Samambaias epífitas em trilhas do Parque Guairacá, município de Paula Freitas, Paraná / Epiphytic ferns in trails of the Guairacá Park, municipality of Paula Freitas, Paraná state

Os epífitos desempenham importantes funções ecológicas, e em particular as samambaias, mostram uma diversidade significativa em ambientes florestais, ocupando microambientes específicos e diversos. A diversidade de samambaias epifíticas no estado do Paraná ainda é relativamente pouco conhecida. A região de Paula Freitas, em particular, não apresenta estudos específicos para este grupo de plantas. Neste sentido, o presente estudo teve por finalidade avaliar a riqueza de espécies de samambaias epífitas em regiões de trilhas no Parque Municipal Guairacá em Paula Freitas, Paraná. Foram registradas 10 espécies distribuídas em oito gêneros e quatro famílias. A família Polypodiaceae foi a mais rica na área avaliada (oito espécies), reflexo das características morfoanatômicas comuns às espécies da família. Os resultados encontrados contribuem com o reconhecimento das características florísticas e ecológicas de samambaias epífitas ocorrentes no estado do Paraná.(AU)

Epiphytes play important ecological role, and the ferns shows a significant diversity in the forest environments, due to the numerous specific and diverse microenvironments. The diversity of epiphytic ferns in Paraná state is still relatively unknown. The Paula Freitas region, in particular, does not present specific studies for this group of plants. In this sense, the present study aimed to evaluate the diversity of epiphytic ferns in regions of trails in the Guairacá Municipal Park in Paula Freitas, Paraná. Ten species in eight genera and four families were recorded. The family Polypodiaceae (eight species) was the richest in the evaluated area, reflecting the morphoanatomic characteristics common to the family species. The results contribute to the recognition of the floristic and ecological characteristics of epiphytic ferns occurring in the state of Paraná.(AU)

Structural adaptations of two sympatric epiphytic orchids (Orchidaceae) to a cloudy forest environment in rocky outcrops of Southeast Brazil / Adaptaciones estructurales de dos orquídeas epífitas simpátricas (Orchidaceae) en un bosque nuboso de un campo rupestre del sureste de Brasil

The survival of plants in epiphytic environments depends on vegetative adaptations capable to defraud different stresses. Based on the structural diversity of the Orchidaceae, the current study has the objective of relating the anatomical structure of Dichaea cogniauxiana and Epidendrum secundum with the distinct environments where they live. It was expected that, despite structural similarities as strategies for resource acquisition, some peculiar variations related to the distinct light microenvironments (inside or in the edge of the nebular forest, near to “campo rupestre” area) might be found. Leaves and roots of both species were collected in a nebular forest located at a “campo rupestre” area at Serra da Piedade, Brazil), in January and February 2005. D. cogniauxiana is adhered to trunks, in sites with high atmospheric humidity and shaded, while E. secundum is located at the edge of the nebular forest, in more luminous sites. The leaves of E. secundum had thicker cuticle and higher number of stomata per area than those of D. cogniauxiana, characteristics coherent with their distinct pattern of exhibition to sun light. The suprastomatic chambers formed by the thicker cuticle may function as a barrier of resistance to water evaporation. The succulence of the leaves of E. secundum propitiates organic acids storage at night, and the storage of starch may be involved in PEP-carboxylase metabolism, both propitiating CAM mechanism. Roots with larger number of cell layers of the velamen, and specialized thick walled cortical cells (both in E. secundum) help water absorption and indicate better adaptation to an environment with intense solar radiation and a probable higher water deficit. The remarkable cell wall thickening of E. secundum exodermis can confer more efficient protection against the excess of transpiration at the border of the nebular forest. On the other hand, besides D. cogniauxiana be epiphyte, it is in a low position - in a shaded environment and with high relative humidity. Its thin thickened velamen permits the entrance of the low available light, and photosynthesis, producing oxygen and helping to avoid hypoxia condition. As features registered for D. cogniauxiana and E. secundum roots, we can depict the velamen, distinct exodermis and endodermis, and specialized thick walled cortical cells as characteristic of epiphytic plants.

La sobrevivencia de las plantas epífitas a su ambiente depende de las adaptaciones vegetativas que les permiten afrontar diferentes tipos de estrés. Basado en la diversidad estructural de las Orchidaceae, el presente estudio tiene por objetivo relatar la estructura anatómica de Dichaea cogniauxiana y Epidendrum secundum con relación a los distintos ambientes donde viven. Hojas y raíces fueron recolectados en un bosque nuboso de un campo rupestre en la Serra da Piedade, Brasil. Dichaea cogniauxiana está adherida a los troncos, en sitios con alta humedad atmosférica y sombra, mientras que E. secundum está localizada en el margen del bosque nebular, en sitios más iluminados. Las hojas de E. secundum tienen una cutícula más gruesa y un mayor número de estomas por área que las de D. cogniauxiana, características coherentes con los diferentes patrones de exhibición a la luz del sol. Las cámaras supraestomáticas formadas por la cutícula pueden funcionar como una barrera de resistencia a la evaporación del agua. La suculencia de las hojas de E. secundum propicia el almacenamiento de ácidos orgánicos por la noche, y el almacenamiento de almidón puede estar implícito en el metabolismo de la PEP-carboxilasa. Las raíces con mayor velamen y especializadas paredes gruesas de las células corticales (ambas en E. secundum) ayudan a la absorción e indican una mejor adaptación al ambiente con intensa radiación solar y probable alto déficit de agua. El engrosamiento de la pared celular en la exodermis de E. secundum puede conferir una protección más eficaz contra el exceso de transpiración en el margen del bosque nebular. Por otra parte, D. cogniauxiana además de ser epífita, está en una posición baja, en un ambiente sombreado y con una alta humedad relativa. Su velamen delgado permite la entrada de la baja luz disponible y la fotosíntesis, produciendo oxígeno que ayuda a evitar la condición hipóxica.