The use of scenarios and models to evaluate the future of nature values and ecosystem services in Mediterranean forests

Morán-Ordóñez A., Roces-Díaz J.V., Otsu K., Ameztegui A., Coll L., Lefevre F., Retana J., Brotons L. (2019) The use of scenarios and models to evaluate the future of nature values and ecosystem services in Mediterranean forests. Regional Environmental Change. 19: 415-428.
Link
Doi: 10.1007/s10113-018-1408-5

Abstract:

Science and society are increasingly interested in predicting the effects of global change and socio-economic development on natural systems, to ensure maintenance of both ecosystems and human well-being. The Intergovernmental Platform on Biodiversity and Ecosystem Services has identified the combination of ecological modelling and scenario forecasting as key to improving our understanding of those effects, by evaluating the relationships and feedbacks between direct and indirect drivers of change, biodiversity, and ecosystem services. Using as case study the forests of the Mediterranean basin (complex socio-ecological systems of high social and conservation value), we reviewed the literature to assess (1) what are the modelling approaches most commonly used to predict the condition and trends of biodiversity and ecosystem services under future scenarios of global change, (2) what are the drivers of change considered in future scenarios and at what scales, and (3) what are the nature and ecosystem service indicators most commonly evaluated. Our review shows that forecasting studies make relatively little use of modelling approaches accounting for actual ecological processes and feedbacks between different socio-ecological sectors; predictions are generally made on the basis of a single (mainly climate) or a few drivers of change. In general, there is a bias in the set of nature and ecosystem service indicators assessed. In particular, cultural services and human well-being are greatly underrepresented in the literature. We argue that these shortfalls hamper our capacity to make the best use of predictive tools to inform decision-making in the context of global change. © 2018, Springer-Verlag GmbH Germany, part of Springer Nature.

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Bird community response in mountain pine forests of the Pyrenees managed under a shelterwood system

Ameztegui, A., Gil-Tena, A., Faus, J., Piqué, M., Brotons, L., Camprodon, J. (2018) Bird community response in mountain pine forests of the Pyrenees managed under a shelterwood system. Forest Ecology and Management. 407: 95-105.
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Doi: 10.1016/j.foreco.2017.09.002

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Knowledge gaps about mixed forests: What do European forest managers want to know and what answers can science provide?

Coll, L., Ameztegui, A., Collet, C., Löf, M., Mason, B., Pach, M., Verheyen, K., Abrudan, I., Barbati, A., Barreiro, S., Bielak, K., Bravo-Oviedo, A., Ferrari, B., Govedar, Z., Kulhavy, J., Lazdina, D., Metslaid, M., Mohren, F., Pereira, M., Peric, S., Rasztovits, E., Short, I., Spathelf, P., Sterba, H., Stojanovic, D., Valsta, L., Zlatanov, T., Ponette, Q. (2018) Knowledge gaps about mixed forests: What do European forest managers want to know and what answers can science provide?. Forest Ecology and Management. 407: 106-115.
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Doi: 10.1016/j.foreco.2017.10.055

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Relative size to resprouters determines post-fire recruitment of non-serotinous pines

Sánchez-Pinillos M., Ameztegui A., Kitzberger T., Coll L. (2018) Relative size to resprouters determines post-fire recruitment of non-serotinous pines. Forest Ecology and Management. 429: 300-307.
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Doi: 10.1016/j.foreco.2018.07.009

Abstract:

The persistence of non-serotinous pines in Mediterranean forests can be threatened by climate-mediated changes in fire regimes that may favor the dominance of resprouters or other fire-adapted species. Recovery of non-serotinous pines after large wildfires is often determined by their ability to grow under the canopy of promptly established resprouters. Mechanisms of facilitation or competition between resprouters and pines will thus have a profound effect on forest dynamics. We examined here the effect of neighboring oak resprouts on Pinus nigra Arn. ssp. salzmannii saplings 18 years after a wildfire. We determined the net outcome of interactions between oaks and pines and how they vary with the life stage and size of the interacting plants or the environmental conditions. We did not find any net facilitative effects of oaks on pine sapling growth. The sensitivity of pines to neighbors varied markedly with pine size, and to a lesser extent, with water availability during the growing season. Our findings suggest a self-reinforcing hierarchical process by which early-dispersed seedlings growing in low-competitive microsites can grow faster, mitigating neighboring competition in the later stage of canopy closure. These results entail a potentially critical role of management practices to promote post-fire recovery of non-serotinous pines under expected changing conditions of disturbance regimes. © 2018 Elsevier B.V.

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Managing stand density to enhance the adaptability of Scots pine stands to climate change: A modelling approach

Ameztegui A., Cabon A., De Cáceres M., Coll L. (2017) Managing stand density to enhance the adaptability of Scots pine stands to climate change: A modelling approach. Ecological Modelling. 356: 141-150.
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Doi: 10.1016/j.ecolmodel.2017.04.006

Abstract:

In the Mediterranean region most climatic forecasts predict longer and more intense drought periods that can affect tree growth and mortality over broad geographic regions. One of the silvicultural treatments that has gained currency to lessen the impacts of climatic change is the reduction of stand density by thinning. However, we lack information on how the response of forest stands to different thinning treatments will be affected by climate change, and on the post-thinning temporal dynamics of water balance, specifically blue and green water. We adopted a modelling approach to explore the long-term effects of different thinning intensities on forest dynamics and water balance under climate change scenarios, coupling an individual-based model of forest dynamics (SORTIE-ND) with a mechanistic model of soil moisture dynamics and plant drought stress. We used as a case study three Scots pine plots across a gradient of climatic conditions, and we assessed the effect of site, three climatic scenarios and eight thinning intensities on tree growth, stand productivity, tree drought stress and blue water. The best thinning intensity in terms of stand productivity was obtained when between 20 and 40% of the basal area was removed, whereas the final stand stock rapidly decreased at higher thinning intensities. Moreover, the decrease in final basal area occurred at lower thinning intensities the drier the site conditions. Moderate and heavy thinnings (>30%) doubled basal area increment (BAI) of the following years in all the plots, although the effect vanished after 30–40 years, independently of the site and climate scenario. As expected, thinning was simulated to have an overall positive effect on the blue water yield and tree water status, which increased and also tended to last longer for higher thinning intensities. However, the magnitude of this effect on tree water status was most dependent on the site and climatic scenario, as drier conditions generally raised stronger and longer lasting reductions in drought stress for a given thinning intensity. Furthermore, our results highlight the existence of a site- and climate-dependent trade-off between the gain in stand productivity and the improvement in tree water status obtained by thinning, particularly for moderate or heavy thinning intensities. Our simulations suggest that thinning is a useful management tool to mitigate climate change but strongly argue against the application of general recipes across sites and appeals for carefully taking into consideration local climatic trajectories for management planning. © 2017 Elsevier B.V.

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Land-use legacies rather than climate change are driving the recent upward shift of the mountain tree line in the Pyrenees

Ameztegui A., Coll L., Brotons L., Ninot J.M. (2016) Land-use legacies rather than climate change are driving the recent upward shift of the mountain tree line in the Pyrenees. Global Ecology and Biogeography. 25: 263-273.
Link
Doi: 10.1111/geb.12407

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Aim: To assess the effects of climate change, past land uses and physiography on the current position of the tree line in the Catalan Pyrenees and its dynamics between 1956 and 2006. Location: More than 1000 linear kilometres of sub-alpine tree line in the Catalan Pyrenees (north-east Spain) Methods: Using aerial photographs and supervised classification, we reclassified the images into a binary raster with 'tree' and 'non-tree' values, and determined canopy cover in 1956 and 2006. We then determined the change in position of the tree line between 1956 and 2006 based on changes in forest cover. We used the distance from the position of the tree line in 1956 to the theoretical potential tree line - determined from interpretation of aerial photographs, identifying the highest old remnants of forest for homogeneous areas of the landscape in terms of bioclimatic conditions, bedrock, landform and exposure - as a surrogate of intensity of past land uses. Results: Our analyses showed that the Pyrenean tree line has moved upwards on average almost 40m (mean advance±SE: 35.3±0.5m, P

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Shade tolerance and the functional trait: Demography relationship in temperate and boreal forests

Ameztegui, A., Paquette, A., Shipley, B., Heym, M., Messier, C., Gravel, D. (2016) Shade tolerance and the functional trait: Demography relationship in temperate and boreal forests. Functional Ecology. : 0-0.
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Doi: 10.1111/1365-2435.12804

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Tree light capture and spatial variability of understory light increase with species mixing and tree size heterogeneity

Ligot G., Ameztegui A., Courbaud B., Coll L., Kneeshaw D. (2016) Tree light capture and spatial variability of understory light increase with species mixing and tree size heterogeneity. Canadian Journal of Forest Research. 46: 968-977.
Link
Doi: 10.1139/cjfr-2016-0061

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Mixed and multi-layered forest ecosystems are sometimes more productive than monospecific and single-layered ones. It has been suggested that trees of different species and sizes occupy complementary positions in space, which would act as a mechanism to increase canopy light interception and wood production. However, greater canopy light interception reduces the average amount and variability of transmitted radiation, offering fewer opportunities for all species to regenerate and to maintain forest heterogeneity in the long run. We investigated whether increasing overstory heterogeneity indeed results in greater canopy light interception and lower variability in transmittance. We modeled the three-dimensional structure of forest stands with three typical forest structures, 10 mixtures of four tree species, and three different basal areas. We used the forest light interception model SAMSARALIGHT and performed three-way analyses of covariance to analyze the effects of the three varied components of forest heterogeneity. We found no evidence that increasing structural heterogeneity increases canopy light interception. However, the light interception by mixed canopies was greater than the weighted average of light interception by the corresponding pure canopies. Variability in transmittance increased in some cases with compositional heterogeneity and, to a lesser extent, with tree size inequalities. The advantage of heterogeneous forests is in opportunities for natural regeneration, as well as in opportunities to enhance canopy light interception. © 2016 NRC Research Press.

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Diversifying sub-Mediterranean pinewoods with oak species in a context of assisted migration: Responses to local climate and light environment

Martín-Alcón S., Coll L., Ameztegui A. (2016) Diversifying sub-Mediterranean pinewoods with oak species in a context of assisted migration: Responses to local climate and light environment. Applied Vegetation Science. : 0-0.
Link
Doi: 10.1111/avsc.12216

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Questions: How do thermal migration distance and extreme cold events affect seedling emergence and survival in assisted migration schemes in the sub-Mediterranean context? What role does plant provenance play? Can biotic interactions such as nurse effect of the overstorey and shrub layer buffer the negative responses to plant translocation? Are any of these effects species-specific? Location: Three pinewoods in the Catalan Pre-Pyrenees, northeast Iberian Peninsula. Methods: We used a replicated field trial to test the early years establishment of two contrasted provenances of four Quercus species (Q. coccifera, Q. ilex, Q. faginea and Q. pubescens) that were sown and planted along gradients of elevation and understorey microsite conditions in sub-Mediterranean pinewoods. Seedling responses to translocation were evaluated through seedling emergence, seedling survival and re-sprouting after dieback events according to seedling provenance, thermal migration distance, extreme cold events and microenvironment. Results: The study reports high success of both the planting (with an overall 76.3% of initial 3-yr survival) and sowing (with an overall 50% of seedling emergence) experiments. The results show that: (1) the thermal migration distance and the occurrence of extreme cold events have strong effects on the responses of the translocated species (particularly the evergreen oaks); (2) the forest overstorey plays an important role in attenuating the negative effects of thermal migration distance on seedling survival; and (3) these responses are species-specific. The evergreen Quercus species showed more evidence of high ecotypic differentiation in terms of cold tolerance, enabling local provenances to respond better to translocation. In contrast, marcescent species, showed high phenotypic plasticity that led to a better overall establishment success. Conclusion: The implementation of assisted migration is a feasible option to increase the diversity and resilience of the sub-Mediterranean pinewoods. Assisted migration programmes should manage risks by thoroughly considering thermal migration distances and the occurrence of extreme cold events when selecting species and seed sources, since Mediterranean tree species show different strategies regarding adaptation to cold. Programme managers should also consider the advantage of planting/sowing under relatively closed canopy to buffer some of the negative responses associated with translocation. © 2016 International Association for Vegetation Science.

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Assessing tree germination resilience to global warming: a manipulative experiment using sugar maple (Acer saccharum)

Solarik K.A., Gravel D., Ameztegui A., Bergeron Y., Messier C. (2016) Assessing tree germination resilience to global warming: a manipulative experiment using sugar maple (Acer saccharum). Seed Science Research. : 1-12.
Link
Doi: 10.1017/S0960258516000040

Abstract:

A climate warming of 2–5°C by the end of the century will impact the likelihood of seed germination of sugar maple (Acer saccharum), a dominant tree species which possesses a restricted temperature range to ensure successful reproduction. We hypothesize that seed origin affects germination due to the species' local adaptation to temperature. We tested this by experimentally investigating the effect of incubation temperature and temperature shifting on sugar maple seed germination from seven different seed sources representing the current species range. Survival analysis showed that seeds from the northern range had the highest germination percentage, while the southern range had the lowest. The mean germination percentage under constant temperatures was best when temperatures were ≤5°C, whereas germination percentages plummeted at temperatures ≥11°C (5.8%). Cool shifting increased germination by 19.1% over constant temperature treatments and by 29.3% over warm shifting treatments. Both shifting treatments caused earlier germination relative to the constant temperature treatments. A climate warming of up to +5°C is shown to severely reduce germination of seeds from the southern range. However, under a more pronounced warming of 7°C, seed germination at the northern range become more affected and now comparable to those found from the southern range. This study states that the high seed germination percentage found in sugar maple at the northern range makes it fairly resilient to the warmest projected temperature increase for the next century. These findings provide forest managers with the necessary information to make accurate projections when considering strategies for future regeneration while also considering climate warming. Copyright © Cambridge University Press 2016

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