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991.
József Garay Zoltán Sebestyén Zoltán Varga Manuel Gámez Alejandro Torres José E. Belda Tomás Cabello 《Journal of pest science》2015,88(2):343-358
Over the last few decades, important advances have been made in understanding of host–parasitoid relations and their applications to biological pest control. Not only has the number of agent species increased, but new manipulation techniques for natural enemies have also been empirically introduced, particularly in greenhouse crops. This makes biocontrol more complex, requiring a new mathematical modeling approach appropriate for the optimization of the release of agents. The present paper aimed at filling this gap by the development of a temperature- and stage-dependent dynamic mathematical model of the host–parasitoid system with an improved functional response. The model is appropriate not only for simulation analysis of the efficiency of biocontrol agents, but also for the application of optimal control methodology for the optimal timing of agent releases, and for the consideration of economic implications. Based on both laboratory and greenhouse trials, the model was validated and fitted to the data of Chelonus oculator (F.) (Hym.: Braconidae) as a biological control agent against the beet armyworm, Spodoptera exigua Hübner (Lep.: Noctuidae). We emphasize that this model can be easily adapted to other interacting species involved in biological or integrated pest control with either parasitoid or predator agents. 相似文献
992.
This paper presents results of survey research into the role of the forestry nursery sector in the development of smallholder
forestry in Leyte, Philippines. Seedling production in the province is basically carried out by three categories of nurseries:
individual, communal and the government. Seedlings in the government nurseries are primarily raised for free distribution
to landholders but the extension scheme fails to reach the majority of the smallholder farmers. Seedling demand of landholders
is mostly catered for by the more numerous and accessible individual and communal nurseries. However, problems of capital
outlay, sources and supply of germplasm, technical knowledge in nursery management for both timber and fruit trees and low
sales are among the major impediments in the sustainability of small-scale nurseries. Most of the communal nurseries fail
to sustain the operation after the withdrawal of supporting agencies. Knowledge on site-species matching is needed not only
by small-scale nursery operators but also by the managers of government nurseries. It is concluded that the seedling industry
in the province is not well established and there is a need to organise better the overall nursery system so as to improve
the availability of seedlings and promote appropriate site and species combinations. 相似文献
993.
Xiqun Wang Lüyi Ma Baoxiang Guo Shenhou Fan Jianxi Tan 《Frontiers of Forestry in China》2006,1(3):285-291
Lichuan, located at the foot of the Wuling Mountain in southwest Hubei Province of central China, is well known in the world
for the discovery of the living fossil Metasequoia glyptostroboides Hu & Cheng in the 1940s. Its natural habitat has been well protected by the Chinese government. In order to provide a scientific
foundation for the protection of the Metasequoia resource, it has become necessary to analyze the changes in the original,
natural Metasequoia mother trees (ONMMT) and their environment from 1948 to 2003. The results and countermeasures are as follows:
First, the distribution areas have little changed, involving four towns/farmland, 45 villages, 5,746 individual trees in 1983
and 5,388 trees in 2003, covering nearly 600 km2, with an average density of less than 0.1 tree/hm2. The Metasequoia distribution consists of two main types: a scattered distribution type found mainly at the foothills or
near houses, roads, villages and rivers while the population distribution type is found mainly at the mountains and valleys
with a minority at low elevations in the mountains and basins. The largest Metasequoia populations have 105 and 123 trees.
Second, in the past, attention was only paid to the protection of individual trees while the protection of the Metasequoia
population and environment was neglected. This led to a shift from the past mixed forests to pure Metasequoia forests, with
a simpler structure, reduced biodiversity and conditions non-conducive for natural renewal. From 1983 to 2003, 386 original
Metasequoia mother trees died. So it is vital to enhance the protection of the only original Metasequoia population in the
world and its habitat. Third, modern ecological means should be taken to protect the original Metasequoia population and its
habitat. Research on the restoration and rehabilitation of Metasequoia vegetation should be carried out. Restoration and rehabilitation
should be put into practice in the Xiaohe Valley, where the highest concentration of Metasequoia is found. Fourth, efficient
measures should be taken to stop human activities that are harmful to Metasequoia and to improve the environment of ONMMT
in order to promote the protection of the ONMMT population and its ecosystem. Eco-emigration and the return of marginal agricultural
land to forestry can be practiced.
__________
Translated from Acta Ecologica Sinica, 2005, 25(5): 972–977 [译自: 生态学报, 2005, 25(5): 972–977] 相似文献
994.
Florence Z. Tarun-Acay 《Small-Scale Forestry》2005,4(1):101-116
An assessment was made of the attributes of People’s Organisations (POs) and of the institutional viability of Community-Based
Forest Management (CBFM) programs in three project sites in the Philippines. In CBFM, the capacity of People’s Organisations,
as de facto managers of forest resources, is being developed by non-government organisations under the guidance of local government units
(LGUs) and the Department of Environment and Natural Resources (DENR). A survey was conducted of community members (case informants)
and members of the various agencies (key informants) to ascertain the characteristics of successful POs and the relationship
between these characteristics and the viability of CBFM. Although commendable contributions have been made to the forest management
capability of POs, their standard of living and environmental conditions, there are also many instances in which institutional
conflict among stakeholders is apparent. The great challenge for the various stakeholders is to orchestrate their differing
interests so as to address successfully the critical issues of the low socioeconomic status of PO members, corruption, lack
of transparency and accountability of the organisations involved, loss of interest of PO members in project activities, lack
of technical assistance, loss of credibility of the DENR, and lack of equitable benefit sharing. 相似文献
995.
Nancy Alejandre-Melena Roberto Lindig-Cisneros Cuauhtémoc Sáenz-Romero 《New Forests》2007,34(1):25-30
Major disturbances that remove vegetation cover create conditions that differ greatly from those in adjacent forests. In volcanic
areas, tephra deposition can be a major disturbance that eliminates vegetation cover and creates a barrier for plant establishment.
The eruption of the Paricutín volcano, in Michoacán, México, from 1943 to 1952, created large tephra deposits adjacent to
forest stands. Many of these deposits still lack native vegetation and understanding of the limiting factors for establishment
of native tree species is necessary to restore these areas. Pinus pseudostrobus early growth in response to the amount of fertile growing medium on top of a variable-depth tephra layer was evaluated in
a greenhouse experiment. Increasing amounts of fertile growing medium increased height of 28-week-old plants (no growing medium = 5.5 cm
tall ±1.8 cm, 3 cm of growing medium = 21.2 ± 4.6 cm and 6 cm of growing medium 24.8 ± 4.4 cm). Other variables showed the
same trend (diameter, number of fascicles, belowground biomass and aboveground biomass). Our results suggest that P. pseudostrobus establishment in tephra covered areas will depend on the accumulation of a fertile layer of more than 3 cm in thickness. 相似文献
996.
A provenance trial of Michelia chapensis Dandy in the south of China was carried out in three sites to assess yield and stability analyses. The trials were conducted as randomized, complete block designs with four replications at each site. Additive main effects and multiplicative interaction (AMMI) and genotype main effect and genotype × environment interaction (GGE) were employed in the evaluation of provenances; AMMI analyses showed that significant genotype × environment interaction effects (P < 0.05) existed between provenances, capturing 15.11 % of the total sum of squares. The AMMI stability value revealed that provenance 2 was stable, but had low yield. GGE-biplot models showed that provenances 7, 8, 10, and 11 were more stable and high-yielding. The GGE results also confirmed that among the three sites, site JiuQuShui was the most ideal environment for representation and discrimination. 相似文献
997.
Emila Akroume Bernd Zeller Marc Buée Philippe Santenoise Laurent Saint-André 《Annals of Forest Science》2016,73(4):1005-1013
Key message
Near- and mid-infrared spectroscopy allows for the detection of local patterns of forest soil properties. In combination with dendrometric data, it may be used as a prospective tool for determining soil heterogeneity before setting up long-term forest monitoring experiments.Context
Forest soils and stands generally exhibit higher spatial heterogeneity than other terrestrial ecosystems. This variability needs be taken into account before setting up long-term forest monitoring experiments to avoid multiple interactions between local heterogeneity and the factors tested in the experiment.Aims
We hypothesized that raw near- and mid-infrared spectra can be used as an integrated proxy of a large set of soil properties. The use of this method, in combination with dendrometric data, should provide a quick and cost-effective tool for optimizing the design of experimental forest sites.Methods
We assessed the local soil heterogeneity at 11 experimental sites in oak and beech stands, which belong to a new forest long-term ecological research (LTER) network. We used near- and mid-infrared spectroscopy in soil and litter samples. The spectra were subjected to principal components analyses (PCA) to determine the intra-site variability of the soil and litter layers.Results
Based on mapped PCA coordinates and basic dendrometric data, it was possible to design the experiment and minimize the interactions between the treatment layout and the tested variables. The method was validated with chemical analyses of the soil. No interaction was detected at the set-up of the experiment between the treatment layout and chemical soil properties (C, N, C/N ratio, pH, CEC, Al, Mg, P2O5, Fe, Mn, Na, and K).Conclusion
Near-infrared (NIR) and mid-infrared (MIR) spectroscopy is a useful tool for characterizing the overall heterogeneity of soil chemical properties. It can be used without any preliminary calibration. In combination with dendrometric data, it provides a reliable method for optimizing LTER plots in different types of ecosystems.998.
Shade is one of the important limiting factors in intercropped agro-ecosystems. Objective of this work is to analyze the role
of eight foliar traits of juvenile plants of five different species of Jasminum grown under coconut shade. The results reveal the shade tolerant J. pubescence to produce more number of nodes and longer shoots in all the three seasons studied. J. grandiflorum produced longer leaves and internodal distance than other species tested. Winter season shoots were longer with more number
of nodes and longer internodal distances than rainy season. Results are discussed in relation to the adaptive behavior of
plants to shade. 相似文献
999.
Agroforestry trees are now well known to play a central role in the build up of nutrients pools and their transformations
similar to that of forest ecosystem, however, information on the potential of homegarden trees accumulating and releasing
nitrogen (mineralization) is lacking. The present study reports seasonal variations in pool sizes of mineral N (NH4+-N and NO3−-N), and net N-mineralization rate in relation to rainfall and temperature under coconut (Cocos nucifera L.), clove (Eugenia caryophyllata Thunb) and nutmeg (Myristica fragrans Houtt. Nees) trees in a coconut-spice trees plantation for two annual cycles in the equatorial humid climate of South Andaman
Island of India. Concentration of NH4+-N was the highest during wet season (May–October) and the lowest during post-wet season (November–January) under all the
tree species. On the contrary, concentration of NO3−-N was the lowest in the wet season and the highest during the post-wet season. However, concentrations of the mineral N were
the highest under the nutmeg and the lowest under the coconut trees. Like the pool sizes, mean annual mineralization was the
highest under the nutmeg (561 mg kg−1 yr−1) and the lowest under the coconut trees (393 mg kg−1 yr−1). Rate of mineralization was the highest during the post-wet season and the lowest during the dry season (February–April)
under all the tree species. High rainfall during the wet season, however, reduced the rate of nitrification under all the
tree species. The mean annual mineralization was logarithmically related with rainfall amount and mean monthly temperature. 相似文献
1000.
Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands
Changes in soil chemical and microbiological parameters in small (185 m2) and medium (410 m2) gaps, created in mature silver fir (Abies alba Mill) stands (mean height 30 m) in the Calabrian Apennines (Southern Italy), were studied over 2 years. Medium gaps had high
soil temperature and photosynthetically active radiation (PAR) transmittance and low soil moisture. Within small gaps we detected
a greater amount of organic matter, with respect to under canopy cover sites and medium gaps. Moreover, a different trend
of the organic matter between small and medium gaps was observed. In the medium gaps, with respect to under canopy cover sites
and small gaps, we found a relatively low content of organic matter, associated to a lower amount of humic acid, which suggested
that the organic substrate undergoes a mineralization rather than a humification process. An opposite trend was observed in
small gaps, where the increase of organic matter content, associated to an increase of humic acid and microbial biomass, suggested
a better humification process. Moreover, in small gaps the highest level of urease and the greatest fluorescein diacetate
(FDA) hydrolysis were observed. The different trend of organic matter observed in small and medium gaps may be related to
changes in the environmental conditions. PAR transmittance, significantly higher in medium gaps, contributed to increase soil
temperature and decrease soil moisture, affecting soil microbial populations and organic matter trend. These results suggest
that the creation of small gaps represents the silvicultural practice with minor environmental impact. 相似文献