To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Different disciplines within ecology have used a wide range of approaches to predict the impacts of climate change on forest ecosystems. There has been considerable effort by ecosystem scientists to couple vegetation dynamics to atmospheric circulation models, but the spatial scales inherent in those models have required extremely primitive characterisation of population and community dynamics (Sitch et al. 2008; Smith et al. 2001). Biogeographers have used a variety of approaches to project changes in species distribution under climate change, but those models typically represent steady-state ‘potential’ responses based on a mapping of current species distributions onto predicted future climates (Jeschke & Strayer 2008; Loehle & LeBlanc 1996). Population and community ecologists have used both contemporary field data and palaeoecological methods to understand the consequences of variation in climate for the dynamics of tree species, and have attempted to incorporate those responses into formal models of forest community dynamics (e.g. Bugmann 1996). But it would be fair to say that there is little consensus on the predictive power of any of these approaches.
A challenge faced by all of these approaches has been that climate change is taking place in the context of a broad suite of other anthropogenic impacts on forest ecosystems, ranging from invasive species to air pollution. A number of these clearly have had significant impact on the current distribution and abundance of species, and the functioning of forest ecosystems. In the face of the rapid environmental change of the past century, and given the inherently long time scales of tree population dynamics and forest succession, it seems inescapable that forests are increasingly in disequilibrium, lagging in their responses to both perturbations to species abundances and to changes in the physical and biotic environment. As a corollary, it seems reasonable to expect that the responses of forests to climate change will be conditioned by and interact with transient dynamics already triggered by other aspects of global environmental change. There is also ample evidence that physical and biological legacies of human land-use can persist over time scales from decades to centuries (Foster et al. 2003; Katz et al. 2010), and that these impacts will also need to be considered in predictions of forest response to future climates.
In 1980 S. P. Hubbell and R. B. Foster began a long-term, large-scale study of tropical forest dynamics on Barro Colorado Island (BCI), Panama. The objective of the study was to test competing hypotheses about the maintenance of high tree species richness in the BCI forest, and in tropical moist forests more generally. Hubbell and Foster established a 50-ha permanent plot on the summit plateau of BCI, within which all free-standing woody plants with a stem diameter at breast height (DBH) of a centimetre or larger were tagged, measured, mapped and identified by 1982. Subsequent complete censuses of the BCI plot have been conducted from 1985 to 2000 at 5-year intervals. In setting up the BCI plot, Hubbell and Foster (1983) reasoned that whatever diversity-maintaining mechanisms were important, they would have to operate in a spatially dependent manner in communities of sessile plants such as the BCI tree community, which meant that the trees had to be mapped. A decade earlier, Janzen (1970) and Connell (1971) had independently proposed a spatially explicit ‘enemies hypothesis’, now known as the Janzen–Connell hypothesis. They hypothesized that host-specific seed and seedling predators were responsible for maintaining tropical tree diversity by causing dependence on density and frequency (rare species advantage), through an interaction between seed dispersal and density-dependent seed predation.
In 1980, there were essentially just two principal tropical forest diversity theories to test: the enemies hypothesis and its variants, and the ‘intermediate disturbance’ hypothesis (Connell 1977) and its variants that invoked a role for disturbances associated with opening, growth and closure of light gaps (e.g. Ricklefs 1978; Hartshorn 1978; Orians 1982; Denslow 1987).
Email your librarian or administrator to recommend adding this to your organisation's collection.