Question

what are the survival techniques of vegetation found in the drought region?

Answer 1

Answer:

Droughts are worsening around the world, posing a great challenge to plants in all ecosystems, said Lawren Sack, a UCLA professor of ecology and evolutionary biology and senior author of the research. Scientists have debated for more than a century how to predict which species are most vulnerable.

Sack and two members of his laboratory have made a fundamental discovery that resolves this debate and allows for the prediction of how diverse plant species and vegetation types worldwide will tolerate drought, which is critical given the threats posed by climate change, he said.

The research is currently available in the online edition of Ecology Letters, and will be published in an upcoming print edition.

Why does a sunflower wilt and dessicate quickly when the soil dries, while the native chaparral shrubs of California survive long dry seasons with their evergreen leaves? Since there are many mechanisms involved in determining the drought tolerance of plants, there has been vigorous debate among plant scientists over which trait is most important. The UCLA team, funded by the National Science Foundation, focused on a trait called "turgor loss point, which had never before been proven to predict drought tolerance across plant species and ecosystems.

A fundamental difference between plants and animals is that plant cells are enclosed by cell walls while animal cells are not. To keep their cells functional, plants depend on "turgor pressure" -- pressure produced in cells by internal salty water pushing against and holding up the cell walls. When leaves open their pores, or stomata, to capture carbon dioxide for photosynthesis, they lose a considerable amount of this water to evaporation. This dehydrates the cells, inducing a loss of pressure.

Answer 2

Explanation:

Climate change is predicted to increase the occurrence of extreme droughts, which are associated with elevated mortality rates in tropical trees. Drought-induced mortality is thought to occur by two main mechanisms: hydraulic failure or carbon starvation . This chapter focuses on the strategies that plants use to survive these two drought-induced mortality mechanisms and how these mechanisms are distributed among the immense diversity of tropical tree species. The traits that tropical trees may use to survive drought include (1) xylem that is resistant to drought-induced cavitation , (2) high sapwood capacitance that protects xylem from critically low water potentials , (3) drought deciduousness, (4) photosynthetic stems that have the potential to assimilate carbon at greater water-use efficiency than leaves, (5) deep roots, (6) regulation of gas exchange to reduce leaf water loss or to maintain photosynthesis at low leaf water potential and (7) when all else fails, low cuticular conductance from exposed tissues during extended drought. To date, most research has focused on deciduousness, resistant xylem, soil water, gas exchange behavior and sapwood capacitance, whereas little is known about the role of photosynthetic stems or cuticular conductance during extreme extended drought, making these processes a high priority for a complete understanding of tropical tree physiology during drought.