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Indigenous Trees (indigenous + tree)

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Life Sciences50%

Terms modified by Indigenous Trees

  • indigenous tree species
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    Selected Abstracts

    Effects of habitat history and extinction selectivity on species-richness patterns of an island land snail fauna

    JOURNAL OF BIOGEOGRAPHY, Issue 10 2009
    Satoshi Chiba
    Abstract Aim, Local-scale diversity patterns are not necessarily regulated by contemporary processes, but may be the result of historical events such as habitat changes and selective extinctions that occurred in the past. We test this hypothesis by examining species-richness patterns of the land snail fauna on an oceanic island where forest was once destroyed but subsequently recovered. Location, Hahajima Island of the Ogasawara Islands in the western Pacific. Methods, Species richness of land snails was examined in 217 0.25 × 0.25 km squares during 1990,91 and 2005,07. Associations of species richness with elevation, current habitat quality (proportion of habitat composed of indigenous trees and uncultivated areas), number of alien snail species, and proportion of forest loss before 1945 in each area were examined using a randomization test and simultaneous autoregressive (SAR) models. Extinctions in each area and on the entire island were detected by comparing 2005,07 records with 1990,91 records and previously published records from surveys in 1987,91 and 1901,07. The association of species extinction with snail ecotype and the above environmental factors was examined using a spatial generalized linear mixed model (GLMM). Results, The level of habitat loss before 1945 explained the greatest proportion of variation in the geographical patterns of species richness. Current species richness was positively correlated with elevation in the arboreal species, whereas it was negatively correlated with elevation in the ground-dwelling species. However, no or a positive correlation was found between elevation and richness of the ground-dwelling species in 1987,91. The change of the association with elevation in the ground-dwelling species was caused by greater recent extinction at higher elevation, possibly as a result of predation by malacophagous flatworms. In contrast, very minor extinction levels have occurred in arboreal species since 1987,91, and their original patterns have remained unaltered, mainly because flatworms do not climb trees. Main conclusions, The species-richness patterns of the land snails on Hahajima Island are mosaics shaped by extinction resulting from habitat loss more than 60 years ago, recent selective extinction, and original faunal patterns. The effects of habitat destruction have remained long after habitat recovery. Different factors have operated during different periods and at different time-scales. These findings suggest that historical processes should be taken into account when considering local-scale diversity patterns. [source]

    Effects of climate on the growth of exotic and indigenous trees in central Zambia

    JOURNAL OF BIOGEOGRAPHY, Issue 1 2005
    E. N. Chidumayo
    Abstract Aim, Climate change has far-reaching effects on species and ecosystems. The aims of this study were to determine how climate factors affect the growth pattern of indigenous and exotic trees in Zambia and to predict tree growth responses to a warmer climate with the use of mathematical models. Location, Two savanna sites in central Zambia. Methods, Diameter at breast height (1.3 m above ground, d.b.h.) of 91 permanently marked trees belonging to three indigenous and four exotic species was measured fortnightly for periods of 1,2 years from 1998 to 2003. Correlation and regression analysis was used to determine the effect of climate factors (minimum, maximum and average temperature and rainfall) on monthly daily d.b.h. increment of each species. Regression models were used to predict the growth behaviour of trees under a 0.5 °C warmer climate. Results, Interactions between temperature and rainfall explained 60,98% of the variation in d.b.h. increment in all the tree species, except the exotic Eucalyptus grandis. For deciduous species, stem expansion was delayed by 2,12 weeks following leaf-flush and d.b.h. increment peaked during the rainy season. Evergreen and deciduous species could not be separated on the basis of annual d.b.h. increment because the higher growth rates of deciduous species compensated for the shorter growing period. Mathematical models predicted slight changes in d.b.h. growth pattern under a 0.5 °C warmer climate in five of the seven species. Significant changes in d.b.h. growth patterns were predicted in the indigenous Bridelia micrantha and exotic Gmelina arborea under a warmer climate. However, models failed to adequately represent potential soil water stress that might result from changes in tree growth patterns and a warmer climate. Main conclusions, Climate factors explained a large proportion of the variation in diameter growth of both indigenous and exotic trees, rendering it possible to model tree growth patterns from climate data. Tree growth models suggest that a rise in temperature of 0.5 °C is unlikely to induce significant changes in the growth behaviour of the majority of the studied species. However, because the growth behaviour of some species may be substantially affected by climate change, it is recommended that strategies for the future production of such climate-sensitive trees should incorporate aspects of climate change. [source]

    Enrichment planting does not improve tree restoration when compared with natural regeneration in a former pine plantation in Kibale National Park, Uganda

    AFRICAN JOURNAL OF ECOLOGY, Issue 4 2009
    Patrick A. Omeja
    Abstract Given the high rates of deforestation and subsequent land abandonment, there are increasing calls to reforest degraded lands; however, many areas are in a state of arrested succession. Plantations can break arrested succession and the sale of timber can pay for restoration efforts. However, if the harvest damages native regeneration, it may be necessary to intervene with enrichment planting. Unfortunately, it is not clear when intervention is necessary. Here, we document the rate of biomass accumulation of planted seedlings relative to natural regeneration in a harvested plantation in Kibale National Park, Uganda. We established two 2-ha plots and in one, we planted 100 seedlings of each of four native species, and we monitored all tree regeneration in this area and the control plot. After 4 years, naturally regenerating trees were much taller, larger and more common than the planted seedlings. Species richness and two nonparametric estimators of richness were comparable between the plots. The cumulative biomass of planted seedlings accounted for 0.04% of the total above-ground tree biomass. The use of plantations facilitated the growth of indigenous trees, and enrichment planting subsequent to harvesting was not necessary to obtain a rich tree community with a large number of new recruits. Résumé Étant donné le rythme élevé de déforestation et, par la suite, d'abandon de terres, il y a des demandes croissantes pour repeupler les terrains dégradés; cependant, de nombreuses surfaces se trouvent dans un état de succession interrompu. Des plantations peuvent mettre fin à cette succession stoppée, et la vente de grumes peut financer les efforts de reforestation. Pourtant, si les prélèvements d'arbres endommagent la régénération naturelle, il peut être nécessaire d'intervenir avec des plantations d'appoint. Malheureusement, il n'est pas toujours facile de savoir quand une intervention est nécessaire. Nous documentons ici le taux d'accumulation de biomasse dans des jeunes arbres replantés par rapport à la régénération naturelle dans une plantation exploitée, à l'intérieur du Parc National de Kibale, en Ouganda. Nous avons établi deux parcelles de deux hectares et, dans une, nous avons repiqué 100 plants de chacune des quatre espèces natives. Nous avons ensuite suivi la régénération de tous les arbres dans cette parcelle et dans la parcelle témoin. Après quatre ans, les arbres provenant de la régénération naturelle étaient beaucoup plus grands, plus gros et plus abondants que les arbres replantés. La richesse en espèces et deux estimateurs nonparamétriques de la richesse étaient comparables dans les deux parcelles. La biomasse cumulée des jeunes arbres plantés comptait pour 0,04% de la biomasse aérienne totale des arbres. Le recours à des plantations a facilité la croissance d'arbres indigènes et la plantation d'appoint faisant suite à l'exploitation ne fut pas nécessaire pour obtenir une communauté d'arbres riche, avec un grand nombre de nouvelles recrues. [source]

    Spontaneous Vegetation on Overburden Piles in the Coal Basin of Santa Catarina, Brazil

    RESTORATION ECOLOGY, Issue 3 2008
    Robson Dos Santos
    Abstract The objective of this work was to select indigenous vegetal species for restoration programs aiming at the regeneration of ombrophilous dense forest. Thirty-five spoil piles located in the county of Sideropolis, Santa Catarina, that received overburden disposal for 39 years (1950,1989) were selected for study because they exhibited remarkable spontaneous regrowth of trees compared to surrounding spoil piles. Floristic inventory covered the whole area of the 35 piles, whereas survey on phytosociology and natural regeneration studies were conducted in 70 plots distributed along the 35 piles. Floristic inventory recorded 83 species from 28 botanical families. Herbaceous terricolous plants constituted the predominant species (47.0%), followed by shrubs (26.5%), trees (19.3%), and vines (7.2%). Results from surveys on phytosociology and natural regeneration, focused on shrubs and trees, recorded incipient ecological succession. In addition, the most adapted species recorded on the overburden piles, as ranked by index of natural regeneration (RNT) plus importance value index (IVI), were as follows: Clethra scabra (RNT = 23.93%; IVI = 17.28%), Myrsine coriacea (RNT = 20.93%, IVI = 11.26%), Eupatorium intermedium (RNT = 7.56%, IVI = 0.40%), Miconia ligustroides (RNT = 5.84%, IVI = 2.37%), Ossaea amygdaloides (RNT = 3.84%, IVI = 1.30%), Tibouchina sellowiana (RNT = 3.29%, IVI = 1.94%), Eup. inulaefolium (RNT = 2.65%, IVI = 0.80%), and Baccharis dracunculifolia (RNT = 2.28%; IVI = 0.56%). High values of IVI and RNT exhibited by the exotic species Eucalyptus saligna (IVI = 21.73%, RNT = 51.41%) indicated strong competition between exotic and indigenous species. Severe chemical (acidic pH and lack of nutrients) and physical (coarse substrate and slope angle of 40,50°) characteristics displayed by the overburden piles constituted limitations to floristic diversity and size of indigenous trees, indicating the need for substrate reclamation prior to forest restoration. [source]