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Tropical rainforests disappear at an alarming rate causing unprecedented losses in biodiversity and ecosystem services (, , , ) with Southeast Asia showing the highest rates of deforestation of any major tropical region (). Despite an increased recognition of the value of these goods at national and international levels, rainforests continue to be seriously threatened by various forms of encroachments such as low-intensity harvesting of non-timber forest products by the rural poor, large-scale plantation forestry by the state or private actors, and the conversion of forested land by smallholder farmers. Transformation of ecosystems and changes in land use affect important ecosystem services and ultimatively human well-being ().

I summarize key findings from the Biological Dynamics of Forest Fragments Project, the world’s largest and longest-running experimental study of habitat fragmentation. Although initially designed to assess the influence of fragment area on Amazonian biotas, the project has yielded insights that go far beyond the original scope of the study. Results suggest that edge effects play a key role in fragment dynamics, that the matrix has a major influence on fragment connectivity and functioning, and that many Amazonian species avoid even small (<100 m wide) clearings. The effects of fragmentation are highly eclectic, altering species richness and abundances, species invasions, forest dynamics, the trophic structure of communities, and a variety of ecological and ecosystem processes. Moreover, forest fragmentation appears to interact synergistically with ecological changes such as hunting, fires, and logging, collectively posing an even greater threat to the rainforest biota.

Tropical forest moth ensembles are often extraordinarily rich in species and complex in structure. There is an increasing number of quantitative studies from all major tropical realms which now allows for a more rigorous assessment of the ways how such ensembles change along habitat transects from the natural forest towards the edge of large conservation areas, or in the course of forest recovery at such margins. Such knowledge is also essential for deciding if moths can be used for monitoring the biotic effects of forest disturbance on mega-diverse insect faunas at all, and which moth groups are the most suitable targets for this purpose. Using very large data sets from low (Mt. Kinabalu National Park, Borneo) and high elevations (Podocarpus National Park, Ecuador), we investigate how species richness and species composition of moths change at small spatial scales along gradients of disturbance at the edge of natural forest reserves. Local species diversity did not always decline, and sometimes even increased, along the gradients. Ensembles of moths from the families Arctiidae or Sphingidae were as rich as in natural forest, or were even more diverse in habitats close to the forest margin. Geometridae and Pyraloidea ensembles, in contrast, tended to be impoverished. Correlations of alpha diversity measures between moth taxa were often poor and thus did not allow for using one group as a ‘biodiversity indicator’ of others. Estimates of local diversity also depended on the temporal scale of assessment. Species composition was remarkably sensitive to habitat alterations at forest edges even at very small spatial scales, despite the high dispersal potential of many moths. Patterns of beta diversity were highly concordant across unrelated moth taxa with very different life history syndromes. Geometridae ensembles responded more sensitively to changes in canopy openness than arctiid moths and yielded more robust results with regard to sampling effects. Therefore geometrids are particularly promising candidates for environmental monitoring in tropical landscapes. Much of the faunal differentiation between forest and margin habitats was due to shifts in abundance relationships, and not to the presence or absence of ‘indicator species’. Therefore, abundance-based monitoring appears more appropriate to detect effects of environmental change on mega-diverse moth ensembles. Our results suggest that patterns of beta (rather than alpha) diversity are generally more meaningful to assess the impact of processes at forest edges relevant to nature conservation and landscape planning.

Timber harvesting is currently the most common commercial utilisation activity in tropical forests. Assessing the effects of logging on different aspects of biodiversity and general ecosystem properties is hence of prime importance if the few remaining areas of intact tropical forest are to be protected effectively and efficiently.

As we will point out in this chapter, tropical amphibian communities are an appropriate model system for studies on the impacts of human-induced environmental changes on the dynamics of complex biological systems. Here, we elaborate on patterns of diversity changes in tropical forest amphibian communities facing habitat alterations associated with selective logging in two globally important eco-regions (Côte d’Ivoire, Upper Guinea, West Africa and Guyana, the Guiana Shield, northern South America), and discuss findings from other previously conducted studies with similar focus.

A key statement that we stress on in this chapter is the fact that common measures of diversity, such as species richness and α-diversity only inadequately reflect processes of diversity change following anthropogenic disturbance. They also fail to describe actual impacts on the dynamics of complex biological systems. We argue that commonly used measures produce an incoherent and insufficient picture of diversity patterns and the underlying processes that shape these patterns. Thus, an understanding of higher levels of diversity, such as β-diversity and functional diversity (and hence compositional patterns) appears to be the key to effectively mitigating the impacts of human-induced disturbance on amphibian communities.

We show that the predictability of amphibian community composition depends on the respective level of anthropogenic disturbance imposed on a particular habitat. Hence, human activities that lead to changes in the structure of a forest, such as logging, not only alter simple system descriptors, such as the number of species in a given community, but rather alter the dynamics of the entire system. In this context, functional diversity is shown to be an important aspect underlying the actual mechanism that leads to the observed change of predictability patterns. Functional differences between species, rather than number of species per se appear to be the decisive factor in sustaining desirable ecosystem states and thus in maintaining important ecosystem services.

Because biological diversity appears to play a substantial role in ecosystem resilience required to safeguard essential ecosystem functions in the face of environmental change, we call for a critical revision of common diversity assessments approaches. We advocate the reconsideration of the uncritical use of widespread measures and descriptors of biodiversity on grounds of inconsistent patterns found throughout numerous studies, including those presented herein.

The complex nature of natural communities and the multiple aspects of biodiversity at different levels, make it necessary to incorporate processes acting on different organizational and spatial scales. When investigating the impacts of human-induced environmental changes on diverse vertebrate communities in the tropics, we should hence address compositional changes, as well as β-, and functional aspects of biodiversity. Special attention should also be drawn to the particular disturbance history of a given site and large scale cross-regional comparisons should be given priority. The consideration of these approaches in future studies would likely provide deeper insight in ecosystem processes at large scales and improve the effectiveness of current ecosystem management strategies.

In most tropical countries, rainforests are encroached by the local population and converted into agricultural land or pasture at constantly high rates. An increasing portion of this new agricultural land is abandoned within a few years and left for succession by woody plants. In many regions, already a considerable fraction of the forested area is covered by secondary forests formed by rapidly growing, short-lived pioneer tree species. In the Lore Lindu National Park on Sulawesi (Indonesia), like in other tropical countries, many of the remaining patches of protected primary forest are also offended at their margins by neighbouring villagers, who practise selective logging or local planting of crops inside the forest. Thus, disturbed old-growth forest and regrowing secondary forest after clearcut represent woody vegetation types, which are of rapidly growing importance throughout the tropics. Considerable research has focused on the effects of disturbance — natural as well as human-induced — on above-ground vegetation in primary forests, and on leaf and canopy characteristics of secondary as compared to primary forest trees. Only a few studies, however, have addressed the effects of disturbance and forest conversion on the below-ground compartment in wet tropical forests.

This review surveys the literature on fine root biomass (roots < 2 mm) and its distribution and activity in disturbed old-growth and secondary tropical moist forests and compares the results with non-disturbed old-growth forests. Particular attention is being paid to the relationship between disturbance intensity, above-ground forest structure and fine root system size and structure. Secondly, we focus on the age-dependence of fine root biomass in regrowing secondary forests and the time required for fine root biomass recovery after clearcut. The results are interpreted with respect to carbon storage in the root system of tropical moist forests and its response to disturbance and conversion.

The global carbon cycle is being perturbed by changes in land-use, especially in the tropics. This chapter compares surface soil organic carbon stocks, carbon mineralization rates and soil CO efflux between an undisturbed forest and a clearing at Barro Colorado Island and between a pasture and plantation at Sardinilla, Central Panama. Our results on C cycling at two study sites with contrasting parent material and soil type were compared with other studies throughout the moist tropics. Differences in soil carbon stocks in the topsoil (0–5 cm) of the clearing (15 Mg C ha) and the undisturbed forest site (22 Mg C ha) were statistically not significant. Our inventory revealed that the highest carbon stock (29 Mg C ha) was found under the native tree plantation, although at least part of this high value is site-related. Thus, no carbon change could be detected two years after the conversion of the site from a pasture into a native tree plantation. Soil CO efflux rates at the pasture site (8 µmol CO m s) were significantly higher than in forest, clearing and plantation (5–6 µmol CO m s). Large CO flux rates in the pasture might be explained by high belowground biomass production which leads to high root respiration rates. Our incubation experiment showed that pasture and clearing soil had a higher proportion of active pool carbon than plantation and forest. Higher amounts of active pool C indicate the existence of carbon readily mineralizable by microbes. Our results demonstrate that the active pool C is a good predictor of soil respiration. Thus, active soil organic carbon is a sensitive indicator for changes in soil organic carbon following land use change.

Due to high deforestation rates, it is likely that in many regions tropical rainforests will survive in protected areas only. These refuges have to be surrounded by buffer zones where low impact forest management is permitted. In fact, increasing parts of the remaining rainforest areas are encroached by different types of low-intensity forest use. However, until now only few data exist on how different practices affect forest structure. The objectives of this study were to analyze differences in aboveground forest stand structure as caused by different types of forest utilization in the margin zone of a protected rainforest. The study was conducted in a lower montane rainforest region (800 – 1140 m) in the vicinity of the village of Toro in Central Sulawesi, Indonesia. We assessed the structure of twelve forest plots (0.15 ha each) which represented four types of forest use which are widespread in the study region. These types were natural forest without major disturbance, forest extraction of small-diameter timber, forest with selective extraction of large timbers and cacao agroforest plantations under trees remaining from the natural forest. The tree basal area ranged from relatively high values in the natural forests (52.5 m per ha) to 19.4 m per ha in the agroforest, and was paralleled by a decrease in tree height. Stem density peaked in stands where large timbers had been extracted and abundant tree regeneration had resumed, and it was lowest in the agroforest stands. Canopy openness, as estimated from 30 hemispheric photographs per plot, was lowest in the natural forest after small timber extraction (7 %) and highest in cacao agroforest (15 %). Leaf area index (LAI), as estimated from the same photos, averaged to 6.2 m m in the natural forest, 5.3 in the forests with small timber extraction, 5.0 in the forests with large timber extraction, and 5.3 on the agroforest plots. The latter result confirms earlier reports of relatively high leaf areas in the cacao agroforestry system. The relatively high LAI in forest stands after major timber extraction indicates a rapid recovery of leaf area after disturbance. We also analyzed the influence of stand structural parameters on rainfall partitioning into throughfall, stemflow and interception. In all forest stands we observed a close negative correlation between mean throughfall and tree height ( = 0.63) indicating a higher interception loss in taller stands. We conclude that local forest management at low to moderate intensities, as it is common in the margin zones of protected forests, has a significant and quantifiable impact on several forest structural parameters which in turn may influence ecosystem functions such as rainfall partitioning in the canopy.

Land use intensification at rainforest margins increases the pressure on the primary rainforest ecosystem, known for its high biodiversity and important functional role in global climate and carbon balances. Studying this system at different levels of disturbance increases our knowledge about its stability and mechanisms of diversity changes. While most studies investigating the effects of disturbance on animal populations focus on canopy communities, the present study reviews the driving factors for soil and litter arthropod communities. In addition, results from a study along a land use gradient in Central Sulawesi (Indonesia) will be discussed.

Within natural forests, litter composition, patchiness and especially litter abundance seem to be key factors driving litter arthropod diversity and densities, by creating microhabitats for many species and individuals. With increasing levels of disturbance in tropical forests, and with forest conversion into agroforestry and agricultural systems, soil/litter temperature and moisture levels become extremely important, leading to reduced densities and species richness. Changes of soil pH, a reduction of the litter habitat and increased anthropogenic disturbance via site management practices add to degradation. In the present study, litter arthropod communities were compared between three levels of forest use (none, small and large timber extraction) and two types of cacao plantations (under natural shade trees and under a polyculture of planted shade trees). The negative effects of increasing gap fraction and thus increasing temperatures accompanied by decreasing moisture levels and litter depth could be confirmed. Abundances of Collembola, Oribatida and Symphyla in litter and soil and the number of ant species in the litter declined with increasing land use intensity. In contrast, spider density and ant activity increased when natural forest sites were compared with the two types of cacao plantations. This can be explained by the shifting community structure of these two taxa, indicating that few, but abundant species of open habitats, such as Lycosidae, were replacing forest species. Surprisingly, the decline in microarthropod abundances along the land use gradient was not linearly correlated with decreasing moisture and litter depth or increasing temperature or litter quality (C-to-N ratio). Rather low microarthropod densities were already measured in little disturbed natural forest sites with small timber extraction. A similar pattern was observed for fungal abundances and root production, indicating that even small levels of disturbance influence the litter and soil system in tropical forests. On the one hand, changing microclimate, limited litter space, reduced availability of microbial resources and increased disturbance by plot maintenance inhibit higher densities of litter and soil animal populations. On the other hand, the simplified habitat structure favours populations of open habitats, especially predatory groups adapted to higher temperatures and/or lower soil moisture. It has to be investigated how a reduction of decomposers and an increase in predators could influence pest control and thus yields in these agroforestry systems.

This paper discusses inter-ethnic relations and patterns of land-use and landownership, and how ethnicity is defined, used to grant preference, and to allocate socio-economic resources, by analysing two forest-margin villages in Sulawesi.

The heavy influx of migrants has altered the proportion of local people to migrants in Sintuwu and Watumaeta, villages located on the eastern border of Lore Lindu National Park. In 2001, there were over one-third households of Bugis — the largest group of ethnic migrants. Social distance, inability to adapt and unwillingness to integrate (, ) were indicated by house-clustering of the ethnic groups.

As most agricultural land inside the village has been sold to migrants, mainly to Bugis, the locals have been transformed from landlords to landless, while the migrants became landlords. In a land-based economy, land scarcity leads to declining socio-economic security. Social destabilization occurs as ethnic frictions result from this shift in resource control.

To gain back their economic power and socio-economic security, locals adopted a strategy of land expansion into ecological buffer zone areas. By outsiders, particularly the State, this is viewed as an encroachment into the national park forest, while to locals this is an attempt to re-secure their economic base. Locals justified their actions by disputing the park boundaries. Subsequently their “illegal” actions were accepted and formalized when they received usufruct rights in the form of SKPL (Letter of Land Utilization) issued by the village head and KKM (Community Conservation Agreement), as was made by the Village Council with Lore Lindu National Park administrators.

Land expansion is also an attempt to re-stabilize relationship between locals and migrants in the face of ethnic conflict. The economic buffer zone has become a socio-political buffer that prevents local tensions from becoming open conflicts. In the absence of ethnic politics at national level, this local innovation in ethnic politics is a means to neutralize destabilization of interethnic relations. Such innovation, however, cannot go on endlessly, for once formalized the locals’ new economic space will most likely be taken over by the migrants, leading to a vicious circle of forest margin destabilization.

The implication of this is the need for a land-use modeling that accounts for social constraints of inter-ethnic relations and land-use systems. Encroachment is not only perceived as an economic action, but also as a political action, as forest has not only economic value, but is also an arena of ethno-political action. Disregarding this reality can trigger, and at times has triggered, ethnic conflicts.

Recognition of the importance of economically sound conservation strategies is one of the foundations of the Convention on Biological Diversity. Because of their exceptional contribution to global biological diversity, the conservation of the Central Sulawesi (Indonesia) rainforests is a particularly important case for a successful application of such strategies. One of the obstacles to the design and implementation of economically sound conservation strategies is the lack of knowledge on the economic value of non-market benefits generated by tropical forest ecosystems and the agricultural land use systems that replace them.

In this paper, we identify and quantify economically relevant preferences towards biological diversity at the rainforest margin that operate at the regional level around Lore Lindu National Park in Central Sulawesi. For economic valuation, choice experiments (CE) were used. We focused on indirect use benefits generated from different local and regional ecosystem functions. An ecosystem service approach was applied to avoid problems of respondent unfamiliarity with ecosystem functioning. One CE study covers preferences for the conservation of the endemic dwarf buffalo anoa, the preponderance of shading trees in cacao plantations, and the availability of water and of rattan. It was conducted in 12 villages across the entire project region (n=249). A second CE was conducted in three selected villages in the Kulawi subdistrict investigating preferences for protection against soil erosion, flooding and — to our knowledge, for the first time ever — for protection against future environmental threats (preferences for “ecosystem health”; n=585).

The results indicate substantial economic preferences for all biodiversity and ecosystem goods and services studied. Preference variations can be explained by attitudes of and perceptions on the human-environment relation. In particular, (i) several attitudinal variables from Protection Motivation Theory explain preference heterogeneity; (ii) preferences for ecosystem health depend on stated respect for — a normative principle on harmony between humans, supreme beings, and the environment. For an optimistic resource and biodiversity protection scenario, total aggregated mean WTP in the project region is 1.6 billion IDR/yri ∼136,000 €/yr). This local demand for the studied environmental non-market services does not suffice to compensate financial benefits from rainforest conversion or agroforestry intensification that accrue to individual households.