The description of identified land use/land cover classes for the images are presented in Table 2 while the classified images of Sta. Rosa city are presented in Figure 7. The classified images have substantial to almost perfect agreement with referenced images according to the results of accuracy assessment which can be found in appendices 4, 5, and 6. The conversion of land use/land cover is evident by the increase of one land use/land cover and the corresponding decrease in another land use/land cover. It can be observed that in 1993, the major land use/land cover was agricultural land. In 2005, the major land use/land cover was idle/grassland (Fig. 7).
Finally, in 2017, the major land use/land cover was built-up. Built-up areas were concentrated at the northeast section of Sta. Rosa City where most of the residential areas are situated; and also at southwest section where industrial zone can be found (santarosacity.gov.ph).
Table 2: Description of the Land Use/Land Cover Classification Used in the Study
Classes Description
Built-up Composed of residential, commercial,
industrial areas, highways and roads Forest/Trees Tree patches/forests, Agroforesty Agricultural land Cultivated and tilled areas
Idle/grassland Open areas, uncultivated or unimproved areas
31 Figure 7: Land Use/Land Cover Classification of Sta. Rosa City in 1993, 2005, and 2017
The changes in area and the rates were computed from the classified images through built-in analysis software in ArcMap. Land use/land cover statistics and change detection analysis are shown in Table 3 and Table 4. There was an increase (10.85%) of built-up from 1993 to 2005 and continued to increase (44.16%) from 2005 to 2017. However, agricultural land decreased (-43.56%) from 1993 to 2005 and still continued to decrease (-49.74%) from 2005 to 2017. Since the 1960’s the agricultural lands in Sta. Rosa city were planted to sugarcane. These agricultural lands were sold to real estate developers in the 1990’s and the agricultural lands became idle lands awaiting development. Idle/grassland increased (50.29%) from 1993 to
32 2005 and decreased (-15.90%) from 2005 to 2017. The decrease in land area of idle lands during this period is attributed to the conversion of these areas into residential and industrial areas.
Meanwhile, forest and patches of trees decreased (-12.39%) from 1993 to 2005 but increased (70.04%) from 2005 to 2017. The decrease in agricultural land and forest/trees can be attributed to the on-going development of the city at the time, wherein Sta. Rosa city reached an income of 54.2 million pesos in 1993 and became a first class town (http://santarosacity.gov.ph/about-sta-rosa/historical-timeline/). In 2005, the city became the fourth largest city in Laguna next to Calamba City, San Pedro, and Biủan City. The increase in forest/trees in 2017 can be attributed to the implemented city programs and activities which promotes the reduction of idle/grassland such as tree planting, regulation of tree cutting activities, adopt-a-lot project, and urban agriculture/vegetable gardening (SEPP Santa Rosa 2013).
Table 3: Land Use/Land Cover Change Statistics of Sta. Rosa City from 1993-2017
Classes
1993 2005 2017
(Ha) (%) (Ha) (%) (Ha) (%)
Built-up 1,148.00 24.10 1,272.75 26.72 1,834.69 38.52 Forest/Trees 441.11 9.26 386.46 8.11 657.14 13.80 Agricultural Land 1,775.30 37.27 1,002.05 21.04 503.62 10.57 Idle/grassland 1,398.60 29.36 2,102.89 44.13 1,767.57 37.11
33 The Land Use/Land Cover Change Map between 1993 and 2017 is shown in Figure 8.Shadings of colors were assigned to each land use/land cover to distinguish the change that happened. Change from agricultural land to idle land can be clearly observed at the southern part of the map and according to the land use profile of Sta.
Rosa City, there is a significant idle land holdings located at the southern part of the city awaiting future development.
Table 4: Changes of Sta. Rosa City from 1993-2017 Presented in Percent
Classes 1993-2005 (%) 2005-2017
(%)
Built-up 10.85 44.16
Forests/Trees -12.39 70.04
Agricultural Land -43.56 -49.74
Idle/grassland 50.29 -15.90
34 In order to know which land use/land cover has contributed the most to built- up conversion, the rate and extent of the changes that occurred is presented at Table 5. It can be inferred that built-up dominated the city of Sta. Rosa at 16.18% and out of all the three land use/land covers (forest/trees, agricultural land, idle/grassland), agricultural land has the biggest (10%) share of conversion to built-up. Sta. Rosa City used to be a sleepy agricultural community prior to its conversion starting in the 1990s. Agricultural lands (both sugarcane and irrigated rice fields) have been continuously converted into residential, industrial and commercial areas, now the city
Figure 8: Land Use/ Land Cover Change Map of Sta. Rosa City from 1993-2017
35 is holding out only a tenth of agricultural rice field (2014-2015, SEPP). The city is also dubbed as the “bedroom area” of Metro Manila since most of the residents in high end subdivisions and residential areas work in Metro Manila during daytime and commute back to Sta. Rosa city at night.