FBO_3_Attachment_A_Tool_for_Assessment_and_Treatment.pdf

Lower Mississippi Valley Joint Venture Tri-State Conservation Coordination Committee

Wetland Reserve Easements Forest Management Working Group

TOOL FOR ASSESSMENT AND TREATMENT

OF REFORESTED BOTTOMLAND HARDWOOD STANDS

ON WETLAND RESERVE EASEMENTS

ATTACHMENT A

Tools for Assessment and Treatment of Reforested Bottomland Hardwood Stands on WRP Easements Solicitation No. 121A2318Q0028 Timber Stand Inmprovement

Plan for USDA NRCS, State of Kentucky

TOOL FOR ASSESSMENT AND TREATMENT

OF REFORESTED BOTTOMLAND HARDWOOD STANDS

ON WETLAND RESERVE EASEMENTS

TABLE OF CONTENTS

Purpose of Document

Introduction

Treatment Indicators and Stand Conditions

Indicator Definitions and Threshold Values

Evaluating Plantations

Developing Harvest Prescriptions

Tree Removal Methods & Patterns

Calculations

Appendix 1. Participants in the Tri-state Conservation Coordination Committee’s Wetland

Reserve Easements Forest Management Working Group

Appendix 2. Non-commercial Treatment Alternatives

Appendix 3. Decision Matrix

Appendix 4. Understory Index, Live Crown Ratio & Invasives Tally Sheet

Appendix 5a. Fixed-area Inventory - Overstory Tally Sheet

Appendix 5b. Sample Fixed-area Inventory - Overstory Tally Sheet

Literature Cited

Purpose of Document This document had been developed by a working group of the Tri-state Conservation Coordination

Committee (Tri-C Partnership) at the request of Natural Resources Conservation Service (NRCS) in

Arkansas, Louisiana and Mississippi. It is intended to assist the NRCS in addressing first entry treatment decisions and support compatible use agreement administration for bottomland hardwood plantations on Wetland Reserve Easements (WRE) in the three states.

The Tri-C Partnership is a collaborative effort chartered by the Lower Mississippi Valley Joint

Venture and guided by a steering committee comprised of representatives from NRCS and conservation partners in Arkansas, Louisiana and Mississippi. Tri-C working groups are established through support of the Arkansas Mississippi Alluvial Valley (MAV) Conservation Delivery Network and Louisiana/Mississippi Delta Conservation Delivery Network to address specific priorities identified by the steering committee. The WRE Forest Management Working Group participants are listed in Appendix 1.

Introduction The great success of the Wetlands Reserve Program (now Agricultural Conservation Easement

Program-Wetland Reserve Easements or ACEP-WRE) has resulted in a MAV of AR, LA and MS, that is replete with young developing bottomland hardwood (BHW) plantations, many of which have reached or are approaching the stem exclusion phase of forest development. These restored BHW plantations are dynamic and develop through multiple seral stages. They generally begin as grassy, herbaceous habitats, and then develop into shrub/scrub, and eventually progress into young forests. As succession advances, canopy closure occurs and understory vegetation becomes sparse.

These conditions often persist until competition induced mortality occurs or the stand incurs catastrophic changes, such as wind-throw. Most plantations lack the species diversity, richness and structure evident in naturally regenerated bottomland hardwoods. In many cases, stand manipulation may be warranted to improve these attributes, enhancing ecological values.

Prescribed treatments within these developing stands may also be necessary to insure that WRE program goals are met. Objectives of ACEP-WRE are to protect, restore and enhance the functions and values of wetland ecosystems to attain the following:

1. Habitat for migratory birds and other wetland–dependent wildlife, including endangered or threatened species of concern.

2. Protection and improvement of water quality

3. Attenuation of floodwater

4. Recharge of ground water

5. Protection and enhancement of open space and aesthetic quality

6. Carbon sequestration

7. Protection of native flora and fauna contributing to the Nation’s natural heritage

8. Contribution to educational and scientific scholarship

These first entry treatment recommendations are intended to support NRCS natural resource professionals and cooperating conservation partners with addressing wildlife habitat concerns in a

ATTACHMENT A

Tools for Assessment and Treatment of Reforested Bottomland manner which is compatible with or furthers ACEP-WRE priority wildlife and other objectives. In addressing these objectives, when active management is determined to be appropriate, it is recommended that stands should be manipulated with the primary goal of creating desired forest conditions for wildlife (DFCW), such as increasing complexity of forest structure and diversity, as described by LMVJV Forest Resource Conservation Working Group (2007).

Stand condition, along with WRE and landowner management objectives, will determine timing and type of treatment used during the first stand entry. Effects of treatment, both short-term and long-term, will be directly related to timing and methodology of the manipulation. Trees may be removed at any stage of stand development however, commercial harvests, wherein sale of forest products financially supports a prescribed treatment, are often the most feasible option. The goal should be to create or enhance stand conditions that meet the ecological needs of WRE priority wildlife, while maintaining a sustainable yield of forest products. This approach provides a cost effective means of accomplishing habitat management whereby DFCW can be created or enhanced in an economically viable manner for most WRE landowners. Overly intensive or premature treatment of developing reforested stands generally should not be prescribed if the result is significant reduction in future silvicultural treatment options. Additionally, such treatments may significantly reduce flexibility in long-term management alternatives. Therefore, the following recommendations focus on developing forest management decisions which allow for more traditional, long-term, commercially based treatment methods. There are less frequent instances however, in which some form of stand manipulation is desired or warranted but commercial treatment methods are infeasible (e.g., absence of local forest products market or abnormally high stem density stands that require much longer development periods before becoming commercially viable). In such circumstances, utilizing non-commercial treatment methods may be acceptable to achieve desired habitat objectives and to improve stand development toward the first commercial thinning treatment. A summary of non-commercial treatment alternatives is included in Appendix

2.

Forest stand development on restored easements can occur rapidly and habitat conditions may warrant manipulation relatively early in the life of the stand. Since wildlife habitat is a primary objective of the WRE program, BHW plantations may benefit from evaluation for possible first entry treatments between the ages of 15 and 25 years. An important first step in evaluating management need is assessing habitat deficiencies and factors limiting stand level growth potential and then taking corrective action if treatment is warranted. Various indicators and stand conditions may be used to determine if, when and how treatments should be administered.

Currently, few specific silvicultural prescriptions exist to guide young bottomland stand development towards desired stand conditions (Meadows 1996) or to promote wildlife habitat.

However, Goelz (1995) and Goelz and Meadows (1997) provide timber production stocking recommendations for even-aged stands that serve as a foundation for guiding management decisions. Their recommendations are based on hypothetical stocking levels provided by Putnam et al. (1960) for bottomland hardwood stands, but residual stocking levels in such stands have received limited experimental evaluation (Goelz and Meadows 1997). However, while evaluating habitat conditions, wildlife resource managers have observed similarities in the “apparent need for thinning” based on habitat conditions and the guidelines presented in Goelz and Meadows stocking guide. As such, use of the stocking guide is advocated as an underlying foundation in stand evaluation. Although in many situations the guide may be used as a “stand-alone” decision tool for identifying desired stocking objectives within a given stand, for the broader wildlife habitat management focus of this document, consideration of additional stand and habitat variables are recommended as well.

Treatment Indicators and Stand Conditions It is recommended that managers utilize three indictors for evaluating BHW plantations to determine if they should be treated: 1) Understory Index, 2) Live Crown Ratio (LCR) of Co-dominant

Trees and 3) Stocking Level (as described in Goelz and Meadows 1997). The decision of how to design treatments should be guided by stand conditions, including species composition, planting density, survival rates, clear bole length and site variables such as soils and hydrology. As managers gain familiarity with recommended indexing methods, basic information needed to evaluate stand conditions may be gathered anecdotally as part of the initial stand inspection and decision-making process. It should be recognized, in conducting an initial stand assessment, there may be instances when habitat conditions appear to warrant manipulation, while the indicators do not clearly suggest the stand is ready for treatment. Approaches to address these situations are presented in the Developing Harvest Prescriptions section as well as within the Decision Matrix (Appendix 3).

General threshold values are presented for each indicator used to assess stands. However, these are only intended to be used as guidelines to support development of sound treatment decisions and may include exceptions.

In some cases, it may be desirable to postpone treatment of overstocked stands (or portions of stands), “pre-maturely” treat understocked stands, or consider creative treatment approaches to address special management concerns or objectives. For example, if desired habitat conditions appear deficient in a stand and indicators point to treatment, but the stand actually comprises a relatively small portion of a larger landscape already supporting desired habitat conditions, delaying treatment may be the most appropriate alternative. In its current condition and position in the landscape, the stand may be providing unique resources or habitat that is generally lacking.

Conversely, there may be situations in which all indicators point to the need for treatment and it may be prudent to treat the stand regardless of landscape conditions, in order to meet objectives that support stand health and long-term habitat management goals. While stand assessment recommendations provided herein are intended to assist land managers in making treatment decisions, these examples demonstrate there is not a single treatment method or prescription that will fit all first-entry stand conditions. Treatment decisions should always be weighed against habitat management objectives and their relationship to the broader landscape.

Indicator Definitions and Threshold Values

Understory Index

There is a strong inverse correlation between stocking levels and density and/or coverage of understory vegetation. A similar relationship exists between stocking levels and overall stand structure, including gaps and vegetative layering. For example, a densely stocked stand will generally contain a sparse, poorly developed understory while a stand with lower stocking, numerous canopy gaps and openings will generally contain greater structural diversity and a more developed understory. Absence of a well-developed understory does not always indicate the stand is ready for thinning, but the presence of such an understory is generally a good indicator it is not.

The understory index should be used during the growing season to evaluate volume/presence of flora from zero to approximately six feet in height. The index considers understory plant density and species diversity, along with plant types (e.g., herbaceous, woody, annual, perennial, vines, shrubs, grasses and forbs). Although ground cover (e.g., grasses or sedges) may be considered as part of the understory index, a well-developed understory, such as Rubus patches or various woody vines, may have little ground cover. In contrast, a heavy ground cover of shade tolerant sedge or grass in the absence of woody species is not considered a well-developed understory. Such monotypic grass or sedge communities may be rated as low or very low when utilizing this initial indexing approach.

Based on field observations, an understory index score can be calculated and used to determine if treatment may or may not be warranted. If the understory index score is less than 220 (assuming it is due to low light conditions and not flooding), there is a strong probability the stand is stocked sufficiently to warrant thinning. An understory index greater than 320 reflects a robust understory and stocking probably is too low to justify thinning. Between these thresholds, a decision to treat the stand is not as clear and evaluation of the other indicators (LCR and stocking) is advised.

Understory Index Descriptions:

VERY LOW = 1 A general absence of understory plants throughout, or a monotypic ground cover of sedges or grasses, with little else present.

LOW = 2 Generally sparse understory but may include small patches of denser vegetation.

MEDIUM = 3 Significant presence and diversity of plant types but access generally un-impeded. Areas of low or very low density may be frequently interspersed.

HIGH = 4 Dense vegetation over majority of area but may be interspersed with areas of medium, low, or very low understory. Access somewhat impeded but not precluded.

VERY HIGH = 5 Consistent occurrence of robust vegetation. Access is difficult.

ATTACHMENT A

Tools for Assessment and Treatment of Reforested Bottomland

Index value 1 2 3 4 5 6 7 8 9 10 % of points computation score very low 1 X 10 10 (1) 10 low 2 X X 20 20 (2) 40 medium 3 X X X X 40 40 (3) 120 high 4 X X 20 20 (4) 80 very high 5 X 10 10 (5) 50

TOTAL 100% 300

plot/point

The following table represents the understory index data collection method.

Live Crown Ratio:

LCR is indicative of tree vigor and is often related to intensity of competition in the upper crown classes. It is estimated as the proportion, expressed as a percent, of healthy foliage relative to a tree’s total height. LCR estimates should only be made from co-dominant trees, from the point where the concentration of canopy foliage actually starts, not at the lowest live limb.

Average LCR may be used at the stand level as a quick, relatively simple index for identifying stands with either very high or very low levels of stocking, but it is not recommended as a stand-alone decision metric. In utilizing this metric, be aware that stocking being equal, LCR can be influenced by shade tolerance and/or predisposition to self-pruning of each species, making its usefulness as an indicator most applicable in generally monotypic, more uniformly stocked stands.

Stands with an average LCR below 40 percent (for most BHW species) are generally at or near full stocking, diameter growth is retarded, and canopy closure does not permit enough light through the canopy for understory vegetation to persist. For these stands, treatment is generally warranted. Conversely, when LCR of co-dominant trees is greater than 70 percent, the stand should not be thinned. For stands between these extremes, managers should refer to other indicators/measures (see Stocking below). Note: If stands are primarily cypress, willow oak and overcup oak, use 50 and 80 percent as decision points; for ash and cottonwood dominant stands use 30 and 60 percent.

Stocking

Stocking is a quantitative measure of area occupied by trees within a stand. It is generally expressed as a percentage based on basal area (BA), number of trees, volume, or other criteria, on a per acre basis. Stocking is generally separated into the following levels:

Live Crown Length 18 Ft

Total Tree Height 30 Ft

LIVE CROWN RATIO =

LIVE CROWN LENGTH

TOTAL TREE HEIGHT

X 100 =

18’ 30’

X 100 = 60%

Table 1. Understory index tally sheet with example data.

https://en.wikipedia.org/wiki/Quantitative_research https://en.wikipedia.org/wiki/Tree

(a) Fully stocked stands – Stands in which all growing space is effectively occupied but still allow ample room for development of crop trees.

(b) Overstocked stands – Stands in which growing space is so completely utilized that growth rates of many trees, including dominants, are being negatively influenced.

(c) Understocked stands – Stands in which growing space is not effectively occupied by crop trees.

Goelz (1995) presents a useful bottomland hardwood stocking guide to aid in determining stand density management for timber production. In the stocking guide (Figure 1), the A-line represents

100 percent stocking and can be used to identify stands which may benefit from thinning. Goelz offers the B-line as a suggested residual stocking after thinning for optimal timber production.

Additionally, Goelz and Meadows (1997) offer alternatives which may be appropriate for other management objectives. One such alternative is the C-10 line (Figure 1), which implies that by reducing stocking to the C-10 level, it would take 10 years for a stand to “recover” to the B-line

(Goelz 1997).

When DFCW is a primary management objective, it may be acceptable to manipulate a stand before it reaches 100 percent stocking. Young, even-aged plantations with 70-80 percent stocking often exhibit deficiencies in understory vegetation, canopy gaps, and structural diversity. Table 2 can be used to evaluate if current stocking levels indicate need for stand treatment. This table applies to stands which can meet reasonable expectations of future merchantability for a given site and species. Stands comprised of species not well suited to current site conditions or stands which developed with low stem density may warrant some type of “rehabilitation” treatment, despite not meeting stocking levels that normally “trigger” manipulation. In such cases, corrective action may include but is not limited to, species conversion through patch cuts designed to release desirable natural regeneration and/or by incorporating additional seedlings within patch cuts.

Stocking Level Treatment Decision

>80 percent Warranted

70 – 80 percent Warranted, but optional

60 – 70 percent Likely not warranted

<60 percent Not warranted

Table 2. Relationship between % stocking and treatment decisions

As an additional reference, Table 3 provides an interpretation of Figure 1 to visually demonstrate the relationship between percent removal (e.g. 50-60%, 40-50%, etc.) and degree of thinning intensities (i.e. light, moderate and heavy). It is not intended as an exhaustive list of alternatives for all situations.

Figure 1. Stocking guide for young bottomland hardwood stands with *quadratic mean diameters between 6-14 inches. Percent stocking is a function of basal area and trees/acre. Desirable stocking levels are indicated, as suggested by Putnam et al. (1960) and Goelz (1995, 1997). (B. Frey, adapted using equations from Goelz (1995) and Goelz

(1997)).

*Note: Quadratic Mean Diameter (QMD) is commonly used in forestry research to provide the most statistically accurate diameter estimate. However, statistical difference between QMD and arithmetic mean diameter (avg. DBH) has been shown to be very small in stands with relatively small and narrow range of diameters (Curtis and Marshall 2000, Technical Note), e.g.

developing WRE BHW plantations. Therefore, in utilizing these recommendations, substituting

DBH in place of QMD will provide sufficient accuracy to develop harvest prescriptions.

QMD TPA BA 50% 55% 60% TPA BA 50% 55% 60% TPA BA 50% 55% 60% TPA BA 50% 55% 60%

5" 448 61 B- B/C C+ 512 70 B B- B/C 576 79 B+ B B- 640 87 B++ B+ B

6" 337 66 B/C C+ C 386 76 B- B/C C+ 434 85 B+ B B/C 482 95 B++ B+ B

7" 263 70 C+ C C- 301 80 B/C C+ C 338 90 B B/C C+ 376 100 B+ B B/C

8" 211 73 C C- C-- 241 84 B/C C+ C- 271 94 B- B/C C+ 301 105 B B- B/C

TPA BA 40% 45% 50% TPA BA 40% 45% 50% TPA BA 40% 45% 50% TPA BA 40% 45% 50%

8" 211 73 B/C C+ C 241 84 B B- B/C 271 94 B+ B B- 301 105 N/A B+ B

9" 172 76 C+ C C 197 87 B- B/C C+ 222 98 B+ B- B/C 246 109 B++ B+ B-

10" 144 78 C+ C C- 164 89 B/C C+ C 185 101 B B- B/C 205 112 B+ B B-

11" 121 80 C C- C-- 139 92 B/C C+ C 156 103 B- B/C C+ 173 114 B B- B/C

TPA BA 30% 35% 40% TPA BA 30% 35% 40% TPA BA 30% 35% 40% TPA BA 30% 35% 40%

11" 121 80 B/C C+ C 139 92 B B- B/C 156 103 B+ B B- 173 114 B++ B+ B

12" 104 82 B/C C+ C 119 93 B- B/C C+ 134 105 B+ B B- 149 117 B++ B+ B

13" 90 83 C+ C C- 103 95 B- B/C C+ 116 107 B B- B/C 129 119 B++ B+ B

14" 79 84 C+ C C- 90 96 B/C C+ C+ 101 108 B B- B/C 112 120 B+ B B-

INITIAL STOCKING

Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) %

Relationship to recommended res idual s tocking l ines i f cut by (x) % InitialInitial

70% 80% 90% 100%

Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) %

INITIAL STOCKING

70% 80% 90% 100%

Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) %

Relationship to recommended res idual s tocking l ines i f cut by (x) %

INITIAL STOCKING

InitialInitial

Relationship to recommended res idual s tocking l ines i f cut by (x) % Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) %

QMD

QMD

70% 80% 90% 100%

Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) % Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) % Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) % Initial

Relationship to recommended res idual s tocking l ines i f cut by (x) %

Relationship to recommended res idual s tocking l ines i f cut by (x) %

Table 3. Thinning intensity alternatives and their relationship to the recommended B-line and C10-line residual stocking (Figure 2) based on initial stocking level and average diameter (DBH). These relationships assume that average DBH remains similar after thinning. If favoring larger diameters for retention, the actual residual stocking will be slightly higher since average DBH will be somewhat increased.

*Refer to the Harvest Intensity Table (Table 4) for treatment alternatives. For most applications, 4th or 5th-row removal for access is the recommended approach.

Table 3. Thinning intensity alternatives and their relationship to recommended B-line and C10-line residual stocking (Figure 1) based on initial stocking level and QMD. These relationships assume average DBH remains similar after thinning. If favoring larger diameters for retention, actual residual stocking will be slightly higher since average DBH will be somewhat increased.

*Refer to Harvest Intensity Table (Table 4) for treatment alternatives. For most applications, 4th or 5th-row removal for access is the recommended approach.

B++ light

B+ light

B light

B- light

B/C moderate

C+ moderate

C heavy

C- heavy

C-- heavybelow C-l ine midway of B&C-l ine just above C-l ine

~at C-l ine just below C-l ine

Position relative to B-line and C10-line above B-l ine

*Thinning intensity s l ightly above B-l ine

~at B-l ine just below B-l ine

LEGEND

ATTACHMENT A

Tools for Assessment and Treatment of Reforested Bottomland

Evaluating Plantations

Stocking is by far most important of the three indicators to consider when determining both ultimate need for and level of treatment within a stand, as it significantly and inversely effects both understory development and LCR. In many cases, stand level stocking could be used alone to determine if treatment is warranted. However, when managers first visually assess stands, the most obvious and telling parameters are condition of the understory plant community and clear bole length or degree of self-pruning as indicated by LCR. Therefore, understory and LCR indicators are intended to be most useful in initially identifying stands at extremes of stocking, leading to an easy decision to delay treatment and prevent the need for the additional work required in conducting an actual stand inventory. If these two indicators suggest the stand is overstocked or indicators are not adequately conclusive to determine if no treatment is warranted, then conducting a fixed-area inventory is recommended to further evaluate stand stocking. Conversely, if the stand is clearly understocked and thinning is not warranted, conducting an inventory is unnecessary and the stand should be revaluated in 3 – 5 years. A systematic approach to evaluating stands is provided below, along with a matrix to help guide decision making.

Step One: Point Cruise and Cursory Observation

Utilize the tally sheet provided in Appendix 4 to conduct a simple point cruise to evaluate understory, LCR, as well as to determine prevalence of invasive species (Chinese tallow tree, autumn olive, privet, etc.). After conducting the point cruise, refer to the Decision Matrix

(Appendix 3) to evaluate data collection results and determine if no treatment is warranted or if it is necessary to conduct an inventory (Step 2) to ascertain actual stocking levels. Experienced managers may be comfortable using their judgement to make these assessments, precluding the need for collecting hard data. In some instances, a manager may choose to skip the point cruise and proceed directly to conducting a fixed-area inventory.

In conducting a point cruise, it is important to gather data around a sufficient number of point locations throughout the entire stand in order to gain an adequate perspective on stand conditions.

Though there is no absolute standard for conducting the point cruise, it is recommended to assess a minimum of 10 points for small, uniform stands <30 acres and 1 point per 3 acres up to 50 ac (i.e., 17 points for a 50-ac stand; 13 for a 40 ac stand, etc.). Stands greater than 50 acres probably should be stratified, bringing each unit down to less than 50 acres and subject to 1 point per 3 acres rule. Homogeneous stands over 50 acres may be indexed more conservatively (e.g., between

10 and 20 points in 75 to 100+ acre stands depending upon observed understory condition – homogeneity vs. diversity).

It is important to note that evaluating understory and LCR may be difficult during winter months and it is recommended data be collected during the growing season or shortly thereafter before leaf fall. Note also that evaluating LCR from directly below a tree often results in an underestimation. One technique to assist with estimation is to stand back far enough from the tree to be able to visually divide the tree in half and if necessary, in half again (quarters). Evaluating LCR in relation to half or quarter tree increments typically increases accuracy of estimation.

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Tools for Assessment and Treatment of Reforested Bottomland

If initial understory index evaluation and/or point cruise determines one or more exotic invasive species are prevalent in the stand, any prescribed stand management activities should be postponed to allow for treatment of invasive(s), rather than facilitate spread throughout the stand.

Chinese tallow-tree (Triadica sebifera), Chinese privet (Ligustrum sinense) and trifoliate orange

(Poncirus trifoliata) will generally be the most problematic invasive plant species within timber stands in the MAV. If identified, all stems of these species should be treated within the affected area. Sites containing seed-bearing individuals will likely take a minimum of two, but most likely three successive years of treatment to control prior to resuming timber harvest. First year treatment prioritizes removal of overstory and seed bearing trees/shrubs, while successive treatments are necessary to control seeds that typically sprout prolifically in the understory following canopy disturbance. Herbicide application will likely be the most suitable treatment method in most situations, but mechanical treatment followed by subsequent herbicide applications could be a viable option in some cases.

Step Two: Fixed-area Inventory

The primary purpose of conducting a fixed-area inventory is to document stand stocking (number of trees per acre [TPA] and average stem diameter) and species composition. This may be best accomplished utilizing a fixed-area plot sampling method. After completing an inventory, refer to the Decision Matrix (Appendix 3) to determine if stand treatment is warranted.

Steps for completing an inventory include:

a) Stratification: The objective of stratification is to identify and delineate potential treatment units within a stand which include areas of relatively uniform species composition, stand density and average DBH. When conducting an inventory, field notes should be made and/or areas mapped to denote significant changes in any of these variables. Stratification, where appropriate, will facilitate and strengthen data analysis and lead to a more effective treatment prescription. For example, changes in elevation or soil type within a reforestation planting unit can result in variations in stand density and/or growth rate. This may result in portions of the planting unit achieving stocking levels which warrant treatment while other areas have not, thus necessitating stratification.

b) Plot Size and Frequency: An intensive inventory is generally not required. A cruise providing a reasonable average estimate is adequate. In most BHW plantations, an inventory of 1 to 2 percent, using plots from 1/100th to 1/20th acre is recommended. For a given cruise intensity, using smaller plots requires more of them, resulting in better distribution throughout the stand.

Therefore, for small acreages or heterogeneous conditions, the smaller plots may be better; if larger plots are used, the cruise percent must be increased to insure adequate plot distribution.

In larger stands or where stem density is low, larger plots may be preferred. For each 10 acres sampled, a one percent inventory requires ten 1/100th acre plots, five 1/50th acre plots or two

1/20th acre plots. For example, a 40-acre stand would require forty 1/100th acre plots, twenty

1/50th acre plots or eight 1/20th acre plots. Sampling at two percent intensity can be achieved by doubling the number of plots.

c) Data Collection:

Tree Sampling: Tally trees (species and DBH) in intermediate, co-dominate, and dominant crown classes (Appendix 5a). Trees with over-topped or suppressed crowns contribute relatively little to stand basal area. However, their occurrence should be noted, particularly when comprised of species generally lacking in the upper crown classes.

Regeneration: As considered here, regeneration is tree seedlings or saplings occurring in the understory or mid-story. In developing BHW plantations, advanced reproduction is more important with regard to increasing species richness rather than stem density, thus it is not always necessary to quantify. Stands sufficiently stocked and developed to warrant evaluation for potential treatment, generally do not need to be regenerated.

However, in the interest of increasing species diversity in stands with a more monotypic overstory, presence of advanced reproduction of other desirable species should be noted.

Environmental conditions under closed canopied, oak-dominated stands are generally not favorable for establishment and/or development of seedlings. However, canopy gaps or site variations may result in occurrence of patches of non-oak regeneration which may influence the type of treatment prescribed (e.g. incorporating group removals or patch cuts intended to release desirable regeneration). Density and competitive position of regeneration should be considered. Stems should be assigned to two broad size-classes;

overtopped saplings > 6’ in height effectively acting as a midstory, and seedlings in the understory. Estimating numbers for each size-class into broad ranges rather than precise counts should be sufficient and will expedite the inventory process. Rounding estimates into categories such as: none, 10/ac, 25/ac, 50/ac, 100/ac, 150/ac, 200/ac and 300+/ac will be sufficient for prescription development. Species should be noted but not necessarily quantified individually.

Habitat Components and Other Conditions: Factors other than stocking may not contribute significantly to the decision of whether or not to treat a stand but may influence how a treatment is administered to better target management objectives.

Desirable habitat components such as vine-laden, broken-topped or senescing trees do not necessarily need to be quantified but should be noted. If they occur frequently throughout the treatment area, special consideration is generally not necessary to insure retention of significant numbers after harvest. However, if these desirable components are generally scarce, some portion may be retained by establishing periodic un-cut rows or no entry zones, establishing rules for avoidance by equipment operator, or identifying as “leave trees” with marking paint. Additional stand conditions which may influence harvest methodology may include:

1) Site Compatibility of Predominant Species—a preponderance of off-site tree species may steer managers to consider regenerating portions of the stand using groups or patch cuts.

2) Tree Growth/Performance—if stocking levels, crown condition or bark patterns indicate growth or health is substantially reduced, a general crown thinning, with or without groups, should be considered rather than groups or patch cuts alone.

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Tools for Assessment and Treatment of Reforested Bottomland

3) Unique or Sensitive Areas – occurrence within treatment units may require modifying the harvest approach or avoiding treatment in these areas.

4) Clear Bole Length—if LCRs are relatively high but treatment is still warranted, light/conservative thinning may be prudent, with groups added to promote more enduring understory development.

5) Invasive Species (which should always be noted and documented in the inventory)— generally call for postponement of treatment until control of infestation is accomplished. Otherwise, an untreated buffer should be established.

A Fixed-area Inventory Overstory Tally Sheet is included for field use in Appendix 5a. In addition, a

Sample Fixed-area Inventory Overstory Tally Sheet is provided in Appendix 5b which contains sample calculations to assist with inventory data analysis.

Developing Harvest Prescriptions

If it is determined treatment is warranted, a harvest prescription should be developed based on stand conditions and management objectives. Stand conditions can be highly variable. Metrics such as species richness in each stratum (i.e., understory, midstory, overstory), average tree diameter, diameter distribution, stocking levels and desirable habitat components (cavities, vines etc.), can vary widely within stands. Information from the inventory, along with the Decision

Matrix table included in Appendix 3, should be used to inform harvest prescriptions to ensure maintaining health, vigor and future merchantability of the stand.

Stand manipulation treatments generally call for removal of overstory trees, either through commercial or non-commercial means. Desired post treatment habitat response and conditions can be largely guided by controlling 1) intensity of tree removal, 2) arrangement of residual stems and 3) selection criteria for either retained or removed trees.

1. Intensity of Tree Removals

Harvest intensity may be viewed as percent reduction in stocking level. When applying general crown thinnings, the stocking chart (Table 3) should be used as a guide to achieve desired intensity (e.g. heavy thin vs light thin). Though patch cuts and group removals reduce stand level stocking, they entail complete overstory removal and are better guided through area regulation (see Tree Removal Methods and Patterns). For example, if the prescription calls for crown thinning with periodic group removals, the desired thinning intensity should be applied to the area between well-defined group openings, and then prescribed proportions of complete overstory removal (i.e. groups) may be achieved by controlling size and frequency of openings.

2. Arrangement of Residual Stems

Residual stocking being equal, variations in spatial distribution of residual trees can create variability in the light environment, which may lead to greater and more diverse understory response. Inconsistencies in arrangement of stems (i.e., variations in size of canopy gaps) may also serve to facilitate crown stratification as well, by providing some individuals

ATTACHMENT A

Tools for Assessment and Treatment of Reforested Bottomland significantly more relief from competition and/or creating conditions which alternately favor shade-tolerant and shade-intolerant trees.

3. Selection Criteria

Random removals can be used to achieve some management objectives, but selective removal can have a greater impact on post-harvest conditions and future stand development. Removing trees randomly reduces basal area and stand density, thereby improving growth of residual trees and fostering some understory development, but it will not change the average tree diameter or favor desired species which are under-represented. An inherent objective is to shorten the time necessary for the restored site to become “mature” BHW. To more rapidly move the planted stand to a forest rich in site-adapted species, including large diameter trees, harvests guidelines should be established to selectively remove trees based on numerous criteria (e.g. species, diameter, bole quality, crown condition, etc.).

Habitat conditions generally warrant treatment before stands attain 100% stocking and manipulations are seldom prescribed in stands with only 60% stocking. Therefore, treatments will most often be applied in stands with 70% to 90% stocking levels. It is recommended that targeted residual stocking levels fall near or between the B-line and C-10 line (Figure 1). In order to achieve recommended residual stocking, stands with smaller average diameters must be reduced by a greater percent than stands of larger stems. For example, stands with an average DBH of 5”- 6” can be reduced 50%-60%, depending on their initial stocking, while stands with average DBH of

13”-14” only need reducing by 30%-40% (Table 3). These percentages can be applied to either stem density or BA if trees are selected without diameter bias, as random diameter removals will generally result in proportionately equal reductions in BA and stems per acre. However, it should be noted that favoring larger stems for retention removes a lesser proportion of BA, resulting in less reduction in stocking level than stem count.

For stands in which the average DBH and/or stocking level varies but is not easily delineated on the ground, a good “rule-of-thumb” is to remove 50 percent of stems; this applies where average diameters range from 5” to 10” and stocking is 70%-90%. In applying this approach, the post-harvest stand will fall within recommended stocking range but intensity of removals will vary throughout the stand, which is both acceptable and often suggested.

A harvest prescription may call for one cutting technique with very simple specifications or it may entail some combination of tree removal patterns and additional cutting “rules” that vary with changing conditions across the treatment area. Habitat treatment prescriptions may include the following decisions:

Can treatment be accomplished through mechanized commercial harvest or must non-commercial means be used.

Invasive control—mechanism, length of time preceding further manipulations

(harvests).

Assuming commercial harvest is used:

Tree removal patterns

- If thinning—what intensity (e.g., heavy, moderate or light).

- If groups are prescribed—what are specifications (e.g., size, proportion of stand, location, etc).

Designation of access row frequency (e.g., every 4th or 5th or alternative approach where rows are not discernable).

Means to retain or increase species diversity (e.g., restrict harvest of certain species as a

“rule”, mark trees, release overtopped advanced regeneration, etc).

Tree selection criteria—will trees be favored by species, diameter, crown position, bole quality, habitat component, etc.

Habitat components such as senescing, broken-topped, or vine-laden trees—is special consideration necessary to insure adequate numbers are retained.

Monotypic, uniformly stocked stands with easily identified rows present the simplest decisions and approaches to treatment. In such situations operator select crown thinning favoring larger diameter trees for retention can be an effective, straightforward approach. Additional variations to enhance habitat diversity can also be incorporated by removing small groups of trees totaling some predetermined percentage of area (e.g., 5 to 10 percent of the stand or even higher [15 to 30%] if management objectives warrant), to create longer lasting canopy gaps scattered throughout the treated stand. In certain circumstances, group removal may be used as a single treatment method, e.g., younger stands where overall thinning may need to be delayed but canopy openings are desired to promote diversity of both habitat and tree species composition.

Mixed species stands with desirable composition are challenging due to differential growth rates of specie. Simply favoring larger diameter trees may lead to bias against some species. It is recommended mixed-species stands be marked for timber sales rather than subject to operator selection. In any case, commercial or non-commercial treatments should not be strongly biased against certain species because species diversity is considered necessary to meet WRE program objectives. Prescriptions for mixed species stands should be developed in a manner that preserves species diversity and richness.

Plantations in which multiple species were used but planted separately in relatively monotypic strips or patches may result in alternating strips of well-stocked areas in “need of thinning” and strips which are not ready to be thinned due to differential growth and/or survival rates of each species. Viewed as a whole, the stand may have adequate understory and structural diversity, thus applying treatments in such stands should be largely based on relative proportion in each condition. If well-stocked strips would benefit from further self-pruning without substantially increased risk to health and vigor, it may be prudent to delay treatment.

Stands of larger diameter trees (i.e. 10” or greater) which developed under relatively low stem density conditions (e.g. 175 TPA) may be stocked in excess of 70 % and only seem to need thinning

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Tools for Assessment and Treatment of Reforested Bottomland

50 every 3rd 2 0 1 out of 4 N/A 55 every 3rd 2 0 2 out of 6 N/A

40 every 4th 2 1 1 out of 4 N/A

45 every 4th 2 1 2 out of 5 N/A

50 every 4th 2 1 2 out of 4 N/A

50 every 4th 3 0 2 out of 5 approx. 1 out 4

60 every 4th 3 0 3 out of 5 approx. 1 out 4 40 every 5th 2 2 2 out of 4 N/A

45 every 5th 3 1 2 out of 4 approx. 1 out 4

45 every 5th 4 0 2 out of 5 approx. 1 out 4

50 every 5th 4 0 2 out of 4 approx. 1 out 4

F. Rate of Tree Removal on

Rows Once Removed from

Access Row

A. Harvest

Intensity -

Approximate %

Stems Removed

B. Access Row -

All Stems

Removed

C. Thinned

Rows Per

Access Row

D. Untreated

Rows Per

Access Row

E. Rate of Tree Removal on Thinned Rows

Adjacent to Access Row based on stocking level. However, such stands may be excessively limby, and for long-term management objectives, regenerating substantial portions of them may be a better decision than simply thinning. As always, landscape perspective is important and managers may accept retention of relatively small areas dominated by short-boled, limby trees, particularly if diverse in species and structure. Conversely, larger expanses of closed canopied, monotypic stands of trees with poor prospects for future merchantability may justify regeneration of plantations despite 20-30 years of growth.

When developing the prescription, consideration should be given to the potential for coppice regeneration. It can be beneficial if developing a two-age stand is desired. Coppice is also often the primary source for midstory development following a treatment. However, vigorous coppice from stumps of planted trees may inhibit viability of seedlings as a source of regeneration, thereby reducing the potential to increase species diversity. Additionally, vigorous oak coppice can rapidly bring the stand right back to a shaded understory condition. It is also important to be aware of flood regimes in the area as flooding during the growing season can greatly reduce coppice sprouting and managers should use caution if counting on it as a source of regeneration.

Table 4 includes a variety of treatment options for removing 40 to 60 percent of stems in a stand and is provided to assist managers in meeting prescribed stocking reductions.

Table 4: Harvest Intensity - Percent removal of stems based on rate of access row removal and treatment within retention rows.

Column A - Harvest Intensity: Harvest intensity may be regulated by controlling percentage of stems or BA removed. Random removals result in proportionately equal reduction in BA and stems per acre while selective removals based on diameter will remove a disproportionate percentage of BA. Controlling number of stems removed is quantitative while controlling BA requires more experience as it is done intuitively. It is generally recommended to retain larger diameter trees, within a given species, assuming other tree characteristics are acceptable. Therefore, for most prescriptions it is recommended to base

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Tools for Assessment and Treatment of Reforested Bottomland harvest intensity on percentage of stems removed with the understanding a lesser percent of BA will be removed and average stem diameter will be increased.

Column B – Access Rows: Complete removal of individual rows is necessary to provide access for harvest equipment. Frequency of access row removal generally occurs every 3rd, 4th or 5th row and accounts for 33, 25 and 20 percent of stem removal, respectively. Fewer access rows allow for more individual tree selections to favor desirable traits, therefore, for most applications, using every 4th or 5th row for access is preferred.

Column C – Thinned Rows: Selective stem removal along rows, both adjacent to and once removed from access rows, can be used to manipulate parameters such as residual stem diameter, species composition, and desirable habitat components.

Column D – Untreated Rows: No removals along uncut rows result in horizontal variability of sunlight penetration as well as retention of habitat components (e.g., stressed, vine-laden or broken top trees). To meet objectives for WRE priority species, it is recommended to retain these habitat components either through leaving periodic uncut rows, tree marking, harvest rules or establishing no-cut zones throughout the treatment area.

Column E – Rate of Tree Removal on Adjacent Rows: Selections for tree removal, by timber marker or cutter operator, are feasible and efficient when evaluating 3 to 5 stems simultaneously. This also facilitates control of proportion of stems removed. When favoring trees based on diameter, average diameter of retained trees will inherently change based on rate of removal on thinned rows. When favoring large diameters, cutting 1 of every 4 stems may result in a relatively small average diameter for trees removed, subsequently reducing the size of canopy gaps. In comparison, cutting 3 of every 4 stems forces markers to select some larger trees for removal, resulting in greater BA and crown size per tree removed. Cutting 2 of every 4 stems seems to provide a desirable balance of achieving intended crown release while not taking a disproportionate amount of larger diameter/preferred trees. Favoring by diameter is most applicable in monospecific stands.

In mixed species stands, caution should be used to prevent disproportionate removals of desirable species with smaller average diameters.

Column F - Rate of Tree Removal on Once Removed Rows: Thinning is most efficient on rows immediately adjacent to access rows and less efficient on rows once removed when conducting selective thinning in a mechanized operation. Therefore, fewer trees will generally be selected and removed from the once removed row.

Tree Removal Methods & Patterns Careful thought should be given to prescribing an effective combination of tree removal treatments to meet management objectives. The following tree removal methods provide key considerations in formulating a harvest prescription. Table 5 represents alternative approaches to applying thinning treatments based on arrangement of trees and alternative tree removal methods described.

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Tools for Assessment and Treatment of Reforested Bottomland

1. Harvest Approach 2. Access Row 3. Thinned 4. Untreated

Frequency Rows Rows every 3rd 2 0 every 4th 3 0 every 5th 4 0 every 4th 2 1 every 5th 2 2 every 5th 3 1

Thinning through retention of small clusters of trees yes may or may not no all but access

E Patch cut N/A N/A N/A

A

B

Thinning along all residual rows

Group removal 4th, 5th or 6th

5th or 6thC

D

N/A

Thinning with retention of untreated row(s)

1) Thinning: Thinning can be described as removal of individual or small groups of trees (e.g. <

1/20-ac or < 15trees) to improve growth and vigor of residual trees by reducing competition from neighboring trees. Lightly thinned stands can result in relatively small canopy openings, and subsequently, crown closure may occur relatively quickly.

Table 5. Alternative approaches to access and retention row thinning based on treatment method.

Row Thinning: Strict single row or multi-row thinning is not recommended, but rather a combination of a periodic, complete row removal for equipment access (Table 5, Column 2), with selective…