Thesis (MScFoodSc) Stellenbosch University, 2014 / ENGLISH ABSTRACT: We aimed to determine how canopy position influences fruit quality and consumer preference for the eating quality and appearance of ‘Forelle’, ‘Bon Chrétien’ and ‘Bon Rouge’ pears. Our hypothesis was that consumer preference would be higher for the appearance and eating quality of outer canopy fruit. Our first trial investigated the effect of canopy position and cold storage duration on quality attributes and consumer preference for ‘Forelle’ pears. Mealiness was much more prevalent in outer canopy fruit in 2012 and after 9 and 12 weeks cold storage in 2011. In 2011, consumers preferred the eating quality of inner canopy pears that had been subjected to 12 and 16 weeks of cold storage while inner canopy pears were generally preferred in 2012. This study provides support for the mandatory 12 weeks cold storage of ‘Forelle’ pears. Our second trial investigated the effect of canopy position and harvest maturity within the commercial picking window on the quality attributes and consumer preferences for ‘Forelle’ pears. Inner canopy pears of harvest 1 (23 February) and harvest 2 (27 February) were significantly preferred in terms of eating quality. The general dislike for harvest 3 (13 March) pears and outer canopy fruit seemed to relate to an incidence of mealiness. Our results suggest that harvesting ‘Forelle’ pears at a firmness ≈6.2 kg will ensure that both inner and outer canopy pears have acceptable eating quality. In our third trial, fruit were harvested at commercial firmness from two orchards in each of Elgin and Ceres to assess the effect of orchard site on quality attributes of ‘Forelle’ pears. Total soluble solids (TSS) were higher in Elgin while flavour attributes were more pronounced in Ceres. In both areas, outer canopy pears were higher in TSS and lower in titratable acidity (TA) but canopy position had no effect on sweet and sour taste. Mealiness incidence was high in outer canopy fruit from Elgin, as well as in one Ceres orchard. Further research over consecutive seasons is needed to determine the reasons for orchard differences in mealiness incidence. Our fourth trial investigated the effect of canopy position on quality attributes and consumer preference for ‘Bon Chrétien’ and ‘Bon Rouge’ pears. Despite a higher TSS:TA ratio in outer canopy ‘Bon Rouge’ pears and a higher TSS and dry matter concentration in outer canopy ‘Bon Chrétien’ pears, canopy position did not affect sensory eating quality attributes. Seen overall, results indicate that canopy position has a minor effect on consumer preference for ‘Bon Chrétien’ and ‘Bon Rouge’ eating quality. No significant differences in colour and consumer preference for appearance were found between outer and inner canopy ‘Bon Chrétien’ pears. Consumers slightly preferred the redder outer canopy ‘Bon Rouge’ pears over the less red inner canopy fruit. Although consumers preferred the red blush colour of outer canopy ‘Forelle’ pears, inner canopy pears also received high scores. Inner canopy ‘Forelle’ pears should not be viewed as inferior to outer canopy fruit with regard to both eating quality and appearance. / AFRIKAANSE OPSOMMING: Ons het gepoog om die effek van boomposisie op vrugkwaliteit en verbruikersvoorkeur vir die eetkwaliteit en voorkoms van ‘Forelle’, ‘Bon Chrétien’ en ‘Bon Rouge’ pere te ondersoek. Ons hipotese was dat verbruikersvoorkeur hoër sou wees vir die voorkoms en eetkwaliteit van pere van die buitekant van die boom se blaredak. Ons eerste proef se doelstelling was om die effek van boomposisie en koelopberging op die kwaliteitseienskappe en verbruikersvoorkeur vir ‘Forelle’ pere te bepaal. Melerigheid was beduidend meer aanwesig in buitevrugte in 2012 asook na 9 en 12 weke koelopberging in 2011. Verbruikersvoorkeur vir eetkwaliteit was die hoogste vir binnevrugte na 12 en 16 weke koelopberging in 2011 terwyl binnevrugte in die algemeen voorkeur geniet het in 2012. Hierdie studie steun die bevindinge van vorige studies dat ‘Forelle’ pere vir ten minste 12 weke koelopgeberg moet word. Die doel van ons tweede proef was om te bepaal of ‘Forelle’ pere wat by verskillende ryphede binne die kommersiële oesperiode geoes is, verskille toon in kwaliteitseienskappe en of hierdie verskille, indien enige, verband hou met verbruikersvoorkeur vir eetkwaliteit. Die eetkwaliteit van binnevrugte van oes 1 (23 Februarie) en oes 2 (27 Februarie) is verkies bo buitevrugte. Die algemene afkeur vir oes 3 (13 Maart) en buitevrugte kan moontlik toegeskryf word aan die hoë voorkoms van melerigheid. Ons resultate dui aan dat beide binne- en buitevrugte aanvaarbare eetkwaliteit behoort te hê indien ‘Forelle’ pere by ‘n fermheid van ≈6.2 kg geoes word. Vir ons derde proef is ‘Forelle’ pere geoes by kommersiële fermheid (≈6.4 kg) vanaf twee boorde in elk van Elgin en Ceres. Totale opgeloste vastestowwe (TOV) was hoër in Elgin pere terwyl geur-eienskappe meer prominent was in Ceres pere. In beide areas het buitevrugte hoër TSS en laer titreerbare sure (TS) gehad, maar boomposisie het egter geen effek op soet en suur smaak gehad nie. Die voorkoms van melerigheid was hoog in buitevrugte van die Elgin boorde, sowel as in een van die Ceres boorde. Verdere navorsing oor opeenvolgende seisoene word benodig om redes vir die verskille in die voorkoms van melerigheid tussen boorde te ondersoek. Die doelstelling van ons vierde proef was om die effek van boomposisie op die kwaliteitseienskappe en verbruikersvoorkeur vir ‘Bon Chrétien’ en ‘Bon Rouge’ pere te ondersoek. Ondanks ‘n hoër TOV:TS ratio in ‘Bon Rouge’ buitevrugte en ‘n hoër TOV en droë massa konsentrasie in ‘Bon Chrétien’ buitevrugte, het boomposisie ‘n minimale impak gehad op sensoriese eetkwaliteitseinskappe en verbruikervoorkeur vir die pere. Boomposisie het geen effek op die kleur en verbruikersvoorkeur vir die voorkoms van ‘Bon Chrétien’ pere gehad nie. Verbruikers het ‘n effense hoër voorkeur getoon vir die rooier ‘Bon Rouge’ buitevrugte. Alhoewel verbruikers die aantreklike rooi bloskleur van ‘Forelle’ buitevrugte verkies het, het die groen tot geel binnevrugte ook hoë voorkeurpunte behaal. Rakende voorkoms en eetkwaliteit, is ‘Forelle’ binnevrugte glad nie minderwaardig teenoor buitevrugte nie.

Made available in DSpace on 2015-03-26T13:30:52Z (GMT). No. of bitstreams: 1 texto completo.pdf: 1172659 bytes, checksum: 09e26b53f58c9c16cf0b8c9ceaf76d98 (MD5) Previous issue date: 2005-02-21 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / The canopy of tropical forests offers a large diversity of resources that are essential for the maintenance of the biodiversity. There is a lack of studies on the effects of canopy habitat structure upon herbivorous communities, mainly at tropical regions. The aim of this study was to answer why herbivorous insect diversity varies within the forest canopy. We tested the hypothesis that herbivores abundance and species richness are affected by canopy structure, comparing two distinct spatial scales and two different feeding guilds: sap-sucking and chewing herbivores. We collected 314 herbivorous insect individuals. Herbivorous chewers was the richest and most abundant guild, with 91 morphospecies and 235 individuals. Canopy structure influences insect herbivore s abundance and species richness in different spatial scales, according to the herbivore s guild. Sap-sucking herbivores respond to plant architecture on a local spatial scale (tree architecture), increase their abundance and species richness with tree size. While chewing herbivores increase their abundance with tree size, and increase their abundance and species richness with leaf density within the canopy, on a larger spatial scale. Neither of the herbivorous guilds species richness were affected by tree crown complexity nor tree species richness. / O dossel de florestas tropicais oferece uma grande diversidade de recursos que são essenciais para a manutenção da biodiversidade. Entretanto, poucos estudos verificaram os efeitos da estrutura do dossel sobre comunidades de insetos herbívoros em regiões tropicais. O objetivo deste estudo foi responder por que a diversidade de insetos herbívoros varia no dossel de uma floresta. Para isso foi testada a hipótese de que a abundancia e riqueza de insetos herbívoros são afetadas pela estrutura do dossel em duas escalas espaciais distintas, verificando estes efeitos em duas guildas alimentares: insetos herbívoros sugadores e mastigadores. Foram amostrados 314 insetos herbívoros. A guilda de insetos herbívoros mastigadores foi mais rica e abundante, apresentando 91 morfoespecies e 235 indivíduos. Foi verificado que a estrutura do dossel influencia a abundancia e riqueza de insetos herbívoros em diferentes escalas espaciais, de acordo com a guilda alimentar. Insetos herbívoros sugadores respondem aos efeitos da arquitetura da árvore hospedeira na escala local (arquitetura da árvore), aumentando a abundancia e riqueza de espécies com o aumento do tamanho da árvore hospedeira. Já insetos herbívoros mastigadores aumentam sua abundancia com o tamanho da árvore hospederia, na escala local, e aumentam a sua abundancia e a riqueza de espécies com a densidade foliar do dossel, na escala regiões do dossel. Ambas as guildas não são afetadas pela complexidade das copas das árvores ou pela riqueza de espécies de árvores.

abstract: Accurate characterization of forest canopy cover from satellite imagery hinges on the development of a model that considers the level of detail achieved by field methods. With the improved precision of both optical sensors and various spatial techniques, models built to extract forest structure attributes have become increasingly robust, yet many still fail to address some of the most important characteristics of a forest stand's intricate make-up. The objective of this study, therefore, was to address canopy cover from the ground, up. To assess canopy cover in the field, a vertical densitometer was used to acquire a total of 2,160 percent-cover readings from 30 randomly located triangular plots within a 6.94 km2 study area in the central highlands of the Bradshaw Ranger District, Prescott National Forest, Arizona. Categorized by species with the largest overall percentage of cover observations (Pinus ponderosa, Populus tremuloides, and Quercus gambelii), three datasets were created to assess the predictability of coniferous, deciduous, and mixed (coniferous and deciduous) canopies. Landsat-TM 5 imagery was processed using six spectral enhancement algorithms (PCA, TCT, NDVI, EVI, RVI, SAVI) and three local windows (3x3, 5x5, 7x7) to extract and assess the various ways in which these data were expressed in the imagery, and from those expressions, develop a model that predicted percent-cover for the entire study area. Generally, modeled cover estimates exceeded actual cover, over predicting percent-cover by a margin of 9-13%. Models predicted percent-cover more accurately when treated with a 3x3 local window than those treated with 5x5 and 7x7 local windows. In addition, the performance of models defined by the principal components of three vegetation indices (NDVI, EVI, RVI) were superior to those defined by the principal components of all four (NDVI, EVI, RVI, SAVI), as well as the principal and tasseled cap components of all multispectral bands (bands 123457). Models designed to predict mixed and coniferous percent-cover were more accurate than deciduous models. / Dissertation/Thesis / M.A. Geography 2012

Submitted by Lara Oliveira (lara@ufersa.edu.br) on 2017-02-01T19:39:30Z No. of bitstreams: 1 ClaraNCV_DISSERT.pdf: 2982680 bytes, checksum: 4c5a62af634af9865426863a56bff0dc (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-03-21T14:44:00Z (GMT) No. of bitstreams: 1 ClaraNCV_DISSERT.pdf: 2982680 bytes, checksum: 4c5a62af634af9865426863a56bff0dc (MD5) / Approved for entry into archive by Vanessa Christiane (referencia@ufersa.edu.br) on 2017-03-21T14:48:08Z (GMT) No. of bitstreams: 1 ClaraNCV_DISSERT.pdf: 2982680 bytes, checksum: 4c5a62af634af9865426863a56bff0dc (MD5) / Made available in DSpace on 2017-03-21T14:49:22Z (GMT). No. of bitstreams: 1 ClaraNCV_DISSERT.pdf: 2982680 bytes, checksum: 4c5a62af634af9865426863a56bff0dc (MD5) Previous issue date: 2016-07-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Brazilian viticulture currently occupies an area of 81,000 hectares, especially the Rio Grande do Sul and the agricultural hub Petrolina / Juazeiro-BA accounted for 95% of national fine table grapes exports. The cultivation of the vine is influenced by climate, which directly affects the development of culture, the occurrence of pests and diseases, the water needs and the quality of fruit. The objectives of this study were to evaluate the phenological development, soil moisture variations and vine production Syrah under five rootstocks (PE) and two driving systems (SC), and the variation of the microclimate in different systems as conduction and interfere with the quality of the fruit. The experiment was developed in the Trough of experimental field, in Petrolina, PE, during the second cycle of 2015. We used the Syrah, which is one of the main varieties used in the production of red wine in the São Francisco Valley, divided into blocks, subdivided into plots at random in each block were implanted two microclimate stations in the center of the area cultivated in both drive systems to obtain the microclimate data divided into blocks and divided in blocks. Throughout the crop development cycle measurements were performed in all treatments (SC x PE), in relation to the leaf area index (LAI), photosynthetic active radiation below the canopy (PARabx), fraction of photosynthetically active radiation intercepted by the crop canopy (Fpari), soil moisture 0,20 me production and soil moisture at depths from 0.00 to 0.60 me fruit quality, in 4 treatments, results were evaluated statistically by the Tukey test a 5% probability. The results found that most microclimate variables only significant difference in the final stages of development of culture, parameters except for: albedo, ratio Rn / Rg and soil moisture. There was a significant difference when compared to the EP and SC. The maximum values of LAI presented in the SC in lira and the EP 'IAC 313'. fPARi presented the maximum values in the SC in lira and espalier, respectively, in the EP 'IAC 572' and 'IAC 313'. In both SC Fpari the minimum values were presented at the EP 'P1103'. The analysis of soil moisture in depth from 0.00 to 0.20 m, in both drive systems, the PE 'SO4' and 'P1103' showed higher water requirements. Analyzing soil moisture in depth from 0.00 to 0.60 m PE with the highest water requirement was 'P1103'. The lira driving system provided higher yield per plant in all PE, highlighting the 'IAC 313' with averages of 4.26 and 2.95 kg plant-1, in systems lira and espalier, respectively. We conclude that the conduction system in lira stands out in the production presented in great quality values, but the highest water requirements compared to the conduction system in espalier, as the rootstock 'IAC 572' showed great leaf development and smaller production values in the evaluated cycle / A viticultura brasileira ocupa atualmente, uma área de 81 mil hectares, com destaque para o Rio Grande do Sul e para o polo agrícola Petrolina-PE/Juazeiro-BA responsável por 95% das exportações nacionais de uvas finas de mesa. O cultivo da videira é influenciado pelo clima, que interfere diretamente no desenvolvimento da cultura, na ocorrência de pragas e doenças, nas necessidades hídricas e na qualidade dos frutos. Os objetivos deste trabalho foram avaliar o desenvolvimento fenológico, as variações de umidade do solo e a produção da videira cultivar Syrah, sob cinco porta-enxertos (PE) e dois sistemas de condução (SC), além da variação do microclima em diferentes sistemas de condução e como interferem na qualidade do fruto. O experimento foi desenvolvido no campo experimental de Bebedouro, em Petrolina, PE, durante segundo ciclo de 2015. Utilizou-se a cultivar Syrah, que é uma das principais cultivares utilizadas na produção de vinho tinto no Vale do São Francisco, dividido em blocos, subdividido em parcelas ao acaso, em cada bloco foram implantadas duas estações microclimáticas no centro da área cultivada em ambos os sistemas de condução para obtenção dos dados microclimáticos, divididos em blocos e subdivididos em blocos ao acaso. Durante todo o ciclo de desenvolvimento da cultura foram realizadas medidas, em todos os tratamentos (SC x PE), no que se refere ao índice de área foliar (IAF), radiação fotossinteticamente ativa abaixo do dossel (PARabx), fração da radiação fotossinteticamente ativa interceptada pelo dossel da cultura (fPARi), umidade do solo a 0,20 m e produção, bem como umidade do solo nas profundidades de 0,00 a 0,60 m e qualidade do fruto, em 4 tratamentos, resultados foram avaliados estatisticamente pelo teste Tukey a 5% de probabilidade. Os resultados constataram que a maioria das variáveis microclimáticas só apresentaram diferença significativa nas fases finais de desenvolvimento da cultura, com exceção dos parâmetros: albedo, relação Rn/Rg e umidade do solo. Verificou-se diferença significativa quando comparados os PE e os SC. Os valores máximos de IAF apresentaram-se no SC em lira e no PE „IAC 313‟. A fPARi apresentou valores máximos nos SC em lira e espaldeira, respectivamente, nos PE „IAC 572‟ e „IAC 313‟. Em ambos os SC os valores mínimos de fPARi foram apresentados no PE „P1103‟. Na análise da umidade do solo na profundidade de 0,00 a 0,20 m, em ambos os sistemas de condução, os PE „SO4‟ e „P1103‟ apresentaram maiores necessidades hídricas. Analisando a umidade do solo na profundidade de 0,00 a 0,60 m o PE que apresentou maior necessidade hídrica foi o „P1103‟. O sistema de condução em lira promoveu maior produção por planta em todos os PE, destacando-se o „IAC 313‟ com médias de 4,26 e 2,95 Kg planta-1, nos sistemas em lira e espaldeira, respectivamente. Concluímos assim que o sistema de condução em lira se destaca na produção apresentado valores de qualidade ótimos, porém apresenta uma necessidade hídrica maior, quando comparado ao sistema de condução em espaldeira, já o porta-enxerto „IAC 572‟ apresentou grande desenvolvimento foliar e menores valores de produção no ciclo avaliado / 2017-02-01

A hipótese desse estudo foi de que o manejo do pasto baseado no comportamento ingestivo (pastoreio Rotatínuo - RN) resulta em maior eficiência de utilização do pasto, mas menor eficiência de colheita quando comparado ao manejo clássico (pastoreio rotativo). O experimento ocorreu na Estação Experimental Agronômica da Universidade Federal do Rio Grande do Sul, Brasil, onde foram contrastadas duas estratégias de manejo (tratamentos) em pastos de azevém anual pastejados por ovinos. No primeiro tratamento foi utilizado o pastoreio Rotativo (RT), com metas de altura de manejo pré-pastejo de 25 cm e pós-pastejo de 5 cm. Este tratamento representou o conceito clássico de manejo que privilegia o período de descanso para acumular forragem, e a ocupação da faixa de forma tal a colher o máximo da massa de forragem acumulada. No segundo tratamento foi utilizado o método RN, onde as metas de pré-pastejo foram de 18 cm e pós-pastejo de 11 cm, metas essas definidas objetivando maximizar a taxa de ingestão. Os animais tinham aproximadamente 10 meses de idade com peso vivo médio de 26,2±0,95 kg, e eram oriundos do cruzamento das raças Texel e Ideal. O delineamento experimental foi em blocos completos casualizados com quatro repetições. Os resultados demonstraram que o RN resultou em ciclos de pastejo mais curtos do que o RT (13 vs 35 dias) que aconteceram em maior quantidade (11 vs 4). A maior quantidade (~20%) de massa de lâminas foliares verdes no pós-pastejo do tratamento RN possibilitou maior interceptação luminosa pela planta (78% vs 63%) resultando em maior produção de matéria seca (PMS) no método RN (9023 kg MS ha-1) comparado ao RT (6819 kg MS ha-1). As diferentes metas de manejo resultaram em maior oferta de lâminas foliares verdes para o RN comparado ao RT, gerando maiores ganhos médio diários por animal (GMD) e também por área (GPV), embora a carga animal tenha sido maior no RT. A eficiência de colheita do pasto (ECP) foi similar entre tratamentos. Por outro lado, registrou-se maior eficiência de utilização do pasto (EUP) no RN, sendo que para cada 1 kg de ganho de peso os animais necessitaram consumir 16,2 e 28,1 kg MS, respectivamente para RN e RT. Conclui-se que as metas de manejo do pasto do método RN, baseadas na maximização da taxa de ingestão, resultam em maior eficiência de utilização sem comprometimento da eficiência de colheita. / We hypothesized that grazing management based on ingestive behavior (named rotatinuos stocking – RN) results in better herbage use efficiency, but in lower harvesting efficiency when compared to classic rotational stocking (RT). This experiment was conducted at the Agronomic Experimental Station of the Federal University of Rio Grande do Sul (UFRGS), Brazil. Two stocking strategies (RN and RT) were used as treatments in annual ryegrass (Lolium multiflorum Lam.) pasture grazed by sheep. In the RT treatment, target height for grazing initiation and stubble were 25 and 5 cm, respectively. This represented the classical management approach where long regrowth intervals are allowed for accumulating maximum forage and pasture is grazed down to a low stubble for maximum harvesting efficiency. In the alternative treatment RN, pre- and post-grazing target heights were 18 and 11 cm, respectively, for maximizing ingestion rate. Animals were Texel and Ideal crossbreed, of approximately 10 months old and averaged 26.2±0.95 kg live weight. The experiment was arranged in a randomized complete block design, with four replicates. Compared with RT, the RN treatment had resulted in shorter (13 vs 35 days, compared to RT) and more frequent (11 vs. 4 days, for RT) regrowth cycles. The greater green leaf blade mass (~20%) post-grazing in the RN treatment allowed more light interception compared with RT (78 vs. 63%, respectively), resulting in greater herbage accumulation (9020 vs. 6819 kg MS ha-1 for RN and RT, respectively). The different grazing strategies resulted in greater allowance of green leaf blades in RN than in RT, resulting in a greater live weight gain per hectare and per animal despite the lower stocking rate in RN. The herbage harvesting efficiency was similar for both treatments. On the other hand, herbage use efficiency was greater for RN, where for 1 kg of live weight gain animals ate 16.2 kg dry matter, compared with 28.1 kg in the RT treatment. In conclusion, pasture management based on maximizing the ingestion rate resulted in greater herbage use efficiency without compromising harvesting efficiency.

In 2009 and 2010 a split, split, split plot experiment with training system, VSP or Smart-Dyson Ballerina (main plot), N, 0 or 33.6 kg/ha (split), crop level, 14.0, 18.7, or 23.4 clusters/m/canopy (split), clone, Cabernet Franc 1,4, 8 and 214 treatments with five replications were established in Union County, Illinois on mature vines. The Smart-Dyson Ballerina training system produced a Ravaz index that was 89% and 28% bigger compared to the VSP respectively in 2009 and 2010. In 2009, the Smart-Dyson Ballerina produced a 80% bigger yield than VSP and in 2010 yield was also larger, but influenced by both training system and crop level. Maintaining a balanced vineyard can increase profit for the grower by up to $6,356.87/ha.

O presente trabalho foi conduzido na EEA/UFRGS entre dezembro de 2009 e abril de 2010, e constituído por dois experimentos. Os tratamentos do experimento 1 (determinação da altura de entrada) consistiram de seis alturas de pasto (30, 40, 50, 60, 70 e 80 cm). No experimento 2 foram determinados níveis de rebaixamento do pasto em função da altura de entrada definida no experimento 1, sendo os tratamentos referentes a 16, 33, 50, 67 e 84% de rebaixamento da altura pré-pastejo O delineamento utilizado, em ambos os experimentos, foi o de blocos completos casualizados, com duas repetições no experimento 1 e três repetições para o experimento 2. Foram utilizadas 4 novilhas com idade e peso médio de 24±2 meses e 306±56,7 kg para o experimento 1. Três desses animais foram utilizados para o experimento 2, na ocasião com 26±2 meses e 339±45,5 kg. A determinação da taxa de ingestão baseou-se na metodologia de dupla pesagem. Para a determinação dos padrões comportamentais os animais foram equipados com aparelho registrador de movimentos mandibulares, denominado IGER-Behaviour recorder. No pasto foram realizadas medições de alturas pré- e pós-pastejo e amostragens para caracterização da massa de forragem pré-pastejo e distribuição vertical dos componentes morfológicos do pasto. Amostras para a caracterização da massa de forragem pós-pastejo foram obtidas para o experimento 2. Os resultados demonstraram que a taxa de ingestão dos animais no experimento 1 responde de forma quadrática em relação às alturas. A massa do bocado é reduzida em estruturas a partir de 50 cm de altura. Da mesma forma a taxa de bocados apresentou comportamento quadrático nas distintas alturas. Concluiu-se desse experimento que a altura que proporciona a melhor estrutura de pasto para pastejo encontra-se próxima a 50 cm. No experimento 2 encontrou-se que a taxa de ingestão, a massa de bocados e a taxa de bocados são constantes até o rebaixamento de 40% da altura pré- pastejo ótima. Desse conjunto de resultados originam-se metas de estruturas de pasto que permitem orientar o ma nejo visando obter elevados níveis de ingestão de forragem, quais sejam, altura ótima de pastejo até 50 cm e o nível de rebaixamento, no caso do método de pastejo com lotação intermitente, não deve ultrapassar 40%. / This study was conducted at the EEA / UFRGS from December 2009 to April 2010 and consisted of two experiments. The treatments of experiment 1 (determination of pre-grazing canopy height) consisted of six canopy heights (30, 40, 50, 60, 70 and 80 cm). At experiment 2, percentages of grazing down according to pre-grazing sward height defined at experiment 1 were determined, being treatments related to the grazing down of 16, 33, 50, 67 and 84% of pre-grazing canopy height. The experimental design used in both experiments was a completely randomized block design, with two replicates in experiment 1, and three replicates in experiment 2. Four heifers ageing 24 ± 2 months and mean weight of 306 ± 56.7 kg were used for experiment 1. Three of these animals were used for experiment 2, at that time with 26 ± 2 months and 339 ± 45.5 kg. The determination of short-term intake rate was based on double weighting technique; for the determination of behavioral patterns, the animals were fitted with a jaw movement automatic recorder, known as IGER Behaviour Recorder. In pasture, measurements of pre- and post-grazing sward height and samplings were proceeded to characterize the pre-grazing forage mass and the vertical distribution of its morphological components. Samples for the characterization of the post-grazing forage mass were also taken in experiment 2. The results showed that the intake rate of animals in experiment 1 have a quadratic respond in relation to the canopy heights. The bite weight fit to a broken line equation, being reduced from 50 cm. The biting rate, in turn, showed a quadratic response along different canopy heights. This experiment defined the canopy height, which provides the best sward structure is around 50 cm. At the experiment 2 the grazing down protocol demonstrated that intake rate, bite weight and biting rate are constant until the depletion of 40% of the optimal pre-grazing canopy height. From these set of results, sward targets are originated and allow for the orientation of management goals aiming to obtain high levels of intake rate. Therefore optimum grazing height around 50 cm, and the rate of grazing down in the case of rotational grazing should not exceed 40%.

Chilling events are infrequent but important disturbances in subtropical Florida. When temperatures drop to near freezing, significant mortality often accrues in mangrove forests. Chilling events play a role in maintaining structural diversity in mangrove forests, and in limiting mangrove poleward distribution. I examined the spatio-temporal distribution of chilling events in mangrove forests of southern Biscayne Bay by using Landsat TM5 images since 1989. Damage was usually confined to dwarf mangrove forest, especially when chilling temperatures were moderate and short in duration. However, damage from extended and severe freezes such as in January 2010 impacted larger trees as well. Recovery is gradual, often extending over multiple years, depending on disturbance severity. Plant communities respond to repeated chilling with increase in the dominance of black mangrove. In the absence of chilling events, patch level dynamics might lead to prevalence of a more homogenous tall red mangrove canopy in these wetlands. Such a trajectory may result with increasing temperatures expected under current global climate change scenarios

Na natureza, durante milhares de anos de convivência, gramíneas forrageiras e herbívoros passaram por um processo de co-evolução desenvolvendo múltiplas estratégias de sobrevivência e de adaptação. Práticas de manejo que interferem na forma como a forragem é disponibilizada aos animais (estrutura do dossel forrageiro) podem causar mudanças dos padrões de procura e ingestão de forragem e interferir com o desempenho animal. Nesse contexto, o objetivo deste estudo foi avaliar a estrutura do dossel forrageiro e a taxa de consumo de forragem em pastos de capim-elefante cv. Napier (Pennisetum purpureum Schum.) submetidos a estratégias de pastejo rotativo. O experimento foi conduzido em área da Escola Superior de Agricultura \"Luiz de Queiroz\", Piracicaba, SP, de janeiro de 2011 a abril de 2012. Os tratamentos corresponderam a combinações entre duas condições pós- (alturas pós-pastejo de 35 e 45 cm) e duas condições pré-pastejo (95% e máxima interceptação de luz pelo dossel forrageiro - IL), alocados às unidades experimentais (piquetes de 870 m²) segundo arranjo fatorial 2x2 e delineamento de blocos completos casualizados, com quatro repetições. Foram avaliadas em pré- e em pós-pastejo as seguintes variáveis-resposta: distribuição vertical dos componentes morfológicos da massa de forragem dos pastos, taxa de bocados, massa do bocado, taxa de consumo e valor nutritivo da forragem consumida (composição morfológica e bromatológica de amostras de extrusa).A estrutura do dossel influenciou fortemente a massa do bocado, a taxa de bocados e a taxa de consumo independente de tratamento e época do ano. Em pré-pastejo, apesar de a massa do bocado ter sido maior nos pastos manejados com a meta ILMáx, não houve diferença em taxa de consumo entre as metas de IL avaliadas, resultado da maior taxa de bocados registrada nos pastos manejados com a meta IL95%. Em pós-pastejo a taxa de consumo também não variou entre as metas de IL avaliadas, sendo observados ajustes na taxa de bocados como forma decompensar as variações em massa do bocado. As metas de altura pós-pastejo modificaram a composição morfológica e bromatológica da forragem consumida, as quais variaram também em função da época do ano. De maneira geral, pastos manejados com a meta IL95% e altura pós-pastejo de 45 cm resultaram em maior porcentagem de folhas na extrusa, o que conferiu melhor taxa de consumo e valor nutritivo da forragem consumida pelos animais em pastejo. / In nature, during thousands of year of co-existence, forage grasses and herbivores underwent a co-evolution process that resulted in multiple survival strategies and adaptations. Management practices that interfere with the way forage is presented to animals (sward structure) may cause changes in patterns of search and consumption of herbage, affecting animal performance. The objective of this experiment was to evaluate sward structure and rate of herbage intake of rotationally stocked elephant grass (Pennisetum purpureumSchum., cv. Napier). The experiment was carried out at Escola Superior de Agricultura \"Luiz de Queiroz\", Piracicaba, SP, Brazil, from January 2011 to April 2012. Treatments corresponded to combinations between two post- (post-grazing heights of 35 and 45 cm) and two pre-grazing swards conditions (95% and maximum canopy light interception - LI), and were allocated to experimental units (870 m2 paddocks) according to a 2x2 factorial arrangement in a complete randomised block design, with four replications. The following response variables were evaluated in both pre- and post-grazing conditions: vertical distribution of morphological components of sward herbage mass, bite rate, bite mass, rate of intake and nutritive value of the consumed herbage (morphological and chemical composition of extrusa samples). Sward structure strongly influenced bite mass, bite rate and rate of intake regardless of treatment and season of the year. At pre-grazing, in spite of the larger bite mass on swards managed with the pre-grazing target LIMax, there was no difference in rate of intake between LI targets, consequence of the higher bite rate recorded on swards managed with the pre-grazing target LI95%. At post-grazing, there was no difference in rate of intake between LI targets, with variations in bite rate used to compensate variations in bite mass. Post-grazing targets altered the morphological and chemical composition of the consumed herbage, which also varied with season of the year. Overall, swards managed with the pre-grazing target LI95% and the 45 cm post-grazing height resulted in larger percentage of leaves in the extrusa, favouring higher rates of intake and nutritive value of the herbage consumed.

A reposição de perfilhos mortos ou consumidos pelo pastejo é ponto chave para manutenção da perenidade e produtividade da pastagem. Dentre outros fatores, a dinâmica com que esse processo ocorre é variável em função das estratégias de manejo utilizadas. Dessa forma, as estratégias de manejo do pastejo afetam a dinâmica do perfilhamento, gerando modificações em densidade populacional de perfilhos e em sua composição, nos padrões de ocupação horizontal da área e na estabilidade da população de perfilhos, características determinantes da perenidade e produtividade da planta forrageira. Com isso, o objetivo com este trabalho foi avaliar a frequência e o tamanho das touceiras, a dinâmica do perfilhamento, a densidade populacional de perfilhos e a participação relativa de perfilhos basais e aéreos na população de plantas de capim-elefante cv. Napier submetido a estratégias de pastejo rotativo de janeiro de 2011 a abril de 2012. Os tratamentos corresponderam a combinações entre duas condições pós- (alturas pós-pastejo de 35 e 45 cm) e duas condições pré-pastejo (95% e máxima interceptação luminosa - IL95% e ILMáx) e foram alocados às unidades experimentais segundo arranjo fatorial 2x2 e delineamento de blocos completos casualizados, com quatro repetições. Foram avaliadas características da estrutura horizontal dos pastos, dinâmica do perfilhamento e população de perfilhos totais e demografia de perfilhos basais e aéreos. Pastos manejados com a meta IL95% apresentaram ocupação mais uniforme da área caracterizada pela maior frequência de touceiras e menor frequência de espaços vazios relativamente àqueles manejados com a meta ILMáx. Independente da meta de IL pré-pastejo, os pastos passaram por um período de adaptação aos tratamentos impostos caracterizado pela redução da variabilidade do perímetro médio das touceiras do início do experimento até o início da primavera. Pastos manejados com a meta ILMáx apresentaram menor índice de estabilidade da população de perfilhos, consequência das maiores taxas de mortalidade relativamente aos pastos manejados com a meta IL95%. A densidade populacional de perfilhos aéreos (DPPa) foi maior que a de perfilhos basais (DPPb) para ambas as metas de IL pré-pastejo. De forma geral, não foi registrada diferença em DPPa entre as metas de IL pré-pastejo, mas a DPPb foi maior nos pastos manejados com a meta IL95%. A estratégia de manejo caracterizada pela meta IL95% favorece menor mortalidade de perfilhos e maior perfilhamento basal que, por sua vez, favorece ocupação mais uniforme da área, sugerindo possíveis benefícios para a habilidade competitiva e produtiva da pastagem. / Replacement of dead or consumed tillers during grazing is a key point for ensuring longevity and productivity of pastures. Among other factors, the dynamics of the tillering process is variable depending on management strategies used. In that context, grazing management strategies affect tillering dynamics causing changes in tiller population density and its composition, patterns of plant horizontal distribution and area occupation and in the stability of tiller population, all important characteristics determining longevity and productivity of forage grass communities. The objective of this study was to evaluate the frequency and size of tussocks, tillering dynamics, tiller population density and the relative contribution of basal and aerial tillers in elephant grass cv. Napier subjected to strategies of rotational stocking management from January 2011 to April 2012. Treatments corresponded to combinations between two post- (post-grazing heights of 35 and 45 cm) and two pregrazing conditions (95% and maximum canopy light interception during regrowth - LI95% and LIMax), and were allocated to experimental units (850 m2 paddocks) according to a 2x2 factorial arrangement in a complete randomised design, with four replications. The following response variables were measured: characteristics of sward horizontal structure, tiller dynamics and population, and demography of basal and aerial tillers. Swards managed with the LI95% target showed a more uniform occupation of the area characterised by higher frequency of tussocks and lower frequency of bare ground areas relat ive to those managed with the LIMax target. Regardless of LI pre-grazing target, swards underwent an adaptation period to treatments imposed characterised by reduction in the variability of the average tussock perimeter from the beginning of the experiment until early spring. Swards managed with the LIMax target had lower population stability index than those managed with the LI95% target, consequence of higher tiller death rates. Population density of aerial tillers (TPDa) was larger than basal tillers (TPDb) for both LI pre-grazing targets. In general, there was no difference in TPDa between LI pre-grazing targets, but TPDb was larger on swards managed with the LI95% target. the management strategy characterised by the LI95% target results in lower tiller death and larger production of basal tillers that, in turn, favours a more uniform occupation of the area, suggesting potential benefits to the competitive and productive ability of pastures.