Assessing forest structure and function from spectral transmittance measurements: a case study in a Mediterranean holm oak forest     

Serrano L  Peñuelas J 《Tree physiology》2005,25(1):67-74

Annual changes in structural attributes and seasonal dynamics in water content, photosynthetic rate and light-use efficiency (LUE) were assessed by spectral transmittance for 4 years (1999-2003) in six stands of a Mediterranean holm oak forest. Green biomass, total biomass and leaf area index (LAI) were determined. In 1999, seasonal dynamics of net carbon dioxide (CO2) exchange and water content were measured. We recorded photosynthetically active radiation (PAR) transmittance and hyperspectral transmittance in the 400-1100 nm region and derived reflectance-based vegetation indices. Transmittance over the PAR region derived from either ceptometer or spectroradiometer measurements (PART and TPAR, respectively) was related to green and total biomass. Both PART and TPAR were also related to LAI (r=0.79 and r=0.70, respectively, P <0.001) and were appropriate for comparison among stands, whereas subtle changes in LAI within a stand were better assessed by the transmittance amplitude in the red edge region (TRE) (within a stand, r=0.77-0.99, P <0.001). Spectral transmittance-based indices successfully captured physiological processes that occurred on temporal (seasonal) and spatial scales. The transmittance-based water index (TWI) was related to both foliage and canopy water content (r=0.69, P <0.001). Estimates of foliage and canopy water content improved in dense (closed) stands (r=0.84 and r=0.87, respectively, P <0.001) compared with low-density stands. Under non-drought conditions, transmittance-based photochemical reflectance index (TPRI) was related to LUE (r=0.58, P <0.05) and net CO2 exchange (r=0.72, P <0.01), and the combined TPAR x TPRI index greatly improved these relationships (r=0.93 and r=0.84, respectively, P <0.01), indicating that both structural and physiological adjustments modified CO2 fixation capacity in these forest stands. Our novel approach to the study of transmitted radiation provides a tool for estimating structural and functional variables such as LAI, LUE and water content, which are key determinants of terrestrial productivity.  相似文献   

Shoot development and dieback in progenies of Nothofagus obliqua     

Javier Puntieri  Javier Grosfeld  Marina Stecconi  Cecilia Brion  María Marta Azpilicueta  Leonardo Gallo  Daniel Barthélémy 《Annals of Forest Science》2007,64(8):839-844

Shoot growth and dieback were compared among progenies of nursery-grown seedlings of Nothofagus obliqua belonging to seven progenies of the same provenance (Quila-Quina, Argentina). First-year shoots consisted of one growth unit (GU) and second-year shoots of one or two GUs. The probability of development of two GU was similar for all progenies. Progenies were different in terms of shoot size, terminal bud abscission, the extent of shoot dieback after shoot extension and the node of origin of the relay shoot on the first shoot. Plants with a second-year shoot consisting of two GUs had a thicker stem and more nodes than those with single-GU shoots. The selection of N. obliqua seed trees based on architectural traits suitable for forestry development at specific sites must contemplate variability among progenies and their probabilities of successful development under different conditions.  相似文献   

Tracking leaf area index and coefficient of light extinction over the harvesting cycle of black wattle     

Alexandre Behling  Carlos Roberto Sanquetta  Ana Paula Dalla Corte  Sylvio Péllico Netto  Aurélio Lourenço Rodrigues  Bráulio Otomar Caron  Augusto Arlindo Simon 《林业研究》2016,27(6):1211-1217

The amount of photosynthetic radiation intercepted by a crop is a function of the incident solar radiation on the plants, the leaf area index (L _AI), and the light extinction coefficient (k). We quantified L _AI and k in stands of black wattle (Acacia mearnsii De Wild.) over a 7-year growth cycle at two locations in the state of Rio Grande do Sul, Brazil. Our study was conducted in commercial stands in agroecological regions with high densities of black wattle plantations. L _AI was calculated as the ratio between the leaf area of a tree and its planting space, and k was derived from Beer’s law. L _AI depends on the planting site and stand age. Between the two sites, the L _AI was similar over time, the amount of variation differed. Values of k depended only on stand age, with the highest average observed for stands up to 5 years old. The trend of k during the plantation cycle was inversely proportional to L _AI and was correlated with L _AI, leaf area, leaf dry mass, canopy volume, height, branches dry mass, total dry mass, and crown diameter.  相似文献   

Response of <Emphasis Type="Italic">Pinus pseudostrobus</Emphasis> Lindl. to fertile growing medium and tephra-layer depth under greenhouse conditions     

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   

Relationship between root growth potential and field performance in Aleppo pine     

Antonio D. Del Campo  Rafael M. Navarro-Cerrillo  Javier Hermoso  Antonio J. Ibáñez 《Annals of Forest Science》2007,64(5):541-548

Commercial stocks of Aleppo pine in Spain vary in quality, but there is no accepted standard for evaluating quality. A RGP test was applied to six commercial seedling stocklots at two dates (November, February) and under two test conditions (growth-chamber, greenhouse). The RGP’s predictive ability was evaluated on two contrasting sites. There was a considerable variation in the RGP depending on application date, test conditions and stock factors. The RGP results for November were correlated with each other but they did not explain outplanting performance. The February results in the growth-chamber correlated well with survival at both sites. Regression models explained survival both in the lower (R ² = 97%) and in the higher (R ² = 92%) quality sites. RGP has a valid predictive ability for this species although it is sensitive to the test conditions. In this sense, a shorter and more intensive test performed right before planting may be more reliable.  相似文献   

Variations in soil chemical properties and microbial biomass in artificial gaps in silver fir stands     

Adele Muscolo  Maria Sidari  Roberto Mercurio 《European Journal of Forest Research》2007,126(1):59-65

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   

Can the use of large,alternative nursery containers aid in field establishment of Juglans regia and Quercus robur seedlings?     

Barbara Mariotti  Alberto Maltoni  Pier Mario Chiarabaglio  Achille Giorcelli  Douglass F. Jacobs  Roberto Tognetti  Andrea Tani 《New Forests》2015,46(5-6):773-794

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Assessment of the gross primary production dynamics of a Mediterranean holm oak forest by remote sensing time series analysis     

Víctor Cicuéndez  Javier Litago  Margarita Huesca  Manuel Rodriguez-Rastrero  Laura Recuero  Silvia Merino-de-Miguel  Alicia Palacios-Orueta 《Agroforestry Systems》2015,89(3):491-510

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Tree rings reflect growth adjustments and enhanced synchrony among sites in Iberian stone pine (Pinus pinea L.) under climate change     

Fabio Natalini  Alexandra Cristina Correia  Javier Vázquez-Piqué  Reyes Alejano 《Annals of Forest Science》2015,72(8):1023-1033

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Identification of PCR-amplified genetically modified organisms (GMOs) DNA by peptide nucleic acid (PNA) probes in anion-exchange chromatographic analysis     

Rossi S  Lesignoli F  Germini A  Faccini A  Sforza S  Corradini R  Marchelli R 《Journal of agricultural and food chemistry》2007,55(7):2509-2516

PCR products obtained by selective amplification of transgenic DNA derived from food samples containing Roundup Ready soybean or Bt-176 maize have been analyzed by anion-exchange HPLC. Peptide nucleic acids (PNAs), oligonucleotide analogues known to bind to complementary single-stranded DNA with high affinity and specificity, have been used as specific probes in order to assess the identity of the peaks observed. Two different protocols were adopted in order to obtain single-stranded DNA: amplification with an excess of one primer or digestion of one DNA strand. The single-stranded DNA was mixed with the PNA probe, and the presence of a specific sequence was revealed through detection of the corresponding PNA:DNA peak with significantly different retention time. Advantages and limits of this approach are discussed. The method was tested with reference materials and subsequently applied to commercial samples.  相似文献