Spatial and temporal variation in crop diversity in agroforestry homegardens of southern Ethiopia

A key assumption in many homegarden studies is that homegardens are ecologically and socio-economically sustainable due to their species diversity. The precise relation between diversity and sustainability is still heavily debated, however. A basic question is how diversity in homegardens can best be characterized in view of the various dimensions of species diversity and their variation in time and space. This paper assesses different types of species diversity in the homegardens of Sidama region of southern Ethiopia. In a survey of crop species in 144 homegardens a total of 78 cultivated crop species (excluding trees) belonging to 10 functional groups were recorded; there were on average 16 crop species and 8 functional groups per farm. Within homegardens, plots differ in species composition and crop diversity. Four types of homegarden systems are distinguished differing in both type and area-share of dominant species, relative orientation at subsistence or cash production and overall crop diversity. The gradual replacement of enset by maize and of coffee by more financially attractive cash crops khat and pineapple causes a decrease in overall crop diversity. Our data demonstrate that it is incorrect to consider homegardens as generic systems with a uniform distribution of species diversity: important within and between homegarden variation exists. Ecological and socio-economic sustainability is not just related to species diversity per se, but rather to more specific features such as presence of keystone species and diversity in functional species groups. Socio-economic sustainability in terms of adjustment to socio-economic change implies dynamics in species diversit

Species Diversity of Trichosanthes in Gunung Halimun National Park

Inventory Trichosanthes L. in Gunung Halimun Nasional Park have been conducted. Seven species recorded occuring in TN Gn.Halimun namely, T. montana, T. ovigera, T. pubera, T. quinquangulata, T. tricuspidata, T. villosa, and T. wawrae.These species are found mostly in humid area in edge forest, or along river sides. Trichosanthes wawrae was found in Cikaniki,whereas the other six species found in Corridor Cianten. Trichosanthes quinquangulata has widelydistributed, it has found in Cibanteng and Leuwijamang as well. Exploration is still continuing to study the distribution of this genus in Gn. Halimun, to recollect the rare species and to do phylogenetic analysis

Plant Species Diversity of Pangi Binangga Nature Reserve, Central Sulawesi

Pangi Binangga Nature Reserve is one of eight nature reserves in Central Sulawesi. In 1998, Pangi Binangga was designated as a conservation area, however, the diversty of the plant species not been recognized and reported. Pangi Binangga Nature Reserve is a lowland forest with vegetation and grassland forest, with primary and secondary forest vegetation. The objectives of this research are to provide informations of plant species in the Pangi Binangga Area. Exploration method was conducted throughout the region, and found 518 species. Rubiaceae, Euphorbiaceae, Moraceae, Compositae, Araceae, Urticaceae dominate in Pangi Binangga forest. Four species of them are endemic to Sulawesi, five species belong to endangered plants and 10 species of invasive

Species and Functional Diversity of Rhizobacteria of Rice Plant in the Coastal Soils of Indonesia

Rhizobacteria are important components of soil and directly or indirectly influence the soils quality and plant growth for maintaining adequate plant nutrition and reducing the negative environmental effects of fertilizers. Applying high dose of chemical fertilizers in most of rice fields in the coastal areas could reduce the quality of the soil in the long time. There are few studies addressed to verify the species and functional diversity of cultivable rhizobacteria associated with rice plant in the coastal soils. The objective of the study was to verify the species and functional diversity of rhizobacteria isolated from the coastal soils of two rice production areas of Subang and Indramayu, West Java. Special focus was given to verify phosphate solubilization, nitrogen fixation, IAA and cellulase production of the selected 78 strains of rice rhizobacteria isolated from the coastal paddy field, as well as taxonomical analyses based on 16S rRNA. The results showed that among 78 bacterial isolates from the coastal paddy field, mostly were belonging to the Firmicutes, most of them affiliated with genera Bacillus, 75 strains produced IAA, 32 strains fixed nitrogen, 37 strains solubilized phosphate and 33 strains produced cellulase. Several strains of the rhizobacteria were capable of producing plant growth promoting substances (PGPR), alone or in combination, such as IAA, fixing nitrogen, solubilizing phosphate, and producing cellulase. Taking all of these diverse PGPR characteristics into account, it is clear that the 78 identified isolates have great potential for improving saline soils of the coastal paddy fields in Indonesia

Species diversity and distribution of ruderal flora on landfills in Maradi city, Niger

Waste management continues to be a critical environmental issue in cities. It impacts on the well being of the population, the environment and the biodiversity. In the city of Maradi, in Niger, more interest is given to the problem in order to understand the whole waste management system. It is in this context that this study is carried out to investigate on the role of ruderal flora on the municipal solid wastes dumpsites and landfill sites in Maradi city. The specific objectives are to determine the floristic diversity and distribution of ruderal flora on the municipal solid waste disposal sites, and to identify potential species that can play an important role in the phytoremediation of these sites. In total, 65 species belonging to 52 genera and 24 families were recorded. These species can be categorised into two groups containing anthropic and nitrophilic species according to the ascending Hierarchical Classification (AHC) at 25% similarity. Characteristic species of the first group G1 are Amaranthus viridis and Cucurbita pepo, and Datura innoxia and Cucumis melo for the second group G2. Other ruderal species, namely Amaranthus spinosus L., Amaranthus viridis L., Celosia trygina L., Datura innoxia Mill., and an introduced woody species, Cuphea hyssopifolia Kunth., found are not included in the Maradi city list of species. Datura innoxia, Amaranthus viridis and Amaranthus spinosus are species known to tolerate different degrees of pollution and their ecology should be further study to better understand how they can be used for phytoremediation on this kind of sites

Subtidal macrozoobenthos communities from northern Chile during and post El Niño 1997–1998

Despite a large amount of climatic and oceanographic information dealing with the recurring climate phenomenon El Niño (EN) and its well known impact on diversity of marine benthic communities, most published data are rather descriptive and consequently our understanding of the underlying mechanisms and processes that drive community structure during EN are still very scarce. In this study, we address two questions on the effects of EN on macrozoobenthic communities: (1) how does EN affect species diversity of the communities in northern Chile? and (2) is EN a phenomenon that restarts community assembling processes by affecting species interactions in northern Chile? To answer these questions, we compared species diversity and co-occurrence patterns of soft-bottoms macrozoobenthos communities from the continental shelf off northern Chile during (March 1998) and after (September 1998) the strong EN event 1997–1998. The methods used varied from species diversity and species co-occurrence analyses to multivariate ordination methods. Our results indicate that EN positively affects diversity of macrozoobenthos communities in the study area, increasing the species richness and diversity and decreasing the species dominance. EN represents a strong disturbance that affects species interactions that rule the species assembling processes in shallow-water, sea-bottom environments

Treefall Gaps and the Maintenance of Species Diversity in a Tropical Forest

The maintenance of species diversity by treefall gaps is a long‐standing paradigm in forest ecology. Gaps are presumed to provide an environment in which tree species of differing competitive abilities partition heterogeneous resources. The empirical evidence to support this paradigm, however, remains scarce, and some recent studies even suggest that gaps do not maintain the diversity of shade‐tolerant species. Although there is evidence that gaps maintain the diversity of pioneer trees, most of this evidence comes from studies that did not make comparisons between gaps and intact forest sites (controls). Further, nearly all studies on the maintenance of diversity by gaps have ignored lianas, an important component of both old‐world and neotropical forests. We tested the hypothesis that treefall gaps maintain shade‐tolerant tree, pioneer tree, and liana species diversity in an old‐growth forest on Barro Colorado Island (BCI), Panama. We compared the density and species richness of these guilds between paired gap and non‐gap sites on both a per‐area and a per‐individual (per capita) basis. We found no difference in shade‐tolerant tree density and species richness between the gap and non‐gap sites. Both pioneer tree and liana density and species richness, however, were significantly higher in the gap than in the non‐gap sites on both a per‐area and a per‐individual basis. These results suggest that gaps maintain liana species diversity and that this effect is not merely a consequence of increased density. Furthermore, our data confirm the long‐held belief that gaps maintain pioneer tree species diversity. Because lianas and pioneer trees combined account for ∼43% of the woody plant species on BCI, and in other forests, our results are likely to be broadly applicable and suggest that gaps play a strong role in the maintenance of woody species diversity

Ecosystems with mutually exclusive interactions self-organize to a state of high diversity

Ecological systems comprise an astonishing diversity of species that cooperate or compete with each other forming complex mutual dependencies. The minimum requirements to maintain a large species diversity on long time scales are in general unknown. Using lichen communities as an example, we propose a model for the evolution of mutually excluding organisms that compete for space. We suggest that chain-like or cyclic invasions involving three or more species open for creation of spatially separated sub-populations that subsequently can lead to increased diversity. In contrast to its non-spatial counterpart, our model predicts robust co-existence of a large number of species, in accordance with observations on lichen growth. It is demonstrated that large species diversity can be obtained on evolutionary timescales, provided that interactions between species have spatial constraints. In particular, a phase transition to a sustainable state of high diversity is identified.Comment: 4 pages, 4 figure