Growth and physiological responses to silviculture for producing solid-wood products from Eucalyptus plantations: An Australian perspective     

David I. Forrester  Jane L. Medhurst  Matthew Wood  Christopher L. Beadle  Juan Carlos Valencia 《Forest Ecology and Management》2010

We review the main silvicultural interventions used when managing Eucalyptus plantations for solid-wood products, including fertilising, pruning and thinning. The growth of a plantation and the quality of the wood produced is closely linked to the development of the tree crowns. These silvicultural interventions influence crown dynamics and can interact with each other, as well as the species, site and the age at which they are applied. This review focuses on the growth and physiological responses observed in Eucalyptus plantations, particularly from an Australian perspective. The implications for wood quality, while given some attention, are beyond the scope of this review.  相似文献   

Two microalgae Crypthecodinium cohnii and Phaeodactylum tricornutum as alternative source of essential fatty acids in starter feeds for seabream (Sparus aurata)     

E. Atalah  C.M. Hernndez Cruz  M.S. Izquierdo  G. Rosenlund  M.J. Caballero  A. Valencia  L. Robaina 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):178-185

Despite oils extracted from algae and other microorganisms that may constitute excellent sources of HUFAs, few studies have determined the nutritional value of different microalgal species for young marine fish. Six thousand gilthead seabream (Sparus aurata) postlarvae (73 mg body weight) were fed for 57 days diets containing either fish oil as a single lipid source or 2 and 4% of Cryptecodinum cohnii or 5% Phaeodactylum tricornutum. Fish oil substitution by C. cohnii resulted in improved fish survival and a very good growth performance, in agreement with a higher proportion of DHA in diets and in total lipids of fish. Incorporation of DHA and other fatty acids was proportional to their contents in diet suggesting the good nutritional utilization of homogenized C. cohnii. Lower survival rates were found in fish fed P. tricornutum and could be related to an epithelial degeneration observed in the anterior intestine. This degeneration could be related to a higher lipid content in these fish or to the strong hornlike cornutate processes found in the valves of the diatom P. tricornutum.  相似文献   

No tillage and crop rotation effects on soil aggregation and organic carbon in a Rhodic Ferralsol from southern Brazil   总被引：9，自引：5，他引：9  

Beta Madari  Pedro L. O. A. Machado  Eleno Torres  Aluísio G. de Andrade  Luis I. O. Valencia 《Soil & Tillage Research》2005,80(1-2):185-200

In Brazil, no tillage (NT) is a soil conservation practice now widely adopted by farmers, including smallholders. The effect of NT and conventional tillage (disc ploughing followed by two light disc harrowings, CT) was investigated on the aggregation properties of a clayey Rhodic Ferralsol from southern Brazil under different crop rotations. The same soil type under secondary forest was used as reference. Macro- and microaggregate classes were separated by wet sieving using a series of eight sieves (8, 4, 2, 1, 0.5, 0.25, 0.125, 0.053 mm) at four sampling layers (0–5, 5–10, 10–20, 20–30 cm). The soil in general had high structural stability. At 0–5 cm, meanweight diameter (MWD, 11.1 mm) and total organic C in macroaggregates (TOC, 39 g kg⁻¹ soil) were highest for the forest soil. Soil under NT had a more similar distribution of aggregate size classes and TOC to the forest soil than CT. The most pronounced difference between tillage systems was observed in the surface soil layer (0–5 cm). In this layer, NT had higher aggregate stability (AS_NT: 96%; AS_CT: 89%), had higher values of aggregate size distribution (MWD_NT: 7.9 mm, MWD_CT: 4.3 mm), and had on average 28% greater TOC in all aggregate size classes than CT. Soil under NT had greater TOC in macroaggregates (NT: 22 g kg⁻¹; CT: 13 g kg⁻¹). Crop rotation did not have a significant effect on soil aggregate distribution and TOC. By increasing macroaggregation NT increased organic carbon accumulation in soil.  相似文献   

Plant species richness and ecosystem multifunctionality in global drylands     

Maestre FT  Quero JL  Gotelli NJ  Escudero A  Ochoa V  Delgado-Baquerizo M  García-Gómez M  Bowker MA  Soliveres S  Escolar C  García-Palacios P  Berdugo M  Valencia E  Gozalo B  Gallardo A  Aguilera L  Arredondo T  Blones J  Boeken B  Bran D  Conceição AA  Cabrera O  Chaieb M  Derak M  Eldridge DJ  Espinosa CI  Florentino A  Gaitán J  Gatica MG  Ghiloufi W  Gómez-González S  Gutiérrez JR  Hernández RM  Huang X  Huber-Sannwald E  Jankju M  Miriti M  Monerris J  Mau RL  Morici E  Naseri K  Ospina A  Polo V  Prina A  Pucheta E 《Science (New York, N.Y.)》2012,335(6065):214-218

Experiments suggest that biodiversity enhances the ability of ecosystems to maintain multiple functions, such as carbon storage, productivity, and the buildup of nutrient pools (multifunctionality). However, the relationship between biodiversity and multifunctionality has never been assessed globally in natural ecosystems. We report here on a global empirical study relating plant species richness and abiotic factors to multifunctionality in drylands, which collectively cover 41% of Earth's land surface and support over 38% of the human population. Multifunctionality was positively and significantly related to species richness. The best-fitting models accounted for over 55% of the variation in multifunctionality and always included species richness as a predictor variable. Our results suggest that the preservation of plant biodiversity is crucial to buffer negative effects of climate change and desertification in drylands.  相似文献   

The importance of demographic niches to tree diversity   总被引：1，自引：0，他引：1  

Condit R  Ashton P  Bunyavejchewin S  Dattaraja HS  Davies S  Esufali S  Ewango C  Foster R  Gunatilleke IA  Gunatilleke CV  Hall P  Harms KE  Hart T  Hernandez C  Hubbell S  Itoh A  Kiratiprayoon S  Lafrankie J  de Lao SL  Makana JR  Noor MN  Kassim AR  Russo S  Sukumar R  Samper C  Suresh HS  Tan S  Thomas S  Valencia R  Vallejo M  Villa G  Zillio T 《Science (New York, N.Y.)》2006,313(5783):98-101

Most ecological hypotheses about species coexistence hinge on species differences, but quantifying trait differences across species in diverse communities is often unfeasible. We examined the variation of demographic traits using a global tropical forest data set covering 4500 species in 10 large-scale tree inventories. With a hierarchical Bayesian approach, we quantified the distribution of mortality and growth rates of all tree species at each site. This allowed us to test the prediction that demographic differences facilitate species richness, as suggested by the theory that a tradeoff between high growth and high survival allows species to coexist. Contrary to the prediction, the most diverse forests had the least demographic variation. Although demographic differences may foster coexistence, they do not explain any of the 16-fold variation in tree species richness observed across the tropics.  相似文献   

Embryonic and Early Foetal Losses in Cattle and Other Ruminants   总被引：1，自引：0，他引：1  

MG Diskin  DG Morris 《Reproduction in domestic animals》2008,43(S2):260-267

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微粉化（细磨）豆粕和全脂大豆对肉鸡氨基酸回肠消化率的影响（文摘）     

Broderick G A Reynal S M 《饲料博览》2009,(8):44-44

试验旨在研究微粉化（细磨）豆粕（SBM）和全脂大豆（FFSB）对23日龄肉鸡氨基酸的表观回肠消化率系数（CIAD）和真消化率系数（CITD）的影响。试验采用完全随机区组设计,按饲粮分为4个处理组,即微粉化SBM组、微粉化FFSB组、粗糙SBM组、粗糙FFSB组,每个处理组设6个重复,每个重复8只。微粉化SBM和FFSB的平均粒径（MPS）分别为47和41μm,而粗糙SBM和FFSB的平均粒径分别为881和778μm。  相似文献   

Activity of alpha-amylase inhibitors from Phaseolus coccineus on digestive alpha-amylases of the coffee berry borer.     

Arnubio Valencia-Jiménez  Jorge W Arboleda Valencia  Maria Fátima Grossi-De-Sá 《Journal of agricultural and food chemistry》2008,56(7):2315-2320

Seeds of scarlet runner bean ( Phaseolus coccineus L.) were analyzed for alpha-amylase inhibitor (alpha-AI) activity. Through the use of polyclonal antibodies raised against pure alpha-AI-1 from common bean ( Phaseolus vulgaris L.), typical alpha-AlphaIota polypeptides (Mr 14-18 kDa) as well as a large polypeptide of Mr 32000 Da, usually referred to as "amylase inhibitor like", were detected. The inhibitor activity present in four accessions of P. coccineus was examined, both in semiquantitative zymograms allowing the separation of different isoforms and in quantitative assays against human salivary amylase, porcine pancreatic amylase, and coffee berry borer, Hypothenemus hampei Ferrari (Coleoptera: Scolytidae) amylase. Differential inhibition curves lead to the suggestion that the gene encoding one of the inhibitors in P. coccineus (in accession G35590) would be a good candidate for genetic engineering of coffee resistance toward the coffee berry borer. An in vitro proteolytic digestion treatment of pure alpha-AlphaIota-1 resulted in a rapid loss of the inhibitory activity, seriously affecting its natural capacity to interact with mammalian alpha-amylases.  相似文献   

Iron supplementation compliance among pregnant women in Bicol, Philippines     

Lutsey PL  Dawe D  Villate E  Valencia S  Lopez O 《Public health nutrition》2008,11(1):76-82

OBJECTIVE: To quantify factors influencing iron supplementation compliance and haemoglobin (Hb) concentrations among pregnant women participating in an iron supplementation programme under routine field conditions. DESIGN: Cross-sectional interviews and Hb measurements. SETTINGS: Albay and Sorsogon provinces, Bicol, Philippines. SUBJECTS: Three hundred and forty-six pregnant women receiving iron supplements via the Philippine iron supplementation programme. RESULTS: Women had a mean Hb concentration of 10.75 +/- 1.43 g dl-1, and 56.4% were anaemic (Hb < 11.0 g dl-1). On average, the first prenatal visit occurred at nearly 4 months (3.80 +/- 1.56). The ratio of visits to number of months pregnant was 0.51 +/- 0.24. Self-reported consumption of pills received was 85% (0.85 +/- 0.23), although pill counts suggested that consumption was 70% (0.70 +/- 0.35). Using multiple regression, an earlier first prenatal visit and greater self-reported compliance were positively associated with Hb concentrations. Additionally, perceived health benefits from taking the supplements and higher health programme knowledge were positively associated with pill consumption, while experiencing side-effects and disliking the taste of the supplements were associated with lower pill consumption. A greater number of living children was negatively associated with the frequency of prenatal visits. The number of children was also directly negatively associated with Hb concentrations. CONCLUSIONS: Compliance was positively related to Hb concentrations. Several factors associated with greater compliance were identified, including marital status, number of children, health programme knowledge, side-effects, perceived health benefits, and dislike of taste. Some of these factors may serve as avenues for interventions to increase compliance, and ultimately Hb concentrations.  相似文献   

Effects of rapid global warming at the Paleocene-Eocene boundary on neotropical vegetation     

Jaramillo C  Ochoa D  Contreras L  Pagani M  Carvajal-Ortiz H  Pratt LM  Krishnan S  Cardona A  Romero M  Quiroz L  Rodriguez G  Rueda MJ  de la Parra F  Morón S  Green W  Bayona G  Montes C  Quintero O  Ramirez R  Mora G  Schouten S  Bermudez H  Navarrete R  Parra F  Alvarán M  Osorno J  Crowley JL  Valencia V  Vervoort J 《Science (New York, N.Y.)》2010,330(6006):957-961

Temperatures in tropical regions are estimated to have increased by 3° to 5°C, compared with Late Paleocene values, during the Paleocene-Eocene Thermal Maximum (PETM, 56.3 million years ago) event. We investigated the tropical forest response to this rapid warming by evaluating the palynological record of three stratigraphic sections in eastern Colombia and western Venezuela. We observed a rapid and distinct increase in plant diversity and origination rates, with a set of new taxa, mostly angiosperms, added to the existing stock of low-diversity Paleocene flora. There is no evidence for enhanced aridity in the northern Neotropics. The tropical rainforest was able to persist under elevated temperatures and high levels of atmospheric carbon dioxide, in contrast to speculations that tropical ecosystems were severely compromised by heat stress.  相似文献