scholarly journals Growth Trends of Coniferous Species along Elevational Transects in the Central European Alps Indicate Decreasing Sensitivity to Climate Warming

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 132 ◽  
Author(s):  
Walter Oberhuber ◽  
Ursula Bendler ◽  
Vanessa Gamper ◽  
Jacob Geier ◽  
Anna Hölzl ◽  
...  

Tree growth at high elevation in the Central European Alps (CEA) is strongly limited by low temperature during the growing season. We developed a tree ring series of co-occurring conifers (Swiss stone pine, Norway spruce, European larch) along elevational transects stretching from the subalpine zone to the krummholz limit (1630–2290 m asl; n = 503 trees) and evaluated whether trends in basal area increment (BAI) are in line with two phases of climate warming, which occurred from 1915–1953 and from 1975–2015. Unexpectedly, results revealed that at subalpine sites (i) intensified climate warming in recent decades did not lead to a corresponding increase in BAI and (ii) increase in summer temperature since 1915 primarily favored growth of larch and spruce, although Swiss stone pine dominates at high elevations in the Eastern CEA, and therefore was expected to mainly benefit from climate warming. At treeline, BAI increases in all species were above the level expected based on determined age trend, whereas at the krummholz limit only deciduous larch showed a minor growth increase. We explain missing adequate growth response to recent climate warming by strengthened competition for resources (nutrients, light, water) in increasingly denser stands at subalpine sites, and by frost desiccation injuries of evergreen tree species at the krummholz limit. To conclude, accurate forecasts of tree growth response to climate warming at high elevation must consider changes in stand density as well as species-specific sensitivity to climate variables beyond the growing season.

2020 ◽  
Author(s):  
Walter Oberhuber ◽  
Ursula Bendler ◽  
Vanessa Gamper ◽  
Jacob Geier ◽  
Anna Hölzl ◽  
...  

<p>It is well established, that tree growth at high elevations is mainly limited by low temperature during the growing season and climate warming was frequently found to lead to more growth and expansion of trees into alpine tundra. However, dendroclimatological studies revealed contradictory growth response to recent climate warming at the upper elevational limit of tree growth, and transplant experiments unveiled that high elevation tree provenances are not adequately benefiting from higher temperatures when planted at lower elevation. We therefore re-evaluated growth response of trees to recent climate warming by developing tree ring series of co-occurring conifers (Swiss stone pine (<em>Pinus cembra</em>), European larch (<em>Larix decidua</em>), and Norway spruce (<em>Picea abies</em>)) along several altitudinal transects stretching from the subalpine zone to the krummholz-limit (1630–2290 m asl; n=503 trees) in the Central European Alps (CEA). We evaluated whether trends in basal area increment (BAI) are in line with two phases of climate warming which occurred from 1915–1953 and from mid-1970s until 2015. We expected that BAI of all species shows an increasing trend consistent with distinct climate warming during the study period (1915–2015) amounting to >2 °C. Although enhanced tree growth was detected in all species in response to climate warming, results revealed that at subalpine sites (<em>i</em>) intensified climate warming since mid-1970s did not lead to corresponding increase in BAI, and (<em>ii</em>) increase in summer temperature primarily favored growth of Norway spruce, although Swiss stone pine dominates at high altitude in the CEA and therefore was expected to mainly benefit from climate warming. At treeline BAI increase was above the determined age trend in all species, whereas at the krummholz-limit only deciduous larch showed minor growth increase. We explain missing adequate growth response to recent climate warming (<em>i</em>) by strengthened competition for resources (primarily nutrients and light) in increasingly denser stands at subalpine sites leading to changes in carbon allocation among tree organs, and (<em>ii</em>) by frost desiccation injuries of evergreen tree species at the krummholz-limit. Our findings indicate that tree growth response to climate warming at high elevation is possibly nonlinear, and that increasing competition for resources and the influence of climate factors beyond the growing season impair stem growth. </p>


2017 ◽  
Vol 61 (12) ◽  
pp. 2085-2096 ◽  
Author(s):  
Jiajia Su ◽  
Xiaohua Gou ◽  
Yang Deng ◽  
Ruibo Zhang ◽  
Wenhuo Liu ◽  
...  

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 744 ◽  
Author(s):  
Oberhuber ◽  
Geisler ◽  
Bernich ◽  
Wieser

At the treeline in the Central European Alps, adverse climate conditions impair tree growth and cause krummholz formation of Swiss stone pine (Pinus cembra L.). Multi-stemmed trees (tree clusters) are frequently found in the treeline ecotone and are generally thought to originate from seed caches (multiple genets) of the European nutcracker (N. caryocatactes) or due to repeated damage of the leader shoot by browsing or mechanical stress (single genet). Additionally, lack of apical control can lead to upward bending of lateral branches, which may obscure single-genet origin if the lower branching points are overgrown by vegetation and the humus layer. The multi-stemmed growth form may serve as a means of protection against extreme environmental stress during winter, especially at wind-exposed sites, because leeward shoots are protected from, e.g. ice particle abrasion and winter desiccation. The aims of this study therefore were to analyze in an extensive field survey: (i) whether weak apical control may serve as a protection against winter stress; and (ii) to what extent the multi-stemmed growth form of P. cembra in the krummholz zone is originating from a single genet or multiple genets. To accomplish this, the growth habit of P. cembra saplings was determined in areas showing extensive needle damage caused by winter stress. Multi-stemmed saplings were assigned to single and multiple genets based on determination of existing branching points below the soil surface. The findings revealed that upward bending of lateral branches could protect saplings against winter stress factors, and, although multi-stemmed P. cembra trees were primarily found to originate from multiple genets (most likely seed caches), about 38% of tree clusters originated from upward bending of (partially) buried branches. The results suggest that weak apical control of P. cembra in the sapling stage might be an adaptation to increase survival rate under severe climate conditions prevailing above treeline during winter.


2017 ◽  
Vol 33 (2) ◽  
pp. 303-311 ◽  
Author(s):  
Yuandong Zhang ◽  
Mingming Guo ◽  
Xiaochun Wang ◽  
Fengxue Gu ◽  
Shirong Liu

2015 ◽  
Vol 6 (1) ◽  
pp. 245-265 ◽  
Author(s):  
U. Schickhoff ◽  
M. Bobrowski ◽  
J. Böhner ◽  
B. Bürzle ◽  
R. P. Chaudhary ◽  
...  

Abstract. Climate warming is expected to induce treelines to advance to higher elevations. Empirical studies in diverse mountain ranges, however, give evidence of both advancing alpine treelines and rather insignificant responses. The inconsistency of findings suggests distinct differences in the sensitivity of global treelines to recent climate change. It is still unclear where Himalayan treeline ecotones are located along the response gradient from rapid dynamics to apparently complete inertia. This paper reviews the current state of knowledge regarding sensitivity and response of Himalayan treelines to climate warming, based on extensive field observations, published results in the widely scattered literature, and novel data from ongoing research of the present authors. Several sensitivity indicators such as treeline type, treeline form, seed-based regeneration, and growth patterns are evaluated. Since most Himalayan treelines are anthropogenically depressed, observed advances are largely the result of land use change. Near-natural treelines are usually krummholz treelines, which are relatively unresponsive to climate change. Nevertheless, intense recruitment of treeline trees suggests a great potential for future treeline advance. Competitive abilities of seedlings within krummholz thickets and dwarf scrub heaths will be a major source of variation in treeline dynamics. Tree growth–climate relationships show mature treeline trees to be responsive to temperature change, in particular in winter and pre-monsoon seasons. High pre-monsoon temperature trends will most likely drive tree growth performance in the western and central Himalaya. Ecological niche modelling suggests that bioclimatic conditions for a range expansion of treeline trees will be created during coming decades.


2018 ◽  
Vol 115 (8) ◽  
pp. 1848-1853 ◽  
Author(s):  
Sabine B. Rumpf ◽  
Karl Hülber ◽  
Günther Klonner ◽  
Dietmar Moser ◽  
Martin Schütz ◽  
...  

Many studies report that mountain plant species are shifting upward in elevation. However, the majority of these reports focus on shifts of upper limits. Here, we expand the focus and simultaneously analyze changes of both range limits, optima, and abundances of 183 mountain plant species. We therefore resurveyed 1,576 vegetation plots first recorded before 1970 in the European Alps. We found that both range limits and optima shifted upward in elevation, but the most pronounced trend was a mean increase in species abundance. Despite huge species-specific variation, range dynamics showed a consistent trend along the elevational gradient: Both range limits and optima shifted upslope faster the lower they were situated historically, and species’ abundance increased more for species from lower elevations. Traits affecting the species’ dispersal and persistence capacity were not related to their range dynamics. Using indicator values to stratify species by their thermal and nutrient demands revealed that elevational ranges of thermophilic species tended to expand, while those of cold-adapted species tended to contract. Abundance increases were strongest for nutriphilous species. These results suggest that recent climate warming interacted with airborne nitrogen deposition in driving the observed dynamics. So far, the majority of species appear as “winners” of recent changes, yet “losers” are overrepresented among high-elevation, cold-adapted species with low nutrient demands. In the decades to come, high-alpine species may hence face the double pressure of climatic changes and novel, superior competitors that move up faster than they themselves can escape to even higher elevations.


2007 ◽  
Vol 56 (1-6) ◽  
pp. 148-158 ◽  
Author(s):  
I. Blada ◽  
F. Popescu

Summary After the nursery testing, twelve Swiss stone pine (Pinus cembra L.) provenances from the Alps and Carpathian Mountains were planted out at two sites located at high elevation in the Southern and Northern Carpathians. Total height growth (H), annual height growth (h), root collar diameter (RCD), branches per whorl (BW) and survival (SV) were measured and analyzed. Analysis of variance showed highly significant (p < 0.01; p < 0.001) differences between provenances for all traits, except survival, suggesting that selection at the provenance level could be possible. Also, over locations analysis revealed significant genotype x environment interaction, demonstrating that some provenances react differently to environmental conditions and, selection should take this into account. The phenotypic coefficient of variation was moderate for growth and high for number of branches per whorl suggesting that selection within provenance can also be applied. Finding of significant and highly significant age-age and trait-trait phenotypic correlations indicated that early and indirect selection in Swiss stone pine species is possible. According to DUNCAN’s multiple range test the best performing provenances of the two mountain ranges were selected for operational planting and breeding programmes. The results of this study validate that a very slow growing species, such as Swiss stone pine may still possess very high genetic variation in growth rate; consequently, this trait can be improved. Finally, an attempt has been made to develop a seed transfer guidelines for the species by using the pattern of geographic variation as a basis.


2021 ◽  
Author(s):  
Tingwan Yang ◽  
Hongyan Zhao ◽  
Zhengyu Xia ◽  
Zicheng Yu ◽  
Hongkai Li ◽  
...  

&lt;p&gt;Montane bogs&amp;#8212;peat-forming ecosystems located in high elevation and receiving their water supply mostly from meteoric waters&amp;#8212;are unique archives of past environmental changes. Studying these ecosystems and their responses to recent climate warming will help improve our understanding of the sensitivity of high-elevation peatlands to regional climate dynamics. Here, we report a post-bomb radiocarbon-dated, high-resolution, and multi-proxy record in Laobaishan bog (LBS), a mountaintop bog from the Changbai Mountains Range in Northeast China. We analyzed plant macrofossils and testate amoebae of a 41-cm peat core dated between 1970 and 2009 to document the ecohydrological response of peatland to the anthropogenic warming in recent decades. We quantitatively reconstruct the surface wetness changes of LBS bog using the first axis of the detrended correspondence analysis (DCA) of plant macrofossil assemblages and depth to water table (DWT) inferred by transfer function of testate amoebae assemblages. We distinguished two hydroclimate stages: the moist stage before the 1990s and the rapidly drying stage since the 1990s. During the moist stage, plant macrofossils were characterized by the low abundance of &lt;em&gt;Sphagnum capitifolium&lt;/em&gt; and &lt;em&gt;Polytrichum strichum&lt;/em&gt; that prefer dry habitats, and testate amoebae assemblages were dominated by low abundance of dry-adapted &lt;em&gt;Assulina muscorum&lt;/em&gt; and &lt;em&gt;Corythion dubium&lt;/em&gt;. High score of first axis and low DWT also suggested a moist habitat at LBS. After the transition into the drying stage, the abundance of &lt;em&gt;S. capitifolium&lt;/em&gt; and &lt;em&gt;P. strichum&lt;/em&gt; increased and that of &lt;em&gt;A. muscorum&lt;/em&gt; and &lt;em&gt;C. dubium&lt;/em&gt; showed similar trend. Score of first axis and DWT reconstructions show that LBS have experienced rapid surface desiccation since the 1990s. Based on the high-resolution gridded reanalysis data, these ecohydrological changes occurred with a rapid increase in temperature (~1&amp;#176;C) but without notable change in total precipitation during the growing season (May&amp;#8211;September) since the 1990s. Besides, backward trajectory analysis showed no apparent changes in atmospheric circulation pattern since the 1990s, supporting our interpretation that the ecohydrological changes in LBS bog were induced by climate warming. These results demonstrate that the plant communities, microbial assemblages, and peatland hydrology of montane peatland show a sensitive response to climate warming that might be in larger amplitude than the low-elevation areas.&lt;/p&gt;


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