Canopy phenology of a dry forest in western Brazil

Abstract

Dry forests are common, although highly threatened in the Neotropics. Their ecological processes are mostly influenced by rainfall pattern, hence their cycles exhibit contrasting phases. We studied the phenology of canopy trees in a primary dry forest in Western Brazil in the foothills of the Urucum mountain chain, in order to improve our knowledge on the functioning of these poorly-known forests. Leaf shedding started in the early dry season and was massive in the latter part of this period. Most leaf loss occurred in dry hills, while wet valleys remained evergreen. Anemochorich and autochorich species predominated in dry hills, presumably due to their tolerance to dry conditions and enhanced exposition to winds, which favour diaspores removal and dispersal. Conversely, zoochorich species dominated the wet valleys. Flowering was intense in the late dry season, the driest period of the year, while fruiting was massive just after the onset of rains, as well as flushing. Therefore, most flowering was unrelated to wet conditions, although such an abiotic factor, potentially, triggered the major fruiting episode, widely comprised by zoochorich species. Anemochorich and autochorich species flowered and fruited in the course of the long dry season. The contrasting environmental conditions present in the hills and valleys determine the arrangement of a mosaic in which patches of zoochorich and evergreen trees alternate with patches of non zoochorich and highly deciduous species. Consequently, species with such syndromes exhibited marked flowering and fruiting patterns, accordingly to the pronounced seasonality.Keywords: canopy trees, deciduous forest, seasonality, dispersal syndromes, flowering and fruiting. Fenologia do dossel em uma mata seca do oeste brasileiro ResumoMatas secas neotropicais estão amplamente distribuídas, porém sob elevado risco de desmatamento. Os processos ecológicos nesses ambientes são fortemente influenciados pelo clima, sobretudo o padrão de chuvas, de tal forma que seus ciclos apresentam fases muito contrastantes. Nesse estudo, avaliamos a produção de folhas, flores e frutos em uma mata seca do oeste brasileiro situada no sopé do maciço do Urucum. A perda de folhas teve início no começo da estação seca, mas foi massiva ao final desse período, o mais seco do ano. Espécies decíduas predominaram nas escarpas secas, enquanto as perenifólias foram comuns nos vales úmidos. Nas escarpas, espécies anemo e autocóricas eram muito comuns, potencialmente, por serem mais tolerantes à baixa umidade, bem como favorecidas por ventos mais fortes. Porém, eram raras ou mesmo ausentes nos vales úmidos dominados por espécies zoocóricas. A floração foi intensa, exibindo um pico acentuado ao final da estação seca, seguida de um pronunciado pico de frutificação e produção de folhas com o início das chuvas. Dessa forma, enquanto a floração massiva não foi influenciada pelas chuvas, a frutificação e produção de novas folhas estiveram fortemente relacionadas a esse fator abiótico. As espécies anemo e autocórica...

Plant food resources exploited by Blue-and-Yellow Macaws (Ara ararauna, Linnaeus 1758) at an urban area in Central Brazil

“…We grouped plant species according to its potential fruiting pattern: asynchronous, when they bore fruits unpredictably during the year; multiple, when they bore fruits more than once in the year and; seasonal, when they bore fruit only once in the year (Milton et al, 1982;Henderson, 2002). In seasonal areas fruiting pattern fluctuates exhibiting short periods of pronounced fruit production followed by abrupt declines (Justiniano and Fredericksen, 2000;Funch et al, 2002;Ragusa-Netto and Silva, 2007). Hence, in the course of a season fruit production fluctuations have influence on frugivores abundance and feeding activity (van Schaik et al, 1993).…”

Chaco Chachalaca (Ortalis canicollis, Wagler, 1830) feeding ecology in a gallery forest in the South Pantanal (Brazil)

“…The predominance of fleshy fruit production during rains has been found in seasonal habitats such as dry forests (Renton, 2001;Ragusa-Netto and Silva, 2007), and apparently is usual for gallery forests within dry areas (Funch et al, 2002;this study). It is important to emphasize the fruit production in the transition from the wet to the dry season (March-April, Figure 1), which aroused from species exposed to floods for longer periods (pers.…”

“…In seasonal forests fruiting pattern fluctuates exhibiting short periods of pronounced fruit enhancement followed by abrupt declines (Funch et al, 2002;Ragusa-Netto and Silva, 2007). Hence, in the course of a season, variations in fruit production have implications for frugivores (van Schaik et al, 1993).…”

The effect of size and density on nut removal in Syagrus loefgrenii Glassman (Arecaceae) in the Brazilian Cerrado

“…In marked seasonal areas, one can expect that large nuts might offer enhanced energetic return and should be preferred by foraging rodents, mainly when food availability is relatively high (Brewer, 2001). This might be the case during the wet season when fruiting is plentiful (Batalha and Martins, 2004;Munhoz and Felfili, 2007;Ragusa-Netto and Silva, 2007). On the other hand, in periods of low fruit availability, nut size may become unimportant in the selection of seeds by foraging rodents under food shortage.…”

“…An area of approximately 50 cm 2 was cleared of grass or leaf litter for the placement of each depot. Taking into account the asynchronous fruiting pattern in S. loefgrenii (Ragusa-Netto, 2016), besides the fact that intra-seasonal changes in general food resources availability, might have implications on seed consumption (Van Schaik et al, 1993;Ragusa-Netto and Silva, 2007), I tested S. loefgrenii endocarp removal in four periods of the year. Depots with endocarps were set out 3 January, 7 April, 1 July, and 4 November 2015 in order to run trials during the middle of each of the four periods of the year (the late wet season [January-March], the early dry season [April-June], the late dry season [July-September], and the early wet season [October-December]).…”