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51.
The balance of planting and mortality in a street tree population   总被引:1,自引:1,他引:0  
Street trees have aesthetic, environmental, human health, and economic benefits in urban ecosystems. Street tree populations are constructed by cycles of planting, growth, death, removal and replacement. The goals of this study were to understand how tree mortality and planting rates affect net population growth, evaluate the shape of the mortality curve, and assess selected risk factors for survival. We monitored a street tree population in West Oakland, CA for 5 years after an initial inventory (2006). We adapted the classic demographic balancing equation to quantify annual inputs and outputs to the system, tracking pools of live and standing dead trees. There was a 17.2 % net increase in live tree counts during the study period (995 in 2006, 1166 in 2011), with population growth observed each year. Of the live trees in 2006, 822 survived to 2011, for an annual mortality rate of 3.7 %. However, population growth was constrained by high mortality of young/small trees. Annual mortality was highest for small trees, and lower for mid-size and large trees; this represents a Type III mortality curve. We used multivariate logistic regression to evaluate the relationship between 2011 survival outcomes and inventory data from 2006. In the final model, significant associations were found for size class, foliage condition, planting location, and a multiplicative interaction term for size and foliage condition. Street tree populations are complex cultivated systems whose dynamics can be understood by a combination of longitudinal data and demographic analysis. Urban forest monitoring is important to understand the impact of tree planting programs.  相似文献   
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Community, national, and international service policies andprograms exist worldwide. Anecdotally, their prevalence hasincreased dramatically in recent years. Their proliferationindicates a tacit presumption of their positive nature. Whileacknowledging the benefits of these programs, we call attentionto the possible limitations of service, including elitism, stateinterests, and imperialism. We emphasize implications for policy,practice, and research.  相似文献   
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Family scholars have developed a greater sensitivity to the relative neglect of families of color in research. However, there are a number of limitations in the research on families of color; specifically, race and ethnicity are often confounded with socioeconomic indicators and community of residence. This makes it difficult to identify the true effects of ethnicity and culture. In addition, race and ethnicity may interact with chronic poverty in such a way as to further interfere with and reduce life opportunities. Here we discuss some of the theoretical and conceptual issues pertaining to race, ethnicity, and culture as they affect family functioning and children's development. In addition, we introduce a collection of papers that address family functioning and children's development among families who are diverse ethnically, racially, socioeconomically, and by geographical location and community. The issues posed in this paper and in the Special Section challenge the field to reconsider how we study families and child development from culturally grounded perspectives.  相似文献   
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Child and Adolescent Social Work Journal - Social connections can act as a protective factor against long term consequences impacting the physical and emotional well-being of youth. This purpose...  相似文献   
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