Institute of Terrestrial Ecosystems

Zürich, Switzerland

Institute of Terrestrial Ecosystems

Zürich, Switzerland
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Snell R.S.,Institute of Terrestrial Ecosystems | Huth A.,Helmholtz Center for Environmental Research | Nabel J.E.M.S.,Swiss Federal Institute of forest | Nabel J.E.M.S.,ETH Zurich | And 14 more authors.
Ecography | Year: 2014

Dynamic vegetation models (DVMs) follow a process-based approach to simulate plant population demography, and have been used to address questions about disturbances, plant succession, community composition, and provisioning of ecosystem services under climate change scenarios. Despite their potential, they have seldom been used for studying species range dynamics explicitly. In this perspective paper, we make the case that DVMs should be used to this end and can improve our understanding of the factors that influence species range expansions and contractions. We review the benefits of using process-based, dynamic models, emphasizing how DVMs can be applied specifically to questions about species range dynamics. Subsequently, we provide a critical evaluation of some of the limitations and trade-offs associated with DVMs, and we use those to guide our discussions about future model development. This includes a discussion on which processes are lacking, specifically a mechanistic representation of dispersal, inclusion of the seedling stage, trait variability, and a dynamic representation of reproduction. We also discuss upscaling techniques that offer promising solutions for being able to run these models efficiently over large spatial extents. Our aim is to provide directions for future research efforts and to illustrate the value of the DVM approach. © 2014 The Authors.


Sayer J.,James Cook University | Sunderland T.,Center for International Forestry Research | Ghazoul J.,Institute of Terrestrial Ecosystems | Pfund J.-L.,Fauna | And 12 more authors.
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

"Landscape approaches" seek to provide tools and concepts for allocating and managing land to achieve social, economic, and environmental objectives in areas where agriculture, mining, and other productive land uses compete with environmental and biodiversity goals. Here we synthesize the current consensus on landscape approaches.This is based on published literature and a consensus-building process to define good practice and is validated by a survey of practitioners.We find the landscape approach has been refined in response to increasing societal concerns about environment and development tradeoffs. Notably, there has been a shift from conservation-orientated perspectives toward increasing integration of poverty alleviation goals. We provide 10 summary principles to support implementation of a landscape approach as it is currently interpreted.These principles emphasize adaptive management, stakeholder involvement, and multiple objectives.Various constraints are recognized, with institutional and governance concerns identified as the most severe obstacles to implementation. We discuss how these principles differ from more traditional sectoral and project-based approaches. Although no panacea, we see few alternatives that are likely to address landscape challenges more effectively than an approach circumscribed by the principles outlined here.


Ziegler A.D.,National University of Singapore | Phelps J.,National University of Singapore | Yuen J.Q.,National University of Singapore | Webb E.L.,National University of Singapore | And 12 more authors.
Global Change Biology | Year: 2012

Policy makers across the tropics propose that carbon finance could provide incentives for forest frontier communities to transition away from swidden agriculture (slash-and-burn or shifting cultivation) to other systems that potentially reduce emissions and/or increase carbon sequestration. However, there is little certainty regarding the carbon outcomes of many key land-use transitions at the center of current policy debates. Our meta-analysis of over 250 studies reporting above- and below-ground carbon estimates for different land-use types indicates great uncertainty in the net total ecosystem carbon changes that can be expected from many transitions, including the replacement of various types of swidden agriculture with oil palm, rubber, or some other types of agroforestry systems. These transitions are underway throughout Southeast Asia, and are at the heart of REDD+ debates. Exceptions of unambiguous carbon outcomes are the abandonment of any type of agriculture to allow forest regeneration (a certain positive carbon outcome) and expansion of agriculture into mature forest (a certain negative carbon outcome). With respect to swiddening, our meta-analysis supports a reassessment of policies that encourage land-cover conversion away from these [especially long-fallow] systems to other more cash-crop-oriented systems producing ambiguous carbon stock changes - including oil palm and rubber. In some instances, lengthening fallow periods of an existing swidden system may produce substantial carbon benefits, as would conversion from intensely cultivated lands to high-biomass plantations and some other types of agroforestry. More field studies are needed to provide better data of above- and below-ground carbon stocks before informed recommendations or policy decisions can be made regarding which land-use regimes optimize or increase carbon sequestration. As some transitions may negatively impact other ecosystem services, food security, and local livelihoods, the entire carbon and noncarbon benefit stream should also be taken into account before prescribing transitions with ambiguous carbon benefits. © 2012 Blackwell Publishing Ltd.


News Article | February 15, 2017
Site: www.eurekalert.org

In order to restore tropical rainforests, it is not enough to simply set up protected areas and leave them to their own devices. In particular, tree species with large fruit and seeds distributed by birds will have to be actively planted. This is one of the conclusions of a large-scale study by scientists from ETH Zurich in the Western Ghats, the mountain range running along the western coast of India. Today, the rainforest that exists there is highly fragmented. In the late 20th century in particular, large areas fell victim to intensive logging and commercial agriculture such as coffee and tea plantations. Working with Indian colleagues, the ETH researchers investigated how well trees from rainforest fragments could spread to areas that had previously been cleared or logged but are now back under forest cover. At the heart of their study was the white cedar (Dysoxylum malabaricum), a tropical species belonging to the mahogany family. "These rainforest giants tower above the other trees and therefore occupy an important ecological niche," says Chris Kettle, a scientist at ETH Zurich's Institute of Terrestrial Ecosystems, who led the study. The seeds don't fall far from the tree The tree's seeds are distributed primarily by a specific species of hornbill, the Malabar grey hornbill, which eats the fleshy, fig-sized fruit and then excretes the seeds. Until now, it was not known how far the hornbills carry the seeds in their bodies. Theoretically, as the birds cover long distances, they could contribute to a rapid distribution of the tree species over a large area. This is not the case, however, as the ETH researchers have now discovered. Through genetic maternity testing of seedlings and adult trees, they were able to show that generally the seedlings grow no more than 200 metres from the mother tree, and in many cases at a distance of just 40 to 100 metres. "We suspect that the hornbills regurgitate the seeds relatively close to the tree from which they fed, so that they don't have to fly with their stomachs full of heavy seeds," says ETH doctoral student Sascha Ismail, first author of the study published in the journal New Phytologist. The results of the research have implications for the restoration of rainforests: "It is highly unlikely that the tree species we studied is able to recolonise cleared patches in a fragmented habitat by natural seed dispersal alone," says Kettle. He adds that the same applies to other endangered species of tropical tree with large fruit and seeds dispersed by birds, as evidence from other fragmented tropical forests around the world shows that seeds of this kind are dispersed only locally. "For rainforest restoration projects to be successful, you have to give special attention to these trees," says Kettle. "If you want to encourage them to spread, the only option is to collect their seeds, set up tree nurseries and then actively plant out the saplings at a later stage." For the parentage analysis, the researchers surveyed exhaustively an area covering 216 km2 (considerably larger than the area of the Swiss National Park). They analysed the DNA of all 235 adult trees found there, as well as of 448 seedlings. "This is the largest study of its kind ever carried out in a fragmented tropical ecosystem," says Kettle. Ismail S, Ghazoul J, Ravikanth G, Kushalappa CG, Shaanker RU, Kettle CJ: Evaluating realized seed dispersal across fragmented tropical landscapes: a two-fold approach using parentage analysis and the neighbourhood model. New Phytologist 2017, doi: 10.1111/nph.14427


News Article | February 15, 2017
Site: phys.org

In order to restore tropical rainforests, it is not enough to simply set up protected areas and leave them to their own devices. In particular, tree species with large fruit and seeds distributed by birds will have to be actively planted. This is one of the conclusions of a large-scale study by scientists from ETH Zurich in the Western Ghats, the mountain range running along the western coast of India. Today, the rainforest that exists there is highly fragmented. In the late 20th century in particular, large areas fell victim to intensive logging and commercial agriculture such as coffee and tea plantations. Working with Indian colleagues, the ETH researchers investigated how well trees from rainforest fragments could spread to areas that had previously been cleared or logged but are now back under forest cover. At the heart of their study was the white cedar (Dysoxylum malabaricum), a tropical species belonging to the mahogany family. "These rainforest giants tower above the other trees and therefore occupy an important ecological niche," says Chris Kettle, a scientist at ETH Zurich's Institute of Terrestrial Ecosystems, who led the study. The seeds don't fall far from the tree The tree's seeds are distributed primarily by a specific species of hornbill, the Malabar grey hornbill, which eats the fleshy, fig-sized fruit and then excretes the seeds. Until now, it was not known how far the hornbills carry the seeds in their bodies. Theoretically, as the birds cover long distances, they could contribute to a rapid distribution of the tree species over a large area. This is not the case, however, as the ETH researchers have now discovered. Through genetic maternity testing of seedlings and adult trees, they were able to show that generally the seedlings grow no more than 200 metres from the mother tree, and in many cases at a distance of just 40 to 100 metres. "We suspect that the hornbills regurgitate the seeds relatively close to the tree from which they fed, so that they don't have to fly with their stomachs full of heavy seeds," says ETH doctoral student Sascha Ismail, first author of the study published in the journal New Phytologist. The results of the research have implications for the restoration of rainforests: "It is highly unlikely that the tree species we studied is able to recolonise cleared patches in a fragmented habitat by natural seed dispersal alone," says Kettle. He adds that the same applies to other endangered species of tropical tree with large fruit and seeds dispersed by birds, as evidence from other fragmented tropical forests around the world shows that seeds of this kind are dispersed only locally. "For rainforest restoration projects to be successful, you have to give special attention to these trees," says Kettle. "If you want to encourage them to spread, the only option is to collect their seeds, set up tree nurseries and then actively plant out the saplings at a later stage." For the parentage analysis, the researchers surveyed exhaustively an area covering 216 km2 (considerably larger than the area of the Swiss National Park). They analysed the DNA of all 235 adult trees found there, as well as of 448 seedlings. "This is the largest study of its kind ever carried out in a fragmented tropical ecosystem," says Kettle. Explore further: The mystery of monodominance—how natural monocultures evolve in the rainforest More information: Sascha A. Ismail et al, Evaluating realized seed dispersal across fragmented tropical landscapes: a two-fold approach using parentage analysis and the neighbourhood model, New Phytologist (2017). DOI: 10.1111/nph.14427


Moradi A.B.,Institute of Terrestrial Ecosystems | Swoboda S.,University of Natural Resources and Life Sciences, Vienna | Robinson B.,Institute of Terrestrial Ecosystems | Prohaska T.,University of Natural Resources and Life Sciences, Vienna | And 4 more authors.
Environmental and Experimental Botany | Year: 2010

Quantitative studies of the distribution pattern of metals in plant tissues provide important information on the potential of metal-accumulator plants for remediation and amelioration of contaminated soils. We used laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as well as staining with dimethylglyoxime (DMG) to investigate the distribution pattern of nickel (Ni) in root cross-sections of the Ni-hyperaccumulator plant Berkheya coddii Rossler. Plants were grown in rhizoboxes containing soil with 125 mg kg-1 Ni. Roots were embedded in resin and cut into sections for LA-ICP-MS analysis. For DMG-staining analysis, fresh root cross-sections were prepared using a microtome. LA-ICP-MS revealed higher Ni concentrations in the cortex (374 ± 66 mg kg-1) than in the stele (210 ± 48 mg kg-1) of the investigated roots. The distribution pattern agreed well with those found by DMG-staining. Higher concentrations of Ni were found in the stele compared to the cortex of roots of the control plants not exposed to elevated soil Ni using both techniques. Our results indicate that an active uptake or ion selection mechanism exists for B. coddii in the absence of available Ni in the rhizosphere. © 2010 Elsevier B.V. All rights reserved.


Knaus F.,Institute of Terrestrial Ecosystems
Eco.mont | Year: 2013

Monitoring is a key activity in biosphere reserves and other parks. It is often used as a basis for evaluating the development of a reserve and the success of the protected area management. Monitoring activities hold many pitfalls, as shown by results from a project in the UNESCO Biosphere Reserve Entlebuch. Creating a causal link between management activities and monitoring results is one major challenge. Additional difficulties arise from often used non-systematic data originating from external sources. Embedding the available data in a simple conceptual model that links aims and key system factors with sustainability indicators could alleviate some of the problems encountered.


PubMed | Institute of Terrestrial Ecosystems
Type: Journal Article | Journal: Ecology letters | Year: 2010

Species extinctions pose serious threats to the functioning of ecological communities worldwide. We used two qualitative and quantitative pollination networks to simulate extinction patterns following three removal scenarios: random removal and systematic removal of the strongest and weakest interactors. We accounted for pollinator behaviour by including potential links into temporal snapshots (12 consecutive 2-week networks) to reflect mutualists ability to switch interaction partners (re-wiring). Qualitative data suggested a linear or slower than linear secondary extinction while quantitative data showed sigmoidal decline of plant interaction strength upon removal of the strongest interactor. Temporal snapshots indicated greater stability of re-wired networks over static systems. Tolerance of generalized networks to species extinctions was high in the random removal scenario, with an increase in network stability if species formed new interactions. Anthropogenic disturbance, however, that promote the extinction of the strongest interactors might induce a sudden collapse of pollination networks.

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