Showing items 1 - 3 of 3

Effects of Acacia invasion on leaf litter nutrient and soil properties of coastal Kerangas forests in Brunei Darussalam

- Yusoff, Aiman, Tennakoon, Kushan, Jaafar, Salwana, Zaman, Dk, Sukri, Rahayu

  • Authors: Yusoff, Aiman , Tennakoon, Kushan , Jaafar, Salwana , Zaman, Dk , Sukri, Rahayu
  • Date: 2019
  • Type: Text , Journal article
  • Relation: Scientia Bruneiana Vol. 18, no. 1 (2019), p. 1-10
  • Full Text:
  • Reviewed:
  • Description: Exotic Acacia were introduced to Brunei Darussalam in the 1990s for plantation forestry and land rehabilitation but are now regarded as invasive. We assessed the effects of Acacia on litter nutrient composition and soil physicochemical properties of Brunei’s coastal Kerangas (heath) forests. Soil and litter samples were collected from ten 20 x 20 m plots in Acacia-invaded Kerangas forests (IKF) and ten uninvaded (UKF) plots. Soil samples were analyzed for pH, gravimetric water content and nutrient concentrations whereas litter samples were analyzed for total nutrients only. We recorded significantly higher concentrations of litter total N and P in the IKF than the UKF plots. In contrast, no significant differences were detected in soil properties, except for topsoil available P and subsoil exchangeable Ca which were both lower in the IKF plots. A significant positive correlation was detected between litter N and topsoil N in the IKF plots. We suggest that the fairly recent timescale of Acacia invasion (< 25 years) of the IKF sites resulted in the lack of significant increase of soil nutrients. In conclusion, Acacia invasion into Brunei’s forests can potentially alter both leaf litter and soil physicochemical properties of Kerangas forests, in particular affecting nutrient availability. This alteration of ecosystem may further enhance the invasion success of Acacia, making restoration attempts more challenging.

Impacts of invasive Acacias on ion deposition in a coastal Bornean tropical heath forest

- Ibrahim, Mohamad, Metali, Faizah, Tennakoon, Kushan, Sukri, Rahayu

  • Authors: Ibrahim, Mohamad , Metali, Faizah , Tennakoon, Kushan , Sukri, Rahayu
  • Date: 2022
  • Type: Text , Journal article
  • Relation: Journal of Forest Research Vol. 27, no. 1 (2022), p. 20-27
  • Full Text: false
  • Reviewed:
  • Description: The uncontrolled invasive spread of exotic Acacias is a growing concern for many tropical ecosystems, particularly due to their negative impact upon nutrient cycling. Studies investigating the effects of Acacia invasion on nutrient cycling have focused on litterfall and litter decomposition, although its impact on ion deposition in tropical ecosystems is less understood. We quantified and compared the rates of ion deposition (Ca2+, Mg2+, NH4+, NO3−) between Acacia-invaded and non-invaded tropical heath (Kerangas) forest sites in Brunei Darussalam, Southeast Asia. Ion exchange resin (IER) sampler, IER ring and IER bags were used to determine ion depositions via throughfall, in soils and in stream water respectively. Throughfall in Acacia-invaded heath forest sites recorded significantly higher NH4+ and Ca2+ depositions but lower Mg2+ than non-invaded, intact sites. For ion deposition in soil, all depths recorded significantly higher Ca2+ (except for 0 cm depth), Mg2+ and NH4+ depositions, but significantly lower NO3− depositions, in Acacia-invaded sites. Ion deposition in stream water showed significant monthly variations, with Acacia-invaded sites recording significantly higher Mg2+ depositions in June, August and September 2015 but lower NH4+ depositions in June, July and September, lower NO3− and Ca2+ depositions in June and September than non-invaded heath forest sites. Overall, these findings demonstrate that ion deposition via throughfall, in soil and in stream water were all affected by Acacia invasion, thus confirming the influence of alien invasive Acacias on nutrient cycling of tropical heath forests. © 2021 The Japanese Forest Society.

Medicinal value of three agricultural weed species of the asteraceae family : a review

- Jayasundera, Mithila, Florentine, Singarayer, Tennakoon, Kushan, Chauhan, Bhagirath

  • Authors: Jayasundera, Mithila , Florentine, Singarayer , Tennakoon, Kushan , Chauhan, Bhagirath
  • Date: 2021
  • Type: Text , Journal article , Review
  • Relation: Pharmacognosy Journal Vol. 13, no. 1 (2021), p. 264-277
  • Full Text:
  • Reviewed:
  • Description: Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L. are well known plant species of the Asteraceae family that are considered weeds in intensive agriculture. These weeds are traditionally known to have medicinal properties and have been used for therapeutic treatments. However, it is only the lack of proper knowledge, awareness and screening that have limited their use in pharmaceutical sectors. This review attempts to consolidate the traditional, phytochemical and pharmacological studies that have been carried out on Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L., which we note are widely spread throughout the world. This study was conducted through a coherent search on Ageratum conyzoides L., Tridax procumbens L. and Bidens pilosa L. with respect to traditional uses, phytochemical and pharmacological studies that have been performed on these three agricultural weeds all over the world. An exploration of reported descriptions of the potential medical importance of three agricultural weed species (A. conyzoides, T. procumbens and B. pilosa) has been presented. The present review would encourage further clinical investigations into these three plants and their extracts to more closely define the range of uses of these herbs for clinical applications. This, in turn, would give a clear understanding whether these weed species might be targeted to be conserved in a sustainable manner rather than eradicated. © 2021 Phcogj.Com. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license.
  • 1