Natural Resource Conservation- Riparian Zones - Rangelands

Riparian Zone

Transitional area of land directly alongside a river/stream edge

• Experiences periodic flooding

• Soils- usually more moisture than in uplands

• Vegetation evolved for these conditions 

  • Ex. Willows

• Size depends on the system, essentially encompasses what the floodplain might be or a little less

Riparian Zone Functions

• Streambank Stabilization and Channel Morphology

  • Plant roots anchor soil- physical barrier to erosion, reduce water velocity

  • Strengthened banks create narrower, deeper channels

• Nutrient and Sediment Interception

  • Water passing over veg gets slowed down, giving time for roots to take up nutrients and sediments

  • Good riparian zone can remove 50-90% of the nitrate

• Thermal Regulation and Baseflow Maintenance

  • Riparian zones can provide canopy cover which keeps streams cool

  • Water infiltrating increases base flow 

• Allochthonous Energy Inputs

  • Good riparian zone introduces C material into system

  • Add woody debris that dissipates flow energy

• Wildlife Corridors and Habitat

  • Diverse transitional zone

  • Facilitates movement

Urban Stream Syndrome

Consistent suite of symptoms in streams draining urban/suburban watersheds (Walsh et al. 2005)

• Increased impervious surfaces lead to increased runoff

• Flashy Hydrology- quick rise and recession of water

  • Erodes stream bed

  • Flash floods

• Simultaneous pollutant inputs

• Biotic Simplification- EPT taxa decline, tolerant generalist fish dominate

Agricultural Nonpoint Pollution: The Tile Drain Problem

• Conventional Tillage

  • P attach to soil particles

  • Surface runoff → particulate P (bound to FE)

  • Riparian buffer captures sediment

  • Less bioavailable P → algae can’t use it

• Conservation Tillage and Tile Drain

  • P accumulates in upper soil layer

  • Tile drain → dissolved reactive P (DRP)

  • Bypasses riparian buffer entirely

  • Most bioavailable form → direct HAB fuel

• Tile Drain Short-Circuit

Tile Drain Short-Circuit

Conservation tillage reduced erosion (good result) but unintentionally made P loading worse (Ex. Lake Erie)

• With tilling, P becomes mixed with the soil profile and binds to soil particles

• Without tilling, P stays at the surface and becomes dissolved in rain

Tile Drain Problem on the National Scale: Gulf of Mexico

• Same mechanism as Lake Erie- eutrophication from agricultural nutrients

• Mississippi-Atchafalaya basin drains ~41% of the contiguous US

• 2019 hypoxic zone- ~8,776 sq miles (size of New Jersey)

  • Corn Belt nitrogen loading drives massive Gulf primary production

  • Decomposition of that production consumes all bottom oxygen

• Annual monitoring- NOAA Gulf of Mexico Dead Zone Program

Great Lakes Region

• 180+ non-native species established since European settlement

  • More invasive species than any other freshwater water body in the world

• Primary Vector- ballast water discharge from oceangoing vessels transiting the St Lawrence Seaway

  • Ballast water- chambers in boats that fill with and empty water, helps with weight distribution/stability 

  • Carry veligers (larvae) and adult organisms

  • Opened in 1959

  • Primary modern entry route

• Dreissenid mussels ranked most impactful (#1 and #2)

  • Usually spread in veliger form

  • Zebra Mussel- first spotted in 1988 in Lake St Clair

  • Quagga Mussel- first documented in 1989, more cold tolerant and can colonize deeper water- ended up outcompeting zebra mussels

• Other Major Invaders- sea lamprey, round goby, Asian carp, Eurasian water milfoil

Dreissenid Mussels: 5 Major Issues

• Filter Power- ~1L/day per mussel

  • Changes the food web of the lake

• Food Web Restructure- strips energy from the pelagic zone and transfers it to the benthos zone

  • Process called benthification

  • Favorable for bottom dwellers

  • Larval fish face food limitation

• Clarity Paradox- more light → explosive Cladophora algae growth → beach fouling and light blocking

• Quagga Expansion- colonize soft substrate and deep water

  • Displaced zebra mussels by 2000s, with quagga mussels making up about 98% of mussels found

  • Recorded 540ft depth

• Economic Cost- $1B/year in infrastructure damage to pipes, water intakes, and cooling systems

Sea Lamprey: A Management Success Story (with Limits)

• 1829- Welland Canal opens full access to upper Great Lakes

  • Only native to Atlantic Welland Canal 8 locks by Niagara Falls

• 1945-1960- lake trout populations collapse in Lakes Michigan, Huron, and Superior

  • Sea lamprey attach to fish (parasites), bore through scales/skin, and feed on blood and body fluids

  • When another stressor present, 1/7 survive

  • One adult lamprey can destroy 40 pounds of fish

• 1954- Great Lakes Fishery Commission established- US and Canada treaty

• 1960s- TFM lampricide + barriers + trapping program begins

  • Control Methods

    • Spawning stream barriers

    • Trapping

    • TFM lampricide- selectively toxic to lamprey larvae at controlled doses

    • Binational coordination (US + Canada)

• Today- ~90% reduction in sea lamprey from peak and lake trout partially recovered

Rangeland

Uncultivated land on which indigenous vegetation is predominantly grasses, grass-like plants, forbs, or shrubs, and which are managed as a natural ecosystem

• Uncultivated- not used for growing crops 

  • Croplands and foraging pastures are not rangelands

• Provides necessities of life for grazing/browsing animals

  • Grazing- consumption of free-standing forage (grasses and forbs) (e.g. cattle)

  • Browsing- consumption of edible leaves and twigs from woody plants (trees and shrubs) (e.g. deer)

Biomes Considered Rangelands

All areas of the world that not barren deserts, farmed/cultivated, or covered by bare soil, rock, ice, or concrete

• Desert- landscape where little precip occurs (<10” per year)

  • Except barren deserts

• Tundra- cold, dry, treeless landscape (arctic, Antarctic, high elevations)

  • All tundras

• Wetland- semi-aquatic landscape with permanent or seasonal flooding of groundcover

  • All vegetation surrounding water bodies

• Savanna- mixed woodland/grassland landscape (trees widely spaced; open canopy)

  • All savannas

• Shrubland- landscape dominated by shrubs (woody plants, 3-5cm)

  • All shrublands

• Forest- tree dominated landscape

  • Only open forests where grass and forbs can grow

• Grassland-landscape where vegetation is dominated by continuous cover of grasses

  • All grasslands

Why Pastureland is NOT Rangeland

• Forage Pasture- lands cultivated for agricultural animal production

• Vegetation Type

  • Pastureland- often introduced or non-native veg (often annual plants)

  • Rangeland- supports native veg (often perennial plants)

    • Can also have introduced/non-native species 

• Management

  • Pastureland- managed by agronomic input rather than ecological principles

    • Irrigated

    • Often seeded for introduced or native plant sp

  • Rangeland- land is managed as a natural ecosystem

    • Primarily by grazing and fire

Distribution of Rangelands

• 70% of world’s surface area is rangeland

• 2.1 billion people (35% of the world’s population) live on or depend directly on rangelands

• Rangelands store 10-30% of all soil organic carbon

• Rangelands represent 91% of global surface devoted to livestock production

• Important Areas- map uses more conservative definition of rangelands in which they make up 50% of world’s surface

  • The Sahel- Africa

  • African Savannas that support the last megafauna

  • Mongolian Step- Central Asia 

  • Tibetan Plateau- Central Asia

  • Patagonian Shrublands- Southern Argentina/Chile

  • Argentine Pampas- Central Argentina

  • Center of Australia- largely uninhabited desert, 70% of continent rangeland

Rangelands in the US

• Rangelands account for 61% of US land surface area

• US has 15 Rangelands Types:

  • Grasslands- majority, 6 types, among the most productive rangeland types

  • Tundra- 1 type

  • Desert Shrublands- 2 types

  • Shrubalands, Woodlands, and Subtropical- 3 types

  • Forests- grazed understory, 3 types

• Michigan- used to have tallgrass prairie but almost completely converted to agricultural

• About ⅔ of all US rangelands are privately owned

  • Management is completely voluntary on private land

  • Includes tribal nations and private ranchers

• About ⅓ of all rangelands federal and state owned

  • Managed by BLM, USFS, NRCS

    • Believe rangelands should be mutli-use- used for grazing and other things

Condition of Rangelands in the US

• Historic Loss- 272 million acres converted from rangeland

• Current Condition- 54 million acres failing health standards

  • Livestock overgrazing is the primary driver

    • Cause of subpar standards on 72% (40 million acres) of failing lands

    • Taylor Grazing Act of 1934- put regulations for grazing on public land

Ecological Characteristics of Rangelands

• High Precipitation Variability

  • Within rangelands annual rainfall variation

    • Between year variability is dangerous with inflexible stocking rates, cannot support same number of animals from good year to bad year

    • Across rangeland types

• Disturbance Adapted- native vegetation has evolved with fire and resistance to drought

  • Occasional fire and drought good for system

• Deep Root Systems- anchors soil, allows plants to access groundwater, can sequester carbon, and allows fire/drought resistance

  • Roots make up most of biomass

  • Taproot- deep growing dominant root, one primary root grows very deep, important for accessing groundwater, allows soil pores for form

  • Fibrous Root- deep expansive network of roots, not as deep as taproot but wider expanding, holds soil in place

  • Annual forbs and grasses- super tiny roots, don’t want

• Biodiversity

  • Rangeland Dependent Species- adapted to live only on rangelands, need rangelands to survive and thrive

    • Ex. Bison, prairie chicken, sage grouse

Rangeland Services

• Livestock Forage- food and fiber from rangeland forage

  • Ex. Wool, leather, meat, etc.

• Carbon Storage

  • 10% terrestrial biomass carbon- stored in living matter

  • 30% global soil organic carbon

• Watershed Function- help water quantity and quality

  • Infiltration, groundwater recharge, base flow

Rangeland Management Strategies

• Proper grazing management

• Fire as an ecological process and tool

• Water development to reduce overgrazing and protect riparian zones

Grazing Management Core Principles

• Stocking Rate and Livestock Type

  • Number of animal units per an area per unit time

  • 1 animal unit = 1,000lb cow/calf

    • 1 animal unit = amount of forage needed to feed one 1,000 cow and her calf

    • Used to standardize stocking rate

• Timing- season

  • More susceptible to overgrazing in spring- plant regrowing after winter, little plant matter to do photosynthesis and using energy stores to regrow

• Distribution

  • Fences- prevent animals from going to certain pastures/areas

  • Water- animals will go 1-2 miles away from water source to graze, surrounding veg suffers

• Duration and Rest- amount of time animals are out in a specific area

  • 50% Utilization Rule- remove (graze) no more than 50% of above-ground forage/plant production in any given area per year

    • More than 50%- plants pull energy from roots to regrow, resulting in risk from drought/fire

Fire as an Ecological Process

• Removes accumulated litter and allows nutrients to cycle

• Controls woody plant encroachment- one of the biggest threats to rangelands

• Wildlife habitat enhancement

  • Clears things like dense veg

Water Development and Riparian Management

• Water development to reduce overgrazing

• Protect riparian zones- cattle naturally congregate around riparian zones, trampling it

  • Can fence them off or move water from riparian area to cattle trough

Threats/Challenges to Rangelands

• Climate Change

  • Increased aridity

  • Drought intensification

  • Fire regime changes

  • Invasive species facilitation

• Woody Plant Encrochament

  • Brush and woody plant in rangeland is not necessarily bad

  • Becomes bad when they push out grassland