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991.
Do multipurpose companion trees affect high value timber trees in a silvopastoral plantation system?
Establishment of native timber trees on deforested land may contribute to the livelihood of farmers, to improved ecosystem
services and to increased greenhouse gas uptake. Here, we present a new silvopastoral planting design to assess species performance
and interspecific competition or facilitation effects among native timber and multipurpose trees in Central America. Two timber
species, Tabebuia rosea and Cedrela odorata, were established in three low-density planting regimes allowing combined tree and future livestock production: (1) solitary
planting, (2) companion planting with Guazuma ulmifolia, and (3) companion planting with the nitrogen-fixing Gliricidia sepium. We quantified survival, growth and reforestation potential of the two timber species subjected to the different planting
regimes for the first 2 years after establishment. Nitrogen concentration as well as stable nitrogen and carbon isotope composition
(δ15N, δ13C) of leaves of the timber saplings were determined. T. rosea showed higher survival and better growth than C. odorata under varying environmental conditions (soil, concomitant vegetation). Performance of the timber saplings was unaffected
by either companion species. Planting regimes had no effect on foliar nitrogen concentration and δ15N of the two timber species, although δ15N values indicated nitrogen fixation activity in G. sepium trees. Planting regimes affected foliar δ13C values in T. rosea. δ13C values were significantly higher in solitarily growing individuals, suggesting lower exposition to water stress conditions
in saplings surrounded by companion species. As we found positively correlated growth traits among timber and multipurpose
trees, a combined planting may benefit farmers by providing additional goods and services. 相似文献
992.
Kevin Lombard Mick O’Neill Robert Heyduck Blake Onken April Ulery John Mexal Adrian Unc 《Agroforestry Systems》2011,81(1):45-56
Composted sewage sludge (biosolids) supply plant available Fe and may represent a sustainable alternative to more costly chelated
Fe fertilizers currently used to supplement nutrition in hybrid poplar test plots of elevated soil pH. To test the response
of poplars, field plots were amended with composted biosolids at two agricultural rates: 22.75 and 44.5 Mg ha−1. Iron EDDHA served as a fertilizer check and control plots received no amendment. The hybrid poplar OP-367 (Populus deltoides × P. nigra) was planted on a 3.6 m grid spacing. Significant amounts of P and Fe originating from the sewage treatment process were
detected in soils 13 months after amending. Chlorosis evaluated with a SPAD-502 meter, showed that poplars amended with biosolids
remained the least chlorotic and had greater tree growth when compared to Fe EDDHA and control plots during two growing seasons.
Biosolids show promise as a cost effective alternative for the remediation of Fe chlorosis in hybrid poplar agroforestry plantations
and present new opportunities in northwestern New Mexico for municipalities seeking solid waste land disposal options. 相似文献
993.
The effect of orientation, location, year, and pruning treatment on mean acorn mass in two open woodland experimental locations (Huelva, South-Western Spain) of Holm Oak (Quercus ilex L. subsp. ballota [Desf.] Samp.) was analyzed during 2001–2006. Data were analyzed by using a mixed linear model, where the covariates were tree size parameters (circumference at 80 cm height, crown size), topographic position (wet index and flow length), intraspecific competition, total acorn crops per tree (weight and number), and climatic parameters. Average estimated acorn mass was 3.17 g acorn?1 in the Calañas location and 4.12 g acorn?1 in the San Bartolomé location, with significant differences between locations, among individual trees and across years. Acorns from the south sides of trees were significantly heavier than those at other positions. The effect of pruning treatment and the interactions location × treatment and treatment × year were not significant. Our study provides no evidence that pruning affects acorn mass. None of the analyzed covariates related to tree size, topographic position and intraspecific competition explained the difference among trees, suggesting that heritable factors play an important role. Specific climatic parameters during September, the most important month for acorn growth, may explain the effects of year and location × year on acorn mass. In addition, there appeared to be a “trade-off” between acorn mass and number of acorns. 相似文献
994.
Adansonia digitata (baobab tree), a multipurpose tree species, occurs throughout semi-arid and arid zones of Africa. Its survival is, however,
threatened by bush fire, over-exploitation, grazing and a lack of natural regeneration. The extent of variation in fruit characteristics,
seed germination and seedling traits of the baobab tree in Benin, was evaluated at climatic zone level. 1,200 fruits were
sampled in each of the three climatic zones of Benin for morphological assessment and to assess germination rate and seedling
growth dynamics according to the climatic zones, the used substrate and the scarification of the seed coat. There were significant
differences in fruit characteristics not only between climatic zones but also between individuals from the same zone and within-trees.
Using mechanical scarification on freshly-collected baobab seeds negatively affected the germination rate of baobab seeds
sampled in the Guinean and Sudano-Guinean zones of Benin. The best-germination rate was recorded for non-treated seeds from
the Guinean zone, up to 57% on day 25. All seeds germinated best on the sand substrate, but supplying organic matter promoted
further seedling growth after 11 days of germination. Based on these observations we propose some strategies for efficient
ex situ conservation of baobab in Benin. 相似文献
995.
Commercial Tectona grandis plantations using clones have attracted considerable interest for lumber production in tropical regions where small areas
are frequent. However, studies on wood properties are limited. Therefore, the purpose of this study is to group clones with
similar wood color characteristics using the CIELab system, and mechanical resistance by dynamic stiffness (Ed) in order to obtain different types of clones for different climate and edaphic conditions. It was found that lightness (L*), yellowness (b*), redness (a*), and Ed are similar to those found for other plantation trees. These wood characteristics are significantly influenced by clone and
site. Variance due to clone and site went from 31 to 53% and from 2.95 to 24.22%, respectively. Another source of variance
was distance from pith, with the exception of parameter b*, which was not affected. Finally, clones were grouped (using multivariate analysis) according to color and mechanical resistance.
This analysis established 4 groups by color and 5 groups by Ed. Clone clustering will allow us to choose or use clones with similar wood properties according to site and environmental
conditions increasing area production and wood quality uniformity. 相似文献
996.
Katja Kehlenbeck Roeland Kindt Fergus L. Sinclair Anthony J. Simons Ramni Jamnadass 《Agroforestry Systems》2011,83(2):133-147
Agroforestry systems are potentially suitable for conservation of tree genetic resources. Farmers around Mt. Kenya usually
integrate trees into their farm. Large parts of these trees seem to be of exotic origin, whereas indigenous species have priority
for conservation. This study aimed at determining on-farm richness, composition and frequency of indigenous and exotic woody
species around Mount Kenya to assess the suitability of farms for the conservation of indigenous tree species. 265 on-farm
plots of 0.5 ha size each were selected in 18 different agro-ecological zones by using a stratified sampling scheme. All woody
species within the plot were recorded with their local and scientific names. Total species richness was 424 (including 306
indigenous ones), mean richness per plot 16.5 species (including 8.8 indigenous ones). Eight out of the 10 most frequent species
were exotic ones with Grevillea robusta from Australia ranking first (found on almost 76% of the surveyed farms). The proportion of indigenous species increased
with increasing aridity and temperature. Dominance of exotic species was found at farms of humid mid- and highlands. Ordination
analysis revealed that mostly exotic species contributed to separation of farms in the highlands and upper midlands, whereas
indigenous species in the lower midlands and lowlands. As the frequencies of most indigenous trees were low, only parts of
the surveyed farms can contribute to conservation of tree genetic resources, particularly the less intensively managed farms
of the more arid lands. Farmers’ access to knowledge on valuable indigenous tree species and to quality seedlings of these
trees need to be improved to increase indigenous species’ frequencies on farms and possibly to replace some of the exotic
species in the future. 相似文献
997.
Keith E. Woeste 《林业研究》2011,22(3):353-359
Three kinds of plant growth regulators, gibberellinA 4/7 (GA 4/7 ), 6-benzylaminopurine (BA), and chlormequat chloride (CCC), were evaluated for their ability to promote strobilus and cone production in a Chinese pine (Pinus tabuliformis Carr.) clonal seed orchard. Treatments (0, 250, 500, or 1000 mg L -1 ) were applied during three periods (June- July, July-August and August-September) in 2005. Of the three plant growth regulators, GA 4/7 was the best for promoting flower and cone production. Trees sprayed... 相似文献
998.
Five different isoforms (IrlVHA-c1-c5) of V-ATPase subunit c (VHA-c) were cloned from a Japanese iris (Iris lactea Pall. var. chinensis Fisch. Koidz) cDNA library using degenerate primers PCR and the 5'-RACE technique. The sequence analysis showed the open reading frame (ORF) of the IrlVHA-c1 c5 to be 495 bp, corresponding to a protein of 164 amino acids. Among the five isoforms, IrlVHA-c1 and IrlVHA-c2 are completely homologous. The IrlVHA-c protein is localized at the vacuolar membrane as indicated by a g... 相似文献
999.
Species diversity and stability of natural secondary communities in different layers with different cutting intensities 10
years later were investigated by calculating Marglef Richness index (R), Shannon-Wiener diversity index (H), Simpson diversity index (P), and Pielou Evenness index (J). Results show that the values of R, H and P among different layers are listed in a decreasing order: the shrub layer > the arbor layer > the herb layer, all the three
indices values reach the maximum under medium selective cutting intensity after 10 years. The J value of the shrub layer shows a concave parabolic change with the increase in cutting intensity; it shows a linear increase
for the arbor layer, whereas the J value of the herb layer shows an opposite change pattern. The values of R at different cutting intensities had high significant difference, but other indices had not significant difference. The stability
of communities at different cutting intensities after 10 years is non-cutting> low selective cutting intensity > medium selective
cutting intensity > high selective cutting intensity > extra-high intensity > clear cutting. The stability of communities
at different cutting intensities after 10 years shows that the greater cutting intensities, the worse the stability is. 相似文献
1000.
Schizostachyum dullooa (Gamble) Majumder ‘dolu bamboo’ is a thin walled sympodial moderate sized to large tufted bamboo, dominant in the successional fallows of northeast India.
The impact of resource management on productivity and sustainability of the species was evaluated by investigating the population
status and regeneration in Cachar tropical semi evergreen forest under private property resource management (PPRM) and common
property resource management (CPRM) regimes. Population status revealed current-year, one-year, two-year and three-year-old
culms contribute 54%, 24%, 16% and 6% of the total culms per clump, respectively, under PPRM. Three-year-old culms were absent
in CPRM and population status was thus represented by current year (83%), one-year (16%) and two-year (1%) old culms. Net
change, rate of change and % gain in population for different age classes showed the prevalence of management practices under
CPRM was unscientific. Efficiency of new culm production per clump used as an index of regeneration was 69.7% in PPRM and
59.88% in CPRM. New culms produced under CPRM were small and thin. We conclude that CPRM is inappropriate for a long term
economic and ecological sustainability of the species and alternative management protocols are needed for conservation of
the species. 相似文献