Spatial distribution analysis of Dicksonia sellowiana Hook. in Araucaria forest fragments with different sizes / Análise da distribuição espacial de Dicksonia sellowiana Hook. em fragmentos de Floresta com Araucária com diferentes tamanhos

Abstract Dicksonia sellowiana Hook. (Dicksoniaceae) is target of extractive exploitation and is threatened with extinction. We analyzed the population structure, the spatial distribution pattern of D. sellowiana and its relationship with environmental parameters within three fragments of Araucaria Forest in Rio Grande do Sul, Brazil. The fragments are of different sizes, namely, large (H1LF) with 246 ha, medium (H2MF) with 57 ha and small (H3SF) with 5.2 ha. Within each site, 1 ha was delimited, divided into 100 subplots (100 m2), of which 20 were selected with a draw. In each subplot, counting of the individuals, the registration of the caudice height and the coverage of leaves (SC) (m2), measurements of photosynthetically active radiation (PAR), canopy opening degree (CO), soil moisture (SM) and litter thickness (LT). The temperature (T) was measured inside each site. A total of 792 plants were sampled, of which 551 were concentrated in H1LF, 108 in H2MF and 133 in H3SF. An average of 1320 ha-1 individuals were estimated. Of the total including the three fragments, 96.9% of the individuals are in the first class of height (up to 0.8 m), indicating a great potential of population development. The spatial distribution pattern (AI) was aggregated in the three populations and the plants presented a heterogeneous total coverage, between 4.73 m2 (H2MF) and 2,223.47 m2 (H1LF). The highest values ​​of SC and SM were more related to the distribution of individuals in H1LF whereas the opposite was recorded in H2MF. The highest values ​​of PAR, LT and CO correlated with the distribution of D. sellowiana in H3SF. In addition to revealing that the H1LF population is among the most dense in southern Brazil, the results demonstrated a significant structural distinction between the interior populations of the fragments, in spite of them being located near to one another and being part of the same natural field matrix.

Resumo Dicksonia sellowiana Hook. (Dicksoniaceae) é alvo de exploração extrativista e encontra-se ameaçada de extinção. Analisamos a estrutura populacional, o padrão de distribuição espacial de D. sellowiana e sua relação com parâmetros ambientais no interior de três fragmentos de Floresta com Araucária, no Rio Grande do Sul (RS), Brasil. Os fragmentos possuem diferentes tamanhos sendo denominados de grande (H1LF) com 246 ha, médio (H2MF) com 57 ha e de pequeno (H3SF) com 5,2 ha. No interior de cada sítio, foi demarcado 1 ha, fracionado em 100 subparcelas (100m2), das quais 20 foram sorteadas. Em cada subparcela foi feita a contagem dos indivíduos, o registro da altura do cáudice e da cobertura (SC) (m2) das folhas, as medições da radiação fotossinteticamente ativa (PAR), grau de abertura do dossel (CO), umidade do solo (SM) e espessura da serapilheira (LT). A temperatura (T) foi medida no interior de cada sítio. Foram amostradas 792 plantas, das quais 551 concentradas no H1LF, 108 no H2MF e 133 no H3SF e em média foram estimados 1320 indivíduos ha-1. Do total dos três fragmentos, 96,9% dos indivíduos estão na primeira classe de altura (até 0,8 m), indicando grande potencial de desenvolvimento das populações. O padrão de distribuição espacial (AI) foi agregado nas três populações e as plantas apresentaram uma cobertura total heterogênea, entre 4,73m2 (H2MF) e 2.223,47m 2 (H1LF). Os maiores valores de SC e de SM foram mais relacionadas com a distribuição dos indivíduos no H1LF enquanto que o contrário foi registrado no H2MF. Os maiores valores de PAR, LT e de CO relacionaram-se com a distribuição de D. sellowiana no H3SF. Além de revelar que a população do H1LF está entre as mais densas já descritas no sul do Brasil, os resultados demonstraram uma significativa distinção estrutural entre as populações dos interiores dos fragmentos com diferentes tamanhos, embora muito próximos geograficamente e inseridos em uma mesma matriz de campo natural.

Early harvest increases post-harvest physiological quality of Araucaria angustifolia (Araucariaceae) seeds

ResumenAraucaria angustifolia es una conífera nativa de Brasil y una especie en peligro de extinción. Sus semillas tienen un corto período de viabilidad, factor que contribuye a su vulnerabilidad. Este estudio tuvo como objetivo evaluar la calidad fisiológica durante el período de desarrollo y post-almacenamiento de semillas de A. angustifolia. Conos de A. angustifolia fueron recolectados en poblaciones naturales en Curitibanos, Santa Catarina, Brasil, en marzo, abril, mayo y junio y clasificados en los estadios de desarrollo cotiledonar i, ii y iii de acuerdo con el mes de recolecta. Un total de 10 conos fueron recolectados para cada estadio. Las semillas fueron almacenadas en refrigerador durante 60 y 120 días y posteriormente sometidas a pruebas de germinación (25 °C - fotoperiodo de 12 h) siendo evaluados el contenido de humedad, tetrazolio y el vigor (conductividad eléctrica [75 mL de agua destilada a 25 °C], índice de velocidad de germinación, y la longitud de la parte aérea y de la raíz). Durante el desarrollo de las semillas, el contenido de humedad se redujo desde el estadio cotiledonar (66.54 %) al estadio iii (47.44%), y el vigor aumentaron en el último estadio. Durante el almacenamiento, el contenido de humedad en el estadio cotiledonar y estadio i fue estable. Entretanto, las semillas almacenadas mostraron una reducción en el contenido de humedad después de 120 días en los estadios ii y iii. La calidad fisiológica en el estadio cotiledonar mostró un aumento de 86 % y 93 % de germinación después de 60 y 120 días de almacenamiento, respectivamente, a diferencia de los estadios ii y iii, los cuales mostraron una disminución en la viabilidad de las semillas y en el vigor después del almacenamiento. La conductividad eléctrica fue mayor para las semillas en estadio cotiledonar recién recolectadas que para aquellas almacenadas durante 60 y 120 días. Sin embargo, en otras estadios, el contenido de lixiviados después de 120 días de almacenamiento aumentó con el avance del período de recolecta. El índice de velocidad de germinación y la longitud de la parte aérea y raíz después del almacenamiento eran más altos para las semillas en el estadio cotiledonar y el estadio i, a diferencia del estadio ii y iii, los cuales tenían raíz y parte aérea de menor longitud durante el almacenamiento. Por lo tanto, el mantenimiento del contenido de humedad de la semilla durante el almacenamiento fue variable y depende del período de recolecta. Además, la calidad fisiológica de las semillas difiere entre los estadios más tempranos o tardíos. Una recolección precoz favoreció la calidad fisiológica de las semillas, y puede ser una estrategia para aumentar la conservación de semillas de A. angustifolia.

AbstractAraucaria angustifolia is a conifer native to Brazil and is an endangered species. Since this species seeds have a short period of viability, its vulnerability is higher. Thus the aim of this study was to evaluate the physiological quality of A. angustifolia seeds during the development and post-storage periods. For this, cones of A. angustifolia were collected from a natural population in Curitibanos, Santa Catarina, Brazil, in March, April, May and June 2012. The collected seeds were classified into developmental stages of cotyledonary, i, ii and iii according to the month of collection; a total of 10 cones were collected for each stage. Seeds were stored in a refrigerator for 60 and 120 days, and were submitted to a chamber germination test (25 °C-photoperiod 12 h). Additionally, seeds were tested for moisture content (105 °C for 24 hours), tetrazolium (0.1 % for 1 hour) and vigor (electric conductivity [75 mL distilled water at 25 °C], germination speed index, and shoot and root length). Our results showed that during seed development, moisture content decreased from the cotyledonary stage (66.54 %) to stage iii (49.69 %), and vigor increased in the last stage. During storage, moisture content at cotyledonary stage and stage i was stable. On the other hand, stored seeds exhibited a decrease in moisture content after 120 days at stages ii and iii. Physiological quality at the cotyledonary stage resulted in an increased germination rate of 86 % and 93 % after 60 and 120 days of storage, respectively; unlike stages ii and iii exhibited a decrease in seed viability and vigor after storage. Electrical conductivity was higher for fresh seeds at the cotyledonary stage, than for those stored for 60 and 120 days. However, in other stages, released leachate content after 120 days of storage, increased with the advance of the collection period. Germination speed index and shoot and root lengths after storage were highest for seeds at the cotyledonary stage and stage i; unlike stages ii and iii which had short root and shoot lengths during storage. Thus, the maintenance of seed moisture content during storage was variable and dependent on the period of collection. Furthermore, the physiological quality differed among earlier and later stages. Early collection favored seed physiological quality, and may be a strategy for better conservation of A. angustifolia seeds. Rev. Biol. Trop. 64 (2): 885-896. Epub 2016 June 01.

Germination and soil seed bank traits of Podocarpus angustifolius (Podocarpaceae): an endemic tree species from Cuban rain forests

Podocarpus angustifolius is an endangered recalcitrant-seeded small tree, endemic to mountain rain forests in the central and Pinar del Río regions in Cuba. In this study, the germination patterns of P. angustifolius seeds were evaluated and the nature of the soil seed bank was determined. Using a weighted two-factor design, we analyzed the combined germination response to seed source (i.e. freshly matured seeds directly collected from trees versus seeds extracted from soil samples) and pretreatment (i.e. seed water-immersion for 48h at room temperature). Germination was delayed for four weeks (≈30 days) in all cases, regardless of both factors analyzed. Moreover, nine additional days were necessary to achieve high germination values (in the case of fresh, pretreated seeds). These results overall may indicate the existence of a non-deep simple morphophysiological dormancy in P. angustifolius seeds. The water-immersion significantly enhanced seed germination, probably as a result of the hydration of recalcitrant seeds. Although germination of seeds extracted from soil samples was low, probably due to aging and pathogen effects throughout the time of burial, the study revealed the existence of a persistent soil seed bank (at least short-termed) of ≈42 viable seeds per m² in the upper 10cm of soil. Such a record is noteworthy since references to persistent soil seed banks in recalcitrant-seeded species are scarce in the literature. The population consequences derived from the formation of persistent soil seed banks in this endangered species are discussed. Rev. Biol. Trop. 59 (3): 1061-1069. Epub 2011 September 01.

Podocarpus angustifolius es un árbol endémico de los bosques lluviosos de la región de Pinar del Río y la parte central de Cuba, que se encuentra en peligro de extinción. En este estudio se evaluó la germinación de sus semillas y la naturaleza del banco de semillas del suelo. Específicamente, se analizó la respuesta germinativa de las semillas a dos factores: su procedencia (recolectadas directamente de los árboles versus extraídas de muestras de suelo) y el pretratamiento (inmersión en agua durante 48h a temperatura ambiente). La germinación no comenzó hasta las cuatro semanas (≈30 días) en todos los casos. Además, fueron necesarios 9 días más para alcanzar un valor elevado de germinación (en el caso de semillas recolectadas del árbol con pretratamiento), lo que parece indicar la existencia de un letargo de tipo morfofisiológico simple no profundo. El pretratamiento incrementó significativamente la germinación, posiblemente por hidratación de las semillas recalcitrantes. El estudio demostró la existencia de un banco de semillas persistente en el suelo, al menos de corta duración de ≈42 semillas viables por m² en los 10 primeros cm del suelo. Dicho hallazgo es destacable, ya que los casos descritos en la literatura sobre bancos persistentes en especies con semillas recalcitrantes son escasos. Además, se discute la importancia que tiene para esta especie amenazada la existencia de un banco de semillas persistente.

Structure of mixed ombrophyllous forests with Araucaria angustifolia (Araucariaceae) under external stress in Southern Brazil

This study is part of the Floristic and Forest inventory of Santa Catarina, conceived to evaluate forest resources, species composition and structure of forest remnants, providing information to update forest conservation and land use policy in Southern Brazilian State of Santa Catarina (95 000km²). In accordance to the Brazilian National Forest inventory (IFN-BR), the inventory applies systematic sampling, with 440 clusters containing four crosswise 1 000m² plots (20x50m) each, located on a 10x10km grid overlaid to land use map based on classification of SPOT-4 images from 2005. Within the sample units, all woody individuals of the main stratum (DBH≥10cm) are measured and collected (fertile and sterile), if not undoubtedly identified in field. Regeneration stratum (height>1.50m; DBH<10cm) is registered in 100m² in each sample unit. Floristic sampling includes collection of all fertile trees, shrubs and herbs within the sample unit and in its surroundings. This study performs analysis based on 92 clusters measured in 2008 within an area of 32 320km² of mixed ombrophyllous forests with Araucaria angustifolia located at the state’s high plateau (500m to 1 560m above sea level at 26º00’-28º30’ S and 49º13’-51º23’ W). Mean density (DBH≥10cm) is 578 individuals/ha (ranging from 85/ha to 1 310/ha), mean species richness in measured remnants is 35 (8 to 62), Shannon and Wiener diversity index (H’) varies between 1.05 and 3.48. Despite high total species diversity (364 Magnoliophyta, five Coniferophyta and one tree fern) and relatively high mean basal area (25.75m²/ha, varying from 3.87 to 68.85m²/ ha), the overwhelming majority of forest fragments are considered highly impacted and impoverished, mostly by logging, burning and extensive cattle farming, turning necessary more efficient protection measures. Basal area was considered an appropriate indicator for stand quality and conservation status. Rev. Biol. Trop. 59 (3): 1371-1387. Epub 2011 September 01.

Este estudio es parte del inventario Florístico Forestal de Santa Catarina, realizado para evaluar los recursos forestales, la composición de especies y la estructura de remanentes de bosque, y proporciona información para actualizar la conservación de los bosques y políticas de uso de la tierra en el estado brasileño de Santa Catarina (95 000km²). El inventario se aplica al muestreo sistemático, de 440 conglomerados en cuatro parcelas de 1 000m² cada una, situados en una red de 10x10km. Dentro de las parcelas, todos los individuos leñosos (DAP≥10cm) fueron medidos. El estrato de regeneración (altura>1.50m, DAP<10cm) se registra en 100m² en cada conglomerado. Este estudio realiza un análisis de 92 conglomerados medidos en 2008 dentro de un área de 32 320km² de bosques ombrófilos mixtos con Araucaria angustifolia ubicados en el altiplano del estado. La densidad media (DAP≥10cm) es de 578 individuos/ha (desde 85/ha hasta 1 310/ha), la media de la riqueza de especies en los remanentes es de 35 (8-62), la diversidad (H’) de Shannon y Wiener varía entre 1.05 y 3.48. A pesar de la alta diversidad total de especies (364 Magnoliophyta, cinco Coniferophyta y un helecho arborescente) y el alto promedio del área basal (25.75m²/ha, variando de 3.87 a 68.85m²/ha), la mayoría de los fragmentos de bosque se consideran altamente impactados por la tala, quema y ganadería extensiva, por lo tanto es necesario más medidas eficaces de protección.

Monoicy in A. angustifolia (Bert. ) O. Kuntze (Araucariaceae): I. Morphological aspects of the reproductive structures

Araucaria angustifolia (Bert.) O. Kuntze is a dioecious conifer species native of Brazil. The rare occurrence of monoiceous specimens have been attributed to pathogenic infections or other injuries in adult trees. Here, the morphological characteristics of male and female cones and pollen grains of a monoiceous A. angustifolia are described. Male and female cones and pollen grains presented normal morphology, lacking any sort of injuries or infection and suggesting the existence of further grounds for the occurrence of monoicy in this conifer species.

Araucaria angustifolia (Bert.) O. Kuntze é uma conífera primariamente dióica nativa do Brasil. A ocorrência de raros exemplares monóicos tem sido creditada a infecções patogênicas ou outras injúrias em árvores adultas. Neste trabalho, as características morfológicas de cones masculinos e femininos e dos grãos de pólen de uma A. angustifolia monóica são descritas. Os cones masculinos e femininos e os grãos de pólen apresentaram morfologia normal, se a presença de qualquer tipo de injuria ou infecção, sugerindo a existência de outros mecanismos para a ocorrência de monoicia nesta conífera.