**9. Drought-induced plant damage**

Drought-induced plant damage was shown in **Table 1**. Among canopy trees and understoried trees, *S. alnifolia* showed very severe damage (**Table 1**). *C. scabrida*, *P. sargentii*, and *Crataegus pinnatifida* showed severe damage, and *Q. mongolica*, *Q. serrata*, and *Q. variabilis* showed severe damage depending on site. *R. pseudoacacia*, *Q. acutissima*, *Q. dentate*, and *P. rigida* showed moderate damage, and *P. densiflora*, *Alnus hirsuta* var. *sibirica*, *Carpinus laxiflora*, and *Styrax obassia* showed moderate damage depending on site. *Fraxinus rhynchophylla*, *F. mandshurica*, and *Lindera obtusiloba* showed slight damage. On the other hand, *Sorbus commixta* and *Acer pseudosieboldianum* did not show any visible damage. Among shrubs, *Parthenocissus tricuspidata* showed very severe damage depending on site. *S. incisa* showed severe damage, and *Juniperus rigida*, *Symplocos chinensis* for. *Pilosa,* and *Weigela florida* showed severe damage depending on site. *Callicarpa japonica*, *R. mucronulatum*, *Lespedeza cyrtobotrya*, *Viburnum erosum*, and *Smilax sieboldii* showed moderate damage. On the other hand, *Corylus heterophylla* showed slight damage.

Around 310 damaged plants in 34 species were observed (**Table 1**). *Sorbus alnifolia*, *Robinia pseudoacacia*, *Q. mongolica*, *P. densiflora,* etc. were the most damaged plants.

Around 107 plants in 7 species died due to drought (**Table 1**). *Sorbus alnifolia, Castanea crenata*, *Robinia pseudoacacia*, *Q. mongolica*, etc. were the plants that died the most*.*


**85**

began to be observed.

Shrub

**Table 1.**

recognized as crisis of urban forest.

*in an urban forest (Mt. Bulam) of Seoul, central Korea.*

*Forest Decline Under Progress in the Urban Forest of Seoul, Central Korea*

*Fraxinus sieboldiana* I 1

*Indigofera kirilowii* II 1 *Stephanandra incisa* IV 20 *Rhododendron mucronulatum* III 8 *Viburnum erosum* III 1 *Smilax sieboldii* III 1 *Rhododendron schlippenbachii* III 3 *Lespedeza cyrtobotrya* III 2 *Symplocos chinensis* for. *pilosa* III - IV 2 *Corylus heterophylla* II 1 *Parthenocissus tricuspidata* I - V 2 *Weigela florida* III - IV 7

**Life form Species Damage** 

Drought-induced plant damage started from withering of leaves of plants introduced for landscaping in the urban area. Over time, branches died and death of the whole plant body followed. We regarded these phenomena due to that they were introduced without ecological consideration at this time. But die-off of *Ligustrum obtusifolium*, *Callicarpa japonica*, *Euonymus japonicas*, etc., which were introduced by reflecting potential natural vegetation, and/or *Pinus densiflora*, *Buxus koreana* etc., which are familiar with present concrete ground or changes of Anthropocene,

*Degree of leaf surface damage, the number of damaged plants, and the number of dead plants due to drought* 

*Callicarpa japonica* III 2 1

**degree**

*Juniperus rigida* III - IV 4 1

**No. of damaged individuals**

**No. of dead individuals**

As drought continues, plant damage spreads toward the urban forest beyond the residential area in the urban center. Damage of exotic plants, such as *Robinia pseudoacacia*, *Crataegus scabrida*, etc., or plants introduced for landscaping such as *Prunus serrulata* var. *spontanea*, *Rhododendron yedoense* for. *Poukhanense*, etc. was observed first of all. But damage of the native plants began to appear soon after. In particular, damage of *Sorbus alnifolia*, the product of retrogressive succession [39], was remarkable. As retrogressive succession has already progressed much and thus the number of individuals of *Sorbus alnifolia* increased greatly (**Figure 7**), it can be

Retrogressive succession from forests of stable late successional stage such as *Quercus* or *Carpinus* dominated forests to *Sorbus alnifolia* or *Styrax japonica* dominated forests, which favor infertile and instable environment of early successional stage, has progressed in urban area of Seoul by complex interactions of chronic air and soil pollution, and urban microclimate regime is changed by excessive land use [39]. Not only biodiversity decreases remarkably but also vegetation stratification became simple, and thus both ecological diversity and ecosystem stability deteriorated severely in the place that retrogressive succession occurred [39]. In this situation, severe drought due to climate change continued for several years and threatened ecological stability of the region substantially. Annual precipitation of the region, which experiences severe drought at present, falls short to the level, about 1000 mm, that temperate forest can establish in this region [110].

*DOI: http://dx.doi.org/10.5772/intechopen.86248*


#### *Forest Decline Under Progress in the Urban Forest of Seoul, Central Korea DOI: http://dx.doi.org/10.5772/intechopen.86248*

#### **Table 1.**

*Forest Degradation Around the World*

slight damage.

damaged plants.

the most*.*

Tree and understory tree

**9. Drought-induced plant damage**

Drought-induced plant damage was shown in **Table 1**. Among canopy trees and understoried trees, *S. alnifolia* showed very severe damage (**Table 1**). *C. scabrida*, *P. sargentii*, and *Crataegus pinnatifida* showed severe damage, and *Q. mongolica*,

*R. pseudoacacia*, *Q. acutissima*, *Q. dentate*, and *P. rigida* showed moderate damage, and *P. densiflora*, *Alnus hirsuta* var. *sibirica*, *Carpinus laxiflora*, and *Styrax obassia*

*F. mandshurica*, and *Lindera obtusiloba* showed slight damage. On the other hand, *Sorbus commixta* and *Acer pseudosieboldianum* did not show any visible damage. Among shrubs, *Parthenocissus tricuspidata* showed very severe damage depending on site. *S. incisa* showed severe damage, and *Juniperus rigida*, *Symplocos chinensis* for. *Pilosa,* and *Weigela florida* showed severe damage depending on site. *Callicarpa japonica*, *R. mucronulatum*, *Lespedeza cyrtobotrya*, *Viburnum erosum*, and *Smilax sieboldii* showed moderate damage. On the other hand, *Corylus heterophylla* showed

Around 310 damaged plants in 34 species were observed (**Table 1**). *Sorbus alnifolia*, *Robinia pseudoacacia*, *Q. mongolica*, *P. densiflora,* etc. were the most

Around 107 plants in 7 species died due to drought (**Table 1**). *Sorbus alnifolia, Castanea crenata*, *Robinia pseudoacacia*, *Q. mongolica*, etc. were the plants that died

**degree**

*Sorbus alnifolia* V 100 96

*Prunus sargentii* IV 9 1 *Quercus mongolica* I – IV 27 6

*Q. variabilis* II – IV 8 1

*Q. aliena* I - V 2 1

*Castanea crenata* IV 3 *Robinia pseudoacacia* III 50

*Pinus densiflora* I – III 23 *P. rigida* III 1 *Quercus serrata* II – IV 15 *Sorbus commixta* I 1

*Q. acutissima* III 2 *Alnus hirsuta* var. *sibirica* II - III 2 *Fraxinus mandshurica* II 1 *Acer pseudosieboldianum* I 1 *F. rhynchophylla* II 2 *Carpinus laxiflora* I- III 2

*Q. dentata* III 1 *Lindera obtusiloba* II 2 *Styrax obassia* II - III 3

**No. of damaged individuals**

**No. of dead individuals**

*Q. serrata*, and *Q. variabilis* showed severe damage depending on site.

showed moderate damage depending on site. *Fraxinus rhynchophylla*,

**Life form Species Damage** 

**84**

*Degree of leaf surface damage, the number of damaged plants, and the number of dead plants due to drought in an urban forest (Mt. Bulam) of Seoul, central Korea.*

Drought-induced plant damage started from withering of leaves of plants introduced for landscaping in the urban area. Over time, branches died and death of the whole plant body followed. We regarded these phenomena due to that they were introduced without ecological consideration at this time. But die-off of *Ligustrum obtusifolium*, *Callicarpa japonica*, *Euonymus japonicas*, etc., which were introduced by reflecting potential natural vegetation, and/or *Pinus densiflora*, *Buxus koreana* etc., which are familiar with present concrete ground or changes of Anthropocene, began to be observed.

As drought continues, plant damage spreads toward the urban forest beyond the residential area in the urban center. Damage of exotic plants, such as *Robinia pseudoacacia*, *Crataegus scabrida*, etc., or plants introduced for landscaping such as *Prunus serrulata* var. *spontanea*, *Rhododendron yedoense* for. *Poukhanense*, etc. was observed first of all. But damage of the native plants began to appear soon after. In particular, damage of *Sorbus alnifolia*, the product of retrogressive succession [39], was remarkable. As retrogressive succession has already progressed much and thus the number of individuals of *Sorbus alnifolia* increased greatly (**Figure 7**), it can be recognized as crisis of urban forest.

Retrogressive succession from forests of stable late successional stage such as *Quercus* or *Carpinus* dominated forests to *Sorbus alnifolia* or *Styrax japonica* dominated forests, which favor infertile and instable environment of early successional stage, has progressed in urban area of Seoul by complex interactions of chronic air and soil pollution, and urban microclimate regime is changed by excessive land use [39]. Not only biodiversity decreases remarkably but also vegetation stratification became simple, and thus both ecological diversity and ecosystem stability deteriorated severely in the place that retrogressive succession occurred [39].

In this situation, severe drought due to climate change continued for several years and threatened ecological stability of the region substantially. Annual precipitation of the region, which experiences severe drought at present, falls short to the level, about 1000 mm, that temperate forest can establish in this region [110].

In addition, aggravation of spring drought, which comes from reduction of snow fall due to temperature rise during winter season and temperature rise and evaporation increase due to climate change, incites vegetation damage [37, 38].

Climate change does not induce temperature rise only simply but accompanies diverse and complex environmental changes likewise drought that we experience now. Moreover, vegetation damage spreads into various native plants beyond several sensitive plants. Environmental change due to climate change may cause additive retrogressive succession into poor vegetation near to open woodland rather than simple change from the deciduous broad-leaved forest to the evergreen broadleaved forest as the general public think.

The damage of *Castanea crenata* and *Prunus sargentii* was severe, and damage of *Q.mongolica* and *Carpinus laxiflora*, which composes late successional vegetation, was also found. Of more concern is that most plants without any relation with species and life form over all layers composing vegetation stratification such as canopy tree, understory tree, shrub, and herb layers were injured or died. For example, *P. densiflora* and *Q. variabilis*, which composes vegetation of the representative dry land and *Juniperus rigida*, *Weigela florida*, *Rhododendron mucronulatum*, etc., which forms their undergrowth, were damaged or died. Indeed, serious phenomenon progressed around us. Continuous monitoring and synthetic consideration for preparing on climate change are urgently required.

### **10. Conclusion**

In Seoul, the capital of South Korea, most flat plains and hilly terrain were transformed from the natural land surface to the artificial impervious one with the increase of population due to both birth and influx from the rural area. Consequently, green space shows imbalanced spatial distribution as it is restricted to the urban fringe, where the land is mountainous and thus development is difficult topographically and deficient in urban center. This imbalanced distribution of green space led to severe urban heat island effect, and the effect was followed by temperature inversion. Subsequently, this change produced altered air circulation patterns specific to city, particularly city with basin-type topography like Seoul [77, 79]. Movement of air pollutants from urban area is likely dominated by this air circulation. In this process, relatively heavy particulates are felled in urban center, while light gaseous pollutants are transported to the forested area in urban boundary. Spatial distribution of physicochemical properties of soil reflects the trends. Forest of this area experiences retrogressive succession from Mongolian oak forest of the late successional stage to Korean mountain ash forest of the earlier successional stage as it is continuously exposed to air pollutants blowing from urban center, and soil is acidified due to the effect. As the results of such changes, urban Mongolian forest shows decline symptom that species composition is different and species diversity is lower than that in natural landscape. Further, the result increases vulnerability to environmental stresses related to climate change including drought.

Plant damage due to drought begun from withering of leaves of plants introduced for landscaping in the urban park. Over time, branches died and death of the whole plant body followed. As drought continues, plant damage spreads toward the urban forest beyond the residential area in the urban center. Damage of exotic plants or plants introduced for landscaping was observed first of all. But damage of the native plants began to appear soon after. In particular, damage of *Sorbus alnifolia*, the product of retrogressive succession, was remarkable. As retrogressive succession has already progressed much and thus the number of individuals of *Sorbus alnifolia* increased greatly, it was surmised as the level so that this phenomenon can

**87**

provided the original work is properly cited.

\*, Songhie Jung1

2 National Institute of Ecology, Seocheon, Korea

\*Address all correspondence to: leecs@swu.ac.kr

1 Seoul Women's University, Seoul, Korea

3 Miami University, Ohio, USA

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

, Bong Soon Lim1

, A Reum Kim1

, Chi Hong Lim2

*Forest Decline Under Progress in the Urban Forest of Seoul, Central Korea*

coping with drought due to climate change are urgently required.

be recognized as crisis of urban forest. In this situation, severe drought due to climate change is being continued for several years; annual precipitation of the region, which experiences severe drought at present, records less than 1000 mm; the level approaches the threshold of ecological condition that forest can be established. In this respect, continuous monitoring and synthetic measure based on the results for

This paper was supported by LTER program of the Ministry of Environment of

This paper was prepared by supplementing and reediting papers that prof.

*DOI: http://dx.doi.org/10.5772/intechopen.86248*

C.S. Lee had published [39, 40, 46, 47, 99].

**Acknowledgements**

**Conflict of interest**

**Author details**

Chang Seok Lee1

and Hansol Lee3

Korea.

*Forest Decline Under Progress in the Urban Forest of Seoul, Central Korea DOI: http://dx.doi.org/10.5772/intechopen.86248*

be recognized as crisis of urban forest. In this situation, severe drought due to climate change is being continued for several years; annual precipitation of the region, which experiences severe drought at present, records less than 1000 mm; the level approaches the threshold of ecological condition that forest can be established. In this respect, continuous monitoring and synthetic measure based on the results for coping with drought due to climate change are urgently required.
