Revisiting the relative growth rate hypothesis for gymnosperm and angiosperm species co-occurrence.

PREMISE OF THE STUDY: It is unclear to what extent the co-occurrence of angiosperm and gymnosperm species in some marginal ecosystems is explained by reduced growth in angiosperms due to carbon (C) limitation and by high stress tolerance in gymnosperms associated with lack of vessels and resource conservation. METHODS: We examined growth patterns and traits associated with C balance in four evergreen angiosperm species (including one vesselless species, Drimys winteri) and three gymnosperm tree species of a cold-temperate rainforest in southern Chile. We measured the mean basal area increment for the first 50 (BAI50 ) and the last 10 years (BAI10 ), wood density, leaf lifespan, and nonstructural carbohydrate (NSC) concentrations in different organs. KEY RESULTS: BAI50 was 6-fold higher in angiosperms than in gymnosperms and ca. 4-fold higher in Drimys than in the fastest-growing gymnosperm. BAI10 and aboveground NSC concentrations were significantly higher and leaf lifespan lower in angiosperms than in gymnosperms; these differences, however, were largely driven by the slow growth and low NSC concentrations of the Cupressaceae species (Pilgerodendron uviferum), while the two Podocarpaceae had BAI10 and NSC concentrations similar to angiosperms. In angiosperms, NSC and starch concentrations were generally higher in species with lower BAI10 , indicating no severe C limitation. CONCLUSIONS: The co-occurrence of angiosperms and gymnosperms in cold-temperate rainforests of southern Chile is not explained by growth disadvantages and C limitation in angiosperms. Long leaf longevity, but not lack of vessels, appeared to favor resource conservation and C balance in some gymnosperms (Podocarpaceae).

[Anatomy and development of stamens and carpels of Drimys granadensis (Winteraceae)]. / Anatomía y desarrollo de estambres y carpelos en Drimys granadensis (Winteraceae).

Winteraceae has long been considered a family with early diversification among angiosperms, with characters such as: flowers with many spirally arranged parts and apocarpic ovary formed by plicated carpels with sessile stigma. In Drimys, the presence or absence of conspicuous glands on the connective of the stamens have been used as a taxonomic character, and it is considered a synapomorphy for the clade including Drimys angustifolia, D. brasiliensis, D. granadensis and D. roraimensis (Northeastern clade); however, the anatomy of stamens and carpels has only been studied in detail for D. winteri (Southwestern clade). In this research, the presence and the structure of glands on the connective of stamens was studied in seven species of the genus from herbarium specimens, and a detailed study of the anatomy and development of stamens and carpels was carried out by scanning electron and optic microscopy in Drimys granadensis. We found similarities between D. granadensis and D. winteri for the following characters: Basic type anther wall formation, secretory tapetum that collapses at maturity, intermediate type microsporogenesis with formation of a transient cell plate in telophase I, ascidiated carpel due to the formation of an adaxial lip during development, stigma closed by interdigitation of epidermal cells. We also determined that the large glands on anther mature connective are originated by an overgrowth of subepidermal oil cells; this character is a Northeastern Drimys clade synapomorphy, while it was absent in both Drimys of Southwestern clade (which includes D. andina, D. confertifolia and D. winteri), and the rest of the Winteraceae. We are proposing the hypothesis that the highly variable enviromental conditions in the tropics where Drimys Northeastern clade is distributed, with a wide range of pollinators, would be associated with the emergence of glandular conspicuously stamens; while, as a prediction to be confirmed, temperated Southwestern clade species, without conspicuous glands, should have a smaller range of visitors and/or pollinators, or even be anemophilous species as Drimys confertifolia.

Anatomía y desarrollo de estambres y carpelos en Drimys granadensis (Winteraceae) / Anatomy and development of stamens and carpels of Drimys granadensis (Winteraceae)

Winteraceae has long been considered a family with early diversification among angiosperms, with characters such as: flowers with many spirally arranged parts and apocarpic ovary formed by plicated carpels with sessile stigma. In Drimys, the presence or absence of conspicuous glands on the connective of the stamens have been used as a taxonomic character, and it is considered a synapomorphy for the clade including Drimys angustifolia, D. brasiliensis, D. granadensis and D. roraimensis (Northeastern clade); however, the anatomy of stamens and carpels has only been studied in detail for D. winteri (Southwestern clade). In this research, the presence and the structure of glands on the connective of stamens was studied in seven species of the genus from herbarium specimens, and a detailed study of the anatomy and development of stamens and carpels was carried out by scanning electron and optic microscopy in Drimys granadensis. We found similarities between D. granadensis and D. winteri for the following characters: Basic type anther wall formation, secretory tapetum that collapses at maturity, intermediate type microsporogenesis with formation of a transient cell plate in telophase I, ascidiated carpel due to the formation of an adaxial lip during development, stigma closed by interdigitation of epidermal cells. We also determined that the large glands on anther mature connective are originated by an overgrowth of subepidermal oil cells; this character is a Northeastern Drimys clade synapomorphy, while it was absent in both Drimys of Southwestern clade (which includes D. andina, D. confertifolia and D. winteri), and the rest of the Winteraceae. We are proposing the hypothesis that the highly variable enviromental conditions in the tropics where Drimys Northeastern clade is distributed, with a wide range of pollinators, would be associated with the emergence of glandular conspicuously stamens; while, as a prediction to be confirmed, temperated Southwestern clade species, without conspicuous glands, should have a smaller range of visitors and/or pollinators, or even be anemophilous species as Drimys confertifolia. Rev. Biol. Trop. 62 (3): 1147-1159. Epub 2014 September 01.

La familia Winteraceae ha sido tradicionalmente considerada como de diversificación temprana entre las angiospermas por varios caracteres, entre ellos: flores con muchas partes distribuidas en espiral y ovario apocarpico formado por carpelos de tipo plicado con estigma sésil. En el género Drimys, la presencia o ausencia de glándulas conspicuas sobre el conectivo de los estambres ha sido usado como un carácter taxonómico, y su presencia se considera como una sinapomorfía del clado formado por Drimys angustifolia, D. brasiliensis, D. granadensis and D. roraimensis (clado nororiental); sin embargo, la anatomía de estambres o carpelos ha sido solamente estudiada en detalle en D. winteri (clado suroccidental). En esta investigación, la presencia y estructura de las glándulas del conectivo fue estudiada en las siete especies del género Drimys a partir de ejemplares de herbario, además, se realizó un estudio detallado de la anatomía y desarrollo de estambres y carpelos de Drimys granadensis empleando microscopía óptica y microscopía de barrido; y se compararon con los resultados previos en Drimys winteri. Se encontraron similitudes en los siguientes caracteres: formación de la pared de la antera de tipo básico, tapetum secretor que colapsa en la madurez, microsporogénesis de tipo intermedio con formación de una placa celular transitoria en telofase I, carpelo ascidiado debido a la formación de un labio adaxial durante el desarrollo, estigma cerrado por interdigitación de células epidérmicas. Se determinó que las glándulas de gran tamaño sobre el conectivo de la antera madura se originaron por sobrecrecimiento de células oleíferas subepidérmicas, siendo una sinapomorfía del clado nororiental, que esta ausente tanto en el clado suroccidental de Drimys (D. andina, D. confertifolia y D. winteri), como en el resto de la familia. Se propone la hipótesis de que las condiciones altamente variables en las zonas tropicales donde se distribuye el clado nororiental de Drimys, con una amplia gama de polinizadores, estarían asociadas al surgimiento de estambres conspicuamente glandulares; en tanto que proponemos como predicción que las especies circunscritas a la zona templada del Sur de Suramérica (Clado suroccidental), sin glándulas conspicuas, deberían presentar una menor variedad de visitantes y/o polinizadores, o incluso ser especies anemófilas como Drimys confertifolia.

Bark harvesting systems of Drimys brasiliensis Miers in the Brazilian Atlantic rainforest.

Drimys brasiliensis Miers, locally known as cataia or casca-de-anta, is a native tree species of the Atlantic Rainforest. Its bark is harvested from natural populations. This study examined the recovery capacity of the bark of D. brasiliensis under different bark harvesting methods, as well as the influence of these approaches on its population dynamics and reproductive biology. While none of these treatments resulted in changes in phenological behavior or the rate of increase of diameter at breast height and tree height, the removal of wider bark strips resulted in lower rates of bark recovery and higher rates of insect attack and diseases. Accordingly, the results recommend using strips of bark 2 cm wide and 2 m long, with 4 cm between strips, for effective rates of bark regrowth and for lower susceptibility to insect attack and diseases. From these studies, we concluded that D. brasiliensis has a high potential for sustainable management of its natural populations, demonstrating the possibility of generating an important supplementary income for farmers and contributing to the use and conservation of the Atlantic Rainforest.

Foliar uptake of fog water and transport belowground alleviates drought effects in the cloud forest tree species, Drimys brasiliensis (Winteraceae).

Foliar water uptake (FWU) is a common water acquisition mechanism for plants inhabiting temperate fog-affected ecosystems, but the prevalence and consequences of this process for the water and carbon balance of tropical cloud forest species are unknown. We performed a series of experiments under field and glasshouse conditions using a combination of methods (sap flow, fluorescent apoplastic tracers and stable isotopes) to trace fog water movement from foliage to belowground components of Drimys brasiliensis. In addition, we measured leaf water potential, leaf gas exchange, leaf water repellency and growth of plants under contrasting soil water availabilities and fog exposure in glasshouse experiments to evaluate FWU effects on the water and carbon balance of D. brasiliensis saplings. Fog water diffused directly through leaf cuticles and contributed up to 42% of total foliar water content. FWU caused reversals in sap flow in stems and roots of up to 26% of daily maximum transpiration. Fog water transported through the xylem reached belowground pools and enhanced leaf water potential, photosynthesis, stomatal conductance and growth relative to plants sheltered from fog. Foliar uptake of fog water is an important water acquisition mechanism that can mitigate the deleterious effects of soil water deficits for D. brasiliensis.

Estrutura populacional e incremento corrente anual de casca-de-anta (Drimys brasiliensis Miers - Winteraceae) em Caçador, Santa Catarina, Brasil / Population structure and annual increment in "casca-de-anta" (Drimys brasiliensis Miers - Winteraceae) from Caçador Municipality, Santa Catarina State, Brazil

Drimys brasiliensis Miers, conhecida como cataia ou casca-de-anta, é árvore nativa da Mata Atlântica e as cascas tem sido utilizadas medicinalmente a partir da exploração de plantas em populações naturais. Este trabalho teve como objetivo estudar a demografia de duas populações naturais de D. brasiliensis, (1) Reserva Genética Florestal de Caçador (RGFC) e (2) Floresta Nacional de Caçador (FLONA), ambas no município de Caçador (SC), visando fundamentar estratégias de exploração sustentável e conservação deste recurso florestal não-madeireiro. A maior luminosidade no sub-bosque existente na FLONA atuou positivamente na espécie, aumentado a capacidade de incremento em diâmetro à altura do peito (DAP), altura (H) e área basal (AB), além de antecipar a reprodução em plantas de menor porte. A análise do padrão espacial das plantas reprodutivas na RGFC mostrou padrão agregado, e na FLONA até a distância de 25 metros. Esse comportamento indicou que a espécie apresenta potencial de manejo em florestas secundárias, formação sucessional em que se encontra a maioria dos remanescentes de Mata Atlântica, além de indicar potencial para cultivo em sistemas agroflorestais.

Known as "cataia" or "casca-de-anta", Drimys brasiliensis Miers is a tree native to the Atlantic Forest and its barks have been medicinally used by exploring natural populations. The present work aimed to study the demography of two D. brasiliensis natural populations, (1) Caçador Forest Genetic Reserve (RGFC) and(2) Caçador National Forest (FLONA), both located in Caçador Municipality, Santa Catarina State, Brazil, in order to establish strategies for sustainable exploration and conservation of such non-timber forest resource. The higher luminosity in FLONA understory was beneficial to the species by increasing their increment capability regarding diameter at breast height (DBH), height (H) and basal area (BA), and made the reproduction in smaller plants earlier. The spatial analysis of reproductive plants in RGFC had an aggregate pattern, whereas in FLONA until 25m distance was detected. Such results indicated that this species presents potential for management in secondary forests, the successional formation where the major Atlantic Forest remnants are found, as well as potential for cultivation in agroforestry systems.