Drylands are predicted to become more arid and saline due to increasing global temperature and drought. Although species from the Caatinga, a Brazilian tropical dry forest, are tolerant to these conditions, the capacity for germination to withstand extreme soil temperature and water deficit associated with climate change remains to be quantified. We aimed to evaluate how germination will be affected under future climate change scenarios of limited water and increased temperature. Seeds of three species were germinated at different temperatures and osmotic potentials. Thermal time and hydrotime model parameters were established and thresholds for germination calculated. Germination performance in 2055 was predicted, by combining temperature and osmotic/salt stress thresholds, considering soil temperature and moisture following rainfall events. The most pessimistic climate scenario predicts an increase of 3.9 °C in soil temperature and 30% decrease in rainfall. Under this scenario, soil temperature is never lower than the minimum and seldomly higher than maximum temperature thresholds for germination. As long as the soil moisture (0.139 cm 3 cm 3 ) requirements are met, germination can be achieved in 1 day.According to the base water potential and soil characteristics, the minimum weekly rainfall for germination is estimated to be 17.5 mm. Currently, the required minimum rainfall occurs in 14 weeks of the year but will be reduced to 4 weeks by 2055. This may not be sufficient for seedling recruitment of some species in the natural environment. Thus, in future climate scenarios, rainfall rather than temperature will be extremely limiting for seed germination.

No abstract

RESUMONa construção de mapas, procura-se representar as feições de maneira que não se percam as suas características geométricas e espera-se que o usuário do mapa compreenda o seu significado independentemente da escala estabelecida para a representação visual. Devido à restrição de espaço para a representação, deve haver a preocupação em simbolizar as informações de forma visível e legível. Se, ao resultado do processo de generalização cartográfica, for aplicada uma simbologia inadequada, pode haver implicações no processo de comunicação cartográfica. Neste trabalho, teve-se por objetivo realizar experimentos de generalização cartográfica para a derivação de representação das feições de vias de acesso, quadras, lotes, edificações e toponímias, nas escalas 1:5.000 e 1:10.000, a partir da escala 1:2.000. O desenvolvimento do trabalho constou da avaliação cartométrica para detectar possíveis problemas geométricos resultantes da redução de escala e a definição dos operadores a serem aplicados às feições. A adoção da simbologia para as escalas menores foi baseada nas respostas obtidas de experimento orientado especificamente à avaliação e escolha da simbologia. A aplicação da simbologia às Bol. Ciênc. Geod., sec. Artigos, Curitiba, v. 16, n o 3, p.386-402, jul-set, 2010.

This study was performed in 2009, 2015 and 2018, at urban areas of Petrolina (state of Pernambuco) and Juazeiro (state of Bahia), at the São Francisco valley, Brazilian Northeast. Trees were identified and investigated for the presence of Plebeia aff. flavocincta nests, in three years: 2009, 2015 and 2018. Data on height at nest entrance (HNE), tree diameter at nest entrance (DNE) and tree diameter at breast height (DBH) were obtained. Trees containing nests were identified and geo-referenced. In Petrolina and Juazeiro, the percentage of bees nests in all checked trees was smaller in 2009 (3.94% and 0.56%) than in 2015 (1.92% and 5.26%) and in 2018 (21.21% and 3.66%). This increase (especially in Petrolina) suggests P. aff. flavocincta is well adapted to urban environments and food and/or nesting resources might be improved along the years. On the other hand, survival of nests was not high: only two nests found in 2009 survived up to 2018. Mortality of nests was mainly due to the cutting of trees. Simultaneously, according to observations, swarming probably occurs, what might have improved the number of nests observed in 2018. The vegetal species most used by the bees was Prosopis juliflora (84.38%). Considering all data, the HNE, DNE, and DHB varied among the cities and years, but the differences were not significant in most of the cases. In Juazeiro, two nests were found also in a wall and another one in a pipe showing the diversity of nesting habits of the species. It is remarkable that despite high levels of stress (caused by noise, pollution, and human interferences) these bees are able to survive and swarm at urban areas.

Na região Semiárida do Estado de Pernambuco existe grande diversidade na paisagem natural, onde a vegetação, os solos e o clima geram uma multiplicidade de situações que concorrem para formação de diferentes ecossistemas e habitats com grande potencial ecológico e ambiental. Nesta região, a vegetação é caracterizada por diferentes fisionomias, variando de áreas com formações arbustivas, com cobertura do solo muito escassa e quase ausente, a formações arbóreas com níveis de cobertura bastante densas. De modo análogo, nesta região ocorre uma grande variedade de solos, que por suas características, manejo e situação no relevo podem potencializar os processos erosivos, determinantes no desencadeamento da desertificação. Considerando as interrelações destas duas variáveis ambientais, este trabalho tem o objetivo de realizar um diagnóstico das áreas susceptíveis à desertificação da Região de Desenvolvimento Sertão do São Francisco - RDSF, tendo como base o cruzamento das informações da cobertura vegetal natural e das classes de solos. Para tanto, foram utilizados o recorte do mapeamento da cobertura vegetal e uso do solo e o recorte do mapeamento de solos da RDSF. Foram estabelecidos critérios para susceptibilidade da cobertura vegetal, assim como para as classes de solos presentes na área. Executou-se a intersecção destas duas bases de informação para o perfil da sensibilidade à desertificação. Os resultados mostram que a RDSF tem os seguintes valores das áreas em processos de desertificação: 1,77% na classe ausente ou fraca; 74,74% na classe moderada; 0,35% na classe acentuada e 23,14% na classe severa. Deste modo, observa-se que aproximadamente 98% da RDSF encontram-se na situação de sensibilidade à desertificação em que predominam as classes de Moderada a Severa. In the semiarid region of the state of Pernambuco there are plenty of biophysics where vegetation, climate, soils, and the various faces and the relationships and processes that take place among them generate the formation of different ecosystems and habitats with great potential ecological and environmental. There are a range of vegetation types, ranging from shrubby coverage areas up to very sparse and mostly absent vegetation areas, which demonstrated high desertification process occurring. Similarly, a variety of soils that is in the region along with vegetation makes this a region of great variation from the viewpoint of environmental supply. This article deals with the realization of a diagnosis of environmental sensitivity to desertification of São Francisco Development Region seeking spatialize the different situations in which the environment fulfills a greater or lesser extent, its role as provider of environmental services. For this, we used the cutting mapping of existing vegetation and soil mapping of the state and the established criteria, as well as edaphic vegetation cover, featuring the susceptibility to degradation and performed the intersection of these two bases of information to profile the sensitivity to desertification. The results show that São Francisco Development Region has the following values of areas undergoing desertification: 1.77% in weak class; 74.74% in the moderate class; 0.35% in sharp class, and 23.14% in severe class. Keywords: desertification, São Francisco, Semi-arid region, soils.