Seed dispersal and predation of Buchenavia tomentosa Eichler (Combretaceae) in a Cerrado sensu stricto, midwest Brazil

Abstract

The ecology of seed dispersal is critical to understand the patterns of distribution and abundance of plant species. We investigated seed dispersal aspects associated with the high abundance of Buchenavia tomentosa in the Serra Azul State Park (PESA). We estimated fruit production and conducted fruit removal experiments. We carried out diurnal and nocturnal observations on frugivory as well as germination tests. Fruiting occurred in the dry season and totaled 1,365,015 ± 762,670 fruits.ha -1 . B. tomentosa fruits were utilized by eight animal species. The lowland tapir (Tapirus terrestris) was considered the main seed disperser. Leafcutter ants (Atta laevigata and Atta sexdens) participated in the seed cleaning and occasionally dispersed seeds. The beetle Amblycerus insuturatus, blue-and-yellow macaw (Ara ararauna) and red-and-green macaw (Ara chloropterus) were considered pre-dispersal seed predators. The seeds manually cleaned presented higher germination rate (100%) and speed index (4.2 seeds.d) than that of seeds with pulp. Germination of seeds found in tapirs'feces was 40%, while for the seeds without pulp it was 25%. The high abundance of B. tomentosa in the cerrado of PESA may be due to massive fruit production, low rates of seed predation, and efficient seed dispersal by tapirs, occurring before the rains which promote germination and recruitment of this species.Keywords: exclusion experiments, fruit production, frugivory, seed germination, tapir dung. Dispersão e predação de sementes de Buchenavia tomentosa Eichler (Combretaceae) em Cerrado sentido restrito, centro-oeste do Brasil ResumoA ecologia da dispersão de sementes é importante para entender a distribuição e abundância das espécies vegetais. Investigamos os fatores relacionados à elevada abundância de B. tomentosa no Parque Estadual da Serra Azul (PESA) avaliando aspectos da dispersão de sementes. Estimamos a produção de frutos e realizamos experimentos de remoção de frutos. Fizemos observações diurnas e noturnas sobre a frugivoria e testamos a germinação de sementes. A frutificação ocorreu na estação seca totalizando 1.365.015 ± 762.670 frutos.ha -1 . Oito espécies de animais utilizaram frutos de B. tomentosa. Anta (Tapirus terrestris) foi considerada o principal dispersor. Saúvas (Atta laevigata e Atta sexdens) participaram na limpeza das sementes e como dispersores ocasionais. O besouro Amblycerus insuturatus, arara-canindé (Ara ararauna) e arara-vermelha (Ara chloropterus) foram considerados predadores pré-dispersão. Sementes despolpadas manualmente tiveram maior percentual (100%) e velocidade de geminação (4,2 sementes.dia -1 ) que aquelas com polpa. Sementes encontradas nas fezes de antas apresentaram 40,0% de germinação e sementes sem polpa 25,0%. A massiva produção de frutos, baixa taxa de predação de sementes, além da eficiente dispersão por antas, antes da estação chuvosa, favorecem o recrutamento e são fatores que contribuem de forma decisiva para a elevada abundância de B. tomentosa observada no cerrado do PESA.Palavras-chave:...

OCCURRENCE OF INSECT PESTS IN FRUITS OF Caryocar brasiliense (CARYOCARACEAE) IN THE NORTH OF MINAS GERAIS

“…These authors reported a rate of more than 93% of attacks by this insect in imbuzeiro seeds collected on the ground, which was not observed in the seeds collected directly from the trees. In contrast, Farias et al (2015) studying Buchenavia tomentosa in a Cerrado stricto sensu from the state of Mato Grosso found A. insuturatus larvae in fruit collected in the trees, indicating a pre-dispersion attack. In the same study, the authors also observed signals of emergence of the adult insects, characterized by the endosperm and embryo completely consumed.…”

Germination and seed ecology of Buchenavia tomentosa Eichler (Combretaceae)

“…tomentosa is native from Cerrado and Amazon Rainforest. In the first biome, the trees begin to fruit in March, and the dispersal starts in June (Farias et al, 2015); whereas in the second one, the fructification begins in September, with dispersion in May (Camargo et al, 2008). At Cerrado, due to the occurrence of a well-defined dry season and short water during a long part of year (Figure 1), the seeds are able to germinate only at the time of water availability, which coincides with the period of high average temperatures (Brancalion et al, 2010).…”

“…tomentosa presents intense fruit production, important for the maintenance of Cerrado's flora and fauna, and the fruits are efficiently propagated by several animals, such as ants, deer and mainly by tapir, which consume the pulp. On the tapir's case, the seeds pass through the digestive tract, favors the removal of pulp adhered to the fruits and does not affect the germination potential (Farias et al, 2015). The dispersers can still contribute to the endocarp's remover and faster species populations' formation at Cerrado.…”

Key decision-making criteria for dormancy-breaking and ability to form seed banks of Cerrado native tree species

“…Non-germination of A. subincanum and T. corrugataspecies in the laboratory may be related to the seed lot, type of photoblastism or low seed storage potential, which can reduce seed viability (e.g., A. subincanum, Oliveira et al 2016). Previous experiments suggest that A. subincanum has optimal germination at 25 ºC and a 12-hour photoperiod (Oliveira et al 2016), while 100 % of T. corrugata seeds can germinate in natural temperature and light conditions (Soares et al 2006;Farias et al 2015). Therefore, regarding treatment homogeneity, the germination test simulating darkness of buried seeds and direct sowing conditions shows that direct seeding strategies must also be heterogeneous in the field.…”