Biometric assessment of early stem growth at a commercial stand of African mahogany (Khaya grandifoliola)

African mahogany species (Khaya spp.) have proven to be promising in the Brazilian forestry scenario, replacing native mahogany owing to their medium-fast growth and relevant timber value. This study aimed to carry out forest inventory and assessments of a Khaya grandifoliola plantation in the first years after planting, test hypsometric models to describe tree growth, and identify the maximum commercial stem yield (i.e., greater than 6 m in height). The stand was located in the municipality of Piracanjuba (GO), where seedlings of seed origin were used. Twenty random plots with a 15 m radius were allocated, and the total height (HT), stem height (HS), diameter at breast height (DBH), crown area, and forest canopy were measured. Four hypsometric models were employed in this study. The best equation was selected based on determination coefficients and standard errors. Further, the models were cross-validated to evaluate predictability and bias. At four years of planting, the largest class of HS was found to range from 3.1 to 4.1 m, and most trees had a DBH ranging from 0.084 to 0.126 m. The percentage of trees with stems > 6 m was 8.35%. The linear model ensured more consistent results for estimating HT, while the quadratic and Weibull models led to more consistent results for HS. By using models, stem measurements can be measured based on DBH, ultimately aiding the selection of stem management strategies for the growth of forests with greater commercial value.

Spatial characteristics and economic value of threatened species (Khaya ivorensis).

Khaya ivorensis (K. ivorensis), one of the most valuable tropical hardwood species indigenous to West and Central Africa, has been classified as a threatened tree species. However, information on its remaining population and distribution are limited. We mapped the current K. ivorensis spatial distribution, modelled the spatial autocorrelation and estimated its economic value using volume estimation and market pricing. The study was conducted in Odigbo and Irele local government areas (LGA), Ondo State, Nigeria. Spatially, localities of 97 K. ivorensis were identified across the study area and can be added into a wide range of datasets from local to global inventories. Large trees in diameter and height were statistically clustered in the north of Odigbo and assumed to relate with forest reserve management. Estimated median tree volumes were 0.39 m3 and 0.31 m3 in accordance with the allometric volume function and specific volume function, respectively. The economic values of wood varied approximately from US$111,208 to US$72,081. Findings from this study are a valuable resource for conserving this species and other threatened tree species.

A comparative study of the thermal ranges of three germination criteria of a tropical tree with bioeconomic interest: Carapa surinamensis Miq. (Meliaceae) / Estudo comparativo sobre a variação térmica em três critérios de germinação de uma árvore tropical com interesse econômico: Carapa surinamensis Miq. (Meliaceae)

Abstract Species of the Carapa spp. complex, occurring in the Neotropics, Africa and India, have multiple uses, including timber, with the seed oil being used in phyto-pharmaceutical products and cosmetics. This study aimed to determine the thermal ranges of the germination process, comparing germination criteria used by seed physiologists and seed technologists, and to suggest recommendations for seed quality assessment. Germination was assessed at constant temperatures between 10 ─ 40 °C using three germination criteria: (1) radicle length ≥ 0.5 cm (physiological criterion); (2) epicotyl length ≥ 1 cm; and (3) epicotyl length ≥ 5 cm (criterion for seed quality tests). The base temperature was similar for the three criteria and ranged between 10 ─ 2 °C. The Maguire's Speed Index indicated 30 °C as most adequate. However, the upper temperature limit differed: for radicle protrusion it was above 40 ºC; and for both epicotyl lengths, it was between 35 ─ 40 °C. Seed coat removal accelerated the germination process of these recalcitrant seeds, and is recommended for seed quality assessment, which allows completion of the germination trial in approximately one month.

Resumo As espécies do complexo Carapa spp. ocorrem na região Neotropical, na África e na Índia, têm usos múltiplos, fornece madeira de valor comercial e o óleo extraído das sementes tem uso fitoterápico e cosmético. O objetivo deste trabalho foi determinar a faixa térmica tolerável do processo germinativo, comparando os critérios de germinação utilizados pelos fisiologistas e os tecnólogos de sementes, e sugerir recomendações para a avaliação da qualidade das sementes. A germinação foi avaliada em temperaturas constantes entre 10 e 40 °C utilizando três critérios de germinação: (1) formação da radícula ≥ 0,5 cm (critério fisiológico); (2) alongamento de epicótilo ≥ 1 cm; e (3) alongamento de epicótilo ≥ 5 cm (critério para testes de qualidade de sementes). A temperatura de base foi semelhante para os três critérios entre 10 e 12 °C. O índice de velocidade de Maguire indicou 30 °C como a temperatura mais adequada. O limite superior de temperatura diferiu entre os critérios, sendo acima de 40 ºC para protrusão da radícula e para ambos os alongamentos de epicótilo entre 35 e 40 °C. A remoção do tegumento de semente acelerou o processo de germinação dessas sementes recalcitrantes sendo recomendada para a avaliação da qualidade da semente, o que permite concluir o teste de germinação em aproximadamente um mês.

A comparative study of the thermal ranges of three germination criteria of a tropical tree with bioeconomic interest: Carapa surinamensis Miq. (Meliaceae).

Species of the Carapa spp. complex, occurring in the Neotropics, Africa and India, have multiple uses, including timber, with the seed oil being used in phyto-pharmaceutical products and cosmetics. This study aimed to determine the thermal ranges of the germination process, comparing germination criteria used by seed physiologists and seed technologists, and to suggest recommendations for seed quality assessment. Germination was assessed at constant temperatures between 10 ─ 40 °C using three germination criteria: (1) radicle length ≥ 0.5 cm (physiological criterion); (2) epicotyl length ≥ 1 cm; and (3) epicotyl length ≥ 5 cm (criterion for seed quality tests). The base temperature was similar for the three criteria and ranged between 10 ─ 2 °C. The Maguire's Speed Index indicated 30 °C as most adequate. However, the upper temperature limit differed: for radicle protrusion it was above 40 ºC; and for both epicotyl lengths, it was between 35 ─ 40 °C. Seed coat removal accelerated the germination process of these recalcitrant seeds, and is recommended for seed quality assessment, which allows completion of the germination trial in approximately one month.

Anti-inflammatory, Antioxidant and Antiproliferative Activities from Trichilia silvatica (C.DC).

BACKGROUND: Trichilia silvatica, popularly known as "catiguá-branco", is distributed in Brazil (Mato Grosso do Sul), and members of this genus are commonly used for the treatment of rheumatism (arthritis). The aim of this research was to investigate the anti-inflammatory, antioxidant and antiproliferative activities of the methanolic extract of the leaves (MEL-TS) and bark (MEB-TS) of T. silvatica. We also evaluated the concentration of phenolic compounds, flavonoids, flavonol, and condensed tannins by liquid chromatography - photodiode array (LC/PDA) analysis. METHODS: The MEL-TS and MEB-TS revealed the presence of caffeic acid in both extracts by LC/PDA. The samples were evaluated for antioxidant activity using free-radical scavenging and lipoperoxidation assays. The anti-inflammatory effects were studied in carrageenan-induced paw edema, pleurisy and zymosan-induced arthritis. RESULTS: The MEL-TS and MEB-TS showed the total phenolic concentration (270.8 ± 17.10 mg gallic acid equivalents GAE/g extract and 278.8 ± 25.13 mg GAE/ g extract, respectively), and flavonoids in MEL-TS (209.30 ± 2.91 mg quercetin equivalents QE/ g extract). In the lipoperoxidation assay, exhibited moderate antioxidant activity with IC50 values ≤ 35.32 µg/mL. Both extracts inhibited oedema induced by carrageenan at 2 h and 4 h, inhibited leukocyte migration at 6 h post administration, and did not impact zymosan-induced arthritis. Finally, MEL-TS was particularly effective against prostate cell line (GI50 ≤ 0.22 µg/mL). CONCLUSION: Overall, the results indicated that T. silvatica reduce migration leukocytes activity, edema formation in these models of experimental arthritis could explain the popular use for treatment of inflammatory processes (rheumatism).

Volume equations for Khaya ivorensis A. Chev. plantations in Brazil.

African mahogany (Khaya spp.) plantations are in expansion in Brazil and in the world. This fact justifies the need for studies related to its growth and yield. This paper aimed to evaluate the performance of single-entry and double-entry models for estimating merchantable and total volume for Khaya ivorensis plantations before the first thinning (7 years) and expected final cut (15 years). Volume data was from 100 and 46 trees in Minas Gerais and Pará states, respectively, by using an electronic dendrometer (Criterion RD 1000). Observed volumes were calculated by Smalian's formula. To validate the optical dendrometer, 10 trees were felled and had their volume measured, and compared with the volumes measured indirectly. The results showed that observed and estimated volumes were statistically equal, and that double-entry models were more precise than single-entry models. Schumacher and Hall model was the best equation to estimate merchantable volume for first thinning and for final cut in Minas Gerais stands. Spurr logarithmized model was the best equation to estimate total volume for first thinning and Spurr model for final cut in Pará stands. All chosen equations can be used to quantify merchantable and total volumes of Khaya ivorensis grown under similar conditions.

Seedling growth and survival of five tree species in secondary forests and adjacent pastures in the montane rain forests of Southern Costa Rica / Crecimiento y supervivencia de plántulas de cinco especies de árboles en bosques secundarios y pastizales adyacentes en un bosque lluvioso montano del sur de Costa Rica

Abstract:Successful forest restoration in tropical environments is limited by the paucity of studies on the initial establishment and early survival requirements of seedlings of most native tropical tree species under disturbed conditions. Here, we evaluated the initial growth responses and the regeneration potential of seedlings of five tree species native to Costa Rica (Hasseltia floribunda, Inga densiflora, Persea americana, Tapirira mexicana and Trichilia pittieri). Seedlings were grown in secondary forests and adjacent open pastures under contrasting conditions of light availability. We quantified seedling growth, survival and herbivory from August 2010 to August 2011 on a monthly basis, and measured differences in leaf mass per area (LMA) at the end of the experiment. We found significant variation in growth responses between the understory of secondary forests and pastures. Growth in height was highest in pastures across all species, with I. densiflora, P. americana and T. mexicana showing the most striking differences. In contrast, H. floribunda and T. pittieri did not show differences in diameter growth between environments. Except for T. mexicana, herbivory increased throughout the experiment in all the species. Herbivory increased faster in pastures for H. floribunda and T. pittieri and showed higher rates in the forest understory for I. densiflora and P. americana. Seedling survival showed significant differences for all species across environments. Survival of H. floribunda and I. densiflora was higher in secondary forests, whereas the other species showed higher survival in pastures. LMA showed higher values in the pastures across all species, showing that individuals exposed to high light conditions had great photosynthetic rate and great leaf construction capacity. Due to their rapid growth and high survival, I. densiflora and T. mexicana showed great potential to restore abandoned pastures and secondary forests. Increasing our knowledge on the response of seedlings under disturbed conditions in tropical ecosystems is critical for improving the restoration of altered environments by matching the ecological amplitude of native species with specific environmental conditions. Rev. Biol. Trop. 64 (4): 1565-1583. Epub 2016 December 01.

Resumen:La restauración exitosa del bosque en ambientes tropicales está limitada por la carencia de estudios sobre los requisitos de hábitat, el establecimiento inicial, y la sobrevivencia de las plántulas de la mayoría de las especies de árboles tropicales nativos. En este estudio, evaluamos las respuestas en el crecimiento inicial y el potencial de regeneración de las plántulas de cinco especies de árboles nativos de Costa Rica (Hasseltia floribunda, Inga densiflora, Persea americana, Tapirira mexicana y Trichilia pittieri). Sembramos las plántulas en bosques secundarios y en pastizales abiertos adyacentes con condiciones de luz contrastantes. Cuantificamos el crecimiento, la supervivencia y el daño por herbivoría de las plántulas de forma mensual entre agosto 2010 y agosto 2011, y medimos las diferencias en el la masa foliar por área de la hoja al final del experimento. Existió una variación significativa en el crecimiento de las plántulas expuestas a la sombra en los bosques secundarios y aquellas que crecieron en pastizales. El crecimiento en altura fue mayor en pastizales en todas las especies; I. densiflora, P. americana y T. mexicana mostraron la mayor diferencia entre ambientes. En con- traste, H. floribunda y T. pittieri no mostraron diferencias en el crecimiento del diámetro entre ambientes. Con la excepción de T. mexicana, todas las especies mostraron un aumento en herbivoría durante el estudio. En los pastizales, el incremento de la herbivoría fue más rápido en H. floribunda y T. pittieri, mientras que para I. densiflora y P. americana fue mayor en el bosque. La sobrevivencia de plántulas fue diferente entre ambientes para todas las especies. La sobrevivencia de H. floribunda e I. densiflora fue mayor en el bosque secundario, mientras que en las demás especies hubo mayor sobrevivencia de plántulas en los pastizales. La masa foliar por área fue mayor en las plántulas que crecieron en los pastizales que en bosque secundario para todas las especies, lo que sugiere que los individuos que crecieron en condiciones de alta incidencia de luz tuvieron mayor tasa fotosintética y mayor capacidad de construcción de la hoja. Debido al rápido crecimiento y alta supervivencia I. densiflora y T. mexicana tienen gran potencial para la restauración de bosques secundarios y pastizales abandonados. Generar información sobre la respuesta de plántulas creciendo en bosques secundarios y pastizales en regeneración es crítico para mejorar los procesos de restauración de ambientes alterados. La restauración de estos bosques depende de la correspondencia entre las condiciones específicas de hábitat y la plasticidad ecológica de las especies nativas.

Seedling growth and survival of five tree species in secondary forests and adjacent pastures in the montane rain forests of Southern Costa Rica.

Successful forest restoration in tropical environments is limited by the paucity of studies on the initial establishment and early survival requirements of seedlings of most native tropical tree species under disturbed conditions. Here, we evaluated the initial growth responses and the regeneration potential of seedlings of five tree species native to Costa Rica (Hasseltia floribunda, Inga densiflora, Persea americana, Tapirira mexicana and Trichilia pittieri). Seedlings were grown in secondary forests and adjacent open pastures under contrasting conditions of light availability. We quantified seedling growth, survival and herbivory from August 2010 to August 2011 on a monthly basis, and measured differences in leaf mass per area (LMA) at the end of the experiment. We found significant variation in growth responses between the understory of secondary forests and pastures. Growth in height was highest in pastures across all species, with I. densiflora, P. americana and T. mexicana showing the most striking differences. In contrast, H. floribunda and T. pittieri did not show differences in diameter growth between environments. Except for T. mexicana, herbivory increased throughout the experiment in all the species. Herbivory increased faster in pastures for H. floribunda and T. pittieri and showed higher rates in the forest understory for I. densiflora and P. americana. Seedling survival showed significant differences for all species across environments. Survival of H. floribunda and I. densiflora was higher in secondary forests, whereas the other species showed higher survival in pastures. Leaf mass per area showed higher values in the pastures across all species, it suggests that individuals exposed to high light conditions had great photosynthetic rate and great leaf construction capacity. Due to their rapid growth and high survival, I. densiflora and T. mexicana showed great potential to restore abandoned pastures and secondary forests. Increasing our knowledge on the response of seedlings under disturbed conditions in tropical ecosystems is critical for improving the restoration of altered environments by matching the ecological amplitude of native species with specific environmental conditions.

Tracking Seed Fates of Tropical Tree Species: Evidence for Seed Caching in a Tropical Forest in North-East India.

Rodents affect the post-dispersal fate of seeds by acting either as on-site seed predators or as secondary dispersers when they scatter-hoard seeds. The tropical forests of north-east India harbour a high diversity of little-studied terrestrial murid and hystricid rodents. We examined the role played by these rodents in determining the seed fates of tropical evergreen tree species in a forest site in north-east India. We selected ten tree species (3 mammal-dispersed and 7 bird-dispersed) that varied in seed size and followed the fates of 10,777 tagged seeds. We used camera traps to determine the identity of rodent visitors, visitation rates and their seed-handling behavior. Seeds of all tree species were handled by at least one rodent taxon. Overall rates of seed removal (44.5%) were much higher than direct on-site seed predation (9.9%), but seed-handling behavior differed between the terrestrial rodent groups: two species of murid rodents removed and cached seeds, and two species of porcupines were on-site seed predators. In addition, a true cricket, Brachytrupes sp., cached seeds of three species underground. We found 309 caches formed by the rodents and the cricket; most were single-seeded (79%) and seeds were moved up to 19 m. Over 40% of seeds were re-cached from primary cache locations, while about 12% germinated in the primary caches. Seed removal rates varied widely amongst tree species, from 3% in Beilschmiedia assamica to 97% in Actinodaphne obovata. Seed predation was observed in nine species. Chisocheton cumingianus (57%) and Prunus ceylanica (25%) had moderate levels of seed predation while the remaining species had less than 10% seed predation. We hypothesized that seed traits that provide information on resource quantity would influence rodent choice of a seed, while traits that determine resource accessibility would influence whether seeds are removed or eaten. Removal rates significantly decreased (p < 0.001) while predation rates increased (p = 0.06) with seed size. Removal rates were significantly lower for soft seeds (p = 0.002), whereas predation rates were significantly higher on soft seeds (p = 0.01). Our results show that murid rodents play a very important role in affecting the seed fates of tropical trees in the Eastern Himalayas. We also found that the different rodent groups differed in their seed handling behavior and responses to changes in seed characteristics.

Effects of simulated acid rain on germination, seedling growth and oxidative metabolism of recalcitrant-seeded Trichilia dregeana grown in its natural seed bank.

Increased air pollution in a number of developing African countries, together with the reports of vegetation damage typically associated with acid precipitation in commercial forests in South Africa, has raised concerns over the potential impacts of acid rain on natural vegetation in these countries. Recalcitrant (i.e. desiccation sensitive) seeds of many indigenous African species, e.g. must germinate shortly after shedding and hence, may not be able to avoid exposure to acid rain in polluted areas. This study investigated the effects of simulated acid rain (rainwater with pH adjusted to pH 3.0 and 4.5 with 70:30, H2 SO4 :HNO3 ) on germination, seedling growth and oxidative metabolism in a recalcitrant-seeded African tree species Trichilia dregeana Sond., growing in its natural seed bank. The results suggest that acid rain did not compromise T. dregeana seed germination and seedling establishment significantly, relative to the control (non-acidified rainwater). However, pH 3.0 treated seedlings exhibited signs of stress typically associated with acid rain: leaf tip necrosis, abnormal bilobed leaf tips, leaf necrotic spots and chlorosis, reduced leaf chlorophyll concentration, increased stomatal density and indications of oxidative stress. This may explain why total and root biomass of pH 3.0 treated seedlings were significantly lower than the control. Acid rain also induced changes in the species composition and relative abundance of the different life forms emerging from T. dregeana's natural seed bank and in this way could indirectly impact on T. dregeana seedling establishment success.

Forest trees in human modified landscapes: ecological and genetic drivers of recruitment failure in Dysoxylum malabaricum (Meliaceae).

Tropical agro-forest landscapes are global priority areas for biodiversity conservation. Little is known about the ability of these landscapes to sustain large late successional forest trees upon which much forest biodiversity depends. These landscapes are subject to fragmentation and additional habitat degradation which may limit tree recruitment and thus compromise numerous ecosystem services including carbon storage and timber production. Dysoxylum malabaricum is a large canopy tree species in the Meliaceae, a family including many important tropical timber trees. This species is found in highly fragmented forest patches within a complex agro-forest landscape of the Western Ghats biodiversity hot spot, South India. In this paper we combined a molecular assessment of inbreeding with ecological and demographic data to explore the multiple threats to recruitment of this tree species. An evaluation of inbreeding, using eleven microsatellite loci in 297 nursery-reared seedlings collected form low and high density forest patches embedded in an agro-forest matrix, shows that mating between related individuals in low density patches leads to reduced seedling performance. By quantifying habitat degradation and tree recruitment within these forest patches we show that increasing canopy openness and the increased abundance of pioneer tree species lead to a general decline in the suitability of forest patches for the recruitment of D. malabaricum. We conclude that elevated inbreeding due to reduced adult tree density coupled with increased degradation of forest patches, limit the recruitment of this rare late successional tree species. Management strategies which maintain canopy cover and enhance local densities of adult trees in agro-forest mosaics will be required to ensure D. malabaricum persists in these landscapes. Our study highlights the need for a holistic understanding of the incipient processes that threaten populations of many important and rare tropical tree species in human dominated agro-forest landscapes.

Photosynthesis of seedlings of Otoba novogranatensis (Myristicaceae) and Ruagea glabra (Meliaceae) in abandoned pasture, secondary forest and plantation habitats in Costa Rica.

Enrichment planting in naturally recovering secondary forests or in tree plantations is increasingly being used as strategy to restore later-successional, large-seeded tropical forest trees. We seeded two tree species (Otoba novogranatensis and Ruagea glabra) in three agricultural sites in Southern Costa Rica: abandoned pastures, eight to ten year old secondary forests and three year old tree plantations (containing two N-fixing of four total tree species). We measured micrometeorological conditions, soil water content, plant water potential, leaf area, foliar C and N, and photosynthesis to better understand mechanistic responses of seedlings to conditions in the different successional habitats. Micrometeorological conditions, soil water content, and plant water potential were generally similar across habitats. Certain aspects of leaves (such as Specific Leaf Area and foliar N content), and photosynthesis (e.g. quantum yield and electron transport rate) were highest in the plantations, intermediate in the secondary forests, and lowest in abandoned pastures. Enhanced rates of photosynthetic biochemistry (such as Vxmax and Jmax) and Photosystem II efficiency (e.g. thermal energy dissipation) occurred in leaves from the plantations compared to the abandoned pastures, which may be related to higher leaf %N content. Results suggest that foliar N may be of greater importance than soil water content and micrometeorological factors in driving differences in photosynthetic processes across planting habitats. Planting seeds of these two species in plantations containing three year old trees (including two N-fixing species) enhances certain aspects of their photosynthesis and growth, compared to seedlings in abandoned pastures with non-native grasses, and thus can help increase forest recovery on abandoned agricultural lands.

Photosynthesis of seedlings of Otoba novogranatensis (Myristicaceae) and Ruagea glabra (Meliaceae) in abandoned pasture, secondary forest and plantation habitats in Costa Rica / Fotosíntesis de plántulas de Otoba novogranatensis (Myristicaceae) y Ruagea glabra (Meliaceae) en pastizales abandonados, bosques secundarios y hábitats de plantaciones en Costa Rica

Enrichment planting in naturally recovering secondary forests or in tree plantations is increasingly being used as strategy to restore later-successional, large-seeded tropical forest trees. We seeded two tree species (Otoba novogranatensis and Ruagea glabra) in three agricultural sites in Southern Costa Rica: abandoned pastures, eight to ten year old secondary forests and three year old tree plantations (containing two N-fixing of four total tree species). We measured micrometeorological conditions, soil water content, plant water potential, leaf area, foliar C and N, and photosynthesis to better understand mechanistic responses of seedlings to conditions in the different successional habitats. Micrometeorological conditions, soil water content, and plant water potential were generally similar across habitats. Certain aspects of leaves (such as Specific Leaf Area and foliar N content), and photosynthesis (e.g. quantum yield and electron transport rate) were highest in the plantations, intermediate in the secondary forests, and lowest in abandoned pastures. Enhanced rates of photosynthetic biochemistry (such as Vcmax and Jmax) and Photosystem II efficiency (e.g. thermal energy dissipation) occurred in leaves from the plantations compared to the abandoned pastures, which may be related to higher leaf %N content. Results suggest that foliar N may be of greater importance than soil water content and micrometeorological factors in driving differences in photosynthetic processes across planting habitats. Planting seeds of these two species in plantations containing three year old trees (including two N-fixing species) enhances certain aspects of their photosynthesis and growth, compared to seedlings in abandoned pastures with non-native grasses, and thus can help increase forest recovery on abandoned agricultural lands.

El enriquecimiento de bosques secundarios o plantaciones forestales en proceso de regeneración natural por medio de la siembra de plántulas es una práctica cada vez más utilizada para restaurar bosques tropicales en estado de sucesión tardía. Sembramos dos especies de árboles (Otoba novogranatensis y Ruagea glabra) en pastizales abandonados, bosques secundarios de ocho a diez años de edad y plantaciones forestales de tres años de edad (con dos especies fijadoras de Nitrógeno de un total de cuatro especies) en tres sitios agrícolas en el Sur de Costa Rica. Medimos condiciones micrometeorológicas, contenido de agua del suelo, potencial hídrico de las plantas, área foliar, C y N foliar, y fotosíntesis para entender de una mejor manera las respuestas funcionales de las plántulas ante condiciones de distintos estadíos sucesionales. Las condiciones micrometeorológicas, contenido hídrico del suelo y el potencial hídrico de las plantas fueron mayoritariamente similares entre hábitats. Algunos aspectos de las hojas (como Área Foliar Específica y contenido de N foliar) y fotosíntesis (ej.: rendimiento cuántico y tasa de transporte de electrones) presentaron valores mayores en las plantaciones, intermedios en los bosques secundarios y menores en los pastizales abandonados. Se obtuvo un aumento en las tasas fotosintéticas bioquímicas (como Vcmax, Jmax) y la eficiencia del Fotosistema II (ej.: disipación de energía térmica) en hojas provenientes de las plantaciones comparado a las de los pastizales, posiblemente relacionado a un mayor %N foliar. Los resultados sugieren que el N foliar puede ser más importante que el contenido de agua del suelo y que los factores micrometeorológicos para marcar diferencias en los procesos fotosintéticos entre hábitats. Las plántulas de estas dos especies en las plantaciones con árboles de tres años de edad (incluyendo dos fijadoras de N) incrementaron ciertos aspectos de su fotosíntesis y crecimiento comparado a las plántulas en los pastizales abandonados de especies exóticas, por lo tanto, esta práctica puede ayudar a incrementar la recuperación de los bosques en áreas agrícolas abandonadas.

Root-shoot allometry of tropical forest trees determined in a large-scale aeroponic system.

BACKGROUND AND AIMS: This study is a first step in a multi-stage project aimed at determining allometric relationships among the tropical tree organs, and carbon fluxes between the various tree parts and their environment. Information on canopy-root interrelationships is needed to improve understanding of above- and below-ground processes and for modelling of the regional and global carbon cycle. Allometric relationships between the sizes of different plant parts will be determined. METHODS: Two tropical forest species were used in this study: Ceiba pentandra (kapok), a fast-growing tree native to South and Central America and to Western Africa, and Khaya anthotheca (African mahogany), a slower-growing tree native to Central and Eastern Africa. Growth and allometric parameters of 12-month-old saplings grown in a large-scale aeroponic system and in 50-L soil containers were compared. The main advantage of growing plants in aeroponics is that their root systems are fully accessible throughout the plant life, and can be fully recovered for harvesting. KEY RESULTS: The expected differences in shoot and root size between the fast-growing C. pentandra and the slower-growing K. anthotheca were evident in both growth systems. Roots were recovered from the aeroponically grown saplings only, and their distribution among various diameter classes followed the patterns expected from the literature. Stem, branch and leaf allometric parameters were similar for saplings of each species grown in the two systems. CONCLUSIONS: The aeroponic tree growth system can be utilized for determining the basic allometric relationships between root and shoot components of these trees, and hence can be used to study carbon allocation and fluxes of whole above- and below-ground tree parts.

Temperature and saline stress on seedlings of Swietenia macrophylla: a comparative study.

Physical responses of plants to change in climatic factors like temperature, precipitation and abiotic factors like salinity intrusion may lead positive or negative effects. Some factor may promulgate growth while other may stunts their vigour. Present study seeks growth of a plantation species at its early stage of life towards elevated temperature and saline water stresses. Growth records of Swietenia macrophylla seedlings were enumerated by measuring height, collar diameter and leaf number development of the replicates growing at an environment-controlled plant growth chamber. One experimented with merely elevated temperature while other tries to find results of combined effect of elevated temperature (30, 32 and 34 degrees C) and saline (0.5, 1.5 and 2.5 g L(-1) NaCl) to said species seedlings. Seedling replicates showed diverse response to elevated temperature and saline irrigation at height, collar diameter and leaf number development. Results depict that elevated temperature alone might be positive for S. macrophylla seedlings, rather most favourable for its growth in height, however, collar diameter and leaf number may remain unaffected. Saline treatment along with higher temperature stresses may lead seedlings toward stunted or very low growth. As saline intensity increases, species growth tends to decrease proportionally. Elevated temperature aided with higher salinity may direct further under development of S. macrophylla seedlings which is distressing to plantation establishment of this species in sites which are vulnerable to salinity intrusion due to climate change. However, S. macrophylla may be a promising plantation species in drier part of the globe in near future.

Anatomy, ultrastructure, and secretory activity of the floral nectaries in Swietenia macrophylla (Meliaceae).

PREMISE OF THE STUDY: While mahogany (Swietenia macrophylla) is one of the most important forest species in the Amazon region, little is known about its reproductive biology. Knowledge about the nectary structure and dynamics of nectar production of this species represent a key step toward understanding its relationship with pollinators. • METHODS: Mahogany tree floral buds and flowers in anthesis were collected, fixed, and processed for study by light and transmission and scanning electron microscopy. The chemical composition of nectar and the nectary pigments was also studied. • KEY RESULTS: Both staminate and pistillate flowers have nectaries, which contain a papillose epidermis and stomata. The nectariferous tissue is parenchymatous, with the cell cytoplasm primarily containing mitochondria and plastids. Secretory activity initiates at the beginning of anthesis, which occurs at nightfall. Flowers undergoing anthesis become structurally modified, with starch grains in the plastids disappearing. The number of plastoglobuli in the plastids also increases when nectaries change color from pale yellow to intense red. Pistillate and staminate flowers produce meager nectar rewards. • CONCLUSIONS: Changes in plastoglobuli number seem to be related to an increase in carotenes and color changes during anthesis. Carotenes can be linked to the protection of the plant against oxidative stress, which results from secretory activities. Nectary color has a limited role as a pollinator attractant. Floral rewards comprise small nectar droplets in both flower types, in addition to a few pollen grains in staminate flowers. These meager rewards are probably adapted to attract small generalist insects.

[Seed rain, soil seed bank, and natural regeneration of natural Toona ciliata var. pubescens forest].

Taking the natural Toona ciliata var. pubescens forest in the Jiujiangshan National Nature Reserve in Jiangxi Province of China as test object, an investigation was conducted on the seed rain, soil seed bank, and seedlings number in 2008-2011. The seed rain of the forest was dispersed from late October to the end of December. In 2010, the seed rain intensity in different sampling plots was in the order of Xiagongtang observatory (320.3 +/- 23.5 seeds x m(-2)) > Xiagongtang protection station (284.7 +/- 24.2 seeds x m(-2)) > Daqiutian protection station (251.6 +/- 24.7 seeds x m(-2)), and the quantity of the intact seeds in soil supplied for seed germination and regeneration was 222.0, 34.3, and 22.6 seeds x m(-2), respectively. The seed bank reserves was affected by the seed production amount, bird feeding, and seed viability, etc., of which, bird feeding was the prime factor for the substantial drop of the seed bank reserves. Due to the low resistance against storage and a large number of rot during storage, the seeds in soil could hardly be effectively stored beyond one month. The seedlings germinated in December were averagely less than 2 stands x m(-2), and the soil seed reserves in the next January was the least (6.7-11.8 seeds x m(-2)), with the germinated seedlings averagely 0.4-0.6 stands x m(-2), which was consistent with the rare distribution of natural seedlings in the forest. It was concluded that the small seed rain reserves, low seed vigor of soil seed bank, and low seedling establishment were the important factors impacting the natural regeneration of T. ciliata var. pubescens.

A novel means for cryopreservation of germplasm of the recalcitrant-seeded species, Ekebergia capensis.

Cryopreserved zygotic embryonic axes offer the best means of genetic diversity conservation of recalcitrant-seeded species, but frequently shoots fail to develop following processing for, and after, cryostorage. The present work offers a means to overcome this, by generating adventitious shoots from seedling roots produced after axis cryopreservation. Embryonic axes of Ekebergia capensis were exposed to cryoprotectants, flash dried, and rapidly cooled in nitrogen slush. Cryoprotection was an essential step, with both glycerol and DMSO permitting survival after cryogen exposure, but sucrose alone, or in combination with glycerol, was deleterious. Adventitious shoots were formed from seedling roots developed by axes germinated after cryogen exposure, after being subjected to intermittent flushing with a BAP-containing medium for 24 h in a temporary immersion system and subsequent culture on a semi-solid BAP-containing medium. After excision, a high proportion of the adventitious shoots produced roots in vitro, with most of these rooted plantlets being subsequently successfully acclimated.

Comportamento meiótico durante a microsporogênese em espécies da família meliaceae / Comportamiento meiótica durante la microsporogénesis en especies de la familia meliaceae / Meiotic behavior during microsporogenesis of some species of meliaceae family

A família Meliaceae inclui espécies de grande interesse agronômico, ecológico, econômico e ornamental de alto potencial madeireiro no mundo. No Brasil ocorrem cerca de seis gêneros e 100 espécies. Considerando a falta de estudos citológicos para esse grupo, este trabalho descreve o comportamento meiótico durante a microsporogênese de seis espécies (Trichilia pallida, Trichilia elegans, Trichilia catigua, Cedrela fissilis, Cabralea canjerana, Guarea guidonea) da família Meliaceae, representando quatro dos seis gêneros que estão presentes no Brasil. Inflorescências foram coletadas e fixadas em etanol/ácido acético (3:1 v/v) por 24 horas, transferidos para álcool a 70%, e acondicionadas sob refrigeração. As lâminas foram preparadas pela técnica de esmagamento, coradas com carmim acético a 1%. A análise citogenética revelou poucas irregularidades meióticas, sendo estas relacionadas a segregação dos cromossomos, fusos irregulares e conexão citoplasmática. Como consequência da segregação irregular dos cromossomos na meiose I e II e da organização irregular dos fusos na meiose II, o padrão de citocinese também foi irregular originando tétrades com micrócitos e tríades, resultando em micrósporos desbalanceados e de núcleo restituído (2n).

The Meliaceae family includes the most important species with great agronomic, ecological, economic and ornamental value and high timber potential in the world. In Brazil, approximately six genera and 100 species are found. Considering the lack of cytological studies for its genera, the present study describes the meiotic behavior during microsporogenesis of six species of the Meliaceae family, representing four of the six genera that are present in Brazil; these species are: Trichilia pallida, Trichilia elegans, Trichilia catigua, Cedrela fissilis, Cabralea canjerana, Guarea guidonea. Inflorescences were collected and fixed in ethanol/acetic acid (3:1 v/v) for 24 hours, transferred to alcohol at 70%, and stored under refrigeration. The slides were prepared by squashing, and stained with acetic carmine 1% and observed under optical microscopy. Cytogenetic analysis revealed few meiotic irregularities, which are related to segregation of chromosome spindles and irregular cytoplasmic connection. As a result of irregular segregation of chromosomes during meiosis I and II and the irregular organization of the spindles in meiosis II, the pattern of cytokinesis was also irregular resulting in microcytic tetrads and triads, unbalanced microspores and restored nuclei (2n).

La familia Meliaceae incluye especies de gran interés agronómico, ecológico, económico y ornamental de alto potencial maderero en el mundo. En Brasil ocurren cerca de seis géneros y 100 especies. Considerando la falta de estudios citológicos para ese grupo, este trabajo describe el comportamiento meiótica durante la microsporogénesis de seis especies (Trichilia pallida, Trichilia elegans, Trichilia catigua, Cedrela fissilis, Cabralea canjerana, Guarea guidonea) de la familia Meliaceae, representando cuatro de los seis géneros que están presentes en Brasil. Inflorescencias fueran colectadas y fijadas en etanol/ácido acético (3:1 v/v) por 24 horas, transferidos para alcohol a 70%, y acondicionadas bajo refrigeración. Las láminas fueron preparadas por la técnica de aplastamiento, coloradas con carmín acético a 1%. El análisis citogenética reveló pocas irregularidades meióticas, siendo éstas relacionadas a la segregación de los cromosomas, fusos irregulares y conexión citoplasmática. Como consecuencia de segregación irregular de cromosomas en la meiosis I y II y de la organización irregular de los fusos en la meiosis II, el estándar de citocinesis también fue irregular originando tétradas con micrófitos y tríades, resultando en micros poros desbalanceados y de núcleo restituido (2n).

Exigências nutricionais e crescimento de plantas de mogno (Swietenia macrophylla King) / Nutritional requirements and growth of mahogany (Swietenia macrophylla King) plants

A necessidade de desenvolver pesquisas referentes aos requerimentos nutricionais das espécies florestais, principalmente as essências florestais nativas da Amazônia, como o mogno, é inadiável, visto que as constantes explorações de espécies de alto valor econômico são cada vez maiores. Com o objetivo de avaliar o crescimento e o requerimento nutricional de mudas de mogno, foi realizado um experimento em casa de vegetação com 14 tratamentos. O delineamento experimental foi de blocos casualisados, com 5 repetições. As características de crescimento avaliadas foram: altura da parte aérea, diâmetro de colo, matéria seca da parte aérea, da raiz e total, relação raiz e parte aérea e conteúdo de nutrientes da matéria seca da parte aérea. Os resultados obtidos permitem concluir que: é necessária a correção conjunta da acidez e da fertilidade do solo para solos ácidos e de baixa fertilidade natural, mesmo que o teor de matéria orgânica seja considerado alto; dos nutrientes, P é o que mais limita o desenvolvimento da planta, bem como a absorção dos outros nutrientes; não há necessidade de adição de K para o desenvolvimento das plantas quando se realiza calagem; na ausência de calagem a adição de K deve ser recomendada e o requerimento nutricional do mogno em macronutrientes obedece à ordem decrescente de: P>S>K>N.

The need for developing research related principally to the nutritional requirements of essential native Amazonian forest species, such as mahogany, is urgent, since the exploration of highly valuable species is continually more frequent. With the objective of evaluating the growth and the nutritional requirement of mahogany plants, an experiment in a vegetation house with 14 treatments was undertaken. The experiment outline was of occasional blocks with 5 repetitions. The growth characteristics evaluated were: height of the aerial part, diameter of the bottom, dry material of the aerial part, root and total, relationship of root and aerial part, relationship and nutrient content of dry material of the aerial part. The results lead to the conclusion that: the conjoint correction of acidity and the fertility of the soil for acid soils and low natural fertility is necessary even if the content of the organic material is considered high; of the nutrients, P is the one which limits most the development of the plant, as well as the absorption of other nutrients; there is no need to add K for developing the plants when liming occurs.; addition of K is recommended when liming does not occur; and the nutritional requirement of mahogany in macronutrients obeys the decreasing order of P>S>K.N.