<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ruano-Ramos, A</style></author><author><style face="normal" font="default" size="100%">García-Criado, B</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Near infrared spectroscopy prediction of mineral content in botanical fractions from semi-arid grasslands</style></title><secondary-title><style face="normal" font="default" size="100%">Animal feed science and technology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">forbs</style></keyword><keyword><style  face="normal" font="default" size="100%">Grasses</style></keyword><keyword><style  face="normal" font="default" size="100%">grassland samples</style></keyword><keyword><style  face="normal" font="default" size="100%">legumes</style></keyword><keyword><style  face="normal" font="default" size="100%">Mineral content</style></keyword><keyword><style  face="normal" font="default" size="100%">near infrared spectroscopy</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1999</style></year></dates><volume><style face="normal" font="default" size="100%">77</style></volume><pages><style face="normal" font="default" size="100%">331-343</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Near infrared reflectance spectroscopy (NIRS) was assessed for its capacity to estimate the mineral content of semi-arid grassland samples. NIRS calibrations were derived for P, K, Ca and Mg contents. Four populations of samples were used: total herbage, with a heterogeneous and complex botanical composition, and its botanical components (grasses, legumes and forbs). One set of samples from each population was selected to develop the specific calibration equations using three mathematical data treatments (log 1/R, first derivative, and second derivative). Reference values from the calibration sample set were regressed on the corresponding spectral data using stepwise multiple regression analysis. The equations were validated with samples from the same four populations that had not been included in the calibration. The NIRS method afforded acceptable accuracy in the prediction of P, K, Ca and Mg contents in the total herbage population and its botanical fractions. Botanical composition and mathematical treatment affected both the accuracy and precision of NIRS analyses; in this sense, the best fits were usually obtained using samples of simpler botanical composition (legumes and grasses), while the first derivative usually led to better results in the estimation of most parameters. # 1999 Elsevier Science B.V. All rights reserved.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Joffre, R</style></author><author><style face="normal" font="default" size="100%">Rambal, S</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">HOW TREE COVER INFLUENCES THE WATER-BALANCE OF MEDITERRANEAN RANGELANDS</style></title><secondary-title><style face="normal" font="default" size="100%">ECOLOGY</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">DEEP DRAINAGE</style></keyword><keyword><style  face="normal" font="default" size="100%">Dehesa</style></keyword><keyword><style  face="normal" font="default" size="100%">Evapotranspiration</style></keyword><keyword><style  face="normal" font="default" size="100%">Grasses</style></keyword><keyword><style  face="normal" font="default" size="100%">hydrological equilibrium</style></keyword><keyword><style  face="normal" font="default" size="100%">MEDITERRANEAN OAK WOODLANDS</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus-suber</style></keyword><keyword><style  face="normal" font="default" size="100%">surface runoff</style></keyword><keyword><style  face="normal" font="default" size="100%">Trees</style></keyword><keyword><style  face="normal" font="default" size="100%">water balance</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1993</style></year></dates><publisher><style face="normal" font="default" size="100%">ECOLOGICAL SOC AMER</style></publisher><pub-location><style face="normal" font="default" size="100%">2010 MASSACHUSETTS AVE, NW, STE 400, WASHINGTON, DC 20036</style></pub-location><volume><style face="normal" font="default" size="100%">74</style></volume><pages><style face="normal" font="default" size="100%">570-582</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Dehesa ecosystems of the southwestern Iberian Peninsula are characterized as a savanna-like rangeland dominated by scattered mediterranean evergreen oak trees. We investigated whether isolated trees modify the water balance of this ecosystem and if so, what implications this finding might have on models that assume homogeneity of soil water resources. The water balance of the two ecological components of the dehesas-(1) the tree-grass component, and (2) the open areas between the tree canopies with unshaded grass vegetation-was studied for three consecutive years in three locations in the Sierra Norte de Sevilla region of Andalusia in southern Spain. In this region, annual rainfall was generally between 600 and 800 mm, and the summer drought lasted almost-equal-to 130 d. Soil water storage was measured with a neutron moisture gauge outside and under the tree canopy. Deep drainage between two consecutive census dates was calculated using field-measured drainage characteristics. Evapotranspiration (Ea) and surface runoff were computed from the water balance equation assuming that Ea is limited by Penman potential evapotranspiration. Monthly Ea by annual species in open areas was poorly correlated with rainfall levels in the autumn and was limited during the spring by availability of water in the top 40 cm of soil. During summer, monthly Ea by trees ranged from 30 to 50 mm. Mean annual Ea was 400 mm outside and 590 mm under the tree cover. In open areas, water yield (WY), defined as the sum of deep drainage and surface runoff, ranged from 65 to 100% of total Ea, whereas under the tree canopy WY was only 20 to 40% of the Ea. Under the tree canopy, when annual precipitation was &lt; 570 mm, WY was negligible and all precipitation was lost by evapotranspiration. Outside the tree canopy, WY occurred as soon as annual precipitation exceeded 250 mm. Models of competition between trees and grass generally assume a spatial homogeneity of soil hydrodynamic properties. Our results, however, show that both soil water storage and evapotranspiration are greater for the tree-grass component. Consequently, these models must account for this spatial variability in water resources according to species.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Acosta, F. J.</style></author><author><style face="normal" font="default" size="100%">López, F.</style></author><author><style face="normal" font="default" size="100%">Serrano, J. M.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">The dynamics of a therophytic community in relation to self-regulation, herbivores and environmental variation</style></title><secondary-title><style face="normal" font="default" size="100%">Vegetatio</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Ants</style></keyword><keyword><style  face="normal" font="default" size="100%">Environmental influence</style></keyword><keyword><style  face="normal" font="default" size="100%">Granivory</style></keyword><keyword><style  face="normal" font="default" size="100%">Grasses</style></keyword><keyword><style  face="normal" font="default" size="100%">Markovian models</style></keyword><keyword><style  face="normal" font="default" size="100%">Vegetation dynamics</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">1992</style></year><pub-dates><date><style  face="normal" font="default" size="100%">1992///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.springerlink.com/index/10.1007/BF00031637</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">98</style></volume><pages><style face="normal" font="default" size="100%">59 - 71</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The dynamics of a therophytic plant community in Central Spain has been studied, taking into account endogenous and exogenous factors. Using a simplified descriptive resolution a multi-species grass community and four canopy density types have been described in permanent quadrats. Transition matrices expressing the changes of vegetation state have been constructed. The importance of self- regulation was shown by the dependence of successive transitions on each other (highly significative log-linear models). The functioning cannot however be explained through a strict Markovian model because the transition probabilities are not stationary. The external local factors tested (microtopography, compactness and granivory) do not have a consistent effect on the vegetation dynamics, being variable over years, implying the importance of other more general factors on vegetation dynamics. Making transition probabilities dependent on external environmental factors rep</style></abstract><issue><style face="normal" font="default" size="100%">1</style></issue></record></records></xml>