Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialle...Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings （Tilia cordata Mill.） were planted with a 1 x 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings （2475 cherries and 825 limes） were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots （10 × 10 m） were randomly established in group and row planting stand, respectively. The survival rate, stability （height to diameter ratio）, diameter, and height growth were significantly higher in group planting. In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an important reason for the difference in performance between group and row planting. This study will encourage forest practitioners to establish more cherry group planting trials on multiple sites to test the effectiveness of this alternative technique as a tool of regeneration and restoration silviculture.展开更多
Three decades of vulnerability research have generated a complex and growing body of knowledge.The concept of vulnerability,as well as its implementation in vulnerability assessments,is used in various disciplines and...Three decades of vulnerability research have generated a complex and growing body of knowledge.The concept of vulnerability,as well as its implementation in vulnerability assessments,is used in various disciplines and contexts.Correspondingly,a multitude of ideas and frameworks about how to conceptualize and measure vulnerability exists.To provide a structured representation of vulnerability,we have set up an ontology-based semantic wiki for reviewing and representing vulnerability assessments(www.vuwiki.org).Based on a survey of 55 vulnerability assessment studies,we first developed an ontology as an explicit reference system for describing vulnerability assessments.The ontology was then implemented in a semantic wiki which allows for the classification and annotation of vulnerability assessment.The resulting semantic wiki,Vu Wiki,does not aim at‘‘synthesizing’’a holistic and overarching model of vulnerability,but at(1)providing—both scientists and practitioners—with a uniform ontology as a reference system;(2)providing easy and structured access to the knowledge field of vulnerability assessments with the possibility for any user to retrieve assessments using specific research criteria;and(3)serving as a collaborative knowledge platform that allows for the active participation of those generating and using the knowledge represented in the vulnerability wiki.展开更多
基金financially supported by a research grant from the German Agency for Renewable Resources(Fachagentur Nachwachsende Rohstoffe e.V or FNR,Grant Number:22008813)
文摘Wild cherry trees produce high-quality timber and provide multiple ecosystem services. However, planting and tending cherry stands in conventional rows are too costly. Therefore, low density group planting was trialled as an alternative to row planting. The mortality, growth, and quality of planted cherry trees were compared between the group and row planting. The influence of neighbourhood competition and light availability on growth and quality was studied. The group and row planting of cherry trees were established at a wind-thrown site in southwestern Germany in the year 2000. In group planting, five cherry seedlings and seven lime seedlings （Tilia cordata Mill.） were planted with a 1 x 1 m spacing. In total, 60 groups were planted per hectare with a 13 × 13 m spacing. In contrast, 3300 seedlings （2475 cherries and 825 limes） were planted per hectare in row planting with a 3 × 1 m spacing. Ten groups and plots （10 × 10 m） were randomly established in group and row planting stand, respectively. The survival rate, stability （height to diameter ratio）, diameter, and height growth were significantly higher in group planting. In the group plantings,40.5% of cherry trees had straight stems and 13.5% had a monopodial crown compared with 15% with straight stems and 2% with a monopodial crown in row planting. The proportion of dominant cherry trees in canopy was 49% in groups compared with 22% in rows. The length of branch free bole was significantly higher in cherries planted in groups than those grown in rows. Intra- and interspecific competition reduced the growth and stability of cherry trees in row planting, but not in group planting. Light availability did not cause any significant effects on growth and quality between group and row planting. This first study on cherry group planting indicates that the survival rate, growth, and tree quality were higher in groups than in rows at this early development stage. The competition by naturally born seedlings was an important reason for the difference in performance between group and row planting. This study will encourage forest practitioners to establish more cherry group planting trials on multiple sites to test the effectiveness of this alternative technique as a tool of regeneration and restoration silviculture.
文摘Three decades of vulnerability research have generated a complex and growing body of knowledge.The concept of vulnerability,as well as its implementation in vulnerability assessments,is used in various disciplines and contexts.Correspondingly,a multitude of ideas and frameworks about how to conceptualize and measure vulnerability exists.To provide a structured representation of vulnerability,we have set up an ontology-based semantic wiki for reviewing and representing vulnerability assessments(www.vuwiki.org).Based on a survey of 55 vulnerability assessment studies,we first developed an ontology as an explicit reference system for describing vulnerability assessments.The ontology was then implemented in a semantic wiki which allows for the classification and annotation of vulnerability assessment.The resulting semantic wiki,Vu Wiki,does not aim at‘‘synthesizing’’a holistic and overarching model of vulnerability,but at(1)providing—both scientists and practitioners—with a uniform ontology as a reference system;(2)providing easy and structured access to the knowledge field of vulnerability assessments with the possibility for any user to retrieve assessments using specific research criteria;and(3)serving as a collaborative knowledge platform that allows for the active participation of those generating and using the knowledge represented in the vulnerability wiki.
