Resumo Biological soil crusts (biocrusts) são componentes importantes em regiões áridas e semiáridas, comumente associados à facilitação da flora vascular. Os biocrusts em afloramentos rochosos da Caatinga, no semiárido nordestino, são representados principalmente por populações do musgo pioneiro Campylopus lamellatus. Entretanto, a Caatinga está sob progressivo processo de desertificação, que deve se prolongar pelos próximos 100 anos. Assim, entender a resposta fisiológica de C. lamellatus sob um cenário de mudanças climáticas, deve basear previsões sobre o rumo da flora de ambientes rochosos em cenário futuro. Aqui, nós avaliamos uma população do musgo C. lamellatus durante o efeito prolongado de seca, causado pelo El Niño, e durante a primeira estação chuvosa após o fenômeno. Nós utilizamos a biomassa (massa seca) e proporção de clorofilas como medidas de vigor. Nós identificamos a diminuição do investimento em alocação de biomassa e a degradação dos pigmentos fotossintéticos durante o evento de seca. Em contrapartida, constatamos o rápido aumento das clorofilas durante a estação chuvosa, i.e., investimento em biomassa via regeneração de clorofilas. Desse modo, nós concluímos que a resiliência do C. lamellatus é rápida até mesmo para uma planta fotófila, o que deve assegurar sua função facilitadora em condições de saturação ambiental.

Abstract Biological soil crusts (biocrusts) are important biological components in arid and semi-arid regions because they can serve as ecological facilitators for the vascular flora. Biocrusts of rocky outcrops of the Caatinga biome in the semiarid region of Northeast Brazil are comprised mainly of populations of the pioneer moss Campylopus lamellatus. Meanwhile, the Caatinga is undergoing progressive desertification, which is likely to continue for the next 100 years. Therefore, the physiological responses of C. lamellatus to climate change should be included in predictions regarding the future of the flora of these rocky environments. We evaluated a population of C. lamellatus during a prolonged drought brought about by El Niño, and during the first subsequent rainy season. We used biomass (dry mass) and proportion of chlorophyll as measures of tolerance. We identified decreased investment in biomass allocation and the degradation of photosynthetic pigments during the drought event. In contrast, we observed a rapid increase of chlorophyll during the rainy season, which represents biomass investment via chlorophyll regeneration. We conclude that the resilience of C. lamellatus is rapid, even for a photophilic plant, and should ensure its facilitative function under conditions of water saturation of the environment.

ABSTRACT Notothylas vitalii is an endemic Brazilian hornwort species, easily identified by the absence of pseudoelaters and columella, and the presence of yellow spores. Plant material was collected in Recife, Brazil, and the spores were sown onto Knop’s medium, germinating after thirty days only with the presence of light. Germination occurred outside the exospore, and only after the walls had separated into three or four sections did a globose sporeling initiate its development. Following longitudinal and transversal divisions, the initial loose mass of cells became a thalloid gametophyte, subsequently developing into a rosette-like juvenile thallus with flattened lobes. Additional information concerning sporeling types in key genera of hornworts, such as Folioceros and Phymatoceros, will be crucial for inferring the possible ancestral type and the evolution of this trait among hornworts. Our study supports the necessity of supplementary studies on sporeling development, combined with morphological and phylogenetic investigations, to help elucidate the evolution of the Anthocerotophyta and their distribution patterns.