♪ Instrumental ♪
[cricket sounding]
[birds chirping]
[chicks squeeking]
[eagle calling]
(MALE NARRATOR) EVERYWHERE YOU LOOK IN THIS FOREST,
YOU SEE THE SIGNS OF AN ECOSYSTEM IN BALANCE--
FROM THE HARDINESS OF THE NATIVE PLANTS AND WILDLIFE,
TO THE UNDISTURBED SOIL,
AND CLEAR-RUNNING STREAMS.
[truck engine revving]
THERE ARE ROADS HERE, TOO.
THEY'VE
THEIR CONDITION REFLECTS NOT ONLY THE
OF THE PEOPLE WHO BUILD AND MAINTAIN THEM,
BUT ALSO A KEEN AWARENESS OF THE SURROUNDING ENVIRONMENT,
AND A CONCERN FOR THE FOREST'S FUTURE,
AND OUR OWN.
WE'RE IN THE CORONADO NATIONAL FOREST
EAST OF TUCSON, ARIZONA,
ON A ROAD THAT RUNS FROM THE TURN-OFF BACK THERE,
TO A LITTLE CAMPGROUND ABOUT A MILE FURTHER DOWN.
IN A WAY,
THIS STRETCH OF ROAD IS TYPICAL OF THE ROADS
THROUGHOUT OUR NATIONAL FOREST SYSTEM.
NOT THAT THIS
WE ALSO HAVE ROADS IN NATIONAL FORESTS
THAT ARE CLASSIFIED AS RAINFOREST,
OR EVEN HIGH DESERT.
WHAT'S TYPICAL ABOUT THIS ROAD IS THAT IT'S UNPAVED,
IT SERVES MULTIPLE NEEDS,
AND IT INTERACTS PROFOUNDLY WITH ITS NATURAL SURROUNDINGS.
WEAR AND TEAR FROM TRAFFIC AND WEATHER
MAKE IT NECESSARY TO REPAIR THESE ROADS
AND THEIR DRAINAGE SYSTEMS PERIODICALLY.
BUT, ADVANCES IN SCIENCE AND TECHNOLOGY
HAVE DRAMATICALLY IMPROVED OUR UNDERSTANDING
OF HOW TO GO ABOUT IT--
IN WAYS THAT SUSTAIN BOTH THE ROAD SYSTEM
AND THE SURROUNDING ENVIRONMENT.
AFTER ALL,
NATIONAL FORESTS ARE AMONG OUR MOST VITAL ASSETS.
AND WE NEED TO PRESERVE THEM FOR GENERATIONS TO COME.
♪ Instrumental ♪
(NARRATOR) FOREST SERVICE ROADS
HOLD A UNIQUE PLACE, BOTH IN OUR COUNTRY'S TRANSPORTATION SYSTEM,
AND IN THE NATURAL ENVIRONMENT.
THEY PROVIDE READY ACCESS TO NATURE
FOR THE TRAVELING PUBLIC,
AND FACILITATE THE MANAGEMENT OF NATURAL RESOURCES.
WHEN
AND REMAINS UNTENDED,
IT CAN COMPROMISE THE SAFETY OF DRIVERS
AND THE HEALTH OF NEIGHBORING ECOSYSTEMS.
WHEN THAT ROAD RUNS THROUGH THE COMPLEX ENVIRONMENT OF FORESTS,
ENVIRONMENTAL CONSIDERATIONS BECOME ESPECIALLY IMPORTANT.
TO UNDERSTAND HOW A ROAD INTERACTS WITH A FOREST,
WE FIRST NEED TO LOOK AT WHAT HAPPENS
BETWEEN NATURAL ELEMENTS WHEN THERE
IT'S AN EONS-OLD STORY THAT BEGINS WITH WATER,
AND SOIL.
EACH FOREST HAS A NUMBER OF WATERSHEDS
THAT COLLECT WATER FROM RAIN, AND MELTING ICE, AND SNOW,
OR FROM RAINFALL ALONE.
THE WATER FLOWS OVER AND THROUGH THE FOREST FLOOR
AS SURFACE FLOW AND GROUNDWATER.
AT FIRST, IT MOVES SLOWLY DOWN SLOPE,
DISPERSING OVER A WIDE AREA.
FORCEFUL BUILD-UP, OR
WON'T NORMALLY OCCUR
UNTIL THE WATER ENCOUNTERS AND ENTERS SMALL STREAMS.
FROM SMALLER STREAMS,
IT TRAVELS TO LARGER ONES,
AND FINALLY, INTO THE WATERSHED OUTLET--
USUALLY A RIVER.
A RIVER'S WATER REPRESENTS THE ACCUMULATION OF GROUNDWATER,
SURFACE FLOW, AND STREAM FLOW.
WHEN YOU ADD A
YOU RISK INTERFERING WITH THE NATURAL PROCESS.
ROADS CAN INTERCEPT AND DIVERT NATURAL DIFFUSED WATER FLOW,
CONCENTRATING IT RANDOMLY AND PREMATURELY.
HERE, THE ROAD HAS DIVERTED WATER FROM ITS NATURAL DRAINAGE PATH.
IT NO LONGER DESCENDS DOWNSLOPE
IN A NORMAL DISPERSED PATTERN.
INSTEAD, IT'S BECOME CONCENTRATED,
AND, IN EXTREME CONDITIONS, MAY EVEN BECOME DISPLACED,
OVERLOADING ONE WATERSHED, OR SUB-WATERSHED,
WHILE DEPLETING ANOTHER.
ANOTHER POSSIBLE CONSEQUENCE OF A CHANGE IN NORMAL WATER FLOW PATTERNS
IS FOR DITCHES AND CULVERTS TO CONCENTRATE WATER RUNOFF
SO THAT IT FLOWS DOWN TO SMALL CHANNELS, STREAMS, AND RIVERS
TOO QUICKLY,
OVERBURDENING THEM WITH A HIGHER THAN NORMAL WATER ACCUMULATION,
TAKING PLACE IN A SHORTER THAN NORMAL TIME PERIOD--
INCREASING THE EFFECTS OF PEAK FLOW.
LIKE WIND, RAIN, AND VEHICLE OR EQUIPMENT TRAFFIC,
WATER CONCENTRATION CAN BEGIN THE PROCESS OF EROSION,
SEPARATING SOIL PARTICLES FROM THE GROUND,
AND ALLOWING THEM TO BE TRANSPORTED
UNTIL THEY SETTLE OUT IN OTHER PARTS OF THE FOREST,
INCLUDING LAKES AND STREAMS.
ONCE IN THE STREAM,
THE SEDIMENT CHANGES THE AQUATIC
AND ADJACENT RIPARIAN ECOSYSTEMS.
IT COVERS UP AND FILLS IN SPAWNING BEDS,
SUFFOCATING FISH EGGS,
INSECT LARVAE,
AND OTHER ORGANISMS.
THE SOIL ALSO CLOUDS THE WATER,
MAKING IT HARDER FOR THE STREAM'S INHABITANTS
TO LOCATE THEIR DIMINISHING FOOD SUPPLY.
THOSE THAT DO SURVIVE
OFTEN SUFFER THE ABRASIVE EFFECTS OF THE SOIL PARTICLES
ON THEIR SENSITIVE GILL TISSUES.
SLOWLY BUT SURELY,
AS THE SEDIMENT SETTLES OUT,
THE STREAM BECOMES
FURTHER LOWERING SURVIVAL RATES OF EGGS AND FRY.
THE RAISING OF A STREAMBED
ALSO CAUSES THE STREAM TO BECOME
TO ACCOMMODATE THE NORMAL VOLUME OF WATER.
THIS RESULTS IN EROSION OF OVERHANGS--
THE SHADY INTERLOCKING MASSES OF VEGETATION
THAT NORMALLY PROVIDE A SANCTUARY FOR AQUATIC LIFE
TO HIDE, REST, AND FEED.
AS USUAL IN AN ECOSYSTEM,
LOCAL IMPACTS DON'T REMAIN LOCAL.
AS SMALL CREEKS BECOME SEDIMENT-LADEN AND WARM UP,
THEY, IN TURN, WARM, AND OTHERWISE ALTER,
LARGER ONES DOWNSTREAM.
NEIGHBORING
SEDIMENT INCREASES THE COST OF PURIFYING DRINKING WATER,
AND FILLS IN RESERVOIRS AND CANALS.
IT CAN EVEN DAMAGE TURBINE GENERATORS IN HYDROELECTRIC FACILITIES.
SOME EFFECTS ARE HARDER TO MEASURE THAN OTHERS.
HOW CAN YOU CALCULATE THE COST OF LOSING A CHOICE FISHING HOLE,
OR A FAVORITE HIKING TRAIL, OR CAMPSITE?
(HOST) OF COURSE, QUESTIONS LIKE THAT ARE IMPOSSIBLE TO ANSWER.
BUT THERE'S A RELATED QUESTION
THOSE OF US WHO MAINTAIN FOREST ROADS
ASK EVERYDAY--
HOW CAN WE HAVE THE ROADS WE NEED
AND
THE ANSWER CAN BE FOUND IN THE EARLIER QUESTION
OF WHERE THE WATER WOULD GO IF THE ROAD DIDN'T EXIST.
DO EVERYTHING YOU CAN TO EMULATE THE WAY NATURE MOVES WATER
AND YOU MINIMIZE DISTURBANCE TO BOTH THE ROAD
AND ITS NATURAL SURROUNDINGS.
(NARRATOR) THE KEY TO PUTTING THAT PRINCIPLE INTO PRACTICE
IS
ROAD-DIVERTED WATER FLOW.
THAT MEANS USING THE MOST EFFECTIVE MEASURES AVAILABLE
FOR CONTROLLING THE VOLUME AND VELOCITY OF WATER.
THE FIRST STEP IS TO MAKE SURE THE TRAFFIC-BEARING PORTION OF THE ROAD--
ALSO KNOWN AS THE TRAVELED WAY--
HAS AND MAINTAINS A PROPERLY DEFINED SHAPE.
WATER SHOULD MOVE OFF THAT SURFACE EFFICIENTLY
SO THAT IT DOESN'T DEGRADE THE ROAD.
WHENEVER POSSIBLE,
THE WATER SHOULD BE RELEASED INTO THE FOREST
IN A WELL DISPERSED PATTERN
THAT DOESN'T DISTURB SURROUNDING SOIL.
IN MAINTAINING DRAINAGE STRUCTURES
LIKE THIS LEAD OUT DITCH,
IT'S IMPORTANT TO IMITATE NATURE'S WAY OF PROTECTING EXPOSED AREAS.
VEGETATIVE MATERIALS LIKE THESE
REDUCE THE SPEED,
AND, TO A LESSER DEGREE,
THE CONCENTRATION OF THE WATER.
SO DO DITCH DAMS AND OTHER BARRIERS.
THE FLOW CAN ALSO BE
INTO FLAT, VEGETATED AREAS OF FOREST FLOOR,
ALLOWING THE WATER TO SOAK INTO THE GROUND,
LEAVING THE SEDIMENT BEHIND.
ONE OF OUR PRIMARY OBJECTIVES
WHEN DEALING WITH ROAD DRAINAGE
IS TO REDUCE OR ELIMINATE FINE SEDIMENT
FROM ENTERING THE STREAM CHANNEL.
AND A PARTICULARLY EFFECTIVE
WAY TO DO THAT
IS TO PROVIDE A BUFFER STRIP
BETWEEN THE ROAD AND THE STREAM,
AND THAT BUFFER STRIP CAN CONSIST OF GRASS,
OR SOMETHING CONSIDERABLY MORE DENSE LIKE BRUSH.
WHAT THAT DOES IS
IT ALLOWS THE VELOCITY TO DROP ENOUGH
THAT THE FINE SEDIMENT SETTLES OUT
BEFORE ENTERING THE STREAM CHANNEL.
(NARRATOR)
THEY DO JUST WHAT THEIR NAME IMPLIES--
INTERRUPTING AND SLOWING DOWN THE WATER FLOW
SO THAT SEDIMENT CAN SETTLE OUT,
RATHER THAN CONTINUE ITS JOURNEY TO OTHER PARTS OF THE FOREST.
OF COURSE,
THESE MANMADE SYSTEMS ARE ONLY AS GOOD AS THEIR UPKEEP.
BUT, WITH REGULAR CARE,
THEY FUNCTION EFFECTIVELY
AS PART OF THE FOREST'S DEFENSE AGAINST EROSION AND SEDIMENTATION
CAUSED BY CONCENTRATED WATER FLOW.
OF COURSE, AS WE'VE SEEN,
TOO
WHEN A ROAD DIVERTS WATER FROM ITS NORMAL FLOW PATH,
AND UNNATURALLY CONCENTRATES IT,
THE FLOW MAY ERODE THE GROUND SO DEEP
THAT IT'S BELOW THE NATURAL WATER TABLE.
THIS CAUSES THE WATER LEVEL TO DROP,
KILLING SHALLOW ROOTED GRASSES AND OTHER VEGETATION.
THAT CAN UPSET THE NATURAL BALANCE
BETWEEN AND WITHIN THE FOREST'S PLANT AND ANIMAL SPECIES--
ULTIMATELY LEADING TO EVEN MORE EROSION
AND RELATED CHANGES TO THE FOREST.
FOR EXAMPLE,
IF SHALLOW-ROOTED GRASSES AND OTHER GROUNDCOVER PLANTS DIE OFF,
THEY'RE NO LONGER ABLE TO HELP HOLD THE SOIL TOGETHER,
AND TO SLOW AND DISPERSE CONCENTRATED WATER.
WHEN RAIN
IT FALLS ON SOIL THAT'S MUCH MORE SUSCEPTIBLE TO EROSION.
OF COURSE, NO MATTER HOW SKILLFULLY YOU MAINTAIN THE ROADS,
IT JUST ISN'T POSSIBLE TO STOP ALL EROSION,
BUT IT
EVEN IN EXTREME CONDITIONS.
HERE IN THE SONORAN DESERT OF THE CORONADO NATIONAL FOREST IN SOUTHERN ARIZONA,
THERE'S LESS THAN 12 INCHES OF RAINFALL A YEAR.
CONDUCTING NECESSARY REPAIRS ON THESE ROADWAYS
CAN SERIOUSLY REDUCE THEIR SURFACE COHESIVENESS
IF DONE WITHOUT PROPER MOISTURE CONTENT.
LEFT UNTREATED,
THE SOIL COULD SOON BE CARRIED AWAY BY THE WIND,
AND BY WHATEVER PRECIPITATION DOES OCCUR.
SO, IN A PLACE LIKE THIS,
DURING OPERATIONS LIKE BLADING,
IT'S
TO KEEP THE PROPER MOISTURE CONTENT IN THE ROAD SURFACE
TO ALLOW PROPER SHAPING.
THIS MAY MEAN MECHANICALLY SPRAYING THE ROAD SURFACE WITH WATER,
OR SCHEDULING ROADWORK SOON AFTER A RAINFALL.
IN
BUT ESPECIALLY A DRY ONE LIKE THIS,
COMPACTING THE ROAD IMMEDIATELY FOLLOWING BLADING OPERATIONS
IS ESSENTIAL TO IMPROVING THE SOIL'S COHESIVENESS.
IN SOME SITUATIONS,
SOIL-STABILIZING ADDITIVES MAY ALSO BE NEEDED.
HERE, AS IN ALL FOREST SERVICE ROAD MAINTENANCE,
THE NEW AND IMPROVED RULE OF THUMB IS
"DISTURB THE SOIL ONLY WHEN ABSOLUTELY NECESSARY.
AND, WHEN IT
DOES THIS ROADSIDE DITCH NEED CLEARING AND RESHAPING?
ONLY IF IT'S SENDING WATER BACK ONTO THE ROAD,
OR OTHERWISE FUNCTIONING IMPROPERLY.
EXPERIENCE AND RESEARCH HAVE TAUGHT US THAT
"CLEANER AND CLEARER" ISN'T ALWAYS "BETTER"
WHEN IT COMES TO PROTECTING FOREST SOIL.
(NARRATOR) IN FACT,
THESE ROCKS AND PLANTS ARE HELPING
TO SLOW THE FLOW OF WATER THROUGH THE DITCH
AND HOLD THE SOIL TOGETHER.
IN LIGHT OF MODERN MAINTENANCE POLICIES AND PRACTICES,
THE PRESENCE OF A ROAD IN A FOREST
DOESN'T HAVE TO SIGNAL THE PRESENCE OF EXCESSIVE EROSION
AND ITS CONSEQUENCES--
FROM STREAM SEDIMENTATION TO POSSIBLE SLOPE FAILURE.
PEACEFUL CO-EXISTENCE BETWEEN A ROAD SYSTEM AND AN ECOSYSTEM
IS NOTHING TO TAKE FOR GRANTED.
IT DEMANDS A GREAT DEAL OF PLANNING, CARE, AND SKILL,
BUT IT
AND THE STAKES COULDN'T BE MUCH HIGHER.
AND, SURELY, THE EFFORT IS WORTHWHILE.
NATIONAL FOREST ROADS
AREN'T JUST A MEANS OF ACCESSING AND MANAGING RESOURCES,
OR GETTING FROM ONE PLACE TO ANOTHER
BY WAY OF "THE SCENIC ROUTE."
THEIR CONDITION DIRECTLY IMPACTS THE HEALTH AND LONGEVITY
OF A LIVING TREASURE
WHOSE IMPORTANCE WE'RE JUST BEGINNING TO FULLY UNDERSTAND.
WHETHER OR NOT FORESTS LIKE THIS ONE
CONTINUE TO THRIVE AND PROSPER
DEPENDS LARGELY ON HOW
FOR THE MEN AND WOMEN WHO WORK HANDS-ON
TO MAINTAIN UNPAVED SECONDARY ROADS,
THE TASK COULDN'T BE MORE IMPORTANT OR REWARDING--
TO TRULY MAKE A DIFFERENCE IN THE NATURAL WORLD
BY HELPING TO PRESERVE AND SUSTAIN OUR NATIONAL HERITAGE
FOR GENERATIONS TO COME.
♪ Instrumental ♪