Windthrow plays a critical role in maintaining species diversity in temperate forests. Do large-scale strong wind events(i.e., tropical cyclones, including hurricanes,typhoons and severe cyclonic storms) increase tree...Windthrow plays a critical role in maintaining species diversity in temperate forests. Do large-scale strong wind events(i.e., tropical cyclones, including hurricanes,typhoons and severe cyclonic storms) increase tree diversity in severely damaged forest areas? Do hurricanes(tropical cyclones that occurs in the Atlantic Ocean and northeastern Pacific Ocean) lead to altered relative abundance of shade-tolerant and shade-intolerant species? Did historic hurricanes alter the succession trajectory of the damaged forests? We used nearly 70-year tree demographic data to assess the effects of two major hurricanes on woody species diversity in Piedmont forests, North Carolina, USA. Species richness(S) and Shannon–Wiener's diversity index(H') were used to evaluate the changes in tree diversity. The changes in composition were assessed with Nonmetric Multidimensional Scaling. The pre-hurricane successional phase can strongly influence both the damage severity and subsequent responses. Although there is often an immediate drop in diversity following a hurricane, understory tree diversity quickly increases to levels that exceed those prior to the disturbance. This leads to an increase in diversity in stands that were substantially damaged. Hurricanes significantly decrease the dominance of shade-intolerant canopy species while increasing preestablished, more shade-tolerant species. We conclude that large, and infrequent hurricanes help to maintain local tree diversity, but also accelerate the increase in dominance of understory species such as red maple and beech.展开更多
Abundance distribution models and diversity-area relationships are tools of biological diversity analysis that have been used by ecologists for decades. In a case study by Ibez et al., these techniques are considered ...Abundance distribution models and diversity-area relationships are tools of biological diversity analysis that have been used by ecologists for decades. In a case study by Ibez et al., these techniques are considered in a mor e general setting, and have been applied to explore notions such as pedodiversity (as an example of geodiversity in a broad sense, including also geomorphic diversity), in order to detect the differences and similarities between both natural resources, biological and non-biological.The discussion has mainly been conducted through the study of the Aegean Islands by the Spanish research team. Standard statistical techniques have been applied to analyze how the pedotaxa-abundance distribution conforms to the abundance distribution models and how pedorichness-area data fit to the diversity-area models.No statistically significant difference has been observed between the abundance distribution models and the diversity-area relationships followed by biodiversity and pedodiversity data in similar situations. Thus, the studied results may suggest that some assumptions underlying biodiversity analysis ought to be carefully re-examined.Since results in ecological literature are usually interpreted in biological terms, the analysis by Ibáez et al. may be relevant to offer some suggestions to the following questions: What are the reasons for the similarities obtained between biotic and soil resources? Should the ecological theory modify some of its constructs once the said similarities have been proven? and what are its implications for environmental management and assessment?展开更多
基金supported by a grant from the National Science Foundation(DEB-97-07551)
文摘Windthrow plays a critical role in maintaining species diversity in temperate forests. Do large-scale strong wind events(i.e., tropical cyclones, including hurricanes,typhoons and severe cyclonic storms) increase tree diversity in severely damaged forest areas? Do hurricanes(tropical cyclones that occurs in the Atlantic Ocean and northeastern Pacific Ocean) lead to altered relative abundance of shade-tolerant and shade-intolerant species? Did historic hurricanes alter the succession trajectory of the damaged forests? We used nearly 70-year tree demographic data to assess the effects of two major hurricanes on woody species diversity in Piedmont forests, North Carolina, USA. Species richness(S) and Shannon–Wiener's diversity index(H') were used to evaluate the changes in tree diversity. The changes in composition were assessed with Nonmetric Multidimensional Scaling. The pre-hurricane successional phase can strongly influence both the damage severity and subsequent responses. Although there is often an immediate drop in diversity following a hurricane, understory tree diversity quickly increases to levels that exceed those prior to the disturbance. This leads to an increase in diversity in stands that were substantially damaged. Hurricanes significantly decrease the dominance of shade-intolerant canopy species while increasing preestablished, more shade-tolerant species. We conclude that large, and infrequent hurricanes help to maintain local tree diversity, but also accelerate the increase in dominance of understory species such as red maple and beech.
文摘Abundance distribution models and diversity-area relationships are tools of biological diversity analysis that have been used by ecologists for decades. In a case study by Ibez et al., these techniques are considered in a mor e general setting, and have been applied to explore notions such as pedodiversity (as an example of geodiversity in a broad sense, including also geomorphic diversity), in order to detect the differences and similarities between both natural resources, biological and non-biological.The discussion has mainly been conducted through the study of the Aegean Islands by the Spanish research team. Standard statistical techniques have been applied to analyze how the pedotaxa-abundance distribution conforms to the abundance distribution models and how pedorichness-area data fit to the diversity-area models.No statistically significant difference has been observed between the abundance distribution models and the diversity-area relationships followed by biodiversity and pedodiversity data in similar situations. Thus, the studied results may suggest that some assumptions underlying biodiversity analysis ought to be carefully re-examined.Since results in ecological literature are usually interpreted in biological terms, the analysis by Ibáez et al. may be relevant to offer some suggestions to the following questions: What are the reasons for the similarities obtained between biotic and soil resources? Should the ecological theory modify some of its constructs once the said similarities have been proven? and what are its implications for environmental management and assessment?
