EJAS-17598 Camera Ready.pdf

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European Journal of Applied Sciences – Vol. 12, No. 5

Publication Date: October 25, 2024

DOI:10.14738/aivp.125.17598.

Ingura, I. O., Kirongo, B. B., & Odhiambo, K. O. (2024). Influence of Tree-Crop Distance on Growth of Pinus patula and Cupressus

lusitanica in Plantation Establishment and Livelihood Improvement Scheme. European Journal of Applied Sciences, Vol - 12(5).

146-160.

Services for Science and Education – United Kingdom

Influence of Tree-Crop Distance on Growth of Pinus patula and

Cupressus lusitanica in Plantation Establishment and Livelihood

Improvement Scheme

Isaac Omoding Ingura

University of Eldoret, School of Environmental Science and

Natural Resource Management, Department of Forestry and

Wood Science, P.O. Box 1125-30100, Eldoret, Kenya and

Kenya Forest Service, Karura - off Kiambu Road, P.O.

Box 30513-00100, Nairobi, Kenya

Balozi Bekuta Kirongo

University of Eldoret, School of Environmental Science and

Natural Resource Management, Department of Forestry and

Wood Science, P.O. Box 1125-30100, Eldoret, Kenya

Kenneth Opiyo Odhiambo

University of Eldoret, School of Environmental Science and

Natural Resource Management, Department of Forestry and

Wood Science, P.O. Box 1125-30100, Eldoret, Kenya

ABSTRACT

The Plantation Establishment and Livelihood Improvement Scheme (PELIS), is an

approach of raising young seedlings in a plantation whereby communities are

given small areas of forest land with seedlings to till and take care of the planted

seedlings until they reach canopy closure. But the system has had a number of

managerial issues, the most prominent being that there is no recommended

distance between the seedlings and crops (tree-crop distance). Thus, farmers

plant their food crops immediately next to the young tree seedlings thus

exacerbating intra-specific competition. Some of the crops planted include maize,

cabbages and Irish potatoes. These crops cause excessive competition for

moisture, nutrients, space and light to the detriment of the desired tree seedlings.

The result has been massive failures of young plantations, while those that are

cited as “successful” end up with poor growth rates and poor form not suited for

the objectives of plantation establishment. This study was set up to elucidate the

effects of tree-crop distance on the growth of Pinus patula and Cypress lusitanica

seedlings in a PELIS system so as to come up with an optimum distance for tree- crop in a PELIS system of establishment. The treatments constituted plantation

tree species (P. patula and C. lusitanica) and crops (cabbages and potatoes) at tree- crop distances of 20cm, 50cm, 100cm and 150cm. The control for the experiment

was at tree-crop distance of 20cm. Plots of 5 × 5 tree seedlings with a weed free

zone at the center (3x3 seedlings) were set up for C. lusitanica and P. patula. The

inner 3 × 3 tree seedlings were assessed monthly for height and root collar

diameter growth from time of transplanting while the outer trees formed the

guard row. The experiment was in Complete Randomized Block Design (CRBD) in

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Ingura, I. O., Kirongo, B. B., & Odhiambo, K. O. (2024). Influence of Tree-Crop Distance on Growth of Pinus patula and Cupressus lusitanica in

Plantation Establishment and Livelihood Improvement Scheme. European Journal of Applied Sciences, Vol - 12(5). 146-160.

URL: http://dx.doi.org/10.14738/aivp.125.17598

2 replicates. The study was in two sites, Timboroa and Kipkurere. ANOVA analyses

were performed on the data (P < 0.05) and significant treatments were

discriminated using Turkey’s HSD test. The results showed that the best growth in

RCD and height occurred at tree-crop distance of 100 cm which was significantly

higher than the control (P < 0.05) at both sites. The research demonstrated that in

PELIS tree-crop distance is an important factor that affects the growth of tree

seedlings and therefore we recommend tree-crop distance of 100 cm for

successful C. lusitanica and Pinus patula establishment.

Keywords: Silviculture, Growth, Establishment, Tree-crop distance, Cupressus lusitanica,

Pinus patula

INTRODUCTION

At the global level, the number of people demanding food, energy, wood, medicine,

construction materials among other environmental goods have increased tremendously over

the decades (Jha et al., 2024; Warziniack et al., 2024). The simultaneous demand for

tree/forest products and food especially among adjacent dwellers to forests require strategies

and/or approaches that encourage food systems with trees and forests within the same parcel

of land (Ickowitz et al., 2022; Steel et al., 2024). This has seen increased sustainability in land

use systems which incorporate farming systems such as agri-silviculture in forest lands. This

is where trees are grown together with agricultural crops in an endeavour to ensure

sustainable forest management (Borges et al., 2019; Behera and Bastia, 2024), as well as food

production. The practice of plantation establishment (Pommerening, 2024), is a viable

strategy which helps in accelerating forest growth (Catterall, 2020; Toledo-Aceves et al.,

2021) and forest cover.

Plantation Establishment and Livelihood Improvement Scheme (PELIS); (formerly the

Shamba system or Taungya), is a modified form of non-residential cultivation method of

forest plantation establishment (Agevi, 2016; Pommerening, 2024). It involves planting

plantation tree species seedlings together with food crops in forestland over a defined period

of time, assuring affordable labour for planting and tending the plantation (Mwatika, 2013;

Agevi, 2016). By allowing farmers to utilize the forest land for cropping while tending for the

young plantations during establishment, potential land use conflicts with local communities

that rely on forestland for their subsistence needs are minimized. The adoption of PELIS

system also confers the forest adjacent communities the moral obligation to fulfil corporate

social responsibility of forest management (Van Der Meer Simo, 2020).

Good silvicultural practices of trees and crops in PELIS will secure food and energy resources,

reduce the reforestation cost, create more job opportunities for rural folk and increase the

participation of local people in partaking reforestation (Seneviratne et al., 2015; Kuyah et al.,

2020). One of the silvicultural practices in PELIS is intercropping of tree seedlings and crops.

On this account, several tree species have been intercropped successfully in PELIS including

Eucalyptus saligna, Cupressus lusitanica and Pinus patula (Talema et al., 2019; Kisangau et al.,

2021). Among these tree species, P. patula and C. lusitanica are the most important (Masaba et

al., 2020) in plantation forestry in Kenya where they perform multiple functions such as

timber production, pulp and paper production, and particle board manufacture (Gichuru,

2015 #98)(Masaba, 2020 #93)(Chepkoech, 2023 #123). Meanwhile, there are a variety of

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European Journal of Applied Sciences (EJAS) Vol. 12, Issue 5, October-2024

crops that have been reported in PELIS including single crops such as Irish potatoes (Solanum

tuberosum), peas (Pisum sativum), carrots (Daucus carota subsp. sativus), kale (Brassica

oleracea var. sabellica), and cabbages (Brassica oleracea var. capitata) among other

vegetables. These crops can also be intercropped by farmers in addition to tending the

plantation tree species (Sinange, 2015; Wanjira and Muriuki, 2020). Therefore, growth of the

tree seedlings and food crops and important conditions associated with the growth remain

significant in PELIS.

One of the perturbing practices in many parts of the world is the planting of tree species in

areas where growing conditions may not be suitable (Waruingi et al., 2021). The conditions

influencing plantation tree species’ growth in environments vary with site and species, but

generally include soil pH, bulk density, Carbon, Nitrogen, Phosphorus, temperature, wind and

competition (Andrus, 2018 #65). The interactions of soil pH, bulk density, carbon, nitrogen,

phosphorus, temperature, wind and competition on plantation tree species’ growth can be

influenced by tree-crop distance (Gallo et al., 2023). In a study of the “effects of non-crop

vegetation (weeds) on growth of young radiata pine (Pinus radiata), it was shown that weed

species growing in close proximity to P. radiata seedlings had a huge negative impact on the

growth of the desired P. radiata. The more the tree-crop distance (up to a certain optimum

distance) implied less competition and therefore, better growth performance than their

counterparts in tree-crop distances with most weeds (Kirongo, 2000; Chepkoech et al., 2023).

Raising plantation tree species in several tree-crop distances may result in differential growth

due to variation in the conditions that exist at the tree-crop neighbourhood where the tree

species are being raised (Blanchard and Platt, 2021; Martin et al., 2021).

It is clear that these crop-tree interactive dynamics and variation in tree-crop distance can

also influence the growth of the plantation tree species. A comprehensive understanding of

tree growth is therefore essential. On the basis of the foregoing, this research sought to

determine the influence of tree-crop distance and some soil parameters on growth of young C.

lusitanica and P. patula in a PELIS system in Kenya. In this paper, we report on the effect of

tree-crop distance on growth performance of P. patula and C. lusitanica.

MATERIALS AND METHODS

Study Area

The study was carried out in Timboroa and Kipkurere Forests within Uasin Gishu County,

Kenya (Fig 1). The County lies between longitudes 34o50’ East to 35o37’ East and latitudes

0o03’ South to 0o 55’ North. The County shares common borders with Trans Nzoia County to

the North, Elgeyo Marakwet County to the East, Baringo County to the South East, Kericho

County to the South, Nandi County to the South West and Kakamega County to the North

West. It covers a total area of 3,345.2 km2 (Nyongesa et al., 2023).

The County experiences a high and reliable rainfall with an average annual rainfall ranging

between 624.9 mm to 1560.4 mm. Rainfall occurs between March to September with distinct

peaks in May and August. The dry spell starts in November and end in February. The average

temperature range between 7°C to 29°C (Kimani, 2017; Ongiyo, 2019). Soils in the study area

have low fertility due to leaching and loss of humus through continuous cultivation. The soil is

heavy in texture and mainly orthic ferrasols and humic aerosols (Kiptot et al., 2007).

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Ingura, I. O., Kirongo, B. B., & Odhiambo, K. O. (2024). Influence of Tree-Crop Distance on Growth of Pinus patula and Cupressus lusitanica in

Plantation Establishment and Livelihood Improvement Scheme. European Journal of Applied Sciences, Vol - 12(5). 146-160.

URL: http://dx.doi.org/10.14738/aivp.125.17598

Mixed subsistence agriculture is the main subsistence activity in the study area. Average total

farm size is 0.58 hectares. The sizes of farms slightly increase for households in wealthier

income groups. The major economic activities practiced in the region include large-scale

barley farming, dairy and horticulture farming. Maize is the main food crop. Other crops

grown include; sunflower, wheat, pyrethrum, beans, cabbages and potatoes. The area is

classified under low medium - agro-ecological zone (Akenga et al., 2016).

Figure 1: Map of the study area showing the location of Timboroa forest Station and Kipkurere

Station in Uasin Gishu County (Kenya) (Uasin Gishu Forest Map. Map of Uasin Gishu Forest,

03/02/2024).

Data Collection and Measurements

At the PELIS sites of Timboroa and Kipkurere forests, plots of 5 × 5 tree seedlings with weed

free zone at the centre (3 m × 3 m) were used for C. lusitanica and P. patula. The inner 3 m × 3

m tree seedlings were assessed monthly for height and root collar diameter from time of

transplanting. The inner zone (green for trees and blue for crops (Figure 2) were assessed

monthly while the outer trees (orange) formed the guard row. The RCD was marked 5 cm

above ground level with permanent marker to ensure same position of measurement every

time and the height was measured from RCD line to ensure consistency. The experiment was

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done in Complete Randomized Block Design (CRBD) in 2 replicates in each site. The

treatments were tree-crop distances of 20 cm, 50 cm, 100 cm and 150 cm. The control for the

experiment was at tree-crop distance 20 cm.

Figure 2: Plot layout showing 5×5 tree arrangement with weed free zone at the centre (3x3).

Tree spacing for Pinus patula was 2.75 m × 2.75 m while that of Cupressus lusitanica was 2.5 m

× 2.5 m.

Data Analysis

Growth of P. patula and C. lusitanica were measured in terms of RCD (cm) and height (cm).

Mean values of RCD (cm) and height (cm) between treatments were tested using Analysis of

variance (ANOVA). Significantly different means (P < 0.05) were discriminated using Turkey’s

HSD test. The interaction between tree-crop distance and cropping system was analyzed

using Response surface methodology (RSM).

20 cm tree-crop distance

10 cm 10 cm 10 cm 10 cm 10 cm 10 cm

50 cm tree-crop distance

25 cm 25 cm 25 cm 25 cm 25 cm 25 cm

100 cm tree-crop distance

50 cm 50 cm 50 cm 50 cm 50 cm 50 cm

150 cm tree-crop distance

75 cm 75 cm 75 cm 75 cm 75 cm 75 cm

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Ingura, I. O., Kirongo, B. B., & Odhiambo, K. O. (2024). Influence of Tree-Crop Distance on Growth of Pinus patula and Cupressus lusitanica in

Plantation Establishment and Livelihood Improvement Scheme. European Journal of Applied Sciences, Vol - 12(5). 146-160.

URL: http://dx.doi.org/10.14738/aivp.125.17598

RESULTS

Growth Trends for Pinus patula

The final height of P. patula with respect to tree-crop distance in Timboroa and Kipkurere

forests after 6 months experimental period is presented in Figure 3. Turkey’s comparison of

the data is presented Table 1. There were significant differences in the final height of P. patula

in Timboroa (F (3,60) = 42.89, P = <0.001). Similarly, differences in the height of P. patula under

different tree-crop distances was significant in Kipkurere (F (3,68) = 274.135, P = <0.001).

Based on Tukey’s HSD test, there were similar responses to treatment. Height at tree-crop

distance sizes of 50 cm and 100 cm were similar but were higher than control (20 cm) and

150 cm tree-crop distance. Heights at tree-crop distance of 20 cm were similar to 150 cm.

Figure 3: Final height (Mean  SD) of Pinus patula with respect to tree-crop distance in

Timboroa and Kipkurere forests after 6 months of experimental period

Table 1: ANOVA and Turkey pairwise comparison of Pinus patula height at the two

sampling sites

One Way ANOVA

Timboroa Kipkurere

F 42.89 274.135

df 3 3

P-value <0.001 <0.001

Tukey’s mean Pairwise comparison Mean

100-50 4.939 9.803

100-150 39.633*** 41.862***

100-20 46.064*** 52.025***

50-20 41.125*** 32.222***

50-150 34.694*** 22.059***

150-20 6.431 10.163

Growth trends in height of P. patula over the 6 months period (5 months after planting in

Timboroa and Kipkurere Forest stations) are provided in Figure 4. In both forests, the height

of P. patula planted at 100 cm tree-crop distance maintained the highest growth trends

reaching a height of 124.2 cm in Timboroa and 109.6 cm in Kipkurere. The lowest trend in

height occurred at tree-crop distance 150 cm throughout the experimental period.

100

120

140

20 50 100 150

Tree-crop distance (cm)

Height in cm

Timboroa

Kipkurere

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Ingura, I. O., Kirongo, B. B., & Odhiambo, K. O. (2024). Influence of Tree-Crop Distance on Growth of Pinus patula and Cupressus lusitanica in

Plantation Establishment and Livelihood Improvement Scheme. European Journal of Applied Sciences, Vol - 12(5). 146-160.

URL: http://dx.doi.org/10.14738/aivp.125.17598

P-value <0.001 <0.001

Tukey’s mean Pairwise

comparison

Mean

100-50 0.1318 9.803

100-150 0.7830*** 41.862***

100-20 0.9102*** 52.025***

50-20 1.0420*** 32.222***

50-150 0.9148*** 22.059***

150-20 0.1272 10.163

Growth trends of RCD in P. patula over the 6 months period is provided in Figure 6. In both

Forest stations, the RCD of P. patula at tree-crop distance of 100 cm maintained the highest

growth trend, followed by growth trend of P. patula under tree-crop distance of 50 cm which

were better than growth trend under control (20 cm). The lowest growth trend of P. patula

occurred at tree-crop distance of 150 cm for 6 months.

Figure 6: Growth trends in RCD of Pinus patula after planting in Timboroa and Kipkurere

forests for 6 months

Growth Trends for Cupressus lusitanica

The final height of Cupressus lusitanica with respect to tree-crop distance in Timboroa and

Kipkurere during the 6 months experimental period is presented in Figure 7, with a Tukey’s

pairwise comparison (Table 3). There were significance differences in height of P. patula in

Timboroa (F = 48.4523, df = 3, P = <0.0001) and Kipkurere (F = 51.457, df = 3, P = <0.0001).

The best growth in height occurred at tree-crop distance of 100 cm followed by 50 cm which

were significantly higher than control (P < 0.05) both in Timboroa and Kipkurere. The least

final height of P. patula occurred at 150 cm tree-crop distances.

Site 1 (Timboroa)

20 cm

50 cm

100 cm

150 cm

0.40

0.80

1.20

1.60

0 1 2 3 4 5 6 7

Time in months RCD (cm)

Site 2 (Kipkurere)

20 cm

50 cm

100 cm

150 cm

0.40

0.80

1.20

1.60

0 1 2 3 4 5 6 7

Time in months

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European Journal of Applied Sciences (EJAS) Vol. 12, Issue 5, October-2024

Figure 7: Final height (Mean  SD) of Cupressus lusitanica with respect to tree-crop distance in

Timboroa and Kipkurere after 6 months of experimental period

Table 3: ANOVA and Turkey pairwise comparison of Cupressus lusitanica height at the

two sampling sites

One Way ANOVA

F 43.76 62.44

df 3 3

P-value <0.001 <0.001

Tukey’s mean Pairwise comparison Mean

100-50 5.337 12.606

100-150 45.591*** 47.787***

100-20 52.942*** 59.651***

50-20 47.605*** 37.045***

50-150 40.254*** 25.181***

150-20 7.351 11.864

Changes in height of Cupressus lusitanica over the 6 months period is provided in Figure 8. In

both Forest stations, the height of tree under 100 cm tree-crop distance maintained the

highest growth trends reaching a height of 124.2 cm in Timboroa and 109.6 cm in Kipkurere.

The lowest trend in height occurred at tree-crop distance 150 cm throughout the

experimental period.

100

120

140

20 50 100 150

Tree-crop distance (cm)

Height in cm

Timboroa Kipkurere