Ecological value of tropical evergreen Aglaia-Streblus forest carbon pools at Meru Betiri National Park, East Java, Indonesia

Increasing forest destruction initiates ecological studies on sustainable natural ecosystem conservation. As main carbon sequester, the existence of plant species in the forest ecosystem becomes important. There is a need to appraise the contribution of plant species based on its ecoval of structure and functions to the system. This study, therefore, was done to develop ecological valuation tools for assigning forest biomass, necromass and soil organic matter ecovals in a natural ecosystem to determine the ecological value of the structure and dynamics of forest biomass, forest necromass and forest soil matter at tropical evergreen Aglaia-Strebus forest of Meru Betiri National Park, East Java, Indonesia. Comprehensive analysis and review of many publication on ecological valuation, tree appraisals, landscape appraisals and any appraisal methods were done to determine of parameters of ecological value (ecoval) appraisal. Cost based approach and simple mathematical method were used to propose the equations. Plotting method was used to collect plant species, woody debris and litterfall and soil organic matter. Direct measurements of soil moisture, temperature and pH were taken in the field. Semi and non-destructive methods were used to get wood chips or core of plant species, and phytomass of shrubs and herbs. The soil samples were extracted from six points of soil solum using soil auger. All fresh materials of plant species, woody debris, litterfall, and soils were weighed and oven dried in the laboratory. Allometric equations and volume were used to calculate biomass and necromass. The values were converted into carbon content using conversion factor of 0.5. The woody debris was classified into fine woody debris (FWD 5 cm) and coarse woody debris (CWD greater than or equal to 5 cm). Visual classifications were used to determine their decay classes. The elements content of organic C,N, P, and K were analyzed and estimated at the laboratory. Three equations of ecological value (IEpsilon) appraisals for biomass, necromass, and soil organic matter (SOM) were developed. This IEpsilon was the sum of ecological structure (S) and function (F) values. The equations were applicable to get information on the current condition of ecological structure and function of certain natural ecosystems. The information can be used as database or ecological consideration to generate policy, to make condition and to preserve the natural ecosystems. There were about 43 families, 67 genera, and 78 species of plants found in TMBNP. The diversity index of plant species in height: greater than or equal to m was moderate (2.71), while others were low. The Aglaia argentea-Streblus spinosus were dominant plant species greater than or equal to 1 m height, unidentified seedlings-Tetracera scandens, Donax canniformis-Panuicum repens were dominant species of understory, while Schizostachyum zollinger-Caryota mitis were the dominant species of three like. The plant species in greater than or equal to 1 m height of MBNP contributed the highest forest biomass (Nearly 3,500 Mg/ha) ecoval resulted in high carbon content (1,749 Mg/ha). Appraising ecological value accounted about 601,362-1,081,495 USD or 7,705,255,1267-13,857,197,433 IDR per ha. Total of 8,650 pieces/ha woody debris were found at the site giving impact on their high volume (340.92 m3/ha). Log input was 7,410 pieces/ha higher than both snags (700 pieces/ha) and stumps (540 pieces/ha). Based on the size classes, about 51.79% or 4480 pieces/ha of woody debris were contributed by the FWD and 48.21% or 4180 pieces/ha were contributed by the CWD. In addition to necromass of Pringtali area, the total litterfall covered about 67% per m2 or 0.8362 Mg/ha fresh weight in average. High accumulation of deadwood or woody debris resulted in 120.29 Mg/ha organic matter which was about 99.17% contributed by CWD and 0.83% by FWD. This value gave impact on 60.15 Mg/ha carbon content deposited in the pool. Furthermore, the ecoval of litterfall necromass was very small (0.235 Mg/ha), compared to that of woody debris, which was mostly deposited by the dead leaves. All these ecovals of necromass contributed ecoval of about 13,471-19,004 USD/ha or 172,608,716-243,509,464 IDR/ha which was about 94-98% contributed mostly by CWD. The result showed that SOM contributed higher ecoval of organic C (66.03 Mg/ha) than other elements. Compared to P and K elements, N had the highest stock of element content. However among other ecosystems, the ecovals of SOM elements in TMBNP was relatively low because of its natural geomorphological features. In conclusion, the total of the IEpsilon indicated that there were tremendous stocking organic matters and carbon deposited as biomass, necromass and SOM that reflects good ecosystem health of Aglaia-Streblus forest in the MBNP. These ecovals should be preserved for conservation to maintain biodiversity, biogeochemical cycles, and to sustain ecological processes and functions at the forest site. All the management and policies correlated to this protected area should consider this valuable information for their forest management policy.