, are needed to stimulate reforestation, especially among small and medium-sized farmers with limited financial resources. This project evaluates growth of native and exotic tree species on plantations in small and medium-sized farms in the Atlantic humid lowlands of Costa Rica, Central America. A total of 210 pure plantations, ranging in age from 6 to 11 years, were evaluated on 123 farms that had used government incentives for reforestation, and had received technical advice from local non-government organizations. For each species, seven plantations were chosen at random for study. In each plantation, plots of 15 trees each were chosen systematically for evaluation of diameter at breast height (dbh), total height, number of trees per hectare, tree form and spacing.
Terminalia
amazonia (J.F. Gmel) Exell,
Hieronyma alchorneoides Allemao, and
Vochysia
guatemalensis Donn. Sm. were the most frequent species found in plantations in the region of study.
Gmelina
arborea Roxb. (exotic) and
V. guatemalensis (native) had the highest mean annual diameter increment with 2.90 and 2.59
cm, respectively.
Calophyllum
brasiliense Cambess. (native) had the lowest mean annual diameter increment (1.48
cm).
G.
arborea and
V.
guatemalensis had the highest mean annual volume increment, followed by
Tectona grandis (L.f) Lam. (exotic), and
T. amazonia and
Cordia alliodora (R&P) Cham. (both native). Although
G. arborea had the greatest mean annual diameter increment, it had the lowest plantation density and problems with form.
V. guatemalensis and
T. amazonia, two native species, were the most promising species for reforestation, due to good growth in volume, good form, and adaptability to a variety of sites. The poor form of exotic species was related to the low intensity management methods of small farmers. Exotic species had the highest performance variability between sites, while native species showed relatively high growth homogeneity. Therefore, native species seem more promising than exotics for general use across varying ecological conditions.
Individual leaf area (LA) is a key variable in studies of tree ecophysiology because it directly influences light interception, photosynthesis and evapotranspiration of adult trees and seedlings. We ...analyzed the leaf dimensions (length - L and width - W) of seedlings and adults of seven Neotropical rainforest tree species (Brosimum rubescens, Manilkara maxima, Pouteria caimito, Pouteria torta, Psidium cattleyanum, Symphonia globulifera and Tabebuia stenocalyx) with the objective to test the feasibility of single regression models to estimate LA of both adults and seedlings. In southern Bahia, Brazil, a first set of data was collected between March and October 2012. From the seven species analyzed, only two (P. cattleyanum and T. stenocalyx) had very similar relationships between LW and LA in both ontogenetic stages. For these two species, a second set of data was collected in August 2014, in order to validate the single models encompassing adult and seedlings. Our results show the possibility of development of models for predicting individual leaf area encompassing different ontogenetic stages for tropical tree species. The development of these models was more dependent on the species than the differences in leaf size between seedlings and adults.
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