Assessing landscape health, Part 2: diagnosis

You learned the basics of landscape assessment in Part 1 of this article. Here's your chance to test your knowledge. How healthy are these landscapes?

Kachana Pastoral Co.
bare ground

Northwest Australia: This area gets 300-1500 mm (11-59 inches) rainfall yearly, averaging around 750 mm (29.5"). The wide moisture fluctuations and a long dry season make most of the area brittle. This spot lies in a valley that captures extra moisture.

  • Brittleness: Extreme due to bare soil.
  • Water cycle: Rain pounds the ground, then runs off, causing erosion. Bare soil dries out quickly.
  • Mineral cycle: What minerals are present are in the soil, not living organisms.
  • Energy flow: No green plants, so solar energy is wasted.
  • Succession: Virtually nothing lives here. Seeds in the ground can't sprout successfully.
  • Below ground: No living plants; dryness kills soil organisms.
  • What used to be here? This was a wetland until the 1970s. Under Aboriginal management, it was a rain forest.
Kachana Pastoral Co.
thick grass

Northwest Australia: Same spot seven years later.

  • Brittleness: Moderate.
  • Water cycle: Rain hits living plants or plant litter; soil doesn't erode. Water soaks into the soil and stays. (This is the end of the dry season, yet the grass is still green.) Soil life stays active all year.
  • Mineral cycle: Nutrients are in living organisms and soil humus. Active soil life promotes nutrient cycling year-round.
  • Energy flow: leaves capture sunlight year-round, producing vast quantities of food that support many kinds of life.
  • Succession: The number of plant species and age range of individuals is still limited. Some wildlife is now returning.
  • Below ground: Lots of roots. This area gets thoroughly grazed 3 times per year, which puts an enormous mass of roots into the soil, and lots of dung on it.
Joy Livingwell
dry grass, mostly bare ground on left of fence

Northern central California: Midsummer in an area that usually gets no rain from May 1 to November 1. Rainfall ranges from 300 to 1800 mm (12 to 72 inches) yearly, averaging 850 mm (34 inches).

While the area outside the fence has better plant cover than the ground within, plants on both sides are mainly non-native annuals.

  • Brittleness: Brittle.
  • Water cycle: Ground is hard and dry on both sides of the fence. Rains will produce much runoff. The less-covered soil will erode more.
  • Mineral cycle: Nutrients are locked in dead plant matter and dry cattle dung. Because soil is completely dry, neither can decay.
  • Energy flow: No live plants, therefore no sunlight is getting captured and turned into food. Native perennials go dormant this time of year to conserve water, but these annuals stopped capturing sunlight two months ago.
  • Succession: Very few species live here, and most are non-native annuals. Wildlife and cattle find little to eat.
  • Below ground: Shallow roots can't hold soil well. Soil life is dead or dormant due to dryness and heat from the sun.
  • What used to be here? Before the Europeans, this was a perennial grassland that stayed green all summer, with lots of nitrogen-fixing legumes and high biodivesity. It supported large populations of big game such as deer, bear, cougar, and elk.
Roger Bowe
weedy desert

New Mexico, U.S.A: 46% of this pasture is bare ground, most with a hard crust. Another 44% of the soil surface is covered with litter (dead plant material).

  • Water cycle: Rain will hammer the bare ground, and what soaks in will tend to evaporate again from the soil surface.
  • Mineral cycle: Soil organisms can't thrive where the soil is bare.
  • Energy flow: Low, because so little sunlight falls on leaves. This pasture grew 16 kg of beef per hectare (16 lbs. per acre) in 1984.
  • Succession: 11% of the plants are snakeweed, a noxious weed that provides poor forage for livestock or wildlife and is a sign of low biodiversity). Just 6 perennial grass species remain.
  • Below ground: Bare ground means few roots and poor biological functioning.
  • What used to be here? This was once perennial grassland.
Norman Neave
tall weedy plants

Eastern South Africa: A mild climate without freezes. Rainfall averages around 750 mm (30") yearly, falling mainly from October through February (summer), but can be very erratic with long dry periods.

  • Brittleness: Brittle.
  • Water cycle: Although the ground is protected from pounding rains, its surface is bare. A dam site downstream from this area has completely dried out since the 1960s.
  • Mineral cycle: These plants don't shed their leaves, and grazers don't eat them, so they don't contribute much to the mineral cycle.
  • Energy flow: Sunlight gets captured, but these leaves don't provide good food for wildlife or livestock.
  • Succession: A few species of tap-rooted non-native plants that grazers don't like to at have taken over -- mostly Chromolaena odorata, but also Syringa, Bugweed and Lantana. Most wildlife is gone from this area.
  • Below ground:
  • What used to be here? This was a grassy waterway. The whole area was once a grassland/wetland with vast herds of grazers such as buffalo and wildebeest, plus large numbers of elephant. These were exterminated by hunting in the 1800s and the tsetse fly campaign in the 1950s. Rest then killed the grasses, and tap-rooted plants invaded.
 
tall weedy plants
Joy Livingwell
tall weedy plants

Eastern South Africa: About 40 km from the photo above, at the end of the rainy season, in the Greater St. Lucia Wetland Park.

This meadow looks well-covered from a distance. Digging down to the soil surface reveals that most of these plants have only a few live leaves.

  • Brittleness: Brittle.
  • Water cycle: No water hits bare ground, which is good.
  • Mineral cycle: Most nutrients are tied up in dead leaves. Stunted grass roots can't bring nutrients from deep in the soil.
  • Energy flow: Though this meadow looks green from the side, in fact most sunlight falls on dead leaves and gets wasted.
  • Succession: Low, with masses of the same species of grass. No seedling has the energy to grow up through the mats of dead leaves to reach sunlight; these are all mature plants.
  • Below ground: Few live leaves mean the grasses' roots are stunted and can't do a good job of holding or regenerating soil.
  • What used to be here? Part of the same grassland/wetland complex as above, teeming with game.
Joy Livingwell
some green plants on mostly bare ground

Eastern South Africa: The conventional response to dying, overrested grass such as shown above is to burn it. This part of Hluhluwe-Umfolozi Park, about 70 km inland from the coast, has been repeatedly burned. Beginning of the rainy season.

  • Brittleness: Brittle.
  • Water cycle: Poor. Bare ground is vulnerable to drying, erosion, and capping (forming a crust).
  • Mineral cycle: Poor. Although fire releases some minerals from dead plants, a lot of nutrients escape in the smoke. Dead growth that didn't burn is still standing, rather than protecting the soil.
  • Energy flow: Poor. Most sunlight falls on bare ground.
  • Succession: Bare ground tells us young plants are failing to establish. This area is losing biodivesity.
  • Below ground: New soil cannot form with so few roots and so much bare ground.
  • What used to be here? This area used to support vast herds of game, numbering in the millions. Most game is now gone, yet managers are destocking the park to reduce overgrazing.
Norman Kroon
brush on bare ground

Southern central South Africa: This part of the semi-arid Karoo gets 330 mm (13") of rain annually.

  • Brittleness: Brittle.
  • Water cycle: Bare ground can't absorb rain well, yet is vulnerable to erosion.
  • Mineral cycle: Poor. Soil is hard-capped and white.
  • Energy flow: Much sunlight is wasted. What does get captured stays in the plants -- neither wild grazers or cattle can live on this brush.
  • Succession: Low, mostly invasive Harpuis bush.
  • Below ground: With so much bare ground and so few roots, no new soil can form. In fact, soil is being lost.
  • What used to be here? Early travelers wrote of grass so high it touched their stirrups as they rode by. The area contained many now-vanished springs, and supported vast herds of game.
diverse grass and forbes

Central Kansas, U.S.A.: Hot, humid summers alternate with cold, dry winters with limited snow. This pasture is intensively grazed by cattle, with long rest periods between.

  • Brittleness: Semi-brittle.
  • Water cycle: Excellent. Deep topsoil with high humus content has tremendous water-holding capacity.
  • Mineral cycle: Excellent. These deep-rooted plants bring minerals from deep in the soil to the surface.
  • Energy flow: Excellent. These perennial plants green up early and capture sunlight late into the year.
  • Succession: High, with a diversity of warm- and cool-season grasses, forbes, and nitrogen-fixing legumes.
  • Below ground: Pulse-grazing of deep-rooted perennials provides lots of food for soil-building organisms.
  • What used to be here? This is a never-plowed remnant of the vast prarie that used to cover central North America. Early travelers reported vast numbers of elk and bison, plus abundant deer, waterfowl, and small game.

Updated 31 October 2002