Drought damage in the park forests of the city of Helsinki

Holopainen, Markus; Leino, Olli; Kämäri, Hannu; Talvitie, Mervi

doi:10.1016/j.ufug.2005.11.002

Cited by 32 publications

(18 citation statements)

References 32 publications

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“…At our site we did not examine the biotic factors at all, thus their contribution in the analysed dieback cannot be discarded. On the other hand, no single pathogen or insect can cause oak decline on a large scale (Siwecki and Ufnalski, 1998), but oak forest decline has reported widely all over southern Finland recently (Ympäristörapor-toinnin asiantuntijatyöryhmä, 2004;Holopainen et al, 2006;Helama et al, 2009). Thus, some disease could have contributed to the decline in Tammisto but most probably the weakening and dieback were triggered by a common large-scale factor (e.g.…”

Section: Table 3 Pearson Correlation Coefficients Between the Residumentioning

confidence: 99%

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Oak decline in a southern Finnish forest as affected by a drought sequence

Sohar

Helama²,

Läänelaid

et al. 2013

Geochronometria

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Abstract:We investigated the decline of a pedunculate oak (Quercus robur L.) forest growing on shallow soil at the northern distributional limit of the species in southern Finland, using the dendroclimatic approach. About 200-year-old trees in three vigour classes -healthy, declining and deadwere sampled in 2008. Annual tree-ring, earlywood and latewood widths were measured and chronologies were established. The tree-ring data were correlated with monthly and seasonal climate data. Radial increment of oaks was positively related to the June and July precipitations. This was expressed especially in total ring width and latewood width, whereas the earlywood was more influenced by the warmer winter and spring. Furthermore, the correlation between the current year earlywood width and the preceding year latewood width was higher than between the earlywood and latewood of the same year. The analyses showed that the dead oaks and part of the declining oaks had ceased growing during 2005-2007 after a decade-long summer drought series. This indicates a time lag in the oak dieback. The radial growth of the declining and the dead oaks had dropped already since the 1990s, while the healthy oaks had better long-term growth and higher adaptive capacity to climate variation.

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Section: Table 3 Pearson Correlation Coefficients Between the Residumentioning

confidence: 99%

“…A decline in pedunculate oaks (Quercus robur L.) as well as other tree species has been observed in the Helsinki metropolitan area in Finland during the recent years, especially (Ympäristöraportoinnin asiantuntijatyöryhmä, 2004Holopainen et al, 2006). Finnish oaks grow at the species' northernmost natural regeneration border (e.g.…”

Section: Introductionmentioning

confidence: 99%

Oak decline in a southern Finnish forest as affected by a drought sequence

Sohar

Helama²,

Läänelaid

et al. 2013

Geochronometria

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“…It is consequently worrisome that vegetation damage was also evident in the urban areas and that a large number of trees were reported dead or dying in Helsinki, especially in 2003. This mortality has likewise been associated with the coeval drought that prevailed in the region (Helama et al 2009;Holopainen et al 2006b;Silander and Järvinen 2004;Ympäristöraportoinnin asiantuntijatyöryhmä 2004). Specifically, a detailed study using digital aerial photography and field surveys had shown that the total amount of severely damaged forested areas represented about 25 ha in the city (Holopainen et al 2006b).…”

Section: Introductionmentioning

confidence: 99%

“…Here, we aim toward a deeper understanding of the potential causes and controls of the recent Scots pine (Pinus sylvestris L.) mortality that has been reported in southern Finland, with sites in and around Helsinki (Holopainen et al 2006b). Tree rings of surviving and dead pines were examined in the context of dendroclimatology and dendroecology (Fritts 1976;Fritts and Swetnam 1989).…”

Section: Introductionmentioning

confidence: 99%

Mortality of urban pines in Helsinki explored using tree rings and climate records

Helama

Läänelaid

Raisio³

et al. 2011

Trees

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The mortality of Scots pine trees in and around Helsinki has been reported in recent years, but the causalities of these deaths have not so far been rigorously examined. Tree-ring analyses have previously shown to effectively reveal historical growth variability and thus hint at the stress factors behind tree mortality. Here, we analyzed the tree rings of pines in two tree classes (living and dead) from an urban park in Helsinki to reveal their growth variations and to examine the obtained chronologies along with climatic data. Guided by tree-ring information, the pine growth over the past century could be divided into four episodes: average growth conditions during the first half of the twentieth century, a suppressed growth period during the 1950s and 1960s, a growth release since the mid-1970s, and a period of recent mortality. The two tree classes became particularly differentiated during the release period in that the growth of surviving pines underwent a more positive and abrupt growth anomaly in comparison to dead pines. The survival of pines could also be linked to their sensitivity to droughts in a long-term context: The growth of still-living pines showed a statistically significant moisture sensitivity over the second half of the century only. The period 2002-2003 (coinciding with drought) was observed as a dendrochronologically dated episode with a 40% mortality. Overall, the results point to the importance of tree competitive strength and climate as predisposing and inciting/contributing factors behind the tree mortality.

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“…Holopainen et al 2006;Ringvall et al 2007;Gove et al 2013). Although aspen populations are sparse in general this is not the case in our study data.…”

Section: Discussionmentioning

confidence: 99%

Inventory of aspen trees in spruce dominated stands in conservation area

et al. 2015

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Background: The occurrence of aspen trees increases the conservation value of mature conifer dominated forests. Aspens typically occur as scattered individuals among major tree species, and therefore the inventory of aspens is challenging. Methods: We characterized aspen populations in a boreal nature reserve using diameter distribution, spatial pattern, and forest attributes: volume, number of aspens, number of large aspen stems and basal area median diameter. The data were collected from three separate forest stands in Koli National Park, eastern Finland. At each site, we measured breast height diameter and coordinates of each aspen. The comparison of inventory methods of aspens within the three stands was based on simulations with mapped field data. We mimicked stand level inventory by locating varying numbers of fixed area circular plots both systematically and randomly within the stands. Additionally, we also tested if the use of airborne laser scanning (ALS) data as auxiliary information would improve the accuracy of the stand level inventory by applying the probability proportional to size sampling to assist the selection of field plot locations. Results:The results showed that aspens were always clustered, and the diameter distributions indicated different stand structures in the three investigated forest stands. The reliability of the volume and number of large aspen trees varied from relative root mean square error figures above 50% with fewer sample plots (5-10) to values of 25%-50% with 10 or more sample plots. Stand level inventory estimates were also able to detect spatial pattern and the shape of the diameter distribution. In addition, ALS-based auxiliary information could be useful in guiding the inventories, but caution should be used when applying the ALS-supported inventory technique. Conclusions: This study characterized European aspen populations for the purposes of monitoring and management of boreal conservation areas. Our results suggest that if the number of sample plots is adequate, i.e. 10 or more stand level inventory will provide accurate enough forest attributes estimates in conservation areas (minimum accuracy requirement of RMSE% is 20%-50%). Even for the more ecologically valuable attributes, such as diameter distribution, spatial pattern and large aspens, the estimates are acceptable for conservation purposes.

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Drought damage in the park forests of the city of Helsinki

Cited by 32 publications

References 32 publications

Oak decline in a southern Finnish forest as affected by a drought sequence

Oak decline in a southern Finnish forest as affected by a drought sequence

Mortality of urban pines in Helsinki explored using tree rings and climate records

Inventory of aspen trees in spruce dominated stands in conservation area

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