What explains the variation on the regenerative component dynamics of Araucaria Forests in southern Brazil?

Abstract

The natural regeneration process is essential for forest maintenance since it is critical for establishing new tree individuals. This study aimed to improve the understanding of the regenerative component dynamics of Araucaria Forests in Southern Brazil. We investigated the effects of climate, light, tree component structure and anthropogenic disturbance on tree species regeneration. Regenerating communities from six different fragments in forest remnants of the "Planalto Sul Catarinense" region was evaluated in permanent plots two years after the first inventory. The following demographic rates were determined: recruitment, mortality, net change in the number of individuals and the changes to both upper and lower height classes. The following variables were measured in each fragment: altitude, climatic variables, light environment, tree component density and cattle presence. Association between dynamics rates, regenerating species abundance and explanatory variables was verified by the fourth-corner and RLQ methods. A total of 4,379 and 5,268 individuals were sampled for the first and second inventories, respectively, with recruitment rate (21 % yr -1 ) higher than mortality rate (13 % yr -1 ). The dynamics pattern of the fragment with greater presence of cattle stood out for the intense height increase of regenerating species caused by the presence of fast growth and light-demanding species.Natural regeneration of forest remnants under study is facing a structuring process. The main conclusions of this study were: i) climate and altitude play a relevant role in defining floristic identity and ii) chronic disturbances may influence the definition of ecological strategies.

Dynamics of natural regeneration after disturbance in a remnant of Mixed Ombrophilous Forest in southern Brazil

“…However, despite the decrease in density in the plots, the species were more concentrated spatially in 2012 (FR: 3.2%) than in 2016 (FR: 4.1%). Other studies have also shown that this species had low representativeness (Dalla Rosa et al, 2016;Vefago et al, 2019). According to Dalla Rosa et al (2016), A. angustifolia has a limited number of regenerating individuals in the understory of the MOF and this limitation is even more extreme at high altitudes (>1,500 m).…”

“…Approximately half of the species (51.67%) were found in only 5% of the sample units, demonstrating the great diversity of species present in the regeneration of this forest type. In a study by Vefago et al (2019), Allophylus edulis and Matayba elaeagnoides were also among the most representative species. Araucaria angustifolia (Bertol.)…”

“…The family with the greatest richness was Myrtaceae, followed by Lauraceae. Emphasizing the ecological importance of the Myrtaceae family, it has also been classified as highly representative of MOFs by several authors (Vibrans et al, 2011;Meyer et al, 2013;Santos et al, 2015Santos et al, , 2018Dalla Rosa et al, 2016;Silva et al, 2017;Santana et al, 2018;Vefago et al, 2019), occurring in areas of different altitudes (Dalla Rosa et al, 2016). The H′ and J′ values were 3.15 and 0.81 in 2012 and 3.26 and 0.79 in 2016, respectively.…”

Impacto antrópico na dinâmica de uma floresta nebular do planalto catarinense

“…Para a regeneração natural, ainda foram obtidas as taxas de mudança para classes superiores (5) e inferiores de altura ( 6); e, para o componente arbóreo adulto, as taxas de perda em área basal (7) e ganho (8), assim como a mudança líquida (9) e a rotatividade (10) em área basal (ver GROSS et al, 2018;VEFAGO et al, 2019). ); mi = número de indivíduos que passaram para classes de tamanho inferiores; PAB = Taxa de perda em área basal (%.ano -1 ); AB 0 = Área basal no primeiro inventário (m 2 ); AB m = Área basal de árvores mortas (m 2 ); AB dec = decremento em área basal das árvores sobreviventes (m 2 ); GAB = Taxa de ganho em área basal (%.ano -1 ); AB r = Área basal das árvores recrutadas (m 2 ); AB cresc = crescimento em área basal das árvores sobreviventes (m 2 ); Rot AB = Taxa de rotatividade em área basal (%.ano -1 ) e ML AB = Taxa de mudança líquida em área basal (%.ano -1 ).…”

Dinâmica do componente arbóreo e regenerante em uma floresta nebular no Planalto Sul Catarinense

“…As taxas demográficas (e.g., mortalidade, recrutamento, ganho e perda em área basal) obtidas a partir dos estudos de dinâmica têm apresentado muitas variações de acordo com a floresta estudada (LIEBERMAN; LIEBERMAN, 1987), sendo que pouco se conhece sobre floresta nebular, o que torna maior a necessidade desses estudos, facilitando o planejamento de estratégias de conservação (HIGUCHI et al, 2008). Para a Floresta Ombrófila Mista, em escala regional, se a influência da altitude tem sido evidenciada como um importante fator na distribuição de espécies arbóreas (HIGUCHI et al, 2012), para os padrões de dinâmica e de regeneração natural, o efeito da fragmentação florestal (GROSS et al, 2018) e os distúrbios crônicos (VEFAGO et al, 2019) | Dinâmica do componente arbóreo e regenerante ... 1089 se mostram mais importantes. Além disso, observa-se que, enquanto o componente regenerativo frequentemente apresenta um padrão de estruturação (i.e., aumento na abundância de regenerantes) ao longo do tempo (VEFAGO et al, 2019), o componente adulto frequentemente demonstra um padrão de autodesbaste, com a redução do número de árvores acompanhado pelo aumento da área basal (GROSS et al, 2018).…”