Bamboos are opportunistic species that rapidly colonize open areas following forest disturbance, forming dense clusters that alter the regenerative processes and maintain lower levels of tree diversity. Widespread forest degradation, especially in Latin America and Asia, and human-induced introduction have allowed native and non-native bamboo species to thrive, hindering successional pathways that would otherwise lead to more diverse forests; such a large-scale phenomenon is a key concern in the conservation of forest resources around the globe. Despite previous research on this phenomenon, little is known about the long-term effects of bamboo dominance on forest structure and composition and the corresponding interaction with natural regeneration. As such, we sought to evaluate the long-term effects of bamboo dominance on the dynamics of adult forest populations considering two forest types (Bamboo Forest—BF and Araucaria Forest—AF) over an 11-year period in the Embrapa Research Station in Caçador, Brazil. We monitored 20 plots (15 × 15 m) in each forest type where we tagged, identified, and measured the height and diameter of all the trees taller than 1.5 m (H) and diameter at breast height (DBH) greater than 3.18 cm. Comparisons were based on forest species diversity and structure parameters. In BF, diversity of species increased after the bamboo die-off that occurred in 2006 with a subsequent reduction in the number of pioneer species overtime. However, secondary species remained stagnant demonstrating that recruitment and transition into higher size classes is restricted to the immediate die-off aftermath. On the other hand, plant diversity and structure in the relatively bamboo-free AF were stable with secondary species accounting for the most richness. Our results confirm that BF maintains significantly lower levels of diversity that are restricted to pioneer species; AF structure and diversity are not significantly affected by bamboo die-off and recolonization; and BF tree species are caught in a closed cycle of arrested successional development. The widespread presence of bamboos as dominant species in the region should become a part of the conversation pertaining to forest management and conservation in Brazil and other countries in south America and Asia.

No abstract

RESUMOO bioma florestal mais característico do Sul do Brasil é a Floresta Ombrófila Mista, fortemente marcada pela presença da espécie Araucaria angustifolia. Entretanto, a exploração irracional e descontrolada desta espécie reduziu drasticamente sua área de ocorrência a 2% de sua área original. Assim, esforços devem ser feitos para auxiliar e promover sua regeneração natural, visando a sua preservação e o uso sustentável de seus recursos econômicos. Com o objetivo de avaliar a germinação, sobrevivência e predação de mudas e sementes de Araucaria angustifolia foi implantado um experimento em delineamento inteiramente casualizado, no qual foram investigados os efeitos de dois fatores com dois níveis cada (tipo de plantio: puro/ misto; material plantado: mudas/sementes), com três repetições, perfazendo um total de quatro tratamentos. Após 14 meses restaram 17% das covas ocupadas por mudas e 14% das ocupadas por pinhões; 60% das sementes germinadas foram consumidas pela fauna; o percentual de sobrevivência médio das mudas foi de 41,1% no plantio puro e de 20,0% no plantio misto. No tratamento misto, as perdas de sementes, devido à ação fauna, foram menores (42,2%) quando comparadas ao tratamento puro (68,9%); o contrário foi válido no caso das mudas. Palavras-chave: fauna; predação; pinhão. ABSTRACTThe most characteristic forest type of southern Brazil is the Araucaria Forest, strongly marked by the presence of the species Araucaria angustifolia. However, the overexploitation of the species reduced its range to 2% of its original area. Efforts must be made to support and promote its natural regeneration, seeking the preservation and sustainable use of its economic resources. Therefore, an experiment was conducted to evaluate germination, survival and predation rates of seeds and seedlings of Araucaria angustifolia, analyzed as a randomized factorial design with two factors with two levels each (type of plantation: pure/ mixed; raw material: seeds/seedlings), totaling four treatments, with three replicates each. Fourteen months after planting only 17% of the seed holes contained live plants; 14% of planted seedlings survived; 60% of the seeds were consumed by animals. Seedling survival was 41.1% in the "pure" treatment and 20% in the mixed treatment. In the mixed treatment, seed losses due to fauna attack were lower (42.2%) compared to the 'pure' treatment (68.9%); the opposite behavior was observed in the case of seedlings.

ResumoMorfoanatomia da plântula e comparação da folha nas fases juvenis e adulta de Piptocarpha angustifolia (Asteraceae). O estudo morfológico nas primeiras fases de desenvolvimento permite a observação de estruturas transitórias, que desaparecem com a passagem para a fase adulta. O estudo da morfoanatomia da plântula e das fases juvenis e adulta de Piptocarpha angustifolia foi realizado com o objetivo de se levantar características diagnósticas da espécie, principalmente nos estágios iniciais de desenvolvimento. P. angustifolia é espécie arbórea que ocorre exclusivamente na Floresta Ombrófila Mista Montana. As amostras foram coletadas e fixadas em FAA 50 a partir de plantas cultivadas (13 e 35 dias após germinação) e folhas de indivíduos jovens e adultos no campo. Os caracteres como os tipos de germinação (fanerocotiledonar e epígea) e a morfologia foliar permitem o reconhecimento das plântulas e plantas jovens na mata. Os caracteres estruturais que podem auxiliar no reconhecimento da espécie são: região de transição raiz/caule; nó cotiledonar trilacunar; nó unilacunar do eofilo; presença de hidatódios no eofilo; variação do número de feixes vasculares no pecíolo e nervura mediana nos tipos foliares; dorsiventralidade e a variação no formato e número de células do mesofilo dos cotilédones, eofilos e metafilos. Palavras-chave: cotilédone, desenvolvimento pós-seminal, eofilo, metafilo, plântula. AbstractSeedling morphoanatomy and leaf comparison in juvenile and adult stages of Piptocarpha angustifolia (Asteraceae). Morphology studies of the first development stages of plants allow the observation of transitory structures that disappear when they become mature. The aim of this study is to analyse the morphological and anatomical aspect of the structure of Piptocarpha angustifolia, in seendling, juvenile and adult stages, in order to get up diagnostic characteristics of the species, especially in the early stages of development. P. Angustifolia is a native arboreous species from Mixed Ombrophylous Mountain Forest. Samples were collected and fixed in FAA 50 from cultivated plants (13 and 35 days after germination) and leaves of juvenile and adults stages in the field. The characters as types of germination (phanerocotylar and epigeal) and leaf morphology allow the recognition of seedlings and saplings in the forest. The structural characters that can aid in the recognition of the species are: the root/stem transition zone; the trilacunar cotyledon node; the unilacunar eophyll node; the presence of hydathodes in eophyll; the variation in the number of vascular bundles in the petiole and midrib checked in leaf types; the variation in shape and number of mesophyll cells of cotyledons, and eophylls metaphylls.