Andrés Gerique

Afforestation or intense pasturing improve the ecological and economic value of abandoned tropical farmlands

Increasing demands for livelihood resources in tropical rural areas have led to progressive clearing of biodiverse natural forests. Restoration of abandoned farmlands could counter this process. However, as aims and modes of restoration differ in their ecological and socio-economic value, the assessment of achievable ecosystem functions and benefits requires holistic investigation. Here we combine the results from multidisciplinary research for a unique assessment based on a normalization of 23 ecological, economic and social indicators for four restoration options in the tropical Andes of Ecuador. A comparison of the outcomes among afforestation with native alder or exotic pine, pasture restoration with either low-input or intense management and the abandoned status quo shows that both variants of afforestation and intense pasture use improve the ecological value, but low-input pasture does not. Economic indicators favour either afforestation or intense pasturing. Both Mestizo and indigenous Saraguro settlers are more inclined to opt for afforestation.

Land cover change in the Andes of southern Ecuador - patterns and drivers.

In the megadiverse tropical mountain forest in the Andes of southern Ecuador, a global biodiversity hotspot, the use of fire to clear land for cattle ranching is leading to the invasion of an aggressive weed, the bracken fern, which is threatening diversity and the provisioning of ecosystem services. To find sustainable land use options adapted to the local situation, a profound knowledge of the long-term spatiotemporal patterns of land cover change and its drivers is necessary, but hitherto lacking. The complex topography and the high cloud frequency make the use of remote sensing in this area a challenge. To deal with these conditions, we pursued specific pre-processing steps before classifying five Landsat scenes from 1975 to 2001. Then, we quantified land cover changes and habitat fragmentation, and we investigated landscape changes in relation to key spatial elements (altitude, slope, and distance from roads). Good classification results were obtained with overall accuracies ranging from 94.5% to 98.5% and Kappa statistics between 0.75 and 0.98. Forest was strongly fragmented due to the rapid expansion of the arable frontier and the even more rapid invasion by bracken. Unexpectedly, more bracken-infested areas were converted to pastures than vice versa, a practice that could alleviate pressure on forests if promoted. Road proximity was the most important spatial element determining forest loss, while for bracken the altitudinal range conditioned the degree of invasion in deforested areas. The annual deforestation rate changed notably between periods: ~1.5% from 1975 to 1987, ~0.8% from 1987 to 2000, and finally a very high rate of ~7.5% between 2000 and 2001. We explained these inconstant rates through some specific interrelated local and national political and socioeconomic drivers, namely land use policies, credit and tenure incentives, demography, and in particular, a severe national economic and bank crisis.

Human ecological dimensions in sustainable utilization and conservation of tropical mountain rain forests under global change in southern Ecuador

Profound knowledge of region-specific human ecological parameters is crucial for the sustainable utilization and conservation of tropical mountain rain forests in southern Ecuador, a region with heterogenic ethnic, socio-cultural and socio-economic structures. In order to satisfy the objectives of forest conservation on the one hand and the utilization claims of the local population on the other, an integrated concept of nature conservation and sustainable land use development is being sought (e.g. Ellenberg 1993). Within the human ecological research project of the German Research Foundation (DFG) presented here, four research topics have been explored in detail in indigenous Shuar and Saraguro as well as local Mestizo communities of southern Ecuador:

Mycorrhiza Networks Promote Biodiversity and Stabilize the Tropical Mountain Rain Forest Ecosystem: Perspectives for Understanding Complex Communities

To better understand the mechanisms behind maintenance of the extraordinary plant and fungal diversity in tropical mountain forests we applied, for the first time, network theory to investigate the mycobiont–plant communities. We addressed three different mycorrhizal classes, arbuscular mycorrhizae of tropical trees, mycorrhizae of terrestrial and epiphytic Orchidaceae and cavendishioid mycorrhizae among Ericaceae and Sebacinales. We found significant nestedness (NODF) for arbuscular and orchid mycorrhizal networks. In accordance to previous simulations and verifications of species-rich, mutualistic plant–animal networks, we conclude that preferential attachment of new members to already existing links integrates and maintains rare species and stabilizes our species rich assemblages.

Current Provisioning Services : Pasture Development and Use, Weeds (Bracken) and Management

This chapter reports on the historical expansion and current state of the pastures in the Rio San Francisco valley. Its major part is inhabited by the Mestizos, who do not have a long-standing pasture tradition. Three types of pastures were identified by the dominant grass species: the “pastos azules” (Holcus lanatus), the Yaragua pastures (Melinis minutiflora) and the dominating “pastos mieles” (Setaria sphacelata). The peculiarities, species composition, soil dynamics and agricultural values of these pastures are discussed. Except for the pastos azules on small flattenings in the otherwise steep slopes of the valley, pastures in the area suffer from invasion by aggressive weeds, mainly the tropical bracken fern. Abandonment of pastures is fostered by the use of fire to combat weeds and stimulate grass growth. This type of low-yield pasture farming is not sustainable. The earnings of livestock farming are not sufficient for subsistence. Diversification of the income portfolio is necessary.

Current Provisioning Ecosystem Services for the Local Population: Landscape Transformation, Land Use, and Plant Use

The tropical mountain forest areas of the eastern slopes of the Andes of South Ecuador have been colonized since the early twentieth century by mestizo and later by indigenous Saraguro settlers. As a consequence, the former forest landscape has been replaced by a mixed matrix of forest remnants, pastures, fields/gardens, and wasteland (matorral). This chapter addresses land use, plant use, and the landscape transformation process with its implications for provisioning ecosystem services for the local population. It presents the history of colonization, the policy framework of this process, and its influence on the trajectories of land use/land cover changes in the study area. The current and past practices of resource use, food production, and plant use are analyzed together with the livelihood strategies of the small-scale farming households.

Landscape History, Vegetation History, and Past Human Impacts

Three pollen profiles reveal vegetation changes during the past 16,500 years of the Podocarpus National Park (PNP) in the Southern Ecuadorian Andes. Andean glaciers retreated after the Last Glacial Maximum and the Younger Dryas cold interval, accompanied by a marked decline of paramo vegetation between 11660 and 4280 b.p., and the expansion of subparamo vegetation. Polylepis was widespread during the warm early Holocene, whereupon paramo vegetation increased after 4200 b.p. The upper montane forest became abundant after 4200 b.p., and an increase of paramo taxa since 500 b.p. indicates moister climate since then. Charcoal particle concentration maxima are evident between 1800 to 1600 b.p. and 600 to 400 b.p. The mountain region became permanently settled at the end of the nineteenth century when the exploitation of natural resources was initiated. Decadal variations in ring-width chronology from Cedrela montana are possibly related to large-scale atmospheric pressure variations in the tropical Pacific Ocean.

Conservation, Management of Natural Forests and Reforestation of Pastures to Retain and Restore Current Provisioning Services

Conservation in Ecuador is mainly realised through an extensive network of protected areas. Recently, multi-stakeholder initiatives and payments for environmental services are also implemented to support conservation. Natural forests provide 120 timber species to the Ecuadorian market. Furthermore, they harbour a wealth of different species for non-timber forest uses (NTFPs), which play a substantial role in the livelihoods of small-scale farming households. However, the extent differs among the ethnic groups. Another essential but often neglected service of natural forests is its relevance as a genetic resource for reproductive material. Reforestation of unproductive land is an important option to reduce the pressure on natural forests and to rehabilitate its provisioning services. So far mostly exotic tree species have been used for this. We demonstrate that reforestation programmes with native tree species have a good potential and may generate several thousands of job opportunities and a huge market for forest reproductive material.