共查询到13条相似文献,搜索用时 0 毫秒
1.
S. E. Williams M. van Noordwijk E. Penot J. R. Healey F. L. Sinclair G. Wibawa 《Agroforestry Systems》2001,53(2):227-237
Perennial tree crops are often grown in complex multistrata systems that incorporate natural vegetation. These systems contribute
simultaneously to sustaining rural livelihoods and to the conservation of biodiversity, but their productivity is usually
low. Introduction of high yielding germplasm, usually selected in monocultural plantations, is a potential way to increase
productivity, but a critical requirement is that such plants can be established in a competitive multispecies environment.
The establishment of clonal planting stock in the jungle rubber agroforests of Indonesia was explored through participatory
on-farm research. The trial involved four farmers who grew clonal rubber trees in a total of 20 plots, constituting five replicate
experimental blocks spread across four farms. Unexpectedly, vertebrate pest damage by monkeys (Presbytis melalophos nobilis) and wild pigs (Sus scrofa) was the most important influence on establishment, explaining almost 70% of the variation in rubber tree growth. The amount
of labour invested in weeding was also positively correlated with rubber tree growth. Farmers generally decided to completely
cut back vegetation between rows of rubber trees, including potentially valuable trees, rather than weeding within the rows
and selectively pruning trees in the inter-row. Farmers thought that the inter-row vegetation would harbour vertebrate pests
and compete with the clonal rubber, and they had access to fruits, firewood and other non-timber forest products from other
land. Thus, contrary to expectations, when offered clonal germplasm, farmers opted to use plantation monoculture methods to
protect what they considered a valuable asset, rather than maintain the traditional multispecies strategy they use with local
germplasm.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
2.
The relationship of branch cross sectional area (CS) to leaf biomass (LM) and leaf area (LA) was studied in three agroforestry tree species,Calliandra calothyrsus Maissn.,Erythrina berteroana Urban andErythrina poeppigiana (Walpers) O.F. Cook, to develop a non-destructive method for the estimation of LM and LA for trees managed with periodic pruning. Variation in these relationships was observed according to the bifurcation level and, in theErythrina spp., by clone. All the relationships were linear except the CS-LM relation in small branches ofE. poeppigiana, where it was initially exponential. At main branch level the relationship of CS to LM and LA was linear in all cases but the regression parameter values varied between species and clones, with determination coefficient (R2) 0.88–0.99. It was concluded that the ratio of main branch CS to LM and LA can be used for non-destructive estimation of the latter variables. The method has the additional benefit that the regression parameter value reflects the allocation of dry matter within a tree and, consequently, may give indications about its possible uses in different agroforestry systems.Work carried out at the Centro Agronómico Tropical de Investigación y Enseñanza (CATIE), Turrialba, Costa Rica. 相似文献
3.
Theee trials to evaluat the potential of alley cropping in maize production on the low fertility, acidic soils in Northern Zambia are described. Leucaena leucocephala, Gliricidia sepium, Sesbania sesban, Albizia falcataria, Fleminga congesta, and Cassia spectabilis, were grown in alley crops with hybrid maize and soybean. All trials received recommended rates of P and K fertiliser; N fertiliser was applied at three rates as a subplot treatment. One trial received lime before establishment.Only in the limed trial was there a significant improvement in maize yields through alley cropping; when no N fertiliser was applied, incorporation of Leucaena leucocephala prunings resulted in an increase of up to 95% in yields, with a smaller improvement being produced by Flemingia congesta. There was a significant correlation between the quantity of prunings biomass applied and the proportional increase in maize yields over the control treatment. It is suggested that the lack of effect of most of the tree species on crop yields was due to low biomass production.An economic analysis showed that alley cropping with limed Leucaena was only profitable when fertiliser costs were high in relation to maize prices. However, lime is both expensive and difficult to obtain and transport for most small scale farmers in the region, and is therefore not a practical recommendation. It is suggested that future alley cropping research should focus on screening a wider range of tree species, including other species of Leucaena, for acid tolerance and higher biomass production. 相似文献
4.
Yasuhiro Utsumi Shinya Koga Naoaki Tashiro Atsushi Yamamoto Yukie Saito Takanori Arima Hirokazu Yamamoto Masahiko Kadomatsu Nao Sakanoue 《Journal of Wood Science》2006,52(6):477-482
Of all plant materials used to cover the roofs of traditional Japanese buildings, Japanese cypress (Chamaecyparis obtusa) bark, hiwada, has the longest service life and has been used from ancient times. However, wood and bark properties after hiwada harvest have not been evaluated in detail. We studied whether decortication for hiwada production in winter affected xylem and phloem formation. Decorticated trees still preserved all inner bark and part of the
outer bark, and both decorticated and control trees had similar annual ring structures at all stem heights in the xylem and
phloem. In both xylem and inner bark, no significant difference in ring width at any stem height was found between annual
rings before and after decortication. Thus, this study revealed that the decortication of bark for hiwada production does not affect the formation of xylem and the inner and outer bark if decortication is carried out by highly
skilled workers in winter. 相似文献
5.
The objectives of this study were: (1) to relate the height growth pattern to the GIS-derived site index, (2) to construct various types of polymorphic height curves, and (3) to select the most accurate height curve for Japanese larch (Larix kaempferi). A total of 14 dominant trees were felled for stem analysis. Richards' function was first fitted to the height/age dataset recorded from stem analyses of 14 trees, and its parameters (i.e., A, k, and m) were then estimated for each sample tree. The relationship between parameter A and the GIS-derived site index was significant, while that of parameters k and m were not significant. The 12 height curve equation forms developed from the Richards' function were then fitted to the dataset consisting of 563 observations of height, age, and GIS-derived site index derived from 14 trees. All height curves were unbiased and provided an equally good fit. The shape of the height curves differed among sites of different site indices. These results indicated that Richards' function was sufficiently flexible to represent the polymorphic height growth pattern of Japanese larch. Finally, the best-fit height curve was selected so that accurate height growth predictions would be possible at any given age and site. 相似文献
6.
Yosuke Iimura Madoka Yoshizumi Tomonori Sonoki Mikiko Uesugi Kenji Tatsumi Ken-ichi Horiuchi Shinya Kajita Yoshihiro Katayama 《Journal of Wood Science》2007,53(6):541-544
To assess the possible utility of a fungal gene for manganese-dependent peroxidase (MnP) produced by a transgenic plant in
phytoremediation, we transformed hybrid aspen with a chimeric gene for MnP. Our gene construct allowed expression of the gene
for MnP in plants and relatively high MnP activity was detected in the hydroponic medium in which roots of plants that expressed
the transgene had been cultured. Some of our transgenic plants were able to remove bisphenol A from the medium more efficiently
than wild-type plants. Our results demonstrate that, without any modification of the coding sequence, a chimeric gene for
fungal MnP can be expressed in a woody plant, with secretion of active MnP from roots into the rhizosphere. Our strategy suggests
new options using woody plants for phytoremediation. 相似文献
7.
We determine the relationships of culm surface area to other culm dimensions for one of the largest bamboo species, Phyllostachys pubescens Mazel ex Houzeau de Lehaie. A total number of 150 sample culms were collected from a stand of P. pubescens in Mt. Toshima, Kumamoto Prefecture, western Japan. The culm surface area for each sample was calculated, and then the relationships
of the culm surface area to basal area and product of diameter at breast height (dbh) and culm height were analyzed. The relationship
between culm surface area and basal area could be described successfully by the power equation, whereas there was a linear
relationship of culm surface area to product of dbh and height. Although the regression equations determined here would be
useful in estimating culm surface area of P. pubescens, it is necessary to select an appropriate equation depending on the purpose and available time and labor. 相似文献
8.
A multidisciplinary team undertook a six-year investigation on the agro-ecological and socio-economic aspects of the dehesa system in the Sierra Norte area, a part of the Sierra Morena of the Sevilla Province, Western Andalusia, Spain. This paper summarizes its findings on the various agro-ecological features of the system and evaluates the system's functional aspects vis-a-vis the trends and developments in land use in the region over the past few centuries. The synergistic effects of tree cover on understorey grassland vegetation is discussed in terms of soil fertility build-up and favourable micro-climatic and hydrological features, and the potential use of this information in future research and development programmes to improve the dehesa system in the Mediterranean region is outlined. 相似文献
9.
Richard Joffre Jean Vacher Carlos de los Llanos Gilbert Long 《Agroforestry Systems》1988,6(1-3):71-96
A multidisciplinary team undertook a six-year investigation on the agro-ecological and socio-economic aspects of the dehesa
system in the Sierra Norte area, a part of the Sierra Morena of the Sevilla Province, Western Andalusia, Spain. This paper
summarizes its findings on the various agro-ecological features of the system and evaluates the system's functional aspects
vis-a-vis the trends and developments in land use in the region over the past few centuries. The synergistic effects of tree
cover on understorey grassland vegetation is discussed in terms of soil fertility build-up and favourable micro-climatic and
hydrological features, and the potential use of this information in future research and development programmes to improve
the dehesa system in the Mediterranean region is outlined. 相似文献
10.
The jujube tree (Ziziphus mauritiana Lam., Rhamnaceae family) is an exotic species which is commonly found in the Sahelian and Sudanian areas of Africa. A programme
was undertaken in Senegal to introduce domesticated varieties and adapt them to the edaphic and climatic specificities of
the Sahel. Research focussed on the ‘Gola’ variety, multiplied by an in vitro micrografting technique which is a miniaturisation of the apex splice, involving the aseptic grafting of miniature scions
(5 to 10 mm long) onto the hypocotyl of seedlings in vitro. Studies reported here include the choice and preparation of rootstock, the micrografting technique, acclimation of the grafts,
and transplantation to the field. The outcome of this research is the achievement of successful establishment of over 80%
of the micrografts. However, more work is required to evaluate the transferability of the techniques through a study of their
economic viability, as well as their acceptability to local people.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
11.
Dorthe Veddeler Roland Olschewski Teja Tscharntke Alexandra-Maria Klein 《Agroforestry Systems》2008,73(2):109-114
Fruit set and quality of highland coffee (Coffea arabica) have been experimentally shown to be higher with bee-mediated or manual pollen supplementation than with autonomous self-pollination.
Based on extrapolation from these small-scale experiments, very substantial monetary values for the pollination service have
recently been suggested. However, previous research has not included direct measurement of coffee yield at a farm level in
relation to pollinator activity, testing if pollinators are not only limiting fruit set and quality, but also coffee yield
and farm profit. The extrapolations from small-scale experiments may be subject to error, because resource reallocation during
fruit development, associated with enhanced pollination, was neglected, and many studies were restricted to a single coffee
farm, limiting the validity of extrapolation. Here, we investigate the relationship between coffee yield and the community
of coffee flower-visiting bees on 21 farms in Ecuador, where coffee is grown under tree shade. Our data show, for the first
time on a farm-scale, that coffee yield was positively related to the density of non-managed, social flower-visiting bees
per coffee shrub, but not to the number of inflorescences per shrub. Our data revealed that a fourfold increase in bee density
was associated with an 80% increase in yield and an 800% increase in net revenues. Consequently, in our study higher yield
associated with increased pollination generated higher revenues per hectare, so that farm profit was higher when bees were
abundant. 相似文献
12.
In 2002 and 2003, six field experiments were conducted at three olive groves of southern Spain in order to compare the effects of two types of ethylene treatments (sprayed and diffusers) on the olive losses caused by the olive moth (Prays oleae Bern.) as well as on the activity and effectiveness of oofagous predators. Both treatments showed to be effective to control the pest; in the two years studied the mean reduction in final infestation due to ethylene was of 35% with respect to the controls trees, and none affected negatively the action of natural predators of P. oleae. In addition, the use of diffusers set on the trees at the end of flowering period will help the farmers to overcome the problems of determination of optimum time for sprayed treatments of ethylene. 相似文献
13.
Dry matter (DM) production, crude protein, phosphorus fibre contents and goat preference for eight indigenous browse species,Alchornea cordifolia, Diallum guineense, Ficus capensis, Baphia nitida, Manniophytum fulvum, Homalium aylmeri, Glyphaea brevis andRauwolfia vomitoria, and for two exotics,Leucaena leucocephala andGliricidia sepium, in cultivated plots were compared on acid soil in southeastern Nigeria. Total DM production was higher (P<0.05) forAlchornea cordifolia than for the other browse species.Glyphaea brevis andL. leucocephala were the most preferred species, whileA. cordifolia, G. sepium andR. vomitoria were the least. Mean crude protein content of browse species in this study was higher, whileP and neutral detergent fibre were lower than reported for other browse species in Nigeria. It is argued that the ultimate goal of a crop-livestock agroforestry system such as alley farming, could be better achieved through the complementary use of browse species. 相似文献