Model Struktur Tegakan Hutan Tanaman Agathis (Agathis loranthifolia) di Hutan Pendidikan Gunung Walat Sukabumi Jawa Barat

Abstract

Forest stand structure is the number of trees distribution on various class diameters per unit area and is one of the forms of display of a structure. A diversity of various class diameters are very affected by external and internal factors of tree development. The internal factors that affect : tree growth are types and location of tree developments. Tree types are highly linked with genetic factors, few trees with the same types but different surrogates, then those trees will have different growth for each trees. Meanwhile, the age of tree is linked with diameter growth, the age difference will affect the large or small of the diameter. The external factors that affects tree growth are climatic factor, edapic factor, and biotic. The edapic factor is connected with the soil which is the growth place’s condition. The condition of the said forest stand structur essentially can be identified by looking at the stand structure of the forest. To elaborate the stand structure condition, a famillial distribution method such as : normal distribution family, lognormal, gamma, and negative exponential can be used. The purpose of this study is to gain an agathis plant forest stand structure model in the shape of its family’s distribution, as well as analyzing the skewness value of Agathis loranthifolia’s stand stucture curve. This research was conducted at Gunung Walat University Forest in February 2011. The data used were the tree measurement on breast height of agathis forest stand. The method used to measure the stands was the lines method. The transect chosen is 1 hectare area wide with a 500 meter line length and 20 meter line width. The choosing of the transect location is conducted by purposive sampling. In this research, five transects is chosen that is able to represent the forest stand structure in the study location. The results of study conducted in Gunung Walat University Forest with maximum likelihood function method indicates that the model choosen as the best model in depicting the stand stucture of the agathis cohort and the cohort of all types is the gamma family distribution model. Meanwhile, the best model in depicting the cohort stand structure of types is the lognormal distribution family model. The coefficient skewness value obtained tends towards positive skewness. This indicates that most of the data clusters in the left side end, while in the right side end, the data isn’t that many. So that in its management it will be easier to make the curve to zero skewness by doing regeneration effort by planting on unproductive areas or empty lots, efforts in increasing quality and quantity by thinning, controlling pests and disease, controlling forest fires, climate disturbance, and protecting from disturbances from humans and animals.