Tropics
Online ISSN : 1882-5729
Print ISSN : 0917-415X
ISSN-L : 0917-415X
26 巻, 1 号
選択された号の論文の3件中1~3を表示しています
ORIGINAL ARTICLES
  • Tsuyoshi Yoneda, Hiromi Mizunaga, Toshinori Okuda, Wan Rasidah Kadir
    2017 年 26 巻 1 号 p. 1-15
    発行日: 2017年
    公開日: 2017/06/01
    ジャーナル フリー

    We assessed the spatial variations in net ecosystem productivity (NEP) using a biometric method based on the dynamics of coarse woody organs in a primeval lowland tropical rain forest in Pasoh, Peninsular Malaysia. The average NEP and carbon stocks in biomass and coarse woody debris over 15 years from 1990 to 2005 were -0.75t C ha-1 y-1, 205t C ha-1, and 22t C ha-1, respectively. However, there were large spatial variations among the five communities, which were correlated with edaphic and topographical features. A mature carbon cycling system with high biomass (where NEP ≈ 0) was observed in a sub-community on west-facing slopes of the hill community. Over the course of 15 years, a drought and storms were the major agents causing forest disturbances. These factors affected the spatial variations of NEP through not only spatial distribution patterns in species with different sensitivities to stress but also differences in the extent of stress depending on topography. We modeled the disturbance regime as elapsing from 1907 to 1947 basing on observed values of net primary production and biomass of five communities during the 15 years. When we extrapolated high mortalities of trees under this regime, our simulation suggested that a 50-ha plot will remain a carbon-source system for the atmosphere at an average rate of NEP=-0.95t C ha-1 y-1 until 2060, with different biomass decreases among these five communities.

  • Ryosuke Nakamura, Takashi Oyabu, James K. Ndufa, Bernard K. Kigwa, Ken ...
    2017 年 26 巻 1 号 p. 17-25
    発行日: 2017年
    公開日: 2017/06/01
    ジャーナル フリー

    Midday transpiration rates and daily pan evaporation from forest floor and open area were measured to determine an effective way of controlling water loss from a Melia volkensii plantation. The research was conducted at an M. volkensii plantation in Tiva Pilot Forest, Kenya, during April and May 2014. A leaf porometer (LI-1600) was used to measure midday transpiration rates per unit leaf area (Ta) from 11:00h to 13:00h for four trees at three different leaf heights: top (A), middle (B), and bottom (C) layers of a crown. Midday transpiration rate per layer (Tl) and midday transpiration rate per tree (Tt) were estimated based on Ta and leaf area (LA) of layers. Daily pan evaporation from forest floor and open area were measured using 25 and two evaporation pans, respectively. Ta values for layer A were not significantly different among sample trees, while Tl values for layer A were significantly different, indicating the influence of LA on water loss through transpiration. Since Tl from layers B and C accounted for half of Tt, pruning of these layers could cause a 50% reduction in water loss through transpiration. Daily pan evaporation in the plantation was approximately 70% lower than that in the open area. Therefore, the layer A left after pruning should keep water loss through evaporation from the forest floor lower than that from the open area. Further research is required to determine the effect of pruning on reduction of water loss from the plantation.

FIELD NOTE
  • Yuta Ito, Miki Toda, Misa Masuda
    2017 年 26 巻 1 号 p. 27-36
    発行日: 2017年
    公開日: 2017/06/01
    ジャーナル フリー

    It is well recognized that the marine resources of the Philippines are increasingly and severely damaged by climate change and human interventions, including overfishing and destructive fishing. To manage its marine resources, the government has implemented marine protected area (MPA) systems, expecting the involvement of local communities in its management. Although over 1,600 MPAs had been established by 2014, it is reported that they are not effectively managed. The purpose of the study is to determine the current conditions of MPAs in the Philippines using the MPA Management Effectiveness Assessment Tool (MEAT) developed in 2010, and to identify how MEAT reflects reality through interviews at two MPAs. The MEAT data analysis shows that MEAT has not yet been fully utilized and its information is not representative of all the MPAs in the country. So far, as based on the information provided by MEAT, less than half of the MPAs are effectively managed and management effectiveness is not related to the age of the MPA or evenly distributed across regions. The field study, although limited by the fact that it is based on only two MPAs, raises the question as to whether or not local evaluation has been conducted as intended. Unlike the high expectations of communities as effective MPA management entities, local people in the two cases rely more on local government. The results suggest the necessity of further studies on monitoring the MEAT evaluation process and the importance of field studies regarding the effectiveness of community-based MPA management.

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