- palearctic region
- The Palearctic region stretches halfway around the globe. It includes Europe, Asia north of the Himalayas, and a large part of Arabia and North Africa. It is bounded in the north by the Arctic Ocean and in the south by the Sahara, the Gulf of Oman and the Himalayas. Its western limit is the Atlantic and its eastern frontier is the Pacific Ocean.
- pantropical
- Everywhere in the tropics
- pastoralism
- Herding with a shepherd (lat. pastor)
- permafrost
- Ground (soil or rock, including ice and organic material) that remains at or below 0 °C for at least two consecutive years
- permafrost base
- The surface at the lower boundary of permafrost, above which temperatures are perennially below 0 °C (cryotic) and below which temperatures are perennially above 0 °C (noncryotic)
- permafrost table
- The surface at the upper boundary of permafrost
- pH
- The negative logarithm of the hydrogen ion concentration in a solution. If the hydrogen ion concentration of a solution rises with increasing acidity, the pH will dicrease, and vice versa. Scale: 0-14. A neutral medium has a pH of 7, numbers above indicate alkalinity, numbers below 7 indicate relative acidity.
- phalanx
- A massed arrangement of people, animals or plants. Greek for a closed progressing front of soldiers.
- phenology
- The visible change of developmental stages (e.g. sprouting, flowering, fruiting)
- photoassimilate
- Carbohydrate derived from photosynthesis
- photoperiod
- The duration of daylight
- photoperiodism
- The response of plants to the ratio of the length of the light/dark period
- photosynthate
- Product of photosynthesis (e.g. sugar)
- phototoxicity
- Damage caused by high light intensity
- phyllite
- Fine-grained, low-grade metamorphic rock with a well-developed schistosity and phyllosilicate minerals (e.g. chlorite, muscovite)
- phytogeographic
- Geographic distribution of plants
- phytosociology
- Field of vegetation ecology that deals with the definition, description, and classification of plant communities
- plant community
- Assemblage of populations of different plant species that live in a particular environment and interact with each other as well as with other organisms (fungi, animals, microorganisms). They form a distinctive living system with its specific composition, structure, environmental relations and function.
- Pleistocene
- Geological period following the Tertiary, from about 1.8 million years ago to 10,000 years ago. It was characterized by climatic changes, including the ice ages.
- podzolisation
- A process of soil leaching
- poikilotherm
- Cold-blooded organism whose body temperature is identical to that of the external environment; organism unable to internally regulate its body temperature
- polyploidy
- The ploidy level indicates the number of sets of homologous chromosomes occurring in the genetic material of a certain species. "Haploid" means one set; "diploid" two sets (this is the normal case), and "polyploid" denotes more than two sets.
- polythermal
- A glacier which shows temperatures of both, cold and warm glaciers
- pond
- A relatively small, sometimes ephemeral or seasonal body of fresh water
- pore ice
- Ice occurring in the pores of soils and rocks
- protandry
- Male gender expressed before female gender.
- protogynous
- Referring to a plant in which the female part of the flower matures first
- protogyny
- Female gender expressed before male gender.
- protoplast
- The naked cell (in plants, without the cell wall)
|
back
to top