Challenges to sustaining the productivity of oceanic and coastal fisheries
have become more critical and complex as these fisheries reach the upper
limits to ocean harvests. In addition, it is now clear that we are managing
interactive and dynamic food webs rather than sets of independent single-species
Drawing on the collective expertise of world authorities, Ecological Basis of Agroforestry employs extensive use of tables and figures to demonstrate how ecologically sustainable agroecosystems can meet the challenges of enhancing crop productivity, soil fertility, and environmental sustainability. Divided into four sections, this comprehensive volume begins with a study of tree-crop interaction in tropical and temperate climates.
The late Neogene (the period between − 14 and − 2.4 Ma) is one of the most
interesting phases in understand the present conWguration of terrestrial
ecosystems. It was during this time that the change took place from the
middle Miocene dominant subtropical forests that stretched across southern
Europe and western Asia to a more open but still wooded biotope that
now prevails in warm–temperate areas. This change in vegetation, which
strongly aVected the composition of mammalian faunas, seems to be linked
to the rapid spread of grasses around 8–10 Ma ago....
27 Effects of Contaminants on Trophic Structure and
The empirical patterns are widespread and abundantly documented, but instead of an agreed explanation there is only a list of possibilities to be explored. (May 1981) There has been little synthesis of the relative roles of different ecological forces in determining population change and community structure. Rather, there is a collection of idiosyncratic systems, with their associated protagonists, in which opposing views on the importance of particular factors are debated. (Hunter and Price 1992)
Aquatic scientists have always been intrigued with concepts of scale. This interest perhaps stems from
the nature of ßuid dynamics in oceans and lakes energy cascades from spatial scales of kilometers
down to viscous scales at centimeters or less. Turbulent processes affect not only an organisms perception
of, and response to, the physical environment, but also the interaction between species, both within and
across trophic levels.
Ecology and Evolution of Cambrian Reefs
The history of reef building through the Cambrian records the replacement of predominantly microbial communities by those in which sessile animals participated in construction, so heralding a new reef ecosystem with elaborate trophic webs, complex organism interactions
In the previous chapter we began to consider how population interactions can shape communities. Our focus was on interactions between species occupying the same trophic level or between members of adjacent trophic levels.
This book began its evolution in 1999 when the British Antarctic Survey,
where I worked at the time, began a new research programme on the management
of marine ecosystems. This programme concentrated upon the
krill-based ecosystem at SouthGeorgia which has been the subject of almost
continuous study since the Discovery Expeditions in the 1920s. Latterly,
international efforts to understand the dynamics of this ecosystem and the
wider Southern Ocean have been coordinated by the Commission for the
Conservation of AntarcticMarine Living Resources (CCAMLR)....
As shown later, much of the resultant risk to human
populations and the ecosystems upon which they depend comes from the pro-
jected extremely rapid rate of change in climatic conditions. Indeed, the prospect
of such change has stimulated a great deal of new scientiﬁc research over the
past decade, much of which is elucidating the complex ecological disturbances
that can impact on human well-being and health—as in the following example.