Showing papers on "Biodiversity published in 1977"

Properties and Management of Soils in the Tropics

Abstract: The long-awaited second edition of this classic textbook expands on the first edition to include advances made in the last four decades, bringing the topic completely up to date. The book addresses critical issues such as whether humanity can feed itself, and whether it can do so in environmentally sound and sustainable ways. Written from agronomic, environmental, and ecological standpoints, the textbook employs a multidisciplinary approach, including policymaking and plant genetic improvements, as well as ecosystem services, climate change, biodiversity, sustainability and resilience. New chapters in this second edition focus on organic carbon in soil, soil biology, soils in relation to livestock production and forestry, and agroforestry. The new edition will again be the go-to textbook for courses on tropical soils, and a reference textbook for soil and agricultural scientists and development professionals working in the tropics.

Species diversity in North American temperate forests

Abstract: Samples from temperate forest communities across the North American continent were analysed for correlations of plant species diversity with environment and community structure. Alpha diversity relationships are complicated by different vegetation patterns and community history. The differences in community diversity patterns may be due to the independent evolution of communities in different regions. Results of analyses were: 1) on a continental scale plant species diversity is related to mean annual temperature, but not precipitation; 2) diversity is substantially greater in continental climates than in maritime regions; 3) diversity-community structure relationships are generally weak, except 4) there is an inverse relationship between diversity and abundance of conifer tree species. Attempts to relate diversity to environmental parameters with multiple regression techniques met with only moderate success.

A survey of the strand and dune vegetation along the Pacific and soathem gulf coasts of Baja California, Mexico

Abstract: One hundred and twenty plant species were collected on the dunes along the 1400 km-long western coast of the peninsula of Baja California, Mexico. At sixteen of the thirty-two localities visited, from Tijuana to La Paz, transects were made at right angles to the shore to record cover and zonation of these species. Abronia maritima, a tap-rooted perennial forb, is found along the entire coast and is the major foredune-builder throughout most of its range. The ranges of most of the other species fall into one of three groups corresponding to regions of inland vegetation and to Koppen climatic types of semi-arid (BS) south to 300 N, arid (BW) in the central part, and arid tropical (BSh) south of 240 N. Within each region the vegetation on the dunes immediately above the beach is more uniform than that on the backdunes, where the shrubby vegetation varies according to the degree of surface stabilization. On foredunes, Abronia maritima predominates in the north, in the central sector it is joined by Sesuvium portulacastrum, which has a sirnilar growth habit, and in the Cape region it is replaced as the principal dune-builder by the tropical grasses, Jouvea pilosa and Sporobolus virginicus. These rhizomatous species form flat-topped, continuous dune ridges, in contrast to the individual, conical hillocks built by the tap-rooted forbs to the north. In the arid central sector, salinity of soil water on the fore- dunes increases, and both cover and species-richness decline relative to the values in the northern and southern sectors. Sand grain diameter, which inversely affects rate of burial, is greatest in the Cape region, and may account for the replacement there of A. maritima by grasses. Most species on the foredunes are perennial herbs, whereas a greater diversity of life forms occurs on the back- dunes. Most of the dune species exhibit one of three leaf modifications: succu- lence, canescence, or a hard cuticle. Species having the C4 photosynthetic path- way contribute the majority of the cover in the Cape region, in contrast to the rest of the coast. Dune vegetation on other coasts having similar add to Mediterranean climates is dominated by shrubs on the backdunes and by either grasses (western Australia, Mediterranean Sea) or tap-rooted, perennial forbs

Variation in Waterbird Numbers at Four Swamps on the Northern Tablelands of New South Wales

Abstract: Waterbirds at four northern tableland swamps were counted at monthly intervals. Populations were shown to vary. Rainfall patterns and habits of individual species were postulated as the major factors causing this variation.