Plants
-critical to ecosystem structure and function
-form much of habitat, serve as base of food chains,
regulate microclimate, play a part in many nutrient
cycles, and affect movement of soil and water
-300,000 species worldwide with most being angiosperms
-revegetation is the most common restoration action
worldwide
-may need to address landform, soil and hydrology
problems before attempting revegetation
-invasive species may need to be removed for
establishment of native vegetation
-often will recolonize on its own if seed banks or sources
are nearby Ex. Revegetation efforts on Lower Rio
Grande Valley of Texas since 1958 TJS 54: 163-176
Facilitating natural recolonization and propagule sources
-may be able to mechanically stimulate natural restoration
and ecological function and services without planting
Ex. Restoration of old growth forest, foresters mimic natural
disturbance with prescribed burning to keep forest from
brushing up; Ecological forestry, which leaves behind
trees of varying ages as well as dead logs for nesting,
nutrients, and cover Fig. 8.1
-costs are greatly decreased in vegetative restoration if
plantings and seedings are limited or not used at all.
This is accomplished by using on-site remnant
populations that spread vegetatively or by seed, or
utilizing seeds in soil (soil seed bank).
-remnant populations are often found along borders
(fences), places difficult to reach with tractors or mowers,
and patches protected from disturbances like grazing
Fig. 8.2
Figure 8.1 A forest manager in Finland girdling trees in a boreal forest to create attributes of oldgrowth forest in a stand that had been managed for wood products so there is dead standing wood
for nesting sites
Figure 8.2 Remnants of natural vegetation, such as this strip of tallgrass prairie in the midwestern
U.S., can serve as a source of propagules for plant colonization during restoration
Facilitating natural recolonization- Propagule sources
Seed banks-
Figure 8.3 A germination assay can be performed on soils of a restoration site to determine the
species composition and density of the seed bank
Facilitating natural recolonization- Propagule sources
-dispersal is an important source of new colonists for
restoration sites that are situated near intact natural
ecosystems that can serve as sources of propagules
-closesness to source depends on the agents of dispersal
with gravity-dispersed seeds needing a close source
while water, wind, or animal-dispersed seeds may
establish from a more distant source and thus have
greater source strength Fig. 8.4
Figure 8.4 Recovery of rainforest vegetation in a pasture is often primarily limited by seed
dispersal, as shown for this forest edge in southern Costa Rica. Wind-dispersed seeds had the
greatest source strength as rainforest vegetation became re-established in the pasture
Facilitating natural recolonization- Promoting establishment
Entrapment microsites-places within an ecosystem where
dispersed seeds settle because of being trapped by
features like rocks, vegetation, or topography
-can be created artificially as with restoration of terrain
exposed by diamond mining in South Africa
-used 750 mm high shade cloth fences perpendicular to
prevailing winds at intervals of 6 m. with cardboard
around plantings Fig. 8.5
-in forest restorations, nurse logs are often used and may
foster plant recruitment, increase light availability as they
are elevated above the surface, and trap moisture as
well as provide nutrients via decomposition Fig. 8.6
Figure 8.5 Plant establishment in diamond-mined lands of South Africa can be severely limited by
desiccating winds and very low precipitation and entrapment microsites were constructed from
shade cloth and cardboard
Figure 8.6 Nurse logs facilitate establishment of later successional species
Facilitating natural recolonization- Nurse plants and limitations of natural recolonization
- plant that enhances the establishment of another plant
-nurse plants may provide colonists with more moderate
microclimates, shelter from wind and abrasion, and
greater access to nutrients (nitrogen fixing legumes or
accumulation of detritus by nurse plant) Figure 8.7
-restoration methods vary depending on initial conditions at
site. Table one illustrates this and areas with fair to high
potential for natural recolonization, that is close source
areas or soils with seed banks low in invasive species,
may need little to no planting or weed control while those
with poor sources may require more planting and weed
control Table 8.1
Figure 8.7 (A) Salvia oxyodon. (B) Salvia shrubs act as nurse plants in montane ecosystems in
Spain, facilitating the establishment of native pines
Table 8.1
Invasive Plant Control
-following habitat conversion, many sites are not devoid of
vegetation at the onset of restoration but often these
sites are dominated by invasive species-often introduced
species that rapidly expand their geographic ranges
because of prolific seeding, high germination and growth
rates, short times to maturity, or rapid asexual
propagation Ex. Phragmites Reed Fig. 8.8
-some invasive species are nitrogen fixers, which can
facilitate their spread, and if they may act as nurse plants
for other problematic species Ex. Westhoek Nature
Reserve in Belgium had this situation and woody plants
began encroaching on rare dune communities with
endangered species so restoration involved eliminating
woody species from the dunes Fig. 8.9
Figure 8.8 Creeping stolons of Phragmites australis, an invasive grass in many parts of the world,
rapidly forms dense, single-species stands
Figure 8.9 Sea-buckthorn (Hippophae rhamnoides), a nitrogen-fixing species, spreads into an
active dune at Westhoek Nature Reserve (Belgium) threatening rare, endangered dune species
Invasive Plant Control- Landscape-level invasive plant control
-best not to allow establishment of invasives in the
landscape and the more rapid the response, the easier it
is to stop because populations are small and more
manageable Fig. 8.10
-if allowed to establish in the landscape, than site based
restoration is affected by immigration from landscape
-biological controls such as pathogens and insect
herbivores have been used at landscape level with some
success Ex. Purple loosestrife, introduced from Europe
is invasive in North American wetlands and has been
controlled with a herbivorous beetle that targets the plant
Fig. 8.1
Figure 8.10 Control of invasive species often begins after they have spread extensively, which
makes eradication infeasible and control expensive
Figure 8.11 Purple loosestrife (Lythrum salicaria), introduced to North America from Europe, has
spread extensively and adversely affects wetland ecosystems. Herbivorous beetles reared on
plants in sleeve cages and released in wetlands
Invasive Plant Control- Site-based invasive plant control
Classified as chemical (Fig. 8.12) or non-chemical
-both can affect non-target native species
Non-chemical-Table 8.2
Figure 8.12 Foliar application of an herbicide to an old field as part of restoration site preparation
Table 8.2 (Part 1)
Table 8.2 (Part 2)
Invasive Plant Control- Herbicide use in ecological restoration
Chemical-herbicides Fig. 8.12
Table 8.3 (Part 1) Trichlopyr should be spelled Triclopyr
Table 8.3 (Part 2)
Invasive Plant Control- Herbicide use in ecological restoration
Glyphosphate (Monsanto-Roundup)
Triclopyr (Dow-Remedy, Weed-b-gon, Brush-b-gon)
Invasive Plant Control- Herbicide use in ecological restoration
Clopyralid (Dow Agro Reclaim)
Surfactants that I use with Remedy and Reclaim
Invasive Plant Control- Devising and implementing an invasive plant control strategy
Treatment Regime= combination of methods to be used,
timing of treatments, and number of treatments
-need to experiment to see how any herbicide or surfactant
affects non-target species
-aided by maps of invasive species Ex Western Australia
60 ha restoration that used prescribed fire in areas of
densest invasive veldt grass Fig. 8.13
Other considerations for treatment regimes:
Figure 8.13 This map of invasive veldt grass populations in a 60-ha remnant woodland in Western
Australia was prepared to determine treatment priorities
General Considerations for Planting and Seeding- Species selection
Plant restorations usually involve two categories
Table 8.4 (Part 1)
Table 8.4 (Part 2)
General Considerations for Planting and Seeding- Plants or seeds
Benefits of using plants
Figure 8.14 Restoration of aquatic species, such as the bulrushes being planted along this
lakeshore edge, often relies on the use of plants, which can be attached to the substrate
General Considerations for Planting and Seeding- Plants or seeds
Benefits of using seed
General Considerations for Planting and Seeding- Sources of seeds and plants
-seeds or plants used must provide founding populations
that are well adapted to the restoration site
environmental conditions
-in general, obtain them from as close to the restoration site
as possible
-three basic approaches for matching sources of seed and
plants to conditions at the revegetation site
Figure 8.15 Three different approaches for selecting sources for plants and seeds used for a
restoration project
General Considerations for Planting and Seeding- Sources of seeds and plants
-source choice affects the ability of some plant species to
reproduce, especially if populations are small because
many have evolved mechanisms to prevent selffertilization and promote outcrossing
-successful reproduction only occurs when the pollen
source is a different mating type than the maternal plant
and augmentation of population with different mating
types may need to occur during restoration
Ex Endangered lakeside daisy, which now only occurs in a
few dry grassland around the Great Lakes region were
not producing seed until different mating types were
discovered and augmentation took place Fig. 8.16
Figure 8.16 A lakeside daisy (Hymenoxys acaulis var. glabra) population in Ohio (United States)
underwent restoration involving the addition of new mating types so it could reproduce.
General Considerations for Planting and Seeding- Sources of seeds and plants
-restoration projects that are large relative to the number of
source populations can result in overharvesting of seeds
from remnant populations
-conversely, if collection ranges are too broad, the
populations that establish on restoration sites may not
only perform poorly, but also introduce maladaptive traits
into native populations through pollen or seed dispersal
-sources of seeds and plants can also be cultivated
Ex. Wildseed Farms in Fredericksburg and Native
American Seed in Junction, TX
General Considerations for Planting and Seeding- Cultivar use in ecological restoration
Cultivar-
Figure 8.17 Members of the British Petroleum restoration team cut native tundra sod for
revegetation trials on oil resource development lands in Alaska’s North Slope (Case A)
Using Seeds for Revegetation- Seeds in topsoil transfers
-seeds for revegetation may be obtained as a part of topsoil
transfer because of seed banks present
-appropriate when soil contains banked seeds of target
species but lacks invasive species and the area is slated
for destruction that will remove the soli anyway
-species composition and numbers can be determined by
germination assays
Using Seeds for Revegetation- Designing seed mixes
Seed mix- composition of species and the proportions of
each seeded together on a site Fig. 8.18 and Table 8.5
-seed mixes sometime have a cover crop added because
achieving canopy cover within a few weeks of seeding
can suppress annual weeds, retain soil moisture, and
reduce soil erosion
-cover crops are short-lived and die out as remainder of the
seed mix becomes established Ex. Oats
Figure 8.18 Ancient chalk grassland in Dorset, United Kingdom
Table 8.5
Using Seeds for Revegetation- Seeding rates
Seeding rate-amount of seed (number or mass) sown per
unit area
-most commonly specified by weight and less often by
density
-determined by preliminary trials or adopting rates from
similar revegetation projects
-if seeds are broadcast (sown on the surface) higher rates
are needed than if drilled
-high seed rates are also beneficial if encroachment by
weedy or invasive species is likely
Using Seeds for Revegetation- Seed collecting
-collections from the wild are the main source of seed used
in restoration (Fig 8.19) but producing cultivars can
minimize impacts on native populations (Fig. 8.20) as
long as they are genetically diverse and not maladaptive
-only fully mature seeds should be collected as premature
seeds are more vulnerable to fungi since they are moist
and their seed coats are permeable because the
abscission layer that forms between the maternal plant
and nearly ripe seeds has not cut off the seed water
supply. Once this happens drying triggers seed
maturation
-mechanical harvester that use rotating brushes (Fig. 8.21)
or hand harvesting (trees and shrubs) are used
Figure 8.19 Harvesting ripe seed in a remnant Great Plains grassland (Nebraska)
Figure 8.20 Seed production fields for native species used in public lands revegetation projects in
the Great Basin (United States)
Figure 8.21 The rotating brush of this seed harvester gently strips seeds from plants and pulls
them into a collection hopper
Using Seeds for Revegetation- Seed cleaning and storage
-seeds are often stored after they are harvested
-seeds with fleshy fruits must be depulped by macerating
the flesh and separating it from the seeds Fig. 8.23
-seeds with dry cones, fruits, and/or bracts may be cleaned
by winnowing with screens, flotation, or using air
separators
-clean, dry seed can be stored in breathable bags or boxes
Fig. 8.22
Two types based on moisture requirements in storage:
1. Orthodox- seeds that can be dried to less than 5% of
their fresh weight and remain viable
-can be frozen with -18 C recommended
1. Recalcitrant- seeds with high minimum moisture
contents that cannot be dried and stored, nor frozen
-typical of many aquatic, tropical, and woody species
Figure 8.23 Fleshy fruits, such as these duinebessie (Nylandtia scoparia) from the west coast of
South Africa, need to be depulped prior to storage
Figure 8.22 Air drying of seeds prior to storage
Using Seeds for Revegetation- Dormancy and germination
Dormancy-
Using Seeds for Revegetation- Dormancy and germination
After-ripening-
Using Seeds for Revegetation- Seed quality
Pure live seed (PLS)
PLS = mass of seed X proportion seed (not chaff) X
proportion germinable or viable
Ex. 1000 g of seed is 20% chaff and has 70 % viability
(data from seed assay)
PLS = 1000g X 0.80 seed X 0.70 viable = 560 g.
Allows one to determine seed rates an compare batches of
seeds from different sources
Using Seeds for Revegetation- Seeding methods
-first consideration for sowing seeds is determining whether
the species needs to be at the soil surface or buried to
break dormancy
Broadcasting
-for species that require light
-as simple as hand-casting but on larger sites mechanical
spreaders are more efficient Fig. 8.24
-in rugged or unstable terrain, hydroseeding by mixing
seeds into a slurry with water, mulch, dye, and often
fertilizer and spraying it from a land vehicle below an
incline or by helicopter or plane Fig. 8.25
Drilling
-for species that need to be underground to break
dormancy
-optimal depth depends on stored carbohydrates in seed
Figure 8.24 Broadcasting native seed with a mechanical spreader
Figure 8.25 Hydroseeding a mined land site in South Africa
Using Plants for Revegetation- Nursery-produced plants
-in transplanting, root systems are difficult to excavate
without damage that contributes to high mortality
-exception are plants that reproduce vegetatively,
underground stems like rhizomes or stems with buds
that can be transplanted without killing the parent plant
-nursery-produced plants are produced from seeds or
vegetative cuttings
-seeds are better as they provide more genetic variation
-some plants, often rare, may not be able to be produced in
nurseries and in vitro propagation or tissue culture is
used
-grown in nutrient agar Fig. 8.26 and then transferred to
pots
Figure 8.26 Technicians can use tissue culture to propagate plant species that produce very little
seed or few vegetative propagules
Using Plants for Revegetation- Nursery-produced plants
-restorationists need to decide whether to install young,
typically small plants or larger, more mature plants Fig.
8.27
-plant size is specified by the age of the plant or size of the
container
-for herbaceous plants used in restoration, larger plants are
preferred if the plants are slow-growing or it is going in
with dense vegetation at the restoration site
-plants for arid restoration may need to have deeper pots
so they have deeper root systems
-to increase the survival rates of nursery-grown plants, they
should be hardened or acclimated to field conditions
before transplanting
Figure 8.27 Horticulturalists rear plants propagated from seeds and cuttings in nurseries until they
reach a suitable size for installation
Using Plants for Revegetation- Vegetative transplants
-rhizomes are often used at restoration sites but at some
sites, wind, water, and wave forces are strong and plants
should be grown in mats so they have greater chance of
success Figs. 8.28-8.29
Figure 8.28 Burreed plant (Sparganium eurycarpum) with three rhizomes
Figure 8.29 Where newly established plants are vulnerable to uprooting, installing plants that have
been grown in a fiber mat may reduce this problem
Using Plants for Revegetation- Planting plans
Figure 8.30 Example of a restoration model for Brazilian Atlantic forests
Using Plants for Revegetation- Planting plans
-planting plans may involve maps Ex. New Zealand Mana
Island Revegetation Plan Fig. 8.31
-in restorations where relationships between plants and the
environment is complex, cross-section maps are used to
represent the relationship Ex. Tidal patterns are crucial
to the survival of mangrove plantings Fig. 8.32
Figure 8.31 Revegetation of Mana Island forest and scrub has been guided by a general planting
plan; specific plans are developed for individual project areas on the island
Figure 8.32 Where plant establishment is greatly affected by an environmental factor that is
spatially variable (ie tidal levels and erosion), detailed planting maps are critical for planning
revegetation projects
Using Plants for Revegetation- Plant installation
Preparation of a site for installation begins with the transfer
of information from the planting plan to the ground
-delineate planting areas with stakes or flags with locations
of large plants like trees and shrubs individually marked
-because newly installed plants lack extensive root
systems, they may benefit from watering or
polyacrylamide hydrogels applied to the roots or inside
planting holes Fig. 8.33
Figure 8.33 A member of a Cooplantar (Cooperative of the reforestation workers, SE Brazil)
restoration team (Monte Pascoal-Pau Brasil Corridor project, Case I) applies polyacrylamide
“hydrogel” prior to installation of a tree seedling
Restoring Microbial Mutualists
In intact ecosystems plants are assisted in nutrient
acquisition by microbial mutualists: nitrogen-fixing
bacteria or mycorrhizal fungi
Two groups of nitrogen-fixing bacteria:
Rhizobia (Rhizobium, Bradyrhizobium, Azorhizobium) on
legumes
Frankia (bacteria on wide number of plants including
birches and roses)
-infection by rhizobia or Frankia trigger formation of
nodules on roots Fig. 8.34
-species-specific cultures of rhizobia are propagated in the
laboratory and sold commercially as a peat-based
inoculant, which is mixed with water and added to seeds
before planting coating them with a thin film
Figure 8.34 Nitrogen-fixing Rhizobium nodules on plant roots
Restoring Microbial Mutualists
Two main groups of mycorrhizal fungi (other groups are
associated with particular taxa like orchid mycorrhizae):
-all have thread-like chains of cells called hyphae that form
mycelia, which increase the volume of soil used for
nutrients and water absorption
Figure 8.35 Plant succession in semiarid shrublands in the Great Basin of North America is marked
by a shift from nonmycorrhizal species to those that are highly dependent on mycorrhizal fungi
Establishing and Managing Plant Communities
Aftercare
Establishing and Managing Plant Communities
After care (cont.)
Plant fencing or shelters
-to reduce herbivory
-fencing or plant shelters can be made of a variety of
materials including stiff plastic tubes, lightweight plastic
sheets, or mesh Fig. 8.36
-plastics that deteriorate and do not block light
Weeding, mowing, herbicides, grazing or burning may help
slow invasive species
Ex. Prescribed burning in North American tall grass prairie
restoration early in the growing season coincides with
the peak growth period of introduced grasses Fig. 8.37
Figure 8.36 A plastic mesh bag protects this young transplant from kangaroo herbivory on a
reclaimed mine site being restored to jarrah forest (Case E) in Western Australia
Figure 8.37 Prescribed burning is used at Neal Smith National Wildlife Refuge (Case K) to favor
the growth of native species over that of weeds, many of which reproduce earlier
Monitoring Restored Plant Communities and Populations
“Plants stand still and wait to be counted” John Harper,
renowned plant ecologist (1977)
Following observations are indicators that vegetation is
attaining self sufficiency in a restoration:
Monitoring Restored Plant Communities and Populations
Vegetation parameters that may be monitored fall into three
general categories-1. structure, 2. community
composition, 3. population demography
1. Vegetation structure
-physical form or space created by plants
-changes in structure to the canopy are often easy to see at
a distance and can be measured using aerial
photographs or satellite images
-changes beneath the canopy are observed from the
ground
Ex. Vegetation parameters used in forest restorations in
Victoria Australia Table 8.6
Table 8.6 (Part 1)
Table 8.6 (Part 2)
Monitoring Restored Plant Communities and Populations
Vegetation parameters that may be monitored fall into three
general categories-1. structure, 2. community
composition, 3. population demography
Community structure
-usually measured by recording all the species and their
abundances found within permanently marked fixed plots
or quadrats
-abundance is usually done by visually estimating coverage
-sometimes functional groups (species from a locale with
similar life history and resource use traits) are used Ex
Alcoa’s restoration of bauxite mined land in Australia
looked at four functional groups and compared them to
reference sites Fig. 8.38
Figure 8.38 Establishment of understory plants from some functional groups is greater than for
others in restored jarrah forests after Bauxite mining in Australia
Monitoring Restored Plant Communities and Populations
Vegetation parameters that may be monitored fall into three
general categories-1. structure, 2. community
composition, 3. population demography
Population demography
-when restoring rare species, growth, flowering, seed set
and dispersal, and recruitment are important parameters
Ex. Sargent’s Cherry Palm was extirpated from much of
the Florida Keys by agricultural and residential
development and was reintroduced to sites in 1991-1994
-for each plant in each year, height to the base of the tallest
leaves, diameter at breast height or crown height for
shorter plants, number and condition of leaves, and
whether the plant was flowering or fruiting and data was
assembled into a matrix Table 8.7 and PVA curve
showed unlikely to go extinct Fig. 8.39
Table 8.7
Figure 8.39 Projected Sargent’s cherry palm populations based on simulations that assumed a
10% chance that a catastrophic hurricane would affect all plant stages. Average is solid line and
dashed are +/- one standard deviation.