FORAGE YEILD AND COMPITITION INDICES OF CEREALS MIXED INTERCROPPING WITH FORAGE LEGUMES IN SULAIMANI REGION

The present study was conducted in Sulaimani region at two different locations, Kanipanka and Qlyasan during winter season of 2019-2020 to estimate the response of forage yield and some competition indices to the effect of crop pure stands and their mixtures of barley and triticale intercropped with narbon vetch and grass pea with some different patterns. The experiment was designed according to Completely Randomized Block Design with three replications. As the average of both location the maximum green forage yield was produced by pure narbon vetch 32.610 ton ha-1, while pure barley produce maximum dry forage yield and dry matter % reached 5.506 ton ha-1 and 8.55% at booting stage respectively, but the crop mixture barley/grass pea at a rate 2:1 produce maximum green and dry forage yield 32.083 and 5.616 ton ha-1 respectively at booting stage. The crop mixture barley/vetch 1:1 gave maximum dry matter% 17.88% at the same stage. The highest value for total LER was 1.401recorded by the mixture of triticale/grass pea at elongation stage, while the highest relative crowding coefficient was 1.285 recorded by the same mixture at a rate 1:1 at the same cutting stage. Maximum competitive ratio for cereals was 3.652 recorded by barley in the mixture barley/grass pea 1:2 at elongation stage, while for legume it was 2.292 for narbon vetch in the mixture triticale/vetch 2:1 at booting stage.

Testing the Performance of Some Competition Indices against Experimental Data and Outputs of Spatially Explicit Simulation Models

Three competition indices were tested against experimental data on the growth of individual trees in mapped forest stands and outputs of spatially explicit, process-based models of competition. The comparison showed the fundamental importance of taking into account the spatial structure of stands and, particularly, the relative spatial locations of individual trees (spatial asymmetry) when calculating the competition between trees. Although none of the competition indices are able to take into account the specific processes affecting the development of individual trees, these indices can be used in forest dynamics modeling as a simplified representation of competition between trees for resources.

Competition in Abies kawakamii forests at subtropical high mountain in Taiwan

The spatial patterns of plant species reflect the competitive pressures on individuals. To generate Competition indices (CI), we measured the diameter at breast height (DBH), crown volumes (CV) and the distances between trees. In this study, Abies kawakamii were divided based on the dominant component of the understory (moss or bamboo) to (1) investigate the relationship between the CI and stand structural attributes (SSAs); (2) compare the inter- and intraspecies; CIs as well as living and dead individual CIs; and (3) examine the relationship between the DBH and CI. The current findings indicate that the understory composition affected the CI and SSAs. The interspecies CI was larger than the intraspecies CI when bamboo-dominated the understory. In contrast, the intraspecies CI was larger than the interspecies CI when the understory was dominated by moss. The CI of dead individuals was higher than that of live individuals due to the biological characteristics and regeneration needs of Abies. Additionally, sensitivity to the environment and available resources may exert more pressure on young individuals than mature individuals.

Caractérisation de la compétition et de la croissance de Pericopsis elata (Harms) Van Meeuven dans les plantations de la Réserve Forestière de Deng-Deng (Est, Cameroun)

Pericopsis elata est une espèce ligneuse à grande valeur commerciale menacée d’extinction. Les plantations d’Assamela installées dans la Réserve Forestière de Deng-Deng en 1974 ont été abandonnées après leur mise en place. Dès lors, très peu de connaissances relatives au développement de ces peuplements sont disponibles. L’objectif de la présente étude est de contribuer à la compréhension des conditions de croissance de Pericopsis elata dans la réserve et induire un aménagement efficace. Trois inventaires exhaustifs ont été conduits, au cours desquels les données dendrométriques et structurales ont été collectées. Les indices de compétition de Hegyi, les semi-variogrammes et la distribution spatiale des tiges ont été analysés et interprétés. Les densités actuelles sont sans effet limitant pour la croissance des tiges. Les effets du milieu se révèlent comme étant le facteur qui a plus d’impact sur la croissance des tiges de Pericopsis elata. La plantation de recrû (33,21 cm), moins sensible à l’effet de la densité en termes de croissance comparée aux plantations des grands layons (26,91 cm et 26,89 cm), enregistre les meilleures performances de croissance en diamètre. Ainsi, des travaux d’entretien et des éclaircies portées vers une réduction considérable des compétitions interspécifique et intra spécifique sont nécessaires.Mots clés : Indice de Hegyi, méthodes sylvicoles, modes de compétition, plantations équiennes, semi-variogramme, Cameroun. English Title: Characterization of the competition and growth of Pericopsis elata (Harms) Van Meeuven in the plantations of the Deng-Deng Forest Reserve (East, Cameroon)Pericopsis elata is a valuable woody species threatened with extinction. The Assamela plantations established in the Deng-Deng Forest Reserve in 1974 were abandoned after their establishment. As a result, very little knowledge about the development of these stands is available. The objective of the present study is to contribute to the understanding of the growing conditions of Pericopsis elata in the Reserve and to induce proper management. Three exhaustive inventories were conducted, during which dendrometric data were collected. Hegyi’s competition indices, variograms and spatial distribution of stems were developed. Current densities have no limiting effect on stem growth. Environmental effects were found to be the factor that had the greatest impact on the growth of Pericopsis elata stems. The recruiting plantation (33.21 cm), which is less sensitive to the effect of density in terms of growth compared to the large layon method (26.91 cm and 16.89 cm), has the best growth in diameter performance. Thus, maintenance work and thinning leading to a considerable reduction in interspecific and intraspecific competition is necessary.Keywords: Regular plantations, Hegyi’s competition index, mode of competition, Silvicultural methods, semi-variogram, Cameroon.

Impact of Integrated Nutrient Management on Performance of Oat-grasspea Cropping Systems, Competition Indices and Residual Soil Fertility

A field experiment in 3 times replicated split plot design comprising 4 cropping systems (CS) (CS1-Sole oat, CS2- Sole grasspea, CS3 and CS4-oat-grasspea intercropping in 3:2 and 3:3 row ratios, respectively) in main plot and 3 integrated nutrient managements i.e. N2, N3 and N4- 75% N through urea + rest N through FYM, vermi-compost and mustard oilcake, respectively along with N1 – 100% RDF in sub plot, was carried out at Central Research Farm, B.C.K.V., India during winter season of 2015-16 and 2016-17. Pooled results expressed that highest yield of oat (15.40 q/ha) and grasspea (12.44 q/ha) were obtained from CS4 and CS2, respectively, under application of N3. CS4 exhibited greater competition indices (LER: 1.16, RCC: 3.19, Aggressivity index: 0.184, CR: 1.39) and MAI ( 10,685.02) over CS3 under application of N3, showing 16% yield advantage as compared to sole cropping. Soil fertility remained best under CS2 (OC: 0.53%, available N: 218.39 kg/ha, available P2O5: 49.59 kg/ha, available K2O: 215.28 kg/ha) and among oat based CS, in CS4 with N3 application (OC: 0.52%, available N: 196.32 kg/ha, available P2O5: 44.28 kg/ha, available K2O: 194.95 kg/ha).

Local testing and calibration of species-specific competition indices in Sierran mixed conifer forests: Application transfer to evolving objectives

Forest growth processes are driven by site productivity and species functional traits, ultimately constrained by cumulative resource demand, and resulting in competitive dynamics across successional forest communities. Historic efforts to quantify competition utilize density metrics or neighborhood crowding indices for yield modeling and reforestation surveys. These methods have expanded to dendroclimatology and restoration applications that commonly assume similar competitive response across species of various functional types. We assessed competitive indices of two focal species (Pinus lambertiana Douglas and Pinus ponderosa Lawson & C. Lawson) in Sierra Nevada mixed conifer forests to estimate stem radial growth under current stand structure. We ranked correlations of basal area increment of the last 10 years (BAI10) separately across 20 competition indices (CIs). Best ranked CIs were used to test the relative influence of competition, tree size, and site variables on BAI10 with linear mixed models. While crown overlap was a common variable in CIs among both species, BAI10 of P. lambertiana was less impacted by intraspecific competition, and P. ponderosa appeared sensitive to all competing stems. Results suggest that local calibration of CIs with crown parameters may aid in interpreting Pinus species growth patterns, and the relative impact of competition on growth is species-specific.