What is an Ecosystem? Biotic and abiotic factors.

 

ENVIRONMENTAL FACTORS:

http://www.edistribucion.es/anayaeducacion/8450021/unidad_06.html

http://www.edistribucion.es/anayaeducacion/8450021/recursos/u06/uni_06_video_01seasons.html 

http://es.tiching.com/link/103439