EXPERIMENTAL STUDIES OF RED ALDER NUTRITION ON VANCOUVER ISLAND

Transcription

1 EXPERIMENTAL STUDIES OF RED ALDER NUTRITION ON VANCOUVER ISLAND Kevin Brown, KR Brown and Associates, Victoria, BC Paul Courtin, BC Ministry of Forests, Nanaimo, BC

2 But why nutrition? Alder fixes nitrogen! Importance of fixing atmospheric N 2 and its impact on red alder, coniferous associates, ecosystems has driven much research Much less research on effects of nutrition on red alder

3 Do mineral nutrient deficiencies limit the growth of red alder on Vancouver Island? Rationale: Evidence relating site index and nutrient availability Ongoing study of management regimes: density, pruning, thinning, mixtures in conjunction with HSC at OSU E. Vancouver Island, Sunshine Coast identified as prime areas for intensified management

4 N Glasshouse Single tree plot Stand-level 50 km

5 Previous work on alder nutrition and growth Correlative studies: Courtin 1992; Harrington and Courtin 1994 Field studies: alder after alder or Douglas-fir Cole et al. 1990; Compton et al. 1997; Compton and Cole 2001 Seedling and young plantation studies Binkley 1986; Radwan and DeBell 1994; Hurd and DeBell 2001 P seemed to be important

6 General Questions: Is growth limited by deficiencies of mineral nutrients? If so, which ones and in which sites? What are the long-term effects of adding those nutrients on different sites? Experimental approaches: Potted seedlings Single-tree plot fertilization experiments Multi-tree plot experiments

7 Glasshouse effects of P additions and liming Rationale: indication that P supply might limit growth of alder in lower-ph soils Grew seedlings in soils from alluvial alder stands on Vancouver Island: west of Cowichan Lake and north of Campbell River All sites classified as having rich-very rich soil nutrient regimes 4 sites low ph (4.5) 2 sites high ph (5.5) Fertilized with P, dolomitic lime, grew for three months

8 Soil nutrient regime (SNR) and Soil Moisture Regime (SMR) Integral part of BC biogeoclimatic ecosystem classification system guide to forest management decisions Determined using field-identifiable site and soil characteristics, composition of flora Related to site index SNR related to soil nutrient availability

9 Whole-plant mass (g) Response (%) SY SL Figure 3. projtm vs Bray-P (unfert) BT NI CL KL P1 P2 Growth of unfertilized seedlings increased with Bray-P Response to added P decreased with increasing Bray-P Bray-P (ppm) ns Increase significant in 5 of 6 soils

10 Whole-plant Mass (g) Effect of P greater in low-ph soils 2 P0 P1 P2 P0 P1 P2 "Low-pH" "High-pH"

11 Addition of dolomite increased ph, Mg uptake ---did not affect growth Conclude P deficiencies may limit growth of red alder even in sites classified as very rich

12 Field experiments: single-tree plot Rationale: Confirm whether nutrient deficiencies existed in field sites Only very small plantations available Disadvantage: Can t assess long-term effects at stand level

13 Site Age Dominant Tree Species Bray- P(ppm) CEC(c mol/kg) Malaspina (M) 4 P. menziesii Bowser (B) 4 P. menziesii French Creek (FC) 4 P. menziesii Quinsam (Q) 3 P. menziesii Hillcrest (Hill) 2 P. menziesii FannyBayDry (FBD) 1 A. rubra FannyBayWet (FBW) 1 A. rubra CampbellR Lower (CRL) 1 A. rubra / P.trichocarpa CampbellR Upper(CRU) 1 P. menziesii HarryRoad (HR) 0 A. rubra

14 SOIL NUTRIENT REGIME MOISTURE Very poor Poor Medium Rich VeryRich Very_Dry 0 02 Mod_Dry Mod_Dry 2 Hill CRU FC M Sl_Dry 3 B 01 Fresh 4 Q 05 Moist 5 06 FBD, HR 07 VeryMoist 6 FBW, CRL Wet

15

16 Treatments Added P with or without other elements: 0,10, 20, 30 g P per tree in younger; 0, 20, 40 g P in older Other elements added in appropriate proportion relative to P Older plantations removed understory and then banded fertilizers Younger plantations: placed fertilizer in dibble holes Responses measured for up to three years

17

18 Single-tree plot experiments: Older plantations little or no growth response to either P or blend fertilizer Younger plantations growth response to P, not to other added elements

19 Three year growth response; screening trials, young plantations Stem Volume (dm 3 ) n.c. 3Y VOLUME BY SITE + 80 % + 96 % +45 % + 56 % 3Y HEIGHT + 64 % Best response on relatively moist, fertile sites Height (m) 3 0 Duncan CR-U FB-W CR-L FB-D Harry Rd ? CDF CWHxm

20 Single-tree plot experiment (cont d) P fertilizer increased growth and Y1 foliar concentrations of P, N (all sites) Ca, Mg, S (some sites) decreased Zn (all sites) K, B, Cu, Mn (some sites) Blend fertilizer increased N, K, Mg, S, B, Zn but did not increase growth Conclude P availability limited growth

21 Stem volume (dm3) a M Q B FC Older plantations b Younger plantations Stem Volume (dm 3 ) FBD FBW CRL CRU HR Foliar P (g kg -1 )

22

23 Why were older plantations less responsive? Trees were bigger: volumes in 4 year old plantations 84X greater than in 1 year old, but P addition only 2X Soil in older plantations had higher P levels Foliage in older plantations had greater P concentrations

24 Multi-tree Plot Experiments McColl Road (Bowser) CWHxm ss 01/05 SMR: SD-F SNR: M-R ph: 5.3 Avail P: 10.7 mg kg -1 Planted fall 1999 / fill-planted in spring Plots 25m x 25m with 10m treated buffer and 86 measurement trees per plot

25 Stem volume (cm 3 ) Y = 1.496P r 2 = 0.49 Prior to P additions, stem volume increased with soil Bray-P Soil (Bray-extractable) P (mg kg -1 )

26 Treatments 0, 15, 30 g P per tree in spring 2001 Treatments randomly assigned Attempt to maintain differences in foliar P All trees re-fertilized in 2002, 2003, 2004; cumulative P additions of 0, 41, 88 g P/tree (0, 58, 124 kg P/ha)

27 Stem Volume (cm 3 ) fall 2004 fall 2003 Y0 Y1 Y2 Y3 Y4 Volume increase with P additions Absolute increase greater in 1999 cohort Relative increase greater in 2001 cohort 0 P0 P1 P2 P0 P1 P2 planted 1999 planted 2001

28 Mortality (%) Mortality (%) cohort 2001 cohort Mortality greater in younger trees Unaffected by P treatment through 4 years Mortality greater in 2003, 2004, than in 2002; drought??? P0 P1 P2

29 Precipitation(mm) normal Month Growing season precipitation close to normal in 2001, 2002; Below-normal in 2003, early 2004

30 What we ve learned P additions often increase growth of very young red alder Growth responses are greatest at: addition rates of g P / tree within year of planting low soil P concentrations (< 15 ppm) or low foliar P concentrations (< 0.18 %) Soil or foliar P is a better predictor of response than is BEC soil nutrient regime Haven t seen growth responses to addition of elements other than P

31 Some things we don t know Why were bigger trees less responsive? How long do the effects of P fertilization last? Does P fertilization increase N accumulation? Are of P-fertilized alders more susceptible to frost damage? Are P- fertilized alders more susceptible to moisture stress? At what rate does P fertilization induce deficiencies of other elements?