The greater resilience of mixed forests to drought mainly depends on their composition: Analysis along a climate gradient across Europe

Pardos, Marta; Rı́o, Miren del; Pretzsch, Hans; Jactel, Hervé; Bielak, Kamil; Bravo, Felipe; Brazaitis, Gediminas; Defossez, Emmanuel; Engel, Markus; Godvod, Kšištof; Jacobs, Kristoffel; Jansone, Lelde; Jansons, Āris; Morin, Xavier; Nothdurft, Arne; Oreti, Loredana; Ponette, Quentin; Pach, Maciej; Riofrío, José; Ruíz-Peinado, Ricardo; Tomao, Antonio; Uhl, Enno; Calama, Rafael

doi:10.1016/j.foreco.2020.118687

Cited by 142 publications

(107 citation statements)

References 94 publications

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“…Young trees were reported to have better drought resistance than adult ones (Andivia et al, 2020 ), consistent with the lack of significant difference between Rt and Rc of stands of different densities observed here. Taken together, the findings of this study and earlier studies all indicate that tree response to drought is a complex process (Lloret et al, 2011 ; Pardos et al, 2021 ).…”

Section: Discussionsupporting

confidence: 84%

Long-Term Effects of Climate and Competition on Radial Growth, Recovery, and Resistance in Mongolian Pines

et al. 2021

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Understanding the response of tree growth and drought vulnerability to climate and competition is critical for managing plantation forests. We analyzed the growth of Mongolian pines in six forests planted by the Three-North Shelter Forest Program with tree-ring data and stand structures. A retroactive reconstruction method was used to depict the growth-competition relationships of Mongolian pines during the growth period and their climatic responses under different competition levels. Drought vulnerability was analyzed by measuring the basal area increment (BAI) of different competition indices (CIs). In young trees, differences in BAIs in stands with different CIs were not statistically significant. After 15–20 years, medium- and high-CI stands had significantly lower tree-ring widths (TWs) and BAIs than the low-CI stands (p < 0.05). The standardized precipitation evapotranspiration index (SPEI), precipitation, relative humidity, and vapor pressure deficit were major factors affecting tree growth. On a regional scale, climate outweighed competition in determining radial growth. The relative contribution of climatic factors increased with the gap in SPEI between plantation sites and the native range, while the reverse pattern of the competition-growth relationship was observed. Drought reduced TWs and BAIs at all sites. Stands of different CIs exhibited similar resistance, but, compared with low-CI stands, high- and medium-CI stands had significantly lower recovery, resilience, and relative resilience, indicating they were more susceptible to drought stresses. Modeled CI was significantly negatively related to resistance, resilience, and relative resilience, indicating a density-dependence of tree response to drought. After exposure to multiple sequential drought events, the relative resilience of high-CI stands decreased to almost zero; this failure to fully recover to pre-drought growth rates suggests increased mortality in the future. In contrast, low-CI stands are more likely to survive in hotter, more arid climates. These results provide a better understanding of the roles of competition and climate on the growth of Mongolian pines and offer a new perspective for investigating the density-dependent recovery and resilience of these forests.

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Section: Discussionsupporting

confidence: 84%

Long-Term Effects of Climate and Competition on Radial Growth, Recovery, and Resistance in Mongolian Pines

et al. 2021

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“…They also found that soil water availability was 54% higher in heavily thinned compared to that in unthinned stands during a drought year. The positive effect of increased drought resilience in mixtures compared to monocultures has also been measured recently in closed even-aged, well to fully stock stands (Pardos et al 2021). They found a strong positive effect of conifer-broadleaf mixed stands on drought resilience and resistance, and suggested that the considerably different root morphology and architecture among species leads to trait complementarity, thereby improving the exploitation of belowground resources.…”

Section: The Effect Of Forest Composition and The Geographical Settingmentioning

confidence: 55%

“…Grossiord et al 2014). However, factors such as the type of mixture and tree species identity, depending on site aridity, basal area, and age, greatly modulate the beneficial effects of mixtures regarding drought resilience, which thus cannot be generalized (Pardos et al 2021).…”

Section: Introductionmentioning

confidence: 99%

Magnitude and timing of density reduction are key for the resilience to severe drought in conifer-broadleaf mixed forests in Central Europe

Zamora-Pereira

Yousefpour

Cailleret

et al. 2021

Annals of Forest Science

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Key message We applied a modified forest gap model (ForClim) to depict changes in stand water transpiration via density reduction as a forest adaptation strategy. This approach is the key to analyzing the ecological resilience to drought, stress-induced mortality, and economic efficiency of managed mixed forest stands in Central Europe. The results show that specific geographic conditions and forest composition define the optimal stand density of drought-resilient forests. Context Reducing stand density has been recognized as a valid strategy to increase forest resilience to drought. Moreover, to develop adaptive management strategies (AMS) under climate change, it is crucial to consider not only drought resilience but also the economic efficiency of alternative AMS proposed to alleviate drought effects. Aims To analyze how decreased inter-tree competition among overstorey trees affects stand vulnerability to drought and its expected yield. Methods We integrated experimental thinning data and historical responses to drought years in a climate-sensitive forest gap model, ForClim. We tested a business as usual (BAU) and three alternative AMS (“do-nothing,” low- and high-intensity overstorey removal) in mixed stands of Norway spruce (Picea abies), silver fir (Abies alba), and European beech (Fagus sylvatica) along an elevational gradient of 520–1020 m a.s.l. in Central Europe. Results High-intensity overstorey removal in mixed stands of all three species considerably increased forest volume growth resilience to drought and decreased stress-induced mortality by two-thirds vis à vis a “do-nothing” strategy. In sites including only conifer species, forest resilience was equally improved by high- and low-intensity overstorey removal compared to that in the BAU strategy. Regarding the timber economy, high-intensity overstorey removal resulted in a higher economic revenue of mixed stands (~ 22% higher net present value than other strategies) on the high-elevation sites (> 1000 m a.s.l.). Conclusion Modifying forest density and structure by overstorey removal is principally suitable to increase forest resilience to drought and improve its economic efficiency. The magnitude of the effect however depends on the geographical setting and forest composition.

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“…Forests composed of several tree species are expected to beget biodiversity in the forest habitat, because tree species mixing sets the stage for variation in other structural components (e.g., tree size differentiation, tree layering). Further, several studies have demonstrated that mixed forest communities are generally more productive, resilient and capable of providing more ecosystem services than stands dominated by a single species [3][4][5][6][7][8][9][10]. Albeit that the knowledge about the ecology of mixed Remote Sens.…”

Section: Introductionmentioning

confidence: 99%

Object Oriented Classification for Mapping Mixed and Pure Forest Stands Using Very-High Resolution Imagery

et al. 2021

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The importance of mixed forests is increasingly recognized on a scientific level, due to their greater productivity and efficiency in resource use, compared to pure stands. However, a reliable quantification of the actual spatial extent of mixed stands on a fine spatial scale is still lacking. Indeed, classification and mapping of mixed populations, especially with semi-automatic procedures, has been a challenging issue up to date. The main objective of this study is to evaluate the potential of Object-Based Image Analysis (OBIA) and Very-High-Resolution imagery (VHR) to detect and map mixed forests of broadleaves and coniferous trees with a Minimum Mapping Unit (MMU) of 500 m2. This study evaluates segmentation-based classification paired with non-parametric method K- nearest-neighbors (K-NN), trained with a dataset independent from the validation one. The forest area mapped as mixed forest canopies in the study area amounts to 11%, with an overall accuracy being equal to 85% and K of 0.78. Better levels of user and producer accuracies (85–93%) are reached in conifer and broadleaved dominated stands. The study findings demonstrate that the very high resolution images (0.20 m of spatial resolutions) can be reliably used to detect the fine-grained pattern of rare mixed forests, thus supporting the monitoring and management of forest resources also on fine spatial scales.

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The greater resilience of mixed forests to drought mainly depends on their composition: Analysis along a climate gradient across Europe

Cited by 142 publications

References 94 publications

Long-Term Effects of Climate and Competition on Radial Growth, Recovery, and Resistance in Mongolian Pines

Long-Term Effects of Climate and Competition on Radial Growth, Recovery, and Resistance in Mongolian Pines

Magnitude and timing of density reduction are key for the resilience to severe drought in conifer-broadleaf mixed forests in Central Europe

Object Oriented Classification for Mapping Mixed and Pure Forest Stands Using Very-High Resolution Imagery

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