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<p>Studies have identified that, in Amazonian Forest communities, relatively few species contribute disproportionately to large number of individuals (HA, hyperdominance in abundance, i.e. most common species that hold 50% of individuals) and biomass (HB, hyperdominance in biomass, i.e. most common species that hold 50% of biomass). However, no study to date has investigated how HA and HB are being affected by human disturbances. We studied the abundance and biomass patterns in old European agricultural settlement regions of the Eastern Amazon to answer the following questions: How HA and HB patterns reported for near mature forest differ from those in agricultural land use types? And, how HB and HA relate to land use types and species functional traits (AGB, abundance, diameter breast height and wood density), along of the vertical gradient? Vegetation was sampled in different land covers, namely cassava plantations, pastures, young and old secondary forest, and near old-growth forests in three vegetation strata (upper, middle, and lower). Above-ground biomass (AGB) was estimated using diameter at breast height (DBH) and wood density (WD). HA and HB proportions were calculated for each stratum and land use. The proportion of HA species increased from lower to upper stratum and from cassava crops to near-near mature forests. Almost all HA and HB species were pioneers. Small to medium sized HA species were detected in all forested cover types as well as HB. DBH had moderate effect over AGB while WD was weakly related. The greater the intensity of human disturbance, the stronger the HA effect was. The weak relation between HA and HB with functional traits (DBH and WD) suggests that hyperdominance patterns at anthropogenic landscapes are driven by other variables. The prevalence of pioneer and short-lived species reflects long-term forest degradation, with minimal differences between young and near mature forests in highly disturbed landscapes, indicating limited dispersal of new species and the persistence of impoverished communities.</p>

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Relationships between plant hyperdominance in abundance and biomass in old agricultural landscapes in Eastern Amazonia

  • 期刊论文

  • 发表日期：

    2025年12月4日

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  • Graciliano Galdino Alves dos Santos,
  • Izildinha S. Miranda,
  • Igor Do Vale,
  • Salustiano Vilar Costa Neto,
  • Luiz Gonzaga Silva Costa

摘要

Studies have identified that, in Amazonian Forest communities, relatively few species contribute disproportionately to large number of individuals (HA, hyperdominance in abundance, i.e. most common species that hold 50% of individuals) and biomass (HB, hyperdominance in biomass, i.e. most common species that hold 50% of biomass). However, no study to date has investigated how HA and HB are being affected by human disturbances. We studied the abundance and biomass patterns in old European agricultural settlement regions of the Eastern Amazon to answer the following questions: How HA and HB patterns reported for near mature forest differ from those in agricultural land use types? And, how HB and HA relate to land use types and species functional traits (AGB, abundance, diameter breast height and wood density), along of the vertical gradient? Vegetation was sampled in different land covers, namely cassava plantations, pastures, young and old secondary forest, and near old-growth forests in three vegetation strata (upper, middle, and lower). Above-ground biomass (AGB) was estimated using diameter at breast height (DBH) and wood density (WD). HA and HB proportions were calculated for each stratum and land use. The proportion of HA species increased from lower to upper stratum and from cassava crops to near-near mature forests. Almost all HA and HB species were pioneers. Small to medium sized HA species were detected in all forested cover types as well as HB. DBH had moderate effect over AGB while WD was weakly related. The greater the intensity of human disturbance, the stronger the HA effect was. The weak relation between HA and HB with functional traits (DBH and WD) suggests that hyperdominance patterns at anthropogenic landscapes are driven by other variables. The prevalence of pioneer and short-lived species reflects long-term forest degradation, with minimal differences between young and near mature forests in highly disturbed landscapes, indicating limited dispersal of new species and the persistence of impoverished communities.