Changes in liana community structure and functional traits along a chronosequence of selective logging in a moist semi-deciduous forest in Ghana

ABSTRACT

Background: Lianas are an important component of tropical forests that respond to logging disturbance. Determining liana response to selective logging chronosequence is important for understanding long-term logging effects on lianas and tropical forests.

Aims: Our objective was to quantify the response of liana communities to selective logging chronosequence in a moist semi-deciduous forest in Ghana.

Methods: Liana community characteristics were determined in ten 40 m × 40 m plots randomly and homogenously distributed in each of four selectively logged forest stands that had been logged 2, 14, 40 and 68 years before the surveys and in an old-growth forest stand (ca. >200 years).

Results: Liana species composition differed significantly among the forest stands, as a function of logging time span, while species richness fluctuated along the chronosequence. The abundance of liana communities and of reproductive and climbing guilds was lower in the logged forests than in the old-growth forest. The ratio of liana abundance and basal area to those of trees was similar in the logged forests, but significantly lower than those in the old-growth forest.

Conclusions: Logging impacts on liana community structure and functional traits were largely evident, though no clear chronosequence trends were recorded, except for species composition.     

Growth strategy of the stoloniferous rattan Calamus javensis in Mt. Halimun, Java

Calamus javensis is a widespread understorey rattan in Southeast Asia and is one of the dominant rattan species in Mt. Halimun National Park, West Java. This species can establish clumps either sexually with seeds or clonality with stolons. To analyze the role of sexual reproduction and clonality for clump establishment in C. javensis, we studied the vegetative and genetic structures of the population. Totals of 2,777 ramets comprising 1,321 clumps were found in three 0.16 ha plots. The number of ramets per clump showed reverse J-shaped distribution with a maximum of 15. Clustering and stoloniferous ramets accounted for 62 and 20% of all ramets, respectively. This indicates that C. javensis is actively engaged in clustering clonal growth. The longest stem was 14 m although 75% of all stems were shorter than 1 m long. The stolon ranged from 6 to 538 cm in length, which decreased the local density of ramets. Using randomly amplified polymorphic DNA (RAPD) analysis, we obtained 56 polymorphic bands for 118 clumps sampled from one of the plots. All samples showed different RAPD banding patterns, except one pair at a distance of 225 cm from each other. The genetic similarity among samples closer than 10 m was significantly higher than the expected value from a purely random distribution. These results suggest that most separate clumps are established by recruitment from seeds, and most seeds dispersed near mother plants. Hence, in C. javensis, clonality is more a growth strategy to increase the size of the genet than a dispersion-propagation strategy to expand the habitat.     

A systematic histological study of palm fruits. V. Subtribe Archontophoeniciae (Arecaceae)

Pericarp histology in the Archontophoenicinae provides little to characterize the subtribe as a whole, revealing instead two separate trends with parallels in other subtribes of the Areceae. The data support a close relationship among the three genera occurring in New Caledonia:Chambeyronia, Actinokentia, andKentiopsis, in which there is a complex endocarp consisting of short, oblique fibrous bundles embedded in a thick mantle of brachysclereids, and a loose endocarp of heavily fibrous, flattened vascular bundles adjacent to a relatively thin locular epidermis. The data also support a close relationship between the two genera of the New Zealand/Tasman Sea region:Hedyscepe andRhopalostylis, in which the pericarp is more or less fibrous throughout, with purely fibrous bundles in the outer pericarp and heavily fibrous vascular bundles in the inner pericarp. These results confirm relationships revealed by other morphological data.Archontophoenix appears to be most like the New Caledonian genera in its pericarp structure, with a similar mantle of short fibrous bundles embedded in a a mantle of brachysclereids in the outer pericarp, although it differs significantly in other aspects of morphology and anatomy.     

Effects of construction materials and design of lake and stream banks on climbing ability of frogs and salamanders

With the increasing development of many areas in recent years, concrete structures are often installed along water bodies in order to protect the safety of local residents. However, effects of these concrete structures on environments and mobility of amphibian species are still unknown. The construction of concrete banks along rivers associated with human development has become a serious problem in Taiwan. Most ecosystems used by amphibians are lakes and stream banks, yet no related design solutions to accommodate the needs of amphibians have been used in Taiwan. In this research, we selected eight species of amphibians and investigated their climbing abilities in an effort to improve lake and river bank designs. We evaluated their climbing abilities on five angles of bank slopes, identified relationships between an amphibian's climbing ability and different surface substrates of banks, i.e. Japanese silvergrass (Miscanthus floridulus) mixed with moss, cobblestone, wood (Philippine mahogany), clay, and concrete, under high humidity and different temperatures to simulate changes across the four seasons. The results showed that climbing ability of these amphibians is slightly decreased at low temperatures. For example, on a 45° slope in winter, the average climbing ability decreased 8% from results in summer. The upper limit of bank design slope suitable for Hynobius arisanensis on rock and wood surfaces is 45°. For amphibians from alpine areas in Taiwan, such as Bufo bankorensis, the maximum suitable slope is 15°. With concrete as the water bank material, slopes <30° are preferable. The results presented here can serve as a reference for technicians involved in future ecological engineering designs of banks throughout the world.     

Long-term Persistence of Raphia taedigera Mart. Swamps in Nicaragua1

The palm Raphia taedigera Mart, forms vast, monodominant swamps in Central and South America, but very little is known about the ecology and natural history of these ecosystems. Debate surrounds the issue whether R. taedigera swamps are early successional stages or mature “climax” communities. This paleoecological analysis of a 1.46-m sediment core from swamps on the Caribbean coast of Nicaragua establishes the abundant presence of R. taedigera swamps for at least 2800 ± 90 years. R. taedigera swamps must be considered persistent communities, warranting further study because of their great extension into Central and South America.     

The social context for harvestingIriartea deltoidea (Arecaceae)

Iriartea deltoidea grows abundantly from Nicaragua to Bolivia. The stem is harvested for construction, furniture making, and handicrafts. The objective of my study was to understand the potential for sustainable harvesting of this palm. Ethnographic fieldwork about market patterns and decision-making among harvesters revealed the nature of harvesting pressures near settled areas. The study also demonstrates methods for assessing social and economic influences on harvesting.