In a typical terrestrial ecosystem, energy input comes directly from the sun, and it is converted to chemical energy through photosynthesis. interestingly, an unusual ecosystem can exist in the absence of sunlight. what could be the source of energy?

The oxidation of inorganic substances (H2S etc.) serves as the energy source for hydrothermal vents.

Explanation:

Deep hydrothermal vents (the unusual ecosystems) are located in the depths of oceans where sunlight can not penetrate. These ecosystems have the bacteria that oxidize the inorganic substances such as H2S and the released energy is used to fix the CO2 present dissolved in water.  

Here, the inorganic substances such as hydrogen sulfide are released from the volcanic vents present in the ocean floors.  

increase soil erosion                                             reduce soil erosion

cattle grazing                                                         hydroseeding

deforestation                                                         contour plowing

                                                                                planting vegetation

plant roots basically hold the top soil

together and stop soil erosion because

in such situation top soil is not removed

during flood but cattle grazing causes

soil erosion because cattle consume the

grasses and herbs and top soil is exposed.

same situation occurs because of

deforestation, the trees and plants are cut

down to expose top soil which causes soil

erosion