Dispersal Can Limit Local Plant Distribution

The ability of species to establish new populations at unoccupied sites is a critical feature in the maintenance of biological diversity, and it has taken on new importance as a result of global climate change and expected changes in species distribution. To examine the dispersal potential of plant species, seeds of four annual plant species were experimentally dispersed 40 to 600 m from existing populations in Massachusetts (U.S.A.) to 34 nearby unoccupied but apparently suitable sites. At three of these sites new populations were established that persisted for four generations and expanded slowly in area. At seven sites, a small initial population eventually died out. At the 24 other sites, new populations did not become established, indicating that the sites were in some way unsuitable, that not enough seeds arrived, or that conditions suitable for seed germination do not occur every year. These results suggest that some species may be unable to disperse naturally out of their existing ranges in response to global climate change, particularly if habitat fragmentation creates barriers to dispersal. These species may have to be assisted to reach suitable sites nearby to prevent their extinction in the wild.     

Global warming and flowering times in Thoreau's Concord: a community perspective

As a result of climate change, many plants are now flowering measurably earlier than they did in the past. However, some species' flowering times have changed much more than others. Data at the community level can clarify the variation in flowering responses to climate change. In order to determine how North American species' flowering times respond to climate, we analyzed a series of previously unstudied records of the dates of first flowering for over 500 plant taxa in Concord, Massachusetts, USA. These records began with six years of observations by the famous naturalist Henry David Thoreau from 1852 to 1858, continued with 16 years of observations by the botanist Alfred Hosmer in 1878 and 1888-1902, and concluded with our own observations in 2004, 2005, and 2006. From 1852 through 2006, Concord warmed by 2.4 degrees C due to global climate change and urbanization. Using a subset of 43 common species, we determined that plants are now flowering seven days earlier on average than they did in Thoreau's times. Plant flowering times were most correlated with mean temperatures in the one or two months just before flowering and were also correlated with January temperatures. Summer-flowering species showed more interannual variation in flowering time than did spring-flowering species, but the flowering times of spring-flowering species correlated more strongly to mean monthly temperatures. In many cases, such as within the genera Betula and Solidago, closely related, co-occurring species responded to climate very differently from one another. The differences in flowering responses to warming could affect relationships in plant communities as warming continues. Common St. John's wort (Hypericum perforatum) and highbush blueberry (Vaccinium corymbosum) are particularly responsive to changes in climate, are common across much of the United States, and could serve as indicators of biological responses to climate change. We discuss the need for researchers to be aware, when using data sets involving multiple observers, of how varying methodologies, sample sizes, and sampling intensities affect the results. Finally, we emphasize the importance of using historical observations, like those of Thoreau and Hosmer, as sources of long-term data and to increase public awareness of biological responses to climate change.     

Participatory conservation approaches for satoyama,the traditional forest and agricultural landscape of Japan

The traditional agricultural landscape of Japan, known as satoyama, consists of a mixture of forests, wet rice paddy fields, grasslands, and villages. This landscape supports a great diversity of plant and animal species, many of which are significant to the Japanese culture. The satoyama landscape is currently being rapidly converted to residential and industrial uses in Japan's expanding metropolitan areas, with the local loss of many species. Only 7% of the land in the Yokohama area remains as satoyama. City residents and older farmers have become key participants in programs to protect examples of satoyama. Many urban residents value the experience of participating in agricultural and conservation activities once they are made aware of the threat faced by the satoyama landscape. In one particularly successful program, conservation efforts and fund-raising are linked to "Totoro", an imaginary forest animal featured in a popular animated film.     

对日本传统的农林景观Satoyama的参与性保护途径

日本的传统农业景观,即Satoyama,是森林、水稻田、草地和村庄的混合体.该景观支持着植物和动物种的巨大多样性,其中许多种类对日本文化是意义深长的.目前,在日本日益膨胀的城市地区中,Satoyama景观正被快速地转变为居民区或工业用地,也使许多物种在当地消失.横滨只有7%的土地还保留为Satoyama.在保护Satoyama样地的计划中,城市居民和老农户是关键的参与者.有许多城市居民一旦警觉到Satoyama景观所面临的威胁,他们就会重视这种参与农业和保护活动的经历.在一个特别成功的项目中,保护活动及资金筹措和"Totoro"(一个流行劝画片中的虚构森林动物角色)联系在一起.     

Plant Species Lost in an Isolated Conservation Area in Metropolitan Boston from 1894 to 1993

A recensus was undertaken of the Middlesex Fells (West), a 400-ha woodland park in Metropolitan Boston, to determine how species composition changed between 1894 (the time of first census) and 1993. This park is isolated by an 0.5-km-wide barrier of roads and development from the eastern half of the Fells preserve, is at least 5 km from other protected areas, and is strongly affected by human activity. Out of 422 original plant species, 155 species were no longer present in 1993. Sixty-four new species were recorded on the site in 1993, the majority of them exotic species. The proportion of native species in the flora went from 83% in 1894 to 74% in 1993. Overall, the number of native species is declining at a rate of O.36% per year, whereas the exotic species are increasing at a rate of 0.18% per year. Many of the native species lost were attractive and well-known components of the native flora, such as orchids and lobeliads. Many remaining native plant species have been reduced to one or a few small populations. Species of moist woods were disproportionately lost from the Fells. The loss of species has coincided with an increase in human activity, including ground fires, a greater number of trails and roads, thinning of the forest, and trampling of the vegetation, all of which may have contributed to species loss. A policy to stop and reverse this progressive loss of species might include preventing new trails from being developed, closing off some existing trails, excluding people from sensitive areas, and reintroducing some of the lost species.