Agroecosystems and Rangelands Flashcards
Agroecosystem
a conceptual construct used to describe a geographically and functionally coherent domain of agricultural activity (includes living and non-living components and interactions between them)
agroecosystems services to agriculture
genetic resources
pest control
pollination
soil structure and fertility enhancement
agroecosystem services from agriculture
provisioning services (food,fuel…), soil conservation, habitat provision
agroecosystems disservices to agriculture
past damage
pathogen outbreaks
competion for resources
agroecosystems disservices from agriculture
habitat degredation
soil degredation
water quality degredation
agroecology
the application of ecological principles to agricultural systems and practices
goals of agroecology
enhance ecosystem services through sustainable management of natural resources
reduce imputs to reduce costs and ecological footprint
increase value through social license
weed control
continuous cover reduces barer ground for establishment
diverse crop rotations may increase competition for weeds
allelopathic plants may supress weeds
pest supression
promoting predators and parasitoids can reduce pest outbreaks (reduce pest application, adjacent natural areas)
diverse cropping can dilute effects of species-specific pests
How does diversity help grasslands be productive
inhances productivity in both dry and normal years
driven by presence of drought tolerant plants, increased soil organic matter, and drought resistant soil biota
most ecosystems are _________ by ___________ in plant diversity
enhanced, increases
What are grassland ecozones determined by?
precipitation (greatest effect) and temperature
when do grasses first appear in the fossil record
55 MYA
Major expansion of grasslands
happened worldwide between 4-7 MY ago
Tropical C4 grasslands become wiespread due to declining atmospheric CO2 levels and related diversification of C4 spp.
co-evolution between grasses and grazers
many grasses have silica in cells, which makes them grainy. mammalian herbivores developed high crowned teeth to allow their teeth to grow as they wear down
Grassland controlled fires
prevents encroachment of woody plants into grasslands. Fire return intervals can be very short
How are grassland plants fire resistant?
perennial plants keppmost nutrients and essential organs belowground. As long as it doesnt get really hot, they will just grow right back
How many hectares of grasslands are converted to farmland?
23 million
range health
the ability of rangelads to maintain function and services
rangeland services
forage for livestock and wildlife
wildlife habitat
carbon sequestration
soil conservation
how is range health assessed in Saskatchewan
species composition
vegetation structure
invasive species
site/soil stability
hydrological function and soil protection
tools to maintain range health
appropriate stocking rates
rotational grazing
prescribed fire
invasive plant management