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Articles by Jiaojun Zhu

Category: Research article

article id 7693, category Research article
Chunyu Zhu, Jiaojun Zhu, Xiao Zheng, Deliang Lu, Xiufen Li. (2017). Comparison of gap formation and distribution pattern induced by wind/snowstorm and flood in a temperate secondary forest ecosystem, Northeast China. Silva Fennica vol. 51 no. 5 article id 7693. https://doi.org/10.14214/sf.7693
Highlights: The canopy gaps induced by wind/snowstorm were aggregated in steep slope and high altitude areas, while the gaps formed by flood were gathered in steep slope and low altitude areas; The wind/snowstorm mainly driven the formation of medium gaps, while the flood mainly promoted the percentage of small gaps and vacant lands.

Canopy gap is the driving force of forest succession. Due to the uncontrollability, however, the influences of natural disturbances on gap formation and gap distribution pattern have been rarely understood in temperate secondary forest ecosystems. We monitored the gap formation and gap distribution pattern using high-resolution remote sensing images before and after two disturbances (wind/snowstorm in 2003 and flood in 2013). The results showed that after wind/snowstorm, the gap nearest neighbor index (GNNI) decreased, the vacant land area did not obviously change while the gap fraction and gaps density (especially medium size) increased. After the flood, GNNI decreased, the number of small gaps increased but larger gaps were in many cases extended to vacant land areas leading to a smaller total number of medium and large gaps but considerable increase in vacant land area. We also found that the gap densities increased with slope and altitude for wind/snowstorm-formed gaps, but they increased with increasing slope and decreasing altitude for flood-formed gaps. These results indicated that gaps were aggregated in steep slope and high altitude areas after wind/snowstorm, but in steep slope and low altitude areas after the flood. Medium gaps were mainly created by the wind/snowstorm due to the individual-level death of dominant tree with the continuous fall of surrounding trees. While, vacant lands were obviously created during the flood because of integral sweeping. Besides, smaller trees were easily damaged by runoff of flood, which induced small gaps. In summary, forest managers may pay more attention to use gaps to accelerate forest succession after wind/snowstorms and to restore vegetation in vacant lands after floods.

  • Zhu, ORCID ID:E-mail: Chunyuzhu123@126.com
  • Zhu, ORCID ID:E-mail: jiaojunzhu@iae.ac.cn (email)
  • Zheng, ORCID ID:E-mail: xiaozheng@iae.ac.cn
  • Lu, ORCID ID:E-mail: delianglu14@hotmail.com
  • Li, ORCID ID:E-mail: delianglu14@hotmail.com
article id 1310, category Research article
Deliang Lu, Jiaojun Zhu, Yirong Sun, Lile Hu, Guangqi Zhang. (2015). Gap closure process by lateral extension growth of canopy trees and its effect on woody species regeneration in a temperate secondary forest, Northeast China. Silva Fennica vol. 49 no. 5 article id 1310. https://doi.org/10.14214/sf.1310
Highlights: Gap closure process by lateral extension growth can be described by quadratic functions; Large gaps (514–621 m2) had higher closure rates but lower closure percentages compared with middle (174–321 m2) and small gaps (68–125 m2); Gaps promoted woody species regeneration in early stage; Large and middle gaps would provide opportunities for filling regeneration, but regeneration in small gaps may eventually fail.

Gap formation and its effects on regeneration have been reported as being important in forest development, but seldom studies concentrated on the gap closure process by lateral extension growth of canopy trees surrounding gaps. We monitored the closure process of 12 artificial gaps for 7 years with three size classes: small (from 68 m2 to 125 m2), middle (from 174 m2 to 321 m2), and large (from 514 m2 to 621 m2); and investigated the regeneration twice in a temperate secondary forest, Northeast China. The closure process can be described through quadratic functions, which showed the closure rates slowed down with gap ages. Large gaps had a higher closure rate (39 m2 a–1) than middle gaps (25 m2 a–1) and small gaps (11 m2 a–1). According to the quadratic equations, the lateral growth could last 11, 13 and 16 years for small, middle and large gaps with a remaining size of 12, 69 and 223 m2, respectively. As expected, regeneration exhibited the highest seedling density and volume in large gaps. There was no significant difference in regeneration density between middle gaps, small gaps and forest understory in the final investigation; but the volume of regenerated woody species increased significantly from small gaps to large gaps compared with forest understory. These results may provide references on the choice of appropriate gap sizes to promote the regeneration in temperate secondary forests.

  • Lu, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China;  University of Chinese Academy of Sciences, Beijing 100049, China ORCID ID:E-mail: delianglu14@hotmail.com
  • Zhu, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China ORCID ID:E-mail: jiaojunzhu@iae.ac.cn (email)
  • Sun, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China ORCID ID:E-mail: yirongsun@iae.ac.cn
  • Hu,  Chinese Research Academy of Environmental Sciences, Beijing 100012, China ORCID ID:E-mail: lilehu@gmail.com
  • Zhang, State Key Laboratory of Forest and Soil Ecology, Qingyuan Forest CERN, Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China;  University of Chinese Academy of Sciences, Beijing 100049, China ORCID ID:E-mail: zgq04713@163.com
article id 351, category Research article
Jiaojun Zhu, Xiufen Li, Zugen Liu, Wei Cao, Yutaka Gonda, Takeshi Matsuzaki. (2006). Factors affecting the snow and wind induced damage of a montane secondary forest in northeastern China. Silva Fennica vol. 40 no. 1 article id 351. https://doi.org/10.14214/sf.351
In order to understand the processes of snow and wind induced damage in a natural montane, secondary forest in northeastern China, we examined the impacts of site conditions on the snow and wind damage; analyzed if the dominant tree species differed in their susceptibilities to the damage; and established the relationships between the characteristics of tree and stand and the damage. The results indicated that in regard to the topography factors, slope steepness and soil depth played a relatively important role for the damage. Damage ratios of all types combined were positively related with the composition of dominant tree species. The stand density was also important in determining resistance to the damage, i.e., the densely populated stand exhibited less overall damage ratios; however, the dominant tree species were commonly damaged easily by the snow and wind. Four damage modes found (uprooting, stem breakage, canopy damage and bending) were closely related to the stem taper (p < 0.05), and they could be ranked in following order: bending (92.0 ) > uprooting (85.3) > stem breakage (80.1) > canopy damage (65.0). In regard to differences in tree species’ susceptibilities to the damage, Betula costata exhibited the most uprooting, bending and overall damage ratios; while Quercus mongolica showed the highest breakage (both stem breakage and canopy damage) ratio, and Fraxinus mandshurica exhibited the least damage ratio (overall). The major six tree species could also be divided into two groups according to the overall damage ratios, i.e., more susceptible ones (B. costata, Ulmus laciniata and Q. mongolica), and less susceptible ones (F. mandshurica, Acer mono and Juglans mandshurica) to the snow and wind damage.
  • Zhu, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China ORCID ID:E-mail: zrms29@yahoo.com (email)
  • Li, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China; Graduate School of Chinese Academy of Sciences, Yuquan Road 19-A, Beijing, 100039, China ORCID ID:E-mail:
  • Liu, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China; Graduate School of Chinese Academy of Sciences, Yuquan Road 19-A, Beijing, 100039, China ORCID ID:E-mail:
  • Cao, Institute of Applied Ecology, Chinese Academy of Sciences, Wenhua Road 72, Shenyang 110016, China ORCID ID:E-mail:
  • Gonda, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Niigata, 950-2181, Japan ORCID ID:E-mail:
  • Matsuzaki, Faculty of Agriculture, Niigata University, Ikarashi 2-8050, Niigata, 950-2181, Japan ORCID ID:E-mail:
article id 501, category Research article
Jiaojun Zhu, Yutaka Gonda, Takeshi Matsuzaki, Masashi Yamamoto. (2003). Modeling relative wind speed by optical stratification porosity within the canopy of a coastal protective forest at different stem densities. Silva Fennica vol. 37 no. 2 article id 501. https://doi.org/10.14214/sf.501
Wind speed and optical stratification porosity (OSP) were measured at various heights inside a coastal protective forest thinned to different stem densities to assess whether any characteristics of the wind profile in the coastal protective forest could be predicted from OSP. OSP was defined as vertical distribution of the proportion of sky hemisphere not obscured by tree elements inside a forest stand, and was determined for various heights using hemispherical photographic silhouettes on a computer processing system. The distribution of OSP in the coastal forest follows the Lambert-Beer’s law with an extinction coefficient (v). The relative wind speed within the canopy can be described using an exponential form with an attenuation coefficient (a). Variation in relative wind speed was very closely correlated with the distribution of OSP within the canopy. While below the canopy, i.e., in the trunk space, relative wind speed was little correlated with the distribution of OSP because the distribution of OSP was relatively constant there. Therefore, the linear relationships between relative wind speed and OSP and between the two coefficients v and a were established within the canopy. The results suggest that OSP can be used to predict the wind profile in case of the application within the canopy of the coastal forest.
  • Zhu, Qingyuan Station of Forest Ecology, Institute of Applied Ecology, the Chinese Academy of Sciences, No. 72 Wenhua Road, Shenyang 110016, P.R. China; Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan ORCID ID:E-mail: jiaojunzhu@iae.ac.cn (email)
  • Gonda, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan ORCID ID:E-mail:
  • Matsuzaki, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan ORCID ID:E-mail:
  • Yamamoto, Faculty of Agriculture, Niigata University, Niigata 950-2181, Japan ORCID ID:E-mail:

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