Evaluation of Salacca sumatrana as soil conservation crop in South Tapanuli, North Sumatra, Indonesia

Nasution Y, Rasyidin A, Yulnafatmawita, Saidi A. 2019. Evaluation of Salacca sumatrana as soil conservation crop in South Tapanuli, North Sumatra, Indonesia. Biodiversitas 20: 664-670. Salacca sumatrana Becc (snake fruit; or ‘Salak' in local name) is a profitable commodity. Morphologically, it is characterized by low, wide canopy that is potential intercept rainfall, while its roots are able to withstand soil erosion. This study is aimed to evaluate one variety of S. sumatrana named ‘salak sidimpuan" as commodity crop soil conservation based on its capability to intercept rain and trap soil sediment in the catchment area of S. sumatrana field. The research was conducted on mineral soils at West Angkola Sub-district, South Tapanuli District, North Sumatra Province, Indonesia with an altitude of 350-880 m above sea level. The study was carried out from October 2016 until March 2017 using survey method to calculate on rainfall interception, stemflow and throughfall while measurement of sediment used evaporation method. Statistical analysis was used to observe the difference of sediment trapped on the catchment area of S. sumatrana agroforest and the catchment area of mixed forest using Mann-Whitney Test. The results show that rainfall interception on S. sumatrana agroforest is 74.33% of the average rainfall while the Mann-Whitney Test Sig (2-tailed) is 0.000, indicating significant difference in trapping soil sediment between S. sumatrana agroforest and mixed forest. The amount of soil erosion on the catchment of S. sumatrana agroforest is 15.12 ton/ha/year while the erosion on mixed forest is 194.85 ton/ha/year. Thus S. sumatrana plant is capable to withstand rain interception with the result that soil erosion can be held in the catchment area of S. sumatrana agroforest. Instead of the calculation rain interception and soil erosion, then S sumatrana is classified as a soil conservation crop.

KOMPOSISI DAN STRUKTUR VEGETASI DALAM POTENSINYA SEBAGAI PARAMETER HIDROLOGI DAN EROSI

The magnitude of the rain interception by the canopy is largely determined by vegetation composition and stratification. The kinetic energy of raindrops changes because the role of the vegetation part inhibits the rate of rainwater. This study aims to determine the composition and structure of vegetation in its potency as a parameter of hydrology and soil erosion. This study used a combination method between the pathway and the way the line is laid out on a sample unit which is a 200 m wide line and 20 m wide lane on each right of the river. In that path, the pots are made continuously. The results showed that vegetation composition in upstream sub region of Miu River Basin was higher than the middle and downstream areas of 19-44 species, 13-22 tribes and individual / ha 112-693 (upstream) respectively. 11-20 species, 8-13 tribes and individuals / ha 83-192 (center), 8-15 species, 6-12 tribes and individuals / ha 60-73 (downstream). The potency of vegetation as a hydrological parameter and soil erosion in Miu Sub-District is very high, which is dominated by Ficus spp. (Moraceae) with stratification of 4 levels, namely B, C, D, and E.Keywords: Composition; vegetation; watershedBesarnya intersepsi hujan oleh tajuk sangat ditentukan oleh komposisi dan stratifikasi vegetasi. Energi kinetik dari tetesan air hujan berubah karena peran bagian-bagian vegetasi yang menghambat laju air hujan. Penelitian ini bertujuan untuk mengetahui komposisi dan struktur vegetasi dalam potensinya sebagai parameter hidrologi dan erosi tanah.Penelitian ini menggunakan metode kombinasi antara cara jalur dan cara garis berpetak pada unit contoh yang berbentuk jalur sepanjang 200 m dan lebar jalur 20 m pada masing-masing kiri kanan sungai, pada jalur tersebut dibuat plot-plot berpetak secara kontinu. Hasil penelitian menunjukan komposisi jenis vegetasi pada wilayah hulu Sub DAS Miu lebih tinggi dibandingkan dengan wilayah tengah dan hilir masing-masing sebesar 19-44 jenis, 13-22 suku dan individu/ha 112-693 (hulu). 11-20 jenis, 8-13 suku dan individu/ha 83-192 (tengah). 8-15 jenis, 6-12 suku dan individu/ha 60-73 (hilir). Potensi vegetasi sebagai parameter hidrologi dan erosi tanah di Sub DAS Miu sangat tinggi yang didominasi jenis Ficus spp. (Moraceae), dengan stratifikasi 4 tingkatan yaitu B, C , D, dan E.Kata Kunci: Komposisi, vegetasi, daerah aliran sungai

Woody encroachment and its consequences on hydrological processes in the savannah

Woody encroachment due to changes in climate or in the disturbance regimes (fire and herbivory) has been observed throughout the savannah biome over the last century with ecological, hydrological and socioeconomic consequences. We assessed changes in tree density and basal area and estimated changes in rain interception by the canopies across a 5-year period over a biomass gradient in Cerrado vegetation protected from fire. We modelled throughfall, stemflow and net rainfall on the basis of tree basal area (TBA). Tree density increased by an average annual rate of 6.7%, basal area at 5.7% and rain interception by the canopies at 0.6% of the gross rainfall. Independent of the vegetation structure, we found a robust relationship of 0.9% less rainfall reaching the ground as TBA increases by 1 m 2 ha −1 . Increases in tree biomass with woody encroachment may potentially result in less water available for uptake by plants and to recharge rivers and groundwater reserves. Given that water is a seasonally scarce resource in all savannahs, woody encroachment may threaten the ecosystem services related to water resources. This article is part of the themed issue ‘Tropical grassy biomes: linking ecology, human use and conservation’.

RAIN INTERCEPTION IN A SECONDARY FRAGMENT OF ARAUCARIA FOREST WITH FAXINAL, GUARAPUAVA-PR

ABSTRACT Forest management can alter the structure of vegetation (layer), particularly in areas used for pasture, such as the Faxinal areas in the south central region of Paraná, Brazil. Therefore, the aims of the present study were as follows: a) to assess rain interception in secondary forests; b) to estimate the maximum precipitation intercepted by the forest; and c) to discuss the possible implications of throughfall for the hydrologic processes of the secondary forest (Faxinal). Nine 20-cm-diameter rain gauges (314 cm2) were used. Rain gauges were distributed randomly throughout the forest and were successively rotated after a specific number of rainfalls. A total of 66 rainfall events of different volumes were recorded. We observed that an increase in rain volume tended to homogenize the rainfall interception rate in the forest. Consecutive rainfalls did not significantly influence the interception rate in the secondary forest. However, the interception in the secondary forest (10.5%) was lower than the mean interception rate recorded in other Brazilian forests.

Study on Ecological Benefits of Street Trees in Districts of Harbin, Based on i-Tree MODEL

Based on STRATUM module of i-Tree model, total ecological benefits of street trees in Harbin is 4.5 million dollar per year, the differences between districts are very big. Ecological benefit of Nangang district Account for 22%, the highest one in the whole city, Daowai district is minimum, just 1%. Energy-saving benefit (46%) > rain interception benefits (42%) > CO2 absorption benefit (8%) > air purification benefit (4%) of street trees for the whole study area. The aesthetic benefit is greater than the other street trees ecological benefits. The highest ecological benefit per tree is yielded by Taiping district, with an average 29.81 dollar.

Fog interception by Ball moss (<i>Tillandsia recurvata</i>)

Interception losses are a major influence in the water yield of vegetated areas. For most storms, rain interception results in less water reaching the ground. However, fog interception can increase the overall water storage capacity of the vegetation and once the storage is exceeded, fog drip is a common hydrological input. Fog interception is disregarded in water budgets of semiarid regions, but for some plant communities, it could be a mechanism offsetting evaporation losses. Tillandsia recurvata is a cosmopolitan epiphyte adapted to arid habitats where fog may be an important water source. Therefore, the interception storage capacity by T. recurvata was measured in controlled conditions and applying simulated rain or fog. Juvenile, vegetative specimens were used to determine the potential upperbound storage capacities. The storage capacity was proportional to dry weight mass. Interception storage capacity (Cmin) was 0.19 and 0.56 mm for rainfall and fog respectively. The coefficients obtained in the laboratory were used together with biomass measurements for T. recurvata in a xeric scrub to calculate the depth of water intercepted by rain. T. recurvata contributed 20 % to the rain interception capacity of their shrub hosts: Acacia farnesiana and Prosopis laevigata and; also potentially intercepted 4.8 % of the annual rainfall. Nocturnal stomatic opening in T. recurvata is not only relevant for CO2 but for water vapor, as suggested by the higher weight change of specimens wetted with fog for 1 h at dark in comparison to those wetted during daylight (543 ± 77 vs. 325 ± 56 mg, p = 0.048). The storage capacity of T. recurvata leaf surfaces could increase the amount of water available for evaporation, but as this species colonise montane forests, the effect could be negative on water recharge, because potential storage capacity is very high, in the laboratory experiments it took up to 12 h at a rate of 0.26 l h−1 to reach saturation conditions when fog was applied.