Vegetation diversity of Hevea brasiliensis agroforest system in Tumbang Mantuhe Village, Gunung Mas Regency, Central Kalimantan, Indonesia

A rubber agroforest system is a form of land use that considers ecological and economic aspects that are still maintained by the people of Tumbang Mantuhe Village. This study aims to identify and analyze the diversity of vegetation in the agroforest system in Tumbang Mantuhe Village, Gunung Mas Regency, Central Kalimantan. This research uses purposive sampling and the vegetation analysis method. The results showed that the species of vegetation in the rubber agroforest system amounted to 29 species in 23 families. At the seedling level, it is dominated by Macaranga sp. and Xylopia ferruginea; the sapling level is dominated by H. brasiliensis and Syzygium tawahense; the pole level is dominated by Deplanchea bancana and Xylopia ferruginea; at the tree, the level is dominated by H. brasiliensis and Lithocarpus sp. At the seedling, sapling, pole, and tree levels, the diversity values were moderate and the species richness values were moderate to high, and the species distribution was even (stable). The H. brasiliensis agroforest system with various trees in it is a characteristic of local wisdom that the people of Tumbang Mantuhe Village have applied from generation to generation, which provides a balance between ecology and economy.

Wood Density and Dispersal Modes of Trees Regenerating in Disturbed Forests and Agroforests in Indonesia

Natural regeneration depends on surviving propagules in the soil, seed sources from a surrounding landscape mosaic, and dispersal agents. We compiled and analyzed four sets of case studies varying in degree of disturbance, for secondary forests recovering from logging, fire, and conversion to agroforest in Sumatra or Kalimantan (Indonesia) on mineral and peat soils. Data on tree species diversity, wood density frequency distribution (indicative of successional status, databases with over 6000 species exist), and dispersal modes were compared with those for less disturbed comparator forests for the same landscapes. Undisturbed lowland dipterocarp forest in Kalimantan had close to 200 species of trees of more than 10 cm diameter at a 1 ha sample scale (and 450 at a 10-ha scale), regulation-based logging had little impact. Still, after the repeated fire a sample area of 2 ha was needed to reach the same species numbers. After forest conversion to low-management-intensity rubber agroforest, 50 tree species were found at a ha scale and close to 100 species in 3 ha. Peat swamp forest in Kalimantan and the Sumatra forest samples had close to 100 species in 1 to 2 ha. The Kalimantan forest after a repeated fire had a markedly higher fraction of low-wood-density trees (40%), but otherwise, all forests sampled were similar in overall wood density profiles. Logged-over forest managed by community (village forest) and rubber agroforest in Sumatra contained larger fractions of heavy-wood-density trees (including rubber). The majority of trees (50-70%) had birds, bats, and primates as dispersal agents in all sites. Logged-over forests on mineral soil had higher fractions of autochorous species (15%) compared to other sites. Anemochorous (wind-dispersed) species were most common (20%) in undisturbed lowland Dipterocarp forest and peat swamp forest recovering after logging and fire. Comparison between secondary forests and agroforests showed the influence of farmer selection regarding what is allowed to grow beyond the pole stage. Wood density and seed dispersal profile can be used as degradation indicators of species assemblages across various disturbance levels and types. They can also reflect the habitat quality of the surrounding forming restoration options.

An Overview and Future Outlook of Indonesian Agroforestry: a Bibliographic and Literature Review

Indonesian agroforestry has been developed along the history, since been reported that home garden was practiced from 3,000 BC in Java Island. However, agroforestry practices were recognized to have less contribution to people welfare and environmental sustainability. Bibliometric and literature studies extracting baseline information from thousands of publications were done to analyse history and future projection of Indonesian agroforestry. Research and publication on Indonesian agroforestry is steadily increasing in number and quality. Topics related with traditional land use system and ecosystem services were frequently found, and therefore classified as motor themes. There were 16 most attractive commodities stated in the publications, including palm oil and rubber. Rubber agroforest was the only system that pay interest in several decades. There were many researches on indigenous agroforestry practices in the islands, but mostly (77%) concentrated in Java Island, especially studying private forest and home garden. The research on the issues of population pressure on forestland and efficient use of resources are the most popular topic in the decades. In the recent decade, broader theme of research was found including climate change and long-term livelihood. Based on the study, indigenous agroforestry is still important subject to study, but future roadmap of agroforestry must be developed by integrating forestry and agriculture approaches.

Market-based instruments for risk-averse farmers: rubber agroforest conservation in Jambi Province, Indonesia

This paper investigates the effectiveness of different market-based instruments (MBIs), such as eco-certification premiums, carbon payments, Pigovian taxes and their combination, to address the conversion of agroforests to monoculture systems and subsequent effects on incomes of risk-averse farmers under income uncertainty in Indonesia. For these, the authors develop a farm-level dynamic mean-variance model combined with a real options approach. Findings show that the conservation of agroforest is responsive to the risk-aversion level of farmers: the greater the level of risk aversion, the greater is the conserved area of agroforest. However, for all risk-averse farmers, additional incentives in the form of MBIs are still needed to prevent conversion of agroforest over the years, and only the combination of MBIs can achieve this target. Implementing fixed MBIs also contributes to stabilizing farmers’ incomes and reducing income risks. Consequently, the combined MBIs increase incomes and reduce income inequality between hardly and extremely risk-averse farmers.

Contrasting effects of habitat management on different feeding guilds of herbivorous insects in cacao agroforestry systems

Human pressure on natural habitats increases the importance of agroforests for biodiversity conservation. The objective of this study was to evaluate the role of traditional cacao agroforests, known as “cabrucas,” on the conservation of the herbivorous insect community in compared with that of monodominant rubber agroforests. The insects were sampled in three habitats in southeastern Bahia, Brazil: native forests, cabrucas and rubber agroforests. In each habitat, 18 plots of 10 m²were established, and the structural measures were collected and herbivorous insects were sampled with a Malaise/window trap. The diversity of folivores decreased with the simplification of vegetation structure, but species composition was similar among habitats. In addition to a decrease in the availability of resources in monodominant rubber agroforests, the latex present in these systems limits the occurrence of species that cannot circumvent latex toxicity. The diversity of sap-sucking insects was similar among habitats, but species composition was similar only in the cabruca and native forest, and it was different in the rubber agroforest. We observed turnover and a higher frequency of individuals of the family Psyllidae in the rubber agroforest. The biology and behavior of psyllids and absence of natural enemies enable their diversity to increase when they are adapted to a new host. We observed a shift in the composition of xylophagous insects in the rubber agroforest compared with that of the other habitats. Moreover, this agroforest has low species richness but high individual abundance. Latex extraction is likely an important additional source of volatile compounds discharged into the environment, and it increases the attraction and recruitment of coleoborers to these sites. We conclude that cabrucas have an herbivorous insect community with a structure similar to the community found in native forests of the region, and they present a more interesting conservation strategy when compared with the rubber agroforests. We also emphasize the potential risk of local pest outbreaks in rubber agroforests for both the rubber trees and associated cacao tress.