Seedling Recruitment of Native Tree Species in Active Restoration Forest

Yingluck Ratanapongsai

doi:10.24259/fs.v4i1.9421

Abstract

Since 1970’s, large are of deforestation and forest conversion to agriculture in the northern mountains of Thailand grew concern of environmental impact. Forest restoration became an important strategy to rapidly increase forest habitat in a wide-scale in Thailand. The Framework Species (FWS) technique is an active forest restoration that has been developed to restored forest habitat and ecosystem on former-agriculture land in the northern Thailand. After planting 20-30 framework species, the method then relies on incoming native tree species to sustain forest succession. However, there has been little known about the recruitment of native tree species and factors limiting the recruitment in this area. The study compared recruit native tree species in the seedling community of the FWS restoration and nearby seed source to assess how many of those are recruit or absent from the community. The factor of seed-dispersed agents and seed sized was investigated as the possible limited factors of the recruitment and compared among 3 restoration periods (at age 6, 10, and 14 years). The result reveals half of native species were absent from the seedling community across all 3 restoration ages. Seed available was a major limitation for the recruitment of native tree species. Big-seeded species had higher chance to be limited than small-seeded species to recruit in the restoration site (p-value = 0.0249 by the Tukey test). whilst seed-dispersed agents were not limited (p-values=0.420 by Chi square). The FWS forests efficiently facilitated seedlings of native tree species to recruit at the similar recruitment rates across all 3 ages of restoration. However, the technique was still limited in regard of seed available. Species of less common or rarer might need to be included for the FWS plantation in the future to enhance species diversity and better outcome of the restoration.

Highlights

Since 1970’s, deforestation in Thailand reduced overall forest area from 53% to 26.7% (Oberhauser 1997) and continuously lost 99,600 ha of forest annually from 1991 to 1998 (FAO, 2010)
The technique is adopted from the concept of ‘Framework Species Method’ (FSM) by Tucker and Murphy (1997) using a mixture of native species planted on cleared land to accelerate forest recovery
One of the reasons may have been because they were less common or rarer in the surrounding landscape. This result supports the previous experiment in same study sites of Ban Mae Sa Mai village (BMSM) restoration forests by Sansupan et al (2018) who reported that lack of seed availability or inadequate seed dispersal limit tree species to colonize

Summary

Introduction

Since 1970’s, deforestation in Thailand reduced overall forest area from 53% to 26.7% (Oberhauser 1997) and continuously lost 99,600 ha of forest annually from 1991 to 1998 (FAO, 2010). There was a concerning of environmental impact, especially in the northern mountains, an important water resource for main river in the Central Plain of Thailand. Deforestation and conversion of forest to agriculture is a major environmental problem, in the upland water catchment areas, causing droughts, floods, landslides and contributing to global climate change (Oberhauser 1997). Since 1997, the Chiang Mai University’s Forest Restoration Research Unit (FORRU-CMU) has been studying and developing an active restoration technique called “framework species (FWS)” in order to applied on post-agriculture deforestation land of northern Thailand. The restoration begins with plantation of 20-30 native tree species, followed by a few years of post-planting treatment

Methods

Results

Discussion

Conclusion