Related by context. Frequent words. (Click for all words.) 76 temperate regions 66 subtropical regions 65 tropics 63 latitudes 63 temperate climates 62 temperate forests 61 tropical climates 61 equatorial regions 60 subtropics 59 mid latitudes 58 milder winters 57 colder climates 56 cooler climates 56 Migrating birds 55 temperate 55 arid regions 55 equator 54 herbaceous plants 54 warmer climates 54 hotter summers 54 warmer drier 54 northern latitudes 53 cold winters 53 forbs 52 warmer winters 52 shade tolerant 52 perennial grasses 52 adelgids 52 warm climates 52 cold climates 52 avian influenza viruses 51 boreal forests 51 prolonged droughts 51 poleward 51 subtropical 51 warmer temperatures 51 Northern Hemisphere 51 fungal spores 51 climates 51 megafauna 51 colder winters 51 El Ninos 51 genetic variability 51 insect populations 51 insect borne diseases 51 drylands 50 virulent strains 50 deciduous trees 50 terrestrial ecosystems 50 alkaline soil 50 Droughts 50 nighttime temperatures 50 hickories 50 Cyanobacteria 50 acidic soil 50 nitrogen fixation 50 crop yields 50 drained soils 50 Aphids 49 landmasses 49 Infestations 49 Gypsy moths 49 pollinating insects 49 nitrogen fixing 49 overwinter 49 ant species 49 fertile soils 49 woody plants 49 Migratory birds 49 avian species 49 northern hemisphere 49 japonica 49 ecological niches 49 Phytophthora 49 Warmer temperatures 49 monkeys apes 49 hardier 49 infects humans 49 planktonic 48 atmospheric circulation 48 adelgid 48 avian flu viruses 48 mountain glaciers 48 moister 48 Little Ice Age 48 multicellular organisms 48 equatorial Pacific Ocean 48 overwintering 48 biodiversity hotspots 48 Polar Regions 48 species 48 savannahs 48 Soil moisture 48 equatorial 48 microclimates 48 atmospheric CO2 48 lowlands 48 Arctic tundra 48 flowering plants 48 Volcanic eruptions 48 Poison ivy