Business strategies for conservation on private lands: Koa forestry as a case study.
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Innovative financial instruments are being created to reward conservation on private, working lands. Major design challenges remain, however, to make investments in biodiversity and ecosystem services economically attractive and commonplace. From a business perspective, three key financial barriers for advancing conservation land uses must frequently be addressed: high up-front costs, long time periods with no revenue, and high project risk due to long time horizons and uncertainty. We explored ways of overcoming these barriers on grazing lands in Hawaii by realizing a suite of timber and conservation revenue streams associated with their (partial) reforestation. We calculated the financial implications of alternative strategies, focusing on Acacia koa ("koa") forestry because of its high conservation and economic potential. Koa's timber value alone creates a viable investment (mean net present value = $453/acre), but its long time horizon and poor initial cash flow pose formidable challenges for landowners. At present, subsidy payments from a government conservation program targeting benefits for biodiversity, water quality, and soil erosion have the greatest potential to move landowners beyond the tipping point in favor of investments in koa forestry, particularly when combined with future timber harvest (mean net present value = $1,661/acre). Creating financial mechanisms to capture diverse ecosystem service values through time will broaden opportunities for conservation land uses. Governments, nongovernmental organizations, and private investors have roles to play in catalyzing this transition by developing new revenue streams that can reach a broad spectrum of landowners. (+info)
Anticancer and antimutagenic properties of Acacia nilotica (Linn.) on 7,12-dimethylbenz(a)anthracene-induced skin papillomagenesis in Swiss albino mice.
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We report the chemopreventive activity of Acacia nilotica (Linn.) gum, flower and leaf aqueous extracts, on 7,12-dimethylbenz(a)anthracene (DMBA) induced skin papillomagenesis in male Swiss albino mice. Animals were divided into following groups: Group I (Controls) given DMBA and croton oil, with no extract ; Group II (treatment) animals treated with Acacia nilotica gum (Group II-a) (800 mg/kg body weight), flowers (Group II-b) (800 mg/kg body weight), or leaves (Group II-c) (800 mg/kg body weight) during the peri- and post initiation periods of DMBA and croton oil application. A significant reduction in the values of tumor burden, tumor incidence and cumulative number of papillomas was observed in mice treated by oral gavage with the Acacia nilotica gum, flower and leaf extracts as compared with the control group. The latency period in treatment Group-II (b) and Group-II (c) was significantly increased as compared with the control group. A significant reduction in the frequency of micronuclei was also observed in mice treated by oral gavage with the aqueous extracts, along with significant decrease in total chromosomal aberrations in the form of chromatid breaks, chromosome breaks, centric rings, dicentrics, acentric fragments and exchange. Treatment with Acacia nilotica flower (Group II-B) and leaf (Group II-C) aqueous extracts by oral gavage for 15 days resulted in a highly significant decrease in the lipid peroxidation (LPO) level in the liver, but this was less evident with the gum (Group II-A) . Conversely, reduced glutathione (GSH) content was observed to be significantly elevated as compared with the control group with leaves (Group II-C) and flowers (Group II-B). The chemopreventive and antimutagenic activity of the leaf extract of Acacia nilotica was most significant followed by the flower extract and then by gum. (+info)
Host-driven diversification of gall-inducing Acacia thrips and the aridification of Australia.
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BACKGROUND: Insects that feed on plants contribute greatly to the generation of biodiversity. Hypotheses explaining rate increases in phytophagous insect diversification and mechanisms driving speciation in such specialists remain vexing despite considerable attention. The proliferation of plant-feeding insects and their hosts are expected to broadly parallel one another where climate change over geological timescales imposes consequences for the diversification of flora and fauna via habitat modification. This work uses a phylogenetic approach to investigate the premise that the aridification of Australia, and subsequent expansion and modification of arid-adapted host flora, has implications for the diversification of insects that specialise on them. RESULTS: Likelihood ratio tests indicated the possibility of hard molecular polytomies within two co-radiating gall-inducing species complexes specialising on the same set of host species. Significant tree asymmetry is indicated at a branch adjacent to an inferred transition to a Plurinerves ancestral host species. Lineage by time diversification plots indicate gall-thrips that specialise on Plurinerves hosts differentially experienced an explosive period of speciation contemporaneous with climatic cycling during the Quaternary period. Chronological analyses indicated that the approximate age of origin of gall-inducing thrips on Acacia might be as recent as 10 million years ago during the Miocene, as truly arid landscapes first developed in Australia. CONCLUSION: Host-plant diversification and spatial heterogeneity of hosts have increased the potential for specialisation, resource partitioning, and unoccupied ecological niche availability for gall-thrips on Australian Acacia. (+info)
Seeds use temperature cues to ensure germination under nurse-plant shade in xeric Kalahari savannah.
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BACKGROUND AND AIMS: In arid environments many plant species are found associated with the canopies of woody perennials. Favourable conditions for establishment under canopies are likely to be associated with shade, but under canopies shade is distributed patchily and differs in quality. Diurnal temperature fluctuations and maximum temperatures could be reliable indicators of safe sites. Here, an examination is made as to whether canopy-associated species use temperature cues to germinate in shade patches, rather than matrix areas between trees. METHODS: The study was carried out in arid southern Kalahari savannah (Republic of South Africa). Perennial and annual species associated with Acacia erioloba trees and matrix species were germinated at temperature regimes resembling shaded and unshaded conditions. Soil temperature was measured in the field. KEY RESULTS: Germination of all fleshy-fruited perennial acacia-associated species and two annual acacia-associated species was inhibited by the temperature regime resembling unshaded conditions compared with at least one of the regimes resembling shaded conditions. Inhibition in perennials decreased with seed mass, probably reflecting that smaller seedlings are more vulnerable to drought. Germination of matrix species was not inhibited by the unshaded temperature regime and in several cases it increased germination compared with shaded temperature regimes or constant temperature. Using phylogenetically independent contrasts a significant positive relationship was found between canopy association and the germination at shade temperatures relative to unshaded temperatures. CONCLUSIONS: The data support the hypothesis that canopy species have developed mechanisms to prevent germination in open sun conditions. The results and data from the literature show that inhibition of germination at temperature regimes characteristic of open sun conditions can be found in fleshy-fruited species of widely divergent taxonomic groups. It is predicted that germination mechanisms to detect canopy shade based on temperature cues are widespread in species depending on nurse plants, especially bird-dispersed species. (+info)
Mortality, recruitment and change of desert tree populations in a hyper-arid environment.
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BACKGROUND: Long-term vegetation changes in hyper-arid areas have long been neglected. Mortality, recruitment and change in populations of the ecologically and culturally important and drought persistent Acacia tortilis and Balanites aegyptiaca are therefore estimated in the Eastern Desert of Egypt, and are related to the primary agents of change, water conditions and human intervention. METHODOLOGY: A change analysis using high-resolution Corona images (1965) in combination with field data (2003) is the basis for recruitment, mortality and change estimates. For assessing the influence of water conditions on patterns in recruitment and survival, different types of generalized linear models are tested. CONCLUSIONS: The overall trend in population size in that part of the Eastern Desert studied here is negative. At some sites this negative trend is alarming, because the reduction in mature trees is substantial (>50%) at the same time as recruitment is nearly absent. At a few sites there is a positive trend and better recruitment. Frequent observations of sprouting in saplings indicate that this is an important mechanism to increase their persistence. It is the establishment itself that seems to be the main challenge in the recruitment process. There are indications that hydrological variables and surface water in particular can explain some of the observed pattern in mortality, but our results indicate that direct human intervention, i.e., charcoal production, is the main cause of tree mortality in the Eastern Desert. (+info)
Genetic diversity of rhizobia associated with Acacia longifolia in two stages of invasion of coastal sand dunes.
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We examined the genetic diversity of root nodule bacteria associated with the Australian legume Acacia longifolia in two stages of invasion of a coastal sand dune system. All isolates belonged to the genus Bradyrhizobium. A higher diversity was found in the long-established trees. The results suggest the introduction of exotic bradyrhizobia with the plant. (+info)
Longevity and growth of Acacia tortilis; insights from 14C content and anatomy of wood.
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BACKGROUND: Acacia tortilis is a keystone species across arid ecosystems in Africa and the Middle East. Yet, its life-history, longevity and growth are poorly known, and consequently ongoing changes in tree populations cannot be managed in an appropriate manner. In other arid areas parenchymatic bands marking growth zones in the wood have made dendrochronological studies possible. The possibilities for using pre- and post-bomb 14C content in wood samples along with the presence of narrow marginal parenchymatic bands in the wood is therefore tested to gain further insight into the age, growth and growth conditions of A. tortilis in the hyper-arid Eastern Desert of Egypt. RESULTS: Based on age scenarios and the Gompertz growth equation, the age of trees studied seems to be from 200 up to 650 years. Annual radial growth estimated from calibrated dates based on the post-bomb 14C content of samples is up to 2.4 mm, but varies both spatially and temporally. Parenchymatic bands are not formed regularly. The correlation in band pattern among trees is poor, both among and within sites. CONCLUSION: The post-bomb 14C content of A. tortilis wood gives valuable information on tree growth and is required to assess the age scenario approach applied here. This approach indicates high longevities and slow growth of trees. Special management measures should therefore be taken at sites where the trend in tree population size is negative. The possibilities for dendrochronological studies based on A. tortilis from the Eastern Desert are poor. However, marginal parenchymatic bands can give insight into fine scale variation in growth conditions and the past management of trees. (+info)
Lupane triterpenoids from Acacia mellifera with cytotoxic activity.
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Three new pentacyclic triterpenoids: (20R)-3-oxolupan-30-al (1), (20S)-3-oxolupan-30-al (2) and (20R)-28-hydroxylupen-30-al-3-one (3), along with (20S)-3beta-hydroxylupan-30-al (4), the latter previously described as a constituent of an epimeric mixture, were isolated from Acacia mellifera. In addition, the known metabolites 30-hydroxylup-20-(29)-en-3-one (5), 30-hydroxylup-20-(29)-en-3beta-ol (6), atranorin, methyl 2,4-dihydroxy-3,6 dimethyl benzoate, sitosterol-3beta-O-glucoside and linoleic acid were found in the analyzed plant species for the first time. The structures of the new metabolites were elucidated by extensive spectroscopic analyses and their relative stereochemistry was determined by NOESY experiments. The new metabolite 3 exhibited significant cytotoxic activity against the NSCLC-N6 cell line, derived from a human non-small-cell bronchopulmonary carcinoma. (+info)