2.2.1. Hydroseeding Mixture

After studying the nature of the slope, climate, and soil condition, the experiment was carried out on a steep slope within the study area. We prepared the land and divided the layout into four segments measuring 8 ft in length and 2 ft wide, creating a square-shaped plot of 32 ft on all sides—a rigid distinction made due to a slope gradient and separate subplots. The seeds were separately mixed with fertilizer and liquid seed germinator in the exact quantities and sprayed accordingly. The following samples and mixtures were applied:

G1: Rye grass (*Lolium perenne* L.). Ryegrass originated from Europe, Asia, and North Africa and is mainly cultivated and naturalized in Australia, America, and some islands in Oceania. Characterized by bunch-like growth habits, they are perennial. Perennial ryegrass is significant in forage/livestock systems. The high palatability and quick digestibility characteristics make it highly valuable for dairy and sheep foraging systems. In temperate regions, ryegrass is sometimes called forage grass. Its main features include increased yield potential, faster establishment, appropriate for reduced-tillage renovation, and application on heavy and waterlogged soils (Figure 2a).

**Figure 2.** Seed samples: (**a**) Ryegrass; (**b**) rye corn; (**c**) signal grass; (**d**) couch.

G2: Rye corn (Secale cereale) originates from Turkey. Rye corn is a species of cereal that has been commonly grown on the sandy outlays of the Mallee regions of South Australia and Victoria. A versatile species that tolerate arid conditions and grows well on sandy soil types, it performs best when grown on good fertile soils that respond well to nitrogen applications to gain the most from the shorter growing season soils (Figure 2b).

G3: Signal grass (Brachiaria decumbens/Urochioa Decumbens): It is originally from Uganda and widely grown in tropical and subtropical countries. It forms a thick, highyielding sward that reacts very well to increased nitrogen. It is also a perennial grass with a solid stoloniferous root system and extended training stems that roots down from their nodes. It is recommended for shallow slope erosion control and is predominantly grown on most road cuts in Malaysian highways. Signal grass was initially used in the wet, humid tropics, but in recent years it has been grown over much broader climatic conditions (Figure 2c).

G4: Couch Bermuda grass (Cynodon dactylon) is native to most eastern hemispheres (Afro-Eurasia and Australia). Moreover, it is perennial and has both stolon and rhizomes. The couch is used both as a cover crop and for erosion control. This grass produces good quality hay and grazing. This grass adapts mainly in areas where the annual rainfall varies between 600 mm and 1750 mm (Figure 2d). Table 3 presents the seed sample's origin, quantity, and price.

Bio Green is a concentrated, highly effective, water-soluble, granular fertilizer with the optimum ratio of nutrients. It is highly suitable for grass, greens, and leafy plants. Bio green contains three significant elements, namely Nitrogen, Phosphorus, and Potassium (NPK), which enhance the growth of plants. Nitrogen (N) aids in leaf growth, which then forms proteins and chlorophyll. Phosphorus (P) aids in root development, while Potassium (K) helps in stem and root growth and protein synthesis. Bio-green is a Malaysian formulated product that has undergone extensive research and testing to be equivalent in performance to fertilizers' NPK 15.15.15 range. It is a product of composted organic materials with micro-nutrients naturally present. It contains natural humic and amino compounds and is highly water-soluble, with nutrient leaching being significantly reduced. It also improves soil structure, and its slow-release effect lasts longer compared to other fertilizers of a similar range.


**Table 3.** The quantity, origin, and prices of the seed samples.

#### 2.2.2. Landslide Inventories and Conditioning Factors

A landslide inventory map with 202 landslide sites was obtained from an aerial photo from the UPM's Geospatial Information Science Research Centre (GISRC) database supported with field observation. Furthermore, the landslide inventory was divided into two datasets (ground truth and classified); 70% (141 points) were used as ground truth data to train the models, while 30% (61 points) were used as classified data in a confusion matrix to validate the models.

For this study, LiDAR data were analyzed by a qualitative method. The LiDAR data was captured in 2015 by Ground Data Solution Bhd using a Riegl scanner aboard an EC-120 Helicopter flown over the University Putra Malaysia at an altitude of about 600 m above the terrain surface. The acquired point cloud averages 6 points per square meter, with a 15 cm vertical accuracy on non-vegetated terrain and a 25 cm horizontal accuracy. Based on expert's opinion, literature, and significance to the study area, twelve landslide conditioning factors within and around the study area, namely the elevation, slope, aspect, curvature, hill shade, land use, distance to trees, distance to road, distance to urban, distance to lake, stream power index (SPI), terrain roughness index (TRI), and topographic wetness index (TWI). Slope, aspect, elevation, curvature, and hill shade were directly created from the digital elevation model (DEM) derived from LiDAR data using their layer toolboxes. Stream power index (SPI), topographic wetness index (TWI), and terrain roughness index (TRI) were created from spatial layers such as slope, flow direction, and flow accumulation. Shapefiles of distances to roads, lakes, trees, and build-up were digitized as land-use/landcover from the LiDAR image and produced using the Euclidean distance method in ArcGIS with 10 × 10 cell sizes.

#### 2.2.3. Effects of Climate on Vegetation

Changes in climatic conditions could reduce crop yield [84]. The increase in temperature results in enhanced evapotranspiration, decreasing water availability, and further exacerbating dry months [85]. High storms associated with heavy rainfall increase flood frequency, which negatively impacts vegetation growth. Moreover, an increase in air and the temperature of water reduces the efficiency of plants. Low rainfall and high temperature reduces soil moisture content, water availability for irrigation and impair crop growth in non-irrigated areas. We studied the climatic conditions of the study area (temperature and precipitation) before and after the test (from August to December 2020) to assess its relationship to seed germination, growth, and development. The climate data obtained from the Malaysian Meteorological Department were examined critically and implemented in the study. The study area has a constant annual temperature with a maximum between 31 and 33 ◦C, and minimums usually between 22 and 23.5 ◦C. The average annual rainfall is also about 2400 mm. Table 4 below shows the average climate condition of the study area.


**Table 4.** The annual climatic condition of the study area in 2020 (from climate data).
