Yield Responses of Black Spruce to Forest Vegetation Management Treatments: Initial Responses and Rotational Projections

Table 1

Relative yield responses and associated experimental details ordered by number of sequential treatments (𝑇_𝑁), initial year of treatment application relative to the year of seedling establishment (𝑇_𝐼 (yr)); and length of the observation period relative to the year of seedling establishment (𝑇_𝐿 (yr)).

𝑇𝑁^a	𝑇𝐼^a	𝑇𝐿^a	Relative response^b				Source and treatment details
(𝑛)	(yr)	(yr)	𝑅𝐷	𝑅𝐻	𝑅𝑉	𝑅𝑆
			(%)	(%)	(%)	(%)
1	−1	4	73	43	339	10	Tables 1 and  2 and Figures 1, 4(b), and 6(b) as reported by Pitt et al. [18]; mean responses based on bareroot and container stock-types combined results; treatment = hexazinone (Velpar L) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 20% and 1% in herbaceous and woody vegetation cover, respectively, relative to untreated control plots, at time of last remeasurement.
1	−1	4	67	60	—	8	Tables  1 and  2 and Figures  1(a,b) and 4(b,d) as reported by Reynolds and Roden [19]; mean responses based on spring and fall combined results; treatment = hexazinone (Velpar L) at 2 kg ai/ha (liquid formulation); effectiveness = reduction of 44% in red raspberry (Rubus idaeus L. var. strigosus (Michx.) Maxim.) (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	−1	4	57	48	—	29	Tables  1 and  2 and Figures  1(a,b), and 4(b,d) as reported by Reynolds and Roden [19]; mean responses based on spring and fall combined results; treatment = hexazinone (PRONONE 10 G) at 2 kg ai/ha (granular formulation); effectiveness = reduction of 38% in red raspberry (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	−1	4	31	43	—	26	Tables  1 and  2 and Figures  1(a,b) as reported by Reynolds and Roden [20]; mean responses based on spring and fall combined results; treatment = sulfonylurea (Metsulfuron (ESCORT)) at 72 g ai/ha (liquid formulation); effectiveness = reduction of 47% in red raspberry (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	−1	5	100	63	—	48	Tables  2 and  3 as reported by Wood and von Althen [21]; mean responses based on bareroot and container stock-types combined results; treatment = glyphosate (Roundup) at 2 kg ai/ha (liquid formulation); effectiveness = reductions of 20% and 25% in herbaceous and woody vegetation cover, respectively, relative to the untreated control plots, at time of last remeasurement.
1	0	5	87	35	—	−5	Tables  1 and  2 and Figures  2(b,d) as reported by Reynolds and Roden [19]; mean responses based on spring and fall combined results; treatment = hexazinone (Velpar L) at 2 kg ai/ha (liquid formulation); effectiveness = reduction of 44% in red raspberry (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	0	5	53	25	—	−27	Tables  1 and  2 and Figures  2(a,c) as reported by Reynolds and Roden [19]; mean responses based on spring and fall combined results; treatment = hexazinone (PRONONE 10 G) at 2 kg ai/ha (granular formulation); effectiveness = reduction of 38% in red raspberry (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	0	5	47	23	—	−38	Tables  1 and  2 and Figures  2(a,b) as reported by Reynolds and Roden [20]; treatment = sulfonylurea (Sulfometuron (OUST) at 300 g ai/ha (liquid formulation); effectiveness = reduction of 57% in red raspberry (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	0	5	20	—	—	−15	Tables  1 and  2 and Figure  1(a) as reported by Reynolds and Roden [20]; treatment = sulfonylurea (Metsulfuron (ESCORT) at 72 g ai/ha (liquid formulation); effectiveness = reduction of 47% in red raspberry (major competitor) cover, relative to untreated control plots, at time of last remeasurement.
1	0	5	35	15	112	—	Table  1 as reported by Sutherland et al. [22] and Figure  1(d) as reported by Sutherland and Foreman [23]; treatment = hexazinone (Velpar L) at 3.1 kg ai/ha (liquid formulation); effectiveness = initial reduction of competing vegetation at time of treatment; however, based on a vegetation index metric (height × cover), competition (red raspberry and trembling aspen (Populus tremuloides Michx.) increased 40%, relative to the untreated control plots, at the time of last remeasurement.
1	0	5	26	19	109	−9	Tables  1, 2, 3, and  4 as reported by Jobidon et al. [24]; results for chemical treatment at the Flynn experimental site; treatment = glyphosate (Vision) at 1.5 kg ai/ha (liquid formulation); untreated control plots dominated by red raspberry (63–75% cover) at time of establishment.
1	0	5	42	27	204	−4	Tables  1, 2, 3, and  4 as reported by Jobidon et al. [24]: results for manual treatment at the Flynn experimental site; treatment = physical removal via hedge clipper; untreated control plots dominated by red raspberry (63–75% cover) at time of establishment.
1	0	5	27	13	93	0	Tables  1, 2, 3, and  4 as presented Jobidon et al. [24]; results for chemical treatment at the Joncas experimental site; treatment = glyphosate (Vision) at 1.6 kg ai/ha (liquid formulation); untreated control plots dominated by red raspberry (24–45% cover) at time of establishment.
1	0	5	24	14	86	3	Tables  1, 2, 3, and 4 as reported by Jobidon et al. [24]: results for manual treatment at the Joncas experimental site; treatment = physical removal via machete; untreated control plots dominated by red raspberry (24–45% cover) at time of establishment.
1	0	5	45	20	104	2	Tables  1, 2, 3, and 4 as reported by Jobidon et al. [24]; results for chemical treatment at the Pilote experimental site; treatment = glyphosate (Vision) at 1.6 kg ai/ha (liquid formulation); untreated control plots dominated by red raspberry (71–79% cover) at time of establishment.
1	0	5	40	23	99	13	Tables  1, 2, 3, and 4 as reported by Jobidon et al. [24]: results for manual treatment at the Pilote experimental site; treatment = physical removal via brush cutter; untreated control plots dominated by red raspberry (71–79% cover) at time of establishment.
1	0	5	67	41	—	12	Tables  2 and 3 as reported by Wood and von Althen [21]; mean responses based on bareroot and container stock-types combined results; treatment = glyphosate (Roundup) at 2 kg ai/ha (liquid formulation); effectiveness = reductions of 10% and 42.5% in herbaceous and woody vegetation cover, respectively, relative to untreated control plots, at time of last remeasurement.
1	0	5	68	38	273	5	Table  2 and Figures  1, 4(a), and 6(a) as reported by Pitt et al. [18]; mean responses based on bareroot and container stock-types combined results; treatment = hexazinone (Velpar L) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 20% and 1% in herbaceous and woody vegetation cover, respectively, relative to untreated control plots, at time of last remeasurement.
1	0	5	17	13	69	2	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 10% in herbaceous vegetation cover relative to the untreated control plots at the time of last remeasurement (𝑛., nil competition from woody species).
1	0	10	15	7	—	7	Table  2 as reported by Jobidon and Charette [26]; results for Squatec experimental site; treatment = manual removable via pulling of all vegetation within 60 cm of subject trees; principal competitor species were removed (red raspberry and fireweed).
1	0	10	49	40	—	20	Table  4 as reported by Jobidon and Charette [26]; results for Lake Anna experimental site; treatment = mechanized manual removable via brush cutter of all vegetation within 60 cm of subject trees; principal competitor species were removed (shade intolerant deciduous trees).
1	0	10	79	52	—	11	Table  4 as reported by Jobidon and Charette [26]; results for Lake Anna; treatment = manual removable via pulling of all competing vegetation; principal competitor species were removed (shade intolerant deciduous trees).
1	0	11	78	18	—	−10	Figures 3, 5, and  7 as reported by Wood and Mitchell [27]; results for Bragg experiment; mean responses based on bareroot and container stock-types combined results; treatment = glyphosate (Roundup) at 2.5 kg ai/ha (liquid formulation); effectiveness = reductions of 97% in competing vegetation (principally trembling aspen), relative to the untreated control plots, at time of last remeasurement.
1	0	15	67	48	240	—	Figure  1 as reported by Robinson et al. [28]; mean response of brush control treatment relative to untreated control plots; treatment = glyphosate (Roundup) at 2.2 kg acid equivalent/ha (liquid formulation) on bladed scarified sites; effectiveness: at the time of the 15 yr post-treatment assessment, the treatment had eliminated the noncrop hardwood species.
1	1	5	31	10	—	−11	Tables  2 and 3 as reported by Wood and von Althen [21]; mean responses based on bareroot and container stock-types combined results; treatment = glyphosate (Roundup) at 2 kg ai/ha (liquid formulation); effectiveness = reductions of 5% and 35% in herbaceous and woody vegetation cover, respectively, relative to untreated control plots, at time of last remeasurement.
1	1	11	51	8	—	−7	Figures 3, 5, and  7 as reported by Wood and Mitchell [27]; results for Bragg experiment; mean responses based on bareroot and container stock-types and spring and summer seasonal results combined; treatment = glyphosate (Roundup) at 2.5 kg ai/ha (liquid formulation); effectiveness = reductions of 98% in competing vegetation (principally trembling aspen), relative to the untreated control plots, at time of last remeasurement.
1	2	10	87	46	246	—	Textual description and Figure  1 as reported in Pitt et al. [29] for Corrigal experimental site; annual directed foliar application of 1.58 or 2% liquid solution of glyphosate (Vision); effectiveness: at the time of the 10 yr remeasurement the average of all treatments had reduced the cover of deciduous woody tree species to less than 10%, tall shrub species to 2%, and low shrub species to 20%.
1	2	11	38	25	—	5	Figures 3, 5, and  7 as reported by Wood and Mitchell [27]; results for Kenogaming experiment; mean responses based on bareroot and container stock-types and spring and summer seasonal results combined; treatment = glyphosate (Roundup) at 2.14 kg ai/ha (liquid formulation); effectiveness = reductions of 76% in competing vegetation (principally trembling aspen), relative to the untreated control plots, at time of last remeasurement.
1	2	11	33	11	—	−19	Figures 3, 5, and  7 as reported by Wood and Mitchell [27]; results for Lampugh experiment; mean responses based on bareroot and container stock-types and spring and summer seasonal results combined; treatment = glyphosate (Roundup) at 2.14 kg ai/ha (liquid formulation); effectiveness = reductions of 94% in competing vegetation (principally trembling aspen), relative to the untreated control plots, at time of last remeasurement.
1	3	10	87	8	126	—	Textual description and Figure  1 as reported in Pitt et al. [29] for Hele experimental site; treatment = glyphosate (Vision) at 1.7 kg ai/ha (liquid formulation); effectiveness: at the time of the 10 yr remeasurement the average of all treatments had reduced the cover of deciduous woody tree species to less than 10%, tall shrub species to 2%, and low shrub species to 20%.
1	4	5	24	3	69	−1	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 20% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
2	0, 1	5	59	21	228	−6	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 21% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
2	3, 4	5	40	−1	117	1	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 92% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
3	0, 1, 2	5	82	31	336	−4	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 44% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
3	2, 3, 4	5	79	−2	270	−8	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 93% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
3	0, 2, 4	5	126	26	471	—	Table  1 as reported by Sutherland et al. [22] and Figure  1(d) as presented in Sutherland and Foreman [23]; treatment = hexazinone (Velpar L) at 3.1 kg ai/ha (liquid formulation) in year 0 followed by chemical tending in years 2 and 4 using glyphosate (Vision) at 1.78 kg ai/ha (liquid formulation); effectiveness = reduction of 96% in combined herbaceous and woody vegetation (principally red raspberry and trembling aspen; vegetation measure based on height × cover index), relative to untreated control plots, at time of last remeasurement.
4	0, 1, 2, 3	5	109	22	426	−8	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 57% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
4	1, 2, 3, 4	5	79	15	270	−5	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 94% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
4	−1, 0, 1, 2	14	93	43	125	12	Figures  13, 14, 15, and 16 as reported by Robinson et al. [28]; results for the scarified but unfertilized plots only; treatment = glyphosate (Vision) at 2 kg ai/ha (liquid formulation); effectiveness = approximate reduction of 100% in herbaceous and woody vegetation cover, relative to the untreated control plots, 3 years post-planting.
5	0, 1, 2, 3, 4	5	213	96	—	20	Tables  2 and 3 as reported by Wood and von Althen [21]; mean responses based on bareroot and container stock-types results combined; treatment = annual application of glyphosate (Roundup) at 2 kg ai/ha (liquid formulation); effectiveness = reductions of 90% and 100% in herbaceous and woody vegetation cover, respectively, relative to the untreated control plots, at time of last remeasurement.
5	0, 1, 2, 3, 4	5	108	22	420	12	Table  1 and Figure  2 as reported by Wagner et al. [25]; treatment = glyphosate (Vision) at 4 kg ai/ha (liquid formulation); effectiveness = reduction of 96% in herbaceous vegetation cover, relative to the untreated control plots, at the time of last remeasurement (𝑛., nil competition from woody species).
5	2, 3, 4, 5, 6	10	87	46	246	—	Textual description and Figure  1 as reported in Pitt et al. [29] for Corrigal experimental site; annual directed foliar application of 1.58 or 2% liquid solution of glyphosate (Vision); effectiveness: at the time of the 10 yr remeasurement the average of all treatments had reduced the cover of deciduous woody tree species to less than 10%, tall shrub species to 8%, and low shrub species to 20%.
5	3, 4, 5, 6, 7	10	87	8	126	—	Textual description and Figure  1 as reported in Pitt et al. [29] for Hele experimental site; annual directed foliar application of 1.58 or 2% liquid solution of glyphosate (Vision); effectiveness: at the time of the 10 yr remeasurement the average of all treatments had reduced the cover of deciduous woody tree species to less than 10%, tall shrub species to 2%, and low shrub species to 20%.
6	−1, 0, 1, 2, 3, 4	5	221	95	—	22	Tables  2 and 3 as reported by Wood and von Althen [21]; mean responses based on bareroot and container stock-types results combined; treatment = annual application glyphosate (Roundup) at 2 kg ai/ha (liquid formulation) including pre-planting treatment; effectiveness = reductions of 90% and 100% in herbaceous and woody vegetation cover, respectively, relative to the untreated control plots, at time of last remeasurement.

Note, all selected studies were located within the Great Lakes - St. Lawrence or Boreal Forest Regions [30].
aNumber of sequential treatments (𝑇_𝑁); Initial year of treatment application relative to the year of seedling establishment (−1 = year before planting (e.g., chemical site preparation); 0 = year of seedling establishment; 1, 2, …, 7 years after seedling establishment, resp.; (𝑇_𝐼)); and Length of the observation period relative to the year of seedling establishment (𝑇_𝐿).
b 𝑅_𝑘=100⋅(𝑇_𝑘−𝐶_𝑘)/𝐶_𝑘 where 𝑅_𝑗 is the relative response (%) of the 𝑘th yield variate (𝐷 = basal stem diameter; 𝐻 = total stem height; 𝑉 = total stem volume; and 𝑆 = survival),𝑇_𝑘 is the mean value of the 𝑘th yield variate within the treated population, and 𝐶_𝑘 is the mean value of the 𝑘th yield variate within the untreated control population.