Cambial activity in dry and rainy season on branches from woody species growing in Brazilian Cerrado

Abstract

Seasonal cambial activity was investigated in one-to three-year-old branch modules (branch constructional units) of ten woody species from cerrado sensu stricto, a savanna-like ecosystem, of southern Brazil. Relationships between cambial activity and environmental factors (precipitation, temperature, day length) and leaf production were tested using GLMM. Regardless the plant habit and leaf shedding patterns, cambial activity (about 5 months) corresponded to the core of the rainy season (when at least 66% of the annual precipitation had been reached), even though there was some delay or advance in the timing of cambial activity depending on the branch age or species. Cambial activity began in the dry season and ceased before the end of rainy season. Although cambial activity has been positively correlated with day length, precipitation, temperature, and budding for all species, day length, among the assessed factors, seems to be the best predictor of onset and cessation of cambial activity in the branch modules of cerrado species.

Duration of cambial activity is determined by water availability while cambial stimulus is day-length dependent in a Neotropical evergreen species

“…For each interval, we analyzed the relationship between cambial activity and time, a statistical test not related to any causal hypotheses. Next, we examined the relationship between cambial activity and soil water availability, temperature (maximum and minimum) and day length in accordance with previous causal hypotheses (e. g. Bosio et al, 2016;de Lara and Marcati 2016;Marcati et al, 2016). Due to the potential correlation among temperature and day length, we first verified the product-moment correlation coefficient (r) among them.…”

“…2). We chose these two intervals based on studies of woody species of the Brazilian Cerrado, according to which cambial activity occurs in early spring de Lara and Marcati, 2016;Marcati et al, 2006Marcati et al, , 2008Marcati et al, , 2016 and cambium dormancy in late summer Marcati et al, 2006Marcati et al, , 2016.…”

A Chuva Favorece a Altura E a Quantidade De Regenerantes Em Comunidade Florestal

“…Em razão da baixa pluviosidade, as estratégias de sobrevivência de plântulas a estas condições envolvem fatores de origem física, fisiológicas, adaptações morfológicas e anatômicas (MCLAREN & MCDONALD 2003), dentre elas, podem ser citadas a perda das folhas ou caducifólia (BORGES & DE ASSIS PRADO 2014) e a inibição do crescimento em resposta ao prolongado período seco (MARCATI et al 2016). Adicionalmente, a formação de clareiras em florestas deciduais pode diminuir substancialmente a sobrevivência de plântulas devido ao aumento das temperaturas e redução da umidade.…”

“…A presença de lacunas no dossel de uma floresta, as chamadas clareiras, durante o processo de regeneração, permite uma maior incidência luminosa no ambiente, provocando variações na temperatura e na umidade do solo (VENTUROLI et al 2011;MARCATI et al 2016). Estes fatores acabam por afetar o processo de germinação de sementes e permanência de plântula em ambientes florestais secos, devido à forte limitação imposta pela ausência de água (VIEIRA & SCARIOT 2006).…”

“…O fato de poucas espécies terem bancos de sementes por longo tempo as privam de serem afetadas por perturbações inesperáveis que podem ocorrer no ambiente (MAROD et al 2002), propiciando a dominância de poucas espécies, o que diminui a diversidade do local.…”